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ants2au
11-29-2005, 04:47 PM
Hi,

I stumbled onto this site the usual way (not much happening at work), and boy am I glad it exists.

I am from Sydney Australia, and although I don't have a muscle car (only Italian cars), I have been getting into the rebuild scene ever since I got into shows like Rides, American Hot Rod, Biker Build off etc. So my heart is in the right place.

I have given myself some tasks to do to make the Fiat 124 that I have owned for 21 years a better car.

A couple of the tasks (besides bigger brakes etc) are rebuilding the engine sub frame and changing the rear suspension. I originally considered independent rear suspension converion, but that was put aside as it's not worth the time and expense. But I do want to change it from Panhard rod setup to body mounted center watts link setup. in both cases, I am going to be using chromoly tybing to refabricate the engine subframe and creating the watts links.

Ok the question: how do you spec out the tubing size, and does chromoly come in different metalurgy?
Do you use a finite element program to work out the geometry, or just create a triangulated setup and hope for the best?

I also wanted to change the pressed steel wishbones to chromoly wishbones as well, but I guess, one thing at a time. It's like, whilst I am in there, might as well do this.....

Sorry for the long text, hopefully, it won't be as long later.

Looking forward to more discussions. Body panels are later when I get an english wheel :)

Cheers, Anthony

alloyspec
11-29-2005, 05:26 PM
Welcome to metalmeet, Anthony.
As far as chrome moly tubing goes, most all fabrication work is done with tubing to Condition-N Specs. I believe it is the most popular way to get it these days. That is normalized conition ,to make it easy to bend and work with in general. As far as the design of individual parts, unless you have access to FEA analysis you need to look at several other cars with similar weight to yours.You need to adress tubing thickness as well. I believe FEA addresses stress and loads, not geometry. You will need a cad or design software for that. Or do it the old fashioned way and use cardbord patterns or scaled-down wire mock-ups to play with the geometry. I can suggest several books to you about racing suspensions, but there is a lot of free information out there (Ain't the web wonderfull !). If the car is to be used on the street you will want to overbuild everything to keep from injuring anyone besides yourself (in the event of breakage) and because of potholes and such. Designs are driven by application needs and although you told us the type of car, you really didn't mention how you plan on using the car(road racing, street, autocross?). Let us know how your project goes from time to time.
Alan

ants2au
11-29-2005, 05:51 PM
Thanks Alan for the reply.

Just to answer some questions, the car will be a street car.
There will be no geometry changes to the front suspension, as it works pretty well. I only wanted to change the materials it's made of to make it lighter.

The rear changes (since the car runs solid axle) will make the roll center constant. I can work out the mounting points for that no problems.

The engine subframe is currently made of press welded steel. It's a bit bulky, hence my thoughts on reconstructing it out of tube. I will use it as a template for mounting points for suspension and engine mounts. I guess the question is how do I work out the load, so I can spec the tubing material (N spec as you stated) and tube thickness, coupled with how the tubes are layed out. Maybe two parallel tubes with triangulated tubes between them. This would allow a lower profile subframe, and may allow the engine to drop a cm or two. Coupled with changing the sub frame is to change the steering rack from a worm and roller to a rack and pinion (which I already have). This will allow me to design the mounting points for the rack with a bit more freedom.

If you have seen the Rides show where they built Sic Fish from a Cuda, they replaced the engine subframe with a tube design. I may use that as a starting point on how the frame will look. Then it's just a matter of tube thickness and size. That I am unsure of how to work out.

Sorry one other thing, CAD I thought was just a drawing package, it will not determine how a design will react to a twisting moment or force points, which are needed to be known to make the design. I might just do as you have suggested, look at a similar weighted machine, and copy the tube specs from that. The Cuda is twice as heavy as a Fiat 124 :)






Welcome to metalmeet, Anthony.
As far as chrome moly tubing goes, most all fabrication work is done with tubing to Condition-N Specs. I believe it is the most popular way to get it these days. That is normalized conition ,to make it easy to bend and work with in general. As far as the design of individual parts, unless you have access to FEA analysis you need to look at several other cars with similar weight to yours.You need to adress tubing thickness as well. I believe FEA addresses stress and loads, not geometry. You will need a cad or design software for that. Or do it the old fashioned way and use cardbord patterns or scaled-down wire mock-ups to play with the geometry. I can suggest several books to you about racing suspensions, but there is a lot of free information out there (Ain't the web wonderfull !). If the car is to be used on the street you will want to overbuild everything to keep from injuring anyone besides yourself (in the event of breakage) and because of potholes and such. Designs are driven by application needs and although you told us the type of car, you really didn't mention how you plan on using the car(road racing, street, autocross?). Let us know how your project goes from time to time.
Alan

alloyspec
11-30-2005, 05:26 PM
Anthony,
For a street car you may want to cosider DOM mild steel tubing for the subframe. Several bike-builders prefer it over chrome-moly because by using thicker tubes, it is more resistant to cracking in highly stressed areas. Then the design of the parts is a little less critical. It may be easier for you to get the tubing also. Just something to think about. I believe you will find several arguments for/ against chrome-moly in the bike section of Metalmeet. It is easier and cheaper for me to find small quantities of chrome-moly locally than DOM.
Alan

seasalt
12-01-2005, 04:09 AM
Anthony,
If you intend to register this car in New South Wales, Australia:

It would probably be classified as an Independently Constructed Vehicle, which means it would have to comply with all current ADR's for engine, chassis/monocoque, and body, at the time of inspection, not in the year of original manufacture. It would be viewed as if it were a brand new vehicle for registration.

The fact that you are modifying sub-frames and suspension components may well put the vehicle in that category.......

Before you do this you have to discuss it with an RTA (Roads & Traffic Authority) approved engineer, who will tell you what tube sizes etc you would have to use, for him to sign for it, for you to get your car legally registered.

These laws considerably limit what you can do to a car, and still be able to register it. Check it all out before you go too far.

The engineer I saw said he would waive the $50.00 appointment fee if I was building it within 12 months.....in which case he charges by the number of signatures you end up needing.

From a cost point of view it is good to try to remain within the "Modified Vehicle" category if u can.

NSW Guidelines:
http://members.optusnet.com.au/~saltheart/Resources/vsi06.pdf

(Hey, I allways loved the earlier 124 coupes for their style, before the engine was enlarged and the body was hit in the grille with the ugly stick....)

dude
12-01-2005, 05:10 AM
Anthony,
Hi and welcome to another sydney sider...YEEEEAAAHHHHH, you'll find heaps of knowledge on this site and its one of the friendliest forums around too.


Seasalt, if he uses factory suspension arms etc but fabricates the subframe (or engine crossmember) it won't be an icv, its only when you modify large sections of chassis that you are thrown into this, and with the new national code being introduced its actually easier to modify without going near icv rules.. with the new rules you may even be able to register the car you are designing with no icv

kerrystagmer
12-01-2005, 06:25 AM
cant you just register it FIRST?

ants2au
12-01-2005, 02:31 PM
Just to set everyones' mind at ease, the car is on Historic plates. Probably will never see a green slip again (that's road worthy inspection).

Thing is, even if I do these mods, the local service station who provides road worthiness will never know the difference. To them, a sports car is a sports car. That's what it's supposed to look like underneath.

But I don't want to do this half heartedly, so I will get some help from an engineer at least with tube sizing. I want to at least feel safe in it when I am driving it.


cant you just register it FIRST?

doug_walter2002
12-01-2005, 05:27 PM
My vote would be for DOM tubing.

Boogiemanz1
12-01-2005, 07:33 PM
Mine too.............john

seasalt
12-02-2005, 04:41 AM
Ants2au, Dude, it was modified subframe had me goin'.

My own project fits into "modified vehicle" in which you can't change chassis length or width at all, only have to keep one original crossmember, but have to have same number of crossmembers as original. That's if you've got a chassis. Wasn't sure about monocoques. It would be such a pain to build something u couldn't register..when checking with an engineer could clarify. Happily unnecessary then.

The historic plates sound good. Do they limit u to shakedowns and events? Different to hot rod rego?

[Cars in NSW have a roadworthiness inspection every rego, (in response to "can't you just register it first" suggestion), and if it falls out of registration for more than 3 months, the vehicle is required to undergo a more stringent examination to acquire a "blue slip" before it can be re-registered. If you have an accident, and your vehicle is found to be "illegally modified", I think that voids insurance......NSW has possibly the most stringent rego laws in Australia. Some inspection stations are slacker than others, its true. Ultimately it is up to the individual whether they comply, and with which type of rego too.. Some other states only require safety inspections on sale. Victoria seems to be the Hot Rod state. There's a NSW club hot rod rego for pre 1948 chassis (or approved chassis replica) vehicles, allowing limited use i.e. shake down runs and event attendance, i think.]

True, most mechanics these days wouldn't know what a 124 was supposed to look like. Fair enough. Leave it at that. (Please remember to show us some pics if u do it.)

ants2au
12-03-2005, 03:46 AM
Alan,
Historic plates limit you to shakedowns and club events. luckily, the club plate registrar (SP?) lives out in the sticks. If I need to go somewhere in the car, he said just say you are coming to visit me. Sounds good to me :)

I promise photos. I will start with the original subframe anyway, just so you know what I am working with.

As for DOM steel tubing, this might end up defeating the purpose of making it lighter than the original cast weld subframe. Will look into seing if it will indeed work out lighter in weight.

I love this site :)

Anthony

Ants2au, Dude, it was modified subframe had me goin'.

<STUFF DELETED>

The historic plates sound good. Do they limit u to shakedowns and events? Different to hot rod rego?

<MORE STUFF DELETED>

True, most mechanics these days wouldn't know what a 124 was supposed to look like. Fair enough. Leave it at that. (Please remember to show us some pics if u do it.)

autocol
12-29-2005, 07:01 AM
hi anthony.

i work with tubular 4130 chromoly all the time (i make racing karts), and i USED to own a 1969 Fiat 124 Sport (AC)... for a '69 model car, it really was an awesome bit of kit. owned from brand new by my grandfather, he gave it to me when i turned 18.

funny thing was, dad's name was anthony too, so whenever it broke down i'd walk inside and yell:

F-ix
I-t
A-gain
T-ony!!!

'course, he made me fix it myself, but "fix it again col" isn't anywhere near as funny!

unfortunately i sold the car to a friend (who is a euro-car-nut and really looks after it) about 5 years ago, so i can't have a look at the body to see what you're up against, but i'll throw in my two bobs worth.

firstly, when welding a subframe into a monocoque car, you must carefully consider WHAT you're going to weld to what. reason being - monocoque's are only strong OVERALL, in local areas thin sheetmetal is WEAK! a lot of guys make the mistake of thinking "the thicker the material i weld in here, the better". the truth is, if one section of the car (the bit you fabricate) is really strong, and is welded to the monocoque, you'll crack the welds a year or so into your travels, with potentially fearsome results!

i'm very good friends with an automotive engineer, and he said a LOT of D.I.Y. carbuilders make the mistake of thinking that more is better... i read somewhere in some documentation he sent me, that you should never use material of wall thickness greater than 1.5 times the thickness of the material you're welding TO, because otherwise it will just break it over time.

chromoly is great material, but poorly used in many applications. it's used in race karts because they undergo SEVERE stress, vibration and fatigue, and chromoly has a very high yield strength, and excellent response to heat-treatment. in a car, you really don't need chromoly, because the stress it's under* is much less than in most engineering applications where it's selected (karting is one, the wings of an aeroplane is another). you're also clearly not going to heat-treat the entire car either, so i really don't see the point in paying over 50 bucks a metre for material from British International when you won't see any great gains. DOM is my suggestion.

*yes, a car is a lot heavier than a kart, and creates more load, but the STRESS in any piece of material is the load divided by cross-sectional area. karts and the wings of planes are necessarily sparsely built, loading each individual member heavily. cars need not be.

another problem you may find using tubing is that it's VERY difficult to measure to! i have a fully CNC controlled bender, and a tube that is less than half a degree out in one bend will not go NEAR fitting in a kart jig. it must be VERY precise! i build trailers too, and they are an absolute breeze in comparison. even where there's all sorts of angles at play, at least RHS has nice flat, square edges to measure to! (oh yeah, and it's CHEAP!). actually, mentioning the bender raises the point that, due to it's incredibly high yield strength (95 KSI (tonne's per square inch) off the mill, up to 270KSI), chromoly in the sizes you'd be talking is a BUGGER to bend if you don't have SERIOUS equipment!!

i can't think of anything else right now, and should really be in bed. sorry for writing a novel, hopefully some of it is of use to you.

cheers,

col.

ants2au
01-02-2006, 04:32 PM
Hiya Col.

I have owned my 124 since I was 18. Mine is a BC.
The engine crossmember is bolted to the chassis on these cars.

I wanted to replace the crossmember with something lighter than the cast piece that is there. If DOM fulfils this task, I am happy to use it.
Maybe I should use square section.

It's been the holidays, and I am goig to get off my back side, and take some photos of the existing piece.

Thanks for your thoughts on this subject. Everything helps :)



hi anthony.

i work with tubular 4130 chromoly all the time (i make racing karts), and i USED to own a 1969 Fiat 124 Sport (AC)... for a '69 model car, it really was an awesome bit of kit. owned from brand new by my grandfather, he gave it to me when i turned 18.

funny thing was, dad's name was anthony too, so whenever it broke down i'd walk inside and yell:

F-ix
I-t
A-gain
T-ony!!!

'course, he made me fix it myself, but "fix it again col" isn't anywhere near as funny!

unfortunately i sold the car to a friend (who is a euro-car-nut and really looks after it) about 5 years ago, so i can't have a look at the body to see what you're up against, but i'll throw in my two bobs worth.

firstly, when welding a subframe into a monocoque car, you must carefully consider WHAT you're going to weld to what. reason being - monocoque's are only strong OVERALL, in local areas thin sheetmetal is WEAK! a lot of guys make the mistake of thinking "the thicker the material i weld in here, the better". the truth is, if one section of the car (the bit you fabricate) is really strong, and is welded to the monocoque, you'll crack the welds a year or so into your travels, with potentially fearsome results!

i'm very good friends with an automotive engineer, and he said a LOT of D.I.Y. carbuilders make the mistake of thinking that more is better... i read somewhere in some documentation he sent me, that you should never use material of wall thickness greater than 1.5 times the thickness of the material you're welding TO, because otherwise it will just break it over time.

chromoly is great material, but poorly used in many applications. it's used in race karts because they undergo SEVERE stress, vibration and fatigue, and chromoly has a very high yield strength, and excellent response to heat-treatment. in a car, you really don't need chromoly, because the stress it's under* is much less than in most engineering applications where it's selected (karting is one, the wings of an aeroplane is another). you're also clearly not going to heat-treat the entire car either, so i really don't see the point in paying over 50 bucks a metre for material from British International when you won't see any great gains. DOM is my suggestion.

*yes, a car is a lot heavier than a kart, and creates more load, but the STRESS in any piece of material is the load divided by cross-sectional area. karts and the wings of planes are necessarily sparsely built, loading each individual member heavily. cars need not be.

another problem you may find using tubing is that it's VERY difficult to measure to! i have a fully CNC controlled bender, and a tube that is less than half a degree out in one bend will not go NEAR fitting in a kart jig. it must be VERY precise! i build trailers too, and they are an absolute breeze in comparison. even where there's all sorts of angles at play, at least RHS has nice flat, square edges to measure to! (oh yeah, and it's CHEAP!). actually, mentioning the bender raises the point that, due to it's incredibly high yield strength (95 KSI (tonne's per square inch) off the mill, up to 270KSI), chromoly in the sizes you'd be talking is a BUGGER to bend if you don't have SERIOUS equipment!!

i can't think of anything else right now, and should really be in bed. sorry for writing a novel, hopefully some of it is of use to you.

cheers,

col.

ants2au
01-21-2006, 04:43 AM
How are control arms fabricated with the theaded ends? does anyone have a step by step suggestion?
I thought originally they just welded a nut on the end of the tube, but apon closer inspection, the weld is too clean and doesn't seem to touch the nut on the end. Also I have seen tapered ends on the tubing that meets the nut on the end. How is that acheived?


Also whilst I am at it, any suggestions as to where to buy steel tubing or chromoly her in Sydney Australia (for you local residents).

thanks

dude
01-21-2006, 05:38 AM
Hey Ants!

The best place to get moly and all the little bits you need to do the job you are talking about is Andrews race cars,at Seven hills, speak to ROD, he's a top guy, very helpful, and great prices, otherwise there is British international trading, but they are expensive.

check out the link... www.andrewsracecars.com.au (http://www.andrewsracecars.com.au)


...jason

Peter Miles
01-21-2006, 11:56 AM
You are right, normally you don't just weld a nut to the end of the tubing. From the same source as the previous message, see:
http://www.andrewsracecars.com.au/m5.htm
for examples of weld-in tubing adapters. These are available from a number of sources.

Check the websites of companies that build or sell custom chassis and suspension components.

http://www.andrewsracecars.com.au/image/misc/misc5large.jpg

Try http://www.chassisshop.com/ and look in their catalog at the section on Tube Adapters and Rod Ends. They go for about $6-$8 U.S. per end.

ants2au
01-21-2006, 05:56 PM
I was a bit wary going to race shops to get my materials, as they are usually just the middle men. I was hoping to get materials from wholesale places (Brookvale?).

Maybe I can get threaded ends from these places (thanks for confirming my thoughts about threaded ends). They seem cheap enough to get from the US.

When guys from some race shops (no names will be mentioned) can get huge intercoolers for $80US, someone is making a lot of money here in Australia for this stuff.

Cheers, Ants.

Hey Ants!

The best place to get moly and all the little bits you need to do the job you are talking about is Andrews race cars,at Seven hills, speak to ROD, he's a top guy, very helpful, and great prices, otherwise there is British international trading, but they are expensive.

check out the link... www.andrewsracecars.com.au (http://www.andrewsracecars.com.au)


...jason

dude
01-22-2006, 04:25 AM
Ants,
i can tell you now that rod imports his own moly tube. He is first and foremost a chassis builder, he was sick of paying high prices and started importing it himself. I now buy from him and he is much cheaper than B.I.T(another company i used to buy from)who are the only other importer of moly that i could ever find,(in sydney anyway) and believe me i looked around.



Give him a call, you might be surprised!



.........jason

ants2au
01-22-2006, 02:58 PM
Thanks Jason.
Well Rod can't get a better endorsement than the below.
I will give him a call.

Cheers.

Ants,
i can tell you now that rod imports his own moly tube. He is first and foremost a chassis builder, he was sick of paying high prices and started importing it himself. I now buy from him and he is much cheaper than B.I.T(another company i used to buy from)who are the only other importer of moly that i could ever find,(in sydney anyway) and believe me i looked around.



Give him a call, you might be surprised!



.........jason

Bambi
01-23-2006, 01:08 PM
Use the DOM on the suspension pieces. Use the welded tubing for the structures. Welded tubing is cheaper but the quality today is lots better than it ever was. SCCA and Nascar allow its use in a variety of racers.
As for your questin about the nut. First the tube either has a weld in insert with threads in it or the tube has been tapped, then the sperical end installed, the nut is a jamb nut. A jamb nut locks the joint in solid. Movement at that joint is an acident lookin for a place to happen. DON'T GO AROUND NUTLESS. OR DON'T DRIVE WITH OUT YOUR NUTS.
They have tubing with ID the proper size for running a tap down.
One factor that was not mentioned about your project was what you have for bending equipment and welding equipment. Many things can be built without bending, but its hard to fab something such as this without welding equipment. An arc welder its bare equipment. As for the chrome moly which I hope everyone has talked you out of would require you the have a Tig machine and lots of experience in working with moly.
In reality the weight savings can be nil and cost high.
Goin Nutz

Bambi

ants2au
01-23-2006, 03:19 PM
I will still be using DOM (was just looking to see where people source chromoly). Having said that, I went to a race shop on the weekend (in castle hill) and all custom suspension was done in chromoly (this was on a '50 something 2 door chev). Not that I am confused as to which material to use, well ok I am. I haven't bought anything yet so still planning, and looking at other peoples work at the moment.

As for welding, I will be using a TIG.
For bending, hopefully a hydraulic tube bender.

This latest discussion was for converting the rear from a panhard rod to a watts link setup. So will want to construct the rods with spherical bearing on the end. Everything I have seen done was done with chromoly. Maybe I can just spec it, and get a race shop to fabricate it. Anyway, just thinking aloud.






Use the DOM on the suspension pieces. Use the welded tubing for the structures. Welded tubing is cheaper but the quality today is lots better than it ever was. SCCA and Nascar allow its use in a variety of racers.
As for your questin about the nut. First the tube either has a weld in insert with threads in it or the tube has been tapped, then the sperical end installed, the nut is a jamb nut. A jamb nut locks the joint in solid. Movement at that joint is an acident lookin for a place to happen. DON'T GO AROUND NUTLESS. OR DON'T DRIVE WITH OUT YOUR NUTS.
They have tubing with ID the proper size for running a tap down.
One factor that was not mentioned about your project was what you have for bending equipment and welding equipment. Many things can be built without bending, but its hard to fab something such as this without welding equipment. An arc welder its bare equipment. As for the chrome moly which I hope everyone has talked you out of would require you the have a Tig machine and lots of experience in working with moly.
In reality the weight savings can be nil and cost high.
Goin Nutz

Bambi

autocol
01-24-2006, 07:14 AM
Ants,

In terms of selecting material, here's what you're faced with.

Chromoly -
Pro's:
-High yield strength
-Great response to heat treatment
-High resistance to fatigue
Con's:
-Expensive
-When not utilised correctly, (ie, poor welding or design), benefits are lost
-Expensive
-Have I mentioned expensive yet?

DOM
(which I think you'll find Aussies usually call CDS - cold-drawn seamless):
Pro's:
-Cheap
-Easy to find
-Easier to use and weld
Con's:
-Material properties not as great (yield strength and fatigue resistance)


So, what does all that mean really? Well, you can make lighter structures that are just as STRONG by using chromoly, because the yield strength is higher. That means that it can take more load per unit of cross-sectional area than mild steel.

That's all well and good, but the reality is almost certainly that you're going to over-engineer the thing by a fair bit, because you're probably not sure what the loads are going to be! As a result, you'll probably make the thing heavier than it needs to be anyway, so why pay for chromoly?!

You're almost certainly not going to heat-treat it (which can raise the yield strength even further), which is another advantage of chromoly over mild, and again, you wouldn't be seeing any benefit.

So, the only real benefit remaining is the resistance to fatigue, but I'll bet my life savings that if you do manage to break something, you'll break it where you welded it. Unless your welding is SERIOUSLY top notch (and your junctions are well designed), it's going to be the weakest point in the structure, not the base material.

All up, I really don't see the point in using chromoly.

In terms of bending, you might have some luck finding an exhaust shop to help you out, you'll just need to find out if they have the appropriate size dies for the material you want to bend. If you use DOM/CDS, you should be able to bend it by hand with a relatively sturdy hand bender, but trust me don't even bother if you decide on chromoly. I use 'moly at work all day, and you can absolutely REEF on the stuff and you just can't bend it. My entire body weight (65kg) hanging off a 2 metre extension MIGHT add a quarter of a degree to a bend, if I'm lucky. To straighten a go kart, you either need a 3-4 metre levering bar, or a porta-power.

I've got a CNC hydraulic bender, and am happy to bend something for you (when production has the appropriate dies in) if I have the right dies and mandrels. (We use 5/8", 3/4", 28mm, 30mm, and 1 3/8", so if any of those are the size you want to use you might be in luck). I have chromoly in 28, 30 and 31.8mm (1 3/8") if you'd like to use that, but the wall thickness may not be enough for you (2.1mm, or 85 thou).

Cheers.

ants2au
01-24-2006, 02:30 PM
Thanks. Nice writeup.

I will be trying to visit Rod next week (hoping he is open on Sat). Maybe he will allow me to pick his brains :)




Ants,

In terms of selecting material, here's what you're faced with.

Chromoly -
Pro's:
-High yield strength
-Great response to heat treatment
-High resistance to fatigue
Con's:
-Expensive
-When not utilised correctly, (ie, poor welding or design), benefits are lost
-Expensive
-Have I mentioned expensive yet?

DOM
(which I think you'll find Aussies usually call CDS - cold-drawn seamless):
Pro's:
-Cheap
-Easy to find
-Easier to use and weld
Con's:
-Material properties not as great (yield strength and fatigue resistance)


So, what does all that mean really? Well, you can make lighter structures that are just as STRONG by using chromoly, because the yield strength is higher. That means that it can take more load per unit of cross-sectional area than mild steel.

That's all well and good, but the reality is almost certainly that you're going to over-engineer the thing by a fair bit, because you're probably not sure what the loads are going to be! As a result, you'll probably make the thing heavier than it needs to be anyway, so why pay for chromoly?!

You're almost certainly not going to heat-treat it (which can raise the yield strength even further), which is another advantage of chromoly over mild, and again, you wouldn't be seeing any benefit.

So, the only real benefit remaining is the resistance to fatigue, but I'll bet my life savings that if you do manage to break something, you'll break it where you welded it. Unless your welding is SERIOUSLY top notch (and your junctions are well designed), it's going to be the weakest point in the structure, not the base material.

All up, I really don't see the point in using chromoly.

In terms of bending, you might have some luck finding an exhaust shop to help you out, you'll just need to find out if they have the appropriate size dies for the material you want to bend. If you use DOM/CDS, you should be able to bend it by hand with a relatively sturdy hand bender, but trust me don't even bother if you decide on chromoly. I use 'moly at work all day, and you can absolutely REEF on the stuff and you just can't bend it. My entire body weight (65kg) hanging off a 2 metre extension MIGHT add a quarter of a degree to a bend, if I'm lucky. To straighten a go kart, you either need a 3-4 metre levering bar, or a porta-power.

I've got a CNC hydraulic bender, and am happy to bend something for you (when production has the appropriate dies in) if I have the right dies and mandrels. (We use 5/8", 3/4", 28mm, 30mm, and 1 3/8", so if any of those are the size you want to use you might be in luck). I have chromoly in 28, 30 and 31.8mm (1 3/8") if you'd like to use that, but the wall thickness may not be enough for you (2.1mm, or 85 thou).

Cheers.

dude
01-24-2006, 04:07 PM
ants,

Rod is open til around 12.30 on sat usually, i might even see you down there as i'm going to pick up some more tube for a roll cage i'm doin..

.............jason

ants2au
01-25-2006, 06:01 AM
Sounds cool Jason.

I can't make it this Sat, but I will be trying next one for sure.

Anthony


ants,

Rod is open til around 12.30 on sat usually, i might even see you down there as i'm going to pick up some more tube for a roll cage i'm doin..

.............jason

ants2au
02-01-2006, 02:53 AM
Here are some photos of the rear setup. First pic is of the axle attachment, and the next is to the body.
I may have to put a cross bar, running parallel with the axle line, to mount the center body pivot of the watts link. Also, to keep the bars from the axle to the body at the same angle, one side of the axle connecting point may have to higher.

Jim Dilks
02-01-2006, 02:31 PM
There is a website-"Grannysspeedshop.com" that shows Chevy and Ford V8 conversions for Mazda RX7's. The first generation RX7s had a similar front suspension to the Fiat, except for the struts. They sell a subframe assy that accepts either engine. The pictures are very good of this item. Maybe they can help you design yours. Another consideration might be the Miata front suspension subframe units. They are about the same size cars. I had a Spyder 2000 that I loved. I was thinking of doing a 302 Ford swap in that, but the chassis wasn't quite stiff enough I thought. I replaced the Fiat with a Miata. I knew there were several conversions done with that chassis. But the car was such fun I decided not to do it. The Fiat was a great car. I loved the Pinifarina body design (like the older Ferraris). Good luck.

Jim.

Jim Dilks
02-01-2006, 02:37 PM
Anthony, I forgot to add that the rear suspension of the early RX7 was a lot like the Fiats. I think the Fiats had reliability issues if they had too much power also. The Grannys site shows a 9" Ford rear conversion for those cars too. The Fiat and RX7 rear layout/design reminds me of the Sunbeam Tigers. I think they had early problems with the panard bars breaking on hard road racing. They developed fixes for that too. I remember that the Tigers were leaf spring rears, but they still had a panard bar.

Jim.

Peter Miles
02-01-2006, 03:35 PM
Jim said: There is a website-"Grannysspeedshop.com" that shows Chevy and Ford V8 conversions for Mazda RX7's.

If you just add www. in front of Grannysspeedshop.com in the editor you get www.Grannysspeedshop.com (http://www.grannysspeedshop.com/) which automatically becomes a live, clickable link.

There's a lot of interesting stuff out on that website. I like V8 swaps.

RedSilver
02-19-2006, 09:49 PM
Ant,

Before you start fabricating look under the back of an Alfa-Romeo Spyder 1972 to about 1985 or coupe/sedan thu 1974.

I don't know the technical term, but it's an A-arm turned sideways with a ball joint on top of the diff.
The result was a very sweet handling solid axle car.

You might even rob one out of a breaker's and save a lot of trouble.

ants2au
02-20-2006, 03:47 AM
Will have to get a pic of it. I can't imagine how it's locating laterally.
I used to own a 116 and 115 Alfa (Alfa 90, and Giulietta), and they had a de dion setup. that triangle piece weighted a ton, and the back of it was anchored laterally with a watts link setup, with sides mounted to the body (opposite to what I want)


Ant,

Before you start fabricating look under the back of an Alfa-Romeo Spyder 1972 to about 1985 or coupe/sedan thu 1974.

I don't know the technical term, but it's an A-arm turned sideways with a ball joint on top of the diff.
The result was a very sweet handling solid axle car.

You might even rob one out of a breaker's and save a lot of trouble.

ants2au
06-28-2006, 08:10 PM
Hi,

I have made progress in some sense. I have finally bought my TIG welder. After looking for so long for a good deal, I finally end up with 2.
Silly really, but no one could really answer my questions as to whether an Inverter or a Transformer based TIG was better.

So I have now a Lincoln SquareWave 275 and a Kemppi Mastertig 2000.
I will be trialing both over the comming weeks, and will have to settle for one of them (not sure if the wife is that pleased I have 2, but she hasn't said anything yet).

Any recommendations for a good place (cheap place) to get an Argon bottle in Sydney?
Is there any way to get out of the renting process?

ants2au
07-21-2006, 06:36 PM
Hi,

I know in the US they sell pre-bent exhaust tubing (J, U shaped). Does anyone know if there exists in Australia, places to buy such things?

anything from 2" to 3" I suppose.

thanks, Anthony

dude
07-21-2006, 07:40 PM
Ants, if you are after steel mandrels go to Liverpool exhaust as they sell the bends there, or if you are after stainless try Fagersta stainless at wetherill park.
cheers ,,,,, jason

ants2au
07-22-2006, 04:58 AM
Great stuff. Thanks Jason.

Ants, if you are after steel mandrels go to Liverpool exhaust as they sell the bends there, or if you are after stainless try Fagersta stainless at wetherill park.
cheers ,,,,, jason

ants2au
07-22-2006, 05:02 AM
If anyone is interested, I found a really cheap place for Argon. It's around $70 to fill an E size bottle (Silverwater Welding Supplies). All other places were around $110+ (average $120).



Hi,

I have made progress in some sense. I have finally bought my TIG welder. After looking for so long for a good deal, I finally end up with 2.
Silly really, but no one could really answer my questions as to whether an Inverter or a Transformer based TIG was better.

So I have now a Lincoln SquareWave 275 and a Kemppi Mastertig 2000.
I will be trialing both over the comming weeks, and will have to settle for one of them (not sure if the wife is that pleased I have 2, but she hasn't said anything yet).

Any recommendations for a good place (cheap place) to get an Argon bottle in Sydney?
Is there any way to get out of the renting process?