Wheel studs

[boyracer]

Hello people, I'm looking at making some extra long wheel studs for the rally car I service for. Makes it easier to get to the nuts and you can turn the end down, makes it easier to start as well. But what material to use.
Some of the grades are probably not recognised in Australia, but if you can give an approximate tensile strength as well, I can find something similar.
Thanx

[graham bahr]

i've just had a look at some i have and they have a 8.8 tensile strength, as for exactly what material they are made of im afraid i dont know

[boyracer]

Thanx for that graham, would have thought it was better sort of material (grade) more like a 10 or 12, but there u go.

[alfasud]

I've also been looking to convert from bolts to studs, to aid wheel changing. I've seen a chart of different grade fasteners and class 8.8 is something like 120,000 psi tensile strength.

Now if you do a search on google:
http://www.google.com/search?q=wheel...nsile+strength

It seems that a lot of high performance wheel studs being sold are rated as 190,000 psi tensile strength or at least 170,000 psi. Not sure if you need 190,000 psi tensile strength, but it might be worth considering better than class 8.8 if you can get them.

[boyracer]

Not so sure now. Was talking to a local machine shop who machined up a bunch of wheel studs for another racer and they used 4140 (thats what we call it over here anyway) which has a U.T.S of 750 Mpa approx. And I know that he's competed in the last couple of rallies without a wheel falling off. But I was thinking of using something more akin to an axle steel. Maybe I'm just being over cautious. Alot of rally wheels I've seen don't even fit on the original spigot so that all the shock loads are absorbed by the wheel studs, which I didn't think was a very good idea, but they seem to last.

[KC]

SAE 4140 is a good choice for tensile strength and elasticity. You can use material for axles, but it may not hold up to the stretching forces when a wheel is mounted using an air-impact gun to proper torque.

The next best material I can think of is SAE 1020, it is very strong and easier to machine than 4140. It can also be heat treated easily and will certainly stand up to the abuse.

[boyracer]

Not sure if we're talking bout the same stuff, but the 1020 that I know of is horrible to machine.
The stuff tears rather than chips and has a much lower U.T.S and hardness than 4140.
Besides machining not a big problem as I have access to fully C.N.C. machinery using carbide tips and they have assured me that machining 4140 is not a problem.
Suggested axle steel as I thought it would have some spring ? Hard but also very tough material, should take impact of rattle gun. Besides on rally we never use impact guns to do up bolts, they are nipped with the wheel spanner and torqued to spec, before the car leaves.

[KC]

I've machined tons of SAE 1020 on CNC, WEDM and conventionally with no problems. If you are having tearing problems with 1020 have your tooling supplier offer you some samples of inserts with different chipbreaker shapes on the edge. It can get critical on steels like this to have the correct tool shape to get the chip to break instead of heat up and try to bond back into the steel. 1020 has a higher heat at the point of cut than some other steels and can cause some nasty ripping at the point of the cut. The hardest part about 1020 is trying to take a light finishing cut.

SAE 1020 will not harden to the same Brinell as 4140, but it is more elastic and forgiving. I don't have the specs for axle steels at my desk, but some of those steels are better at compression loading than shear loading. They have a very hard surface and a brittle core to maintain extreme wear resistance, but can become too brittle for stretching. If you used axle grade steel, I would probably temper (draw) it back to a lower hardness than typically used for axles to keep it from becoming too brittle.

What do you manufacture?

[Stacy]

Originally posted by boyracer
Hello people, I'm looking at making some extra long wheel studs for the rally car I service for. Makes it easier to get to the nuts and you can turn the end down, makes it easier to start as well. But what material to use.

Alternatively you could try Gartrac at www.gartrac.co.uk (or .com) and order some Group A studs and inserts if necessary.

Saves re-inventing the wheel (no pun intended).

Stacy

[THR]

ya know normal cap head bolts are all rated to 12.7 cant you just weld a few on?

im fairly sure 8.8 is the normal bolt tho.

not forgetting you have 4 or 5 of um, so thats a HUGE amount of force!!

[norman-normal]

I hate to be a wet blanket, but...stick with you got.
Do you want to re-engineer the car to save a very small amount of time? Not a good enough reason! get better at changing (practice)


"Lifes greatest miseries are a matter of misplaced values"
B. Franklin.

[Stacy]

Originally posted by THR
ya know normal cap head bolts are all rated to 12.7 cant you just weld a few on?

I had a car where that had been done by someone, need to be careful that the metals are compatible - In this case the bolts were high tensile, and the hub was iron. Difficult job welding that up, and it failed leaving me with a wheel disappearing down the road.

Fortunately it happened on a 30mph corner, not a 100mph corner but the point still stuck with me.

Now everything is Gartrac off the shelf.

Stacy

[boyracer]

I thank everyone who replied, sorry I didn't respond sooner but I recently chnaged jobs (bye bye CNC machinery), But I do appreciate all the replies.
However one did get to me a bit, and that was 'Why re-invent the wheel'
I pose the question 'WHY NOT?'
Nothing is so good that it can not be messed with to produce a better product, and while reasons of economics would say that tis better to buy off the shelf tis not necessarily the best way to go.

[Stacy]

Originally posted by boyracer
However one did get to me a bit, and that was 'Why re-invent the wheel'
I pose the question 'WHY NOT?'
Nothing is so good that it can not be messed with

If you're confident of creating a better product then fine, the problem of course is that do you have the engineering know how and financial where with all to produce that product, and know you've done it.

In addition, the studs mentioned are proven in the field very thoroughly so it begs the question, what advantage is there to have in not running them.

Stacy

[MA2]

4130 is a good alloy to use, but it doesn't have as high an impact rating as other alloys. I'd try either 4340 or 8620 if I had the choice. Most stock car axles are made from 4340 as it has good characteristics in torsion. 8620 is a bit cheaper, machines a little bit easier, is easy to get, and has a much higher impact strength rating ( I think the Brit equivalent is EN36) - most carburised gears are made from 8620 (the super-duper ones are made with 9310 DVM). I wouldn't give any thought to 1020 for this purpose.

As to heattreating, for the 4340 & 8620, I'd go to about RC38-42 (353-390 Brinell), which put them in the 172 kpsi to 191 kpsi range - about the range as most lathe and mill tool holders, and you know how tough they are. I've made axles, drive hubs and studs for years out of both, and have never had one break.

6150 would also be an exellent choice - tough as all he!! (hammers are made with it) - but not always easy to find, and it work hardens easily, which might make threading it a bit of a chore.

If you wish to go "bullit-proof", try M3 at the same hardness. M3 is one of the alloys used for CART & F1 axles. Not cheap, but you'll never break one!

Or, you can make it easy on yourself & just buy what you need from ARP!

[boyracer]

Reply to Stacy, I'm a Mechanical Engineer (so I have know how) I'm not paying for them (that's the financial sorted).
To everyone, has now be proven in the field that 4140 is a perfectable acceptable material to use.
Re: why not from ARP, because I have a set of Prodrive originals that I'm going to copy from.
Once again thanx 4 all your help

[avsfan733]

Ummm...as a point, from reading about some WRC cars, its more about failure control then all out strength sometimes. If you were to design it so that the wheels studs would fail before the suspension or hub you might be more apt to have a repairable failure, as opposed to rippin the hub straight off the car. Maybe just have them carry the tools to replace the hubs on a transit and an extra set of studs or two its not much weight.

Is that reasonable or am I way off?