Upgraded axles

[Mpopaj]

Hello
As the title states I need upgraded axles. What are my options? I had a 4.1 lsd and broke the stock BMW left axle. I replaced it with an autozone one and broke it again a week later (likely due to my poor installation. I replaced it with another autozone one and it was fine for about a month. But I recently welded a 3.73 and installed it and the same axle is on its way out. The right one is the one stock original one and has never given me any problems. But I will definitely need an upgrade. Is there any BMW with a stronger axle the can be retrofitted like a Z3m? Or any suggestions for a company that makes upgraded axles
Thank you in advance

[scenturion]

If you contact Driveshaft Shop, I believe they will make you custom z3-spec axles. Bimmerworld lists their E36 axles as "1000hp"

[z3forlife]

M axles are shorter than standard Z. Where are they breaking?

[Mpopaj]

They are breaking in somewhat different spots but are relatively close to the diff. Usually they just snap and leave me on the side of the road but this one was making a cracking noise when I accelerated hard. I obviously stopped doing that. What can be causing it to keep breaking on the left side. Could it be bad wheel bearings or something like that?

[mchart]

They are breaking in somewhat different spots but are relatively close to the diff. Usually they just snap and leave me on the side of the road but this one was making a cracking noise when I accelerated hard. I obviously stopped doing that. What can be causing it to keep breaking on the left side. Could it be bad wheel bearings or something like that?

I know on drag cars you typically make the left shaft larger. Something about the rotational forces, and also introduces some harmonic balance.

[BimmerBreaker]

Autozone parts are junk

And using a car with a welded diff on the street will prematurely wear the axles. Also its frankly not very safe

[z3forlife]

Autozone parts are junk

And using a car with a welded diff on the street will prematurely wear the axles. Also its frankly not very safe

I had a 64 chevelle super sport years ago that had the spiders welded by the PO. One hard acceleration followed by quick slow down blew up the diff when I turned the next corner. Diff has to have some slip.

[Mpopaj]

Ok. Autozone axles are junk. But my stock bmw axle broke when I had an lsd in the car. I literally just installed the welded diff a week ago and the axle hasn’t broke yet. It’s just on its way out. There’s plenty of people daily driving on a welded diff for years.

[BimmerBreaker]

Yeah until the diff blows it's hurting the axles and the tires

Very silly to weld a diff on a street car. Most stock Z3 diffs can handle most anything you want to throw at them including going sideways which I just assume is what OP is after

- - - Updated - - -

If the car is lowered substantially it may benefit from axle spacers, but still, I don't think a welded diff on a street car is a good idea. It will continue to prematurely stress components

Just because a lot of people do or claim to do something doesn't mean it's a good idea

[Mpopaj]

But once again I have yet to completely snap an axle with the welded diff. I was running into more problems with the axles before. This thread is starting to go off topic

[mchart]

Well, you already have your answer. You're going to have to reach out and likely get a custom one made. No one really makes the Z3/M into drag cars. Again, the left will tend to snap due to the natural rotational forces causing the car to squat down more on that side and that side generally experiencing more torque.

[BimmerBreaker]

Well it isn't besides the point. You had problems with the axles before the welded diff and the welded diff will only make the situation worse

The real answer likely lies in figuring out why the first axle broke. It is important to fix the underlying cause instead of just beefing stuff up because it breaks. Without knowing the specifics of the car - like how low it is, how it is driven - we can't give specific answers to that question. Most people are fine with stock axles on a lot more power than you are making now so to simply jump to "stronger axles" does not seem a prudent decision to me. Plus, if you are breaking or damaging axles with such regularity, it raises the question of "if the axles don't break, what is going to break instead?". I have been launching the crap out of my V8 swapped Z3 every time I take it out, on very sticky rubber and my stock 2.3 axles are fine after at least 40 launches by now. I'm also on stock suspension with a stock type differential.

The strongest non-M axles that fit non-M Z3's are Z3 3.0 axles. Beyond that, you are looking at something custom. That answers the "what" of your question but the "why" they are breaking is really the more important question here. It is very possible you will install stronger axles and break those too it may just take longer. Or you will break something else and then you'll be asking "what is the strongest differential" next "what is the the strongest driveshaft"

[Mpopaj]

Well it isn't besides the point. You had problems with the axles before the welded diff and the welded diff will only make the situation worse

The real answer likely lies in figuring out why the first axle broke. It is important to fix the underlying cause instead of just beefing stuff up because it breaks. Without knowing the specifics of the car - like how low it is, how it is driven - we can't give specific answers to that question. Most people are fine with stock axles on a lot more power than you are making now so to simply jump to "stronger axles" does not seem a prudent decision to me. Plus, if you are breaking or damaging axles with such regularity, it raises the question of "if the axles don't break, what is going to break instead?". I have been launching the crap out of my V8 swapped Z3 every time I take it out, on very sticky rubber and my stock 2.3 axles are fine after at least 40 launches by now. I'm also on stock suspension with a stock type differential.

The strongest non-M axles that fit non-M Z3's are Z3 3.0 axles. Beyond that, you are looking at something custom. That answers the "what" of your question but the "why" they are breaking is really the more important question here. It is very possible you will install stronger axles and break those too it may just take longer. Or you will break something else and then you'll be asking "what is the strongest differential" next "what is the the strongest driveshaft"

Funny you say that because I actually just posted in another forum about the 3.0 axles. It seems like that’s what I’ll go with. And as for the why I am trying to figure out the same thing. My stock axle broke when I dumped the clutch but every axle after that was just casually driving. I’m thinking my wheel bearings can be the cause of this. I drive the car pretty hard and dump the clutch pretty often. I am not lowered yet because I scrape my bumper on my driveway on stock suspension. Any other suggestion as to what can cause this would be appreciated.

[mchart]

If your wheel bearing was that locked up, you'd have some other pretty noticeable problems.

[PbFut]

Odd. I have busted a few output flanges but never an axle. Typically the splined section of the candle stick snaps. Where is the axle breaking? I did swap out the inner CV for a larger unit but the rest of the axle is all original with hundreds of race hours using Hoosier rubber and an LS engine.

[KeysCoupe]

X2, what part of the axle are you breaking? The spline on the drive flange that’s part of the diff, the inner or outer CV joint, or the half-shaft between the CV joints? It would help to know whats actually breaking.
The only thing I’ve ever seen break is the spline on the diff flange, or a CV that was run for 10,000 miles with no boot/grease.
Provided you’re running a 188mm diff, you can swap the drive flanges that take the larger CV joints/axles used on M’s and full-size BMWs.
As mentioned, there are 750+ horsepower Z3s running stock axles at the dragstrip, without breaking them. Usually, a stock driveshaft is the first weak point to fail.
I also would never consider driving on the street on a welded diff or spool. Something's got to give when you go around a corner, and unless your spinning the tires, the car will plow straight.
-Donny

[Mpopaj]

I got some 3.0 axles because I was under the impression it’s a direct fit. I dropped them off to my mechanic and just got a call that they don’t fit. Can anyone share some more insight on this.

[BimmerBreaker]

Yes it needs the 3.0 axle stubs too