Stronger driveshafts?

Sun Mar 15, 2015 3:01 pm

M3SAM wrote:Hi there Tom,

After just snapping another reconditioned half shaft last night!!!!

I would be very very interested in a complete solution as my car with a s54 supercharged putting down 550 WHP loves to snap driveshafts!
There are a few considerations to take into account before completing a design or solution.

1. The output flanges on the medium case 188 diffs are a known weak point. They should be changed to either large case E28/E34 or Z3m types but ideally they should also be made from chromoly 4340 or 300M. This will ensure that they have some spring/flex in them.

2. The half shafts should either be changed to chromoly 4340 or 300M rods whilst rifled tube is stronger and lighter but will probably cost a lot more to manufacture. This will ensure that they have some spring/flex in them too that also matches the output flanges spring/flex.

3. The CVs are again prone to shattering too the GKN 108 mm CV joints are a really strong cheap serviceable alternative. However you can use these on the inner sides (diff flanges) without any problems what so ever there are clearance issues on the outer sides (hub side).
This is why people manufacture axle hub stub extensions to bring the outer CV away from the rear hub face. Again these are made from either 4340 or 300M this ensures the load is also spread evenly being that no part is stiffer than the other.

4. The hubs are again a consideration that needs to give some serious thought because they will also be from a inferior metal and can literally detach all the splined surface area from the hub given enough torque and tyre grip.

Maybe we should consider having CVs made with a thicker design rather than a larger diameter on the outer this will ensure adequate clearance around the CV as most serious cars needing uprated shafts will be running rear coil overs.

I am currently looking at lots of possibilities to try and find a comprehensive solution that will never fail below 1000nm but it is all pretty long winded and costly if you have any suggestions please let us know! I am sick of buying reconditioned crap from GSF or ECP but as GKN don't manufacture new e30 CVs anymore there are not many options. Even the ones from the dealers are remanufactured rubbish too........

PM me if you would like to discuss it further.

Sam

Sam I don't want to shit on Tom's solution but have you considered DSS shafts if you are needing a solution quickly?

Mon Mar 16, 2015 12:59 pm

I have 90% of the measurements required for this if you need.

I also have some hubs/strut mock ups to hand and some practical experience of doing this.

For what it's worth, a custom bearing inner could be made for the E36/46 hubs and used to adapt them to the shaft size of the E30.
The problem is also in the offset, attaching the hub nut and then the brakes.

See here:
http://www.e30zone.net/modules.php?name ... light=stud

The upshot of that is that the hubs would need to be completely custom with the flange about 15mm further out than the stock hub. Even then spacers would be needed to get a perfect et40.
Doing it the way above is not ideal as the front and rear offset is about 15 different.

If you use an E36 hub you end up with ET20 and a disc that does not fit hence the spacer.

No magic bullet for the 5 stud problem.

Mon Mar 16, 2015 1:06 pm

HairyScreech wrote:
No magic bullet for the 5 stud problem.

There is, but E30 M3 parts aren't cheap!

Mon Mar 16, 2015 5:05 pm

jmc330i wrote:
HairyScreech wrote:
No magic bullet for the 5 stud problem.
There is, but E30 M3 parts aren't cheap!

Aye there is that, but at best it has 1500-2000 down sides and that's before you rebuild it.

£250 for a wheel bearing anyone?

Mon Mar 16, 2015 6:19 pm

HairyScreech wrote:
jmc330i wrote:
HairyScreech wrote:
No magic bullet for the 5 stud problem.
There is, but E30 M3 parts aren't cheap!
Aye there is that, but at best it has 1500-2000 down sides and that's before you rebuild it.

£250 for a wheel bearing anyone?

Tell me about it

And there's no way I was paying £250 for a bearing... mine were £50-£60 a side

Wed Mar 18, 2015 5:11 pm

Just use e28 bearings £80 a pair and swap the abs rings over?

Fri Feb 05, 2016 2:31 pm

Hello,

Has there been any progress on this?

I would be interested in the hubs and depending on price may also be in the market for a set of bolt on driveshafts and cv joints.