318ti with S54 diff axle problems
 

Hi people,

Im looking for an upgrade to my axles and possibly rear arms etc. I'm currently running an S54 in my 318ti making 280 rwhp (what torque I have.... I'm not sure). there is more power to come out of out of it and I'm also looking at a supercharger system for the future so want a set up that can handle up to 400 rwhp.

I have two question areas, if you have any of the answers I would love to hear from you.

1: I currently have a medium case 6 bolt 3.91 diff and E30 325i axles (same as E30 M3). What power/torque can these handle before they give problems? Is the 8 bolt 210mm diff an over kill? Has any one put one of these in a ti? What diff did the E36 Z3M use?



2: Since my engine upgrade from 180 to 280 rwhp I have not surprisingly broken the stub shaft off the outer CV. I see there are lots of options of using custom axles like here:
https://www.pureperformancemotorspor...ft-axle-s.html

The only problem i see is the area where it broke wont have changed.

I know little of the Z3M upgrade, Does this give you you a larger axle? I believe the off set in the arm is larger. I use a 20mm spacer on the rear so this shouldn't be a problem other than it being very expensive option.



The car is only raced on tarmac roads and I can be pretty rough on my drive line. I'm looking for something strong and reliable.

Thank you in advance

Steve

I have so rear MZ3 trailing arms and shafts that I may put up for sale.

Lino
Texas

Have you looked into the rear end of the z3m coupe that has the s54 stock? I would imagine that would be sufficient since it should be a similar rear end as the 318ti since it's based off the z3 design still

Sent from my SM-N900V using Tapatalk

How do these differ from the E30 325 trailing arms and axles? I see thay have a bar welded across the arm but are they stronger around the hub? and any difference to the axle?

Let me know how much you want for them.

M GmbH: Thank you for that. Parts over in the US are much more available than here in New Zealand.

Marv17:

I think this would be ideal but I cant find much info on the web. Most web sites I go to people know what there talking about but I haven't found an explanation on what the Z3M differences are. I'm quite big on keeping things OE if I can.


Thanks for all you input so far

This one's going in my racecar. LSD, rear rotor are substantially bigger, louvered rear diff cover, larger sway bar. I'm going to run M3 brakes front and rear. I purchased a brake booster and master cylinder from a M roadster to go along with this set up.
http://i759.photobucket.com/albums/x...1EC9DC4CB9.jpg[/URL]

The Z3 based M Coupes and M Roadsters all came with 188mm LSDs. The axles on the Z3 based M cars is thicker than the stock ti and E30 325 axle.

At the bearing, the Z3 M trailing arm is reinforced. You are also correct that the M Z3 axles are offset further in so you will need to add at least 20mm to the spacer you're already using to maintain current wheel position.

That said, I don't think ti arms, E30 axles and a 188mm diff would have any trouble handling 400whp. You can take the arms off and have them reinforced to mimic the reinforcements on the M Z3 arms if you wanted to.

I'm not a fan of the finned diff covers on track cars. They hang too low for my comfort. A real diff cooler is a much better option.

Sweet...Spacers and you got a solid driveline :biggrin:

I forgot about the spacers. We are going to make some Forgelines for the Ti. Hopefully we can still do a Square set up. Was thinking about 17x8.5.
JohnBoy I need to talk to you about a motor.

You looking for an s54 ?

Lino

Thanks for the reply's people.
I agree on the diff cover, I need all the space underneath I can get.

So the Z3M arms are a skinnier track width? I thought they were 20mm wider... If its 20mm skinnier that the standard 318ti this Z3M option wont work. I already run 20mm spacers and cant legally go any thicker than that and I wouldn't really want to either!

How are they stronger at the bearing end? I see the extra bar welded between the two trailing arms. Not saying BMW dont know what there doing but I don't really see the point in adding a bar there? I would think the weak point would be between the shock mount (esp as I've put coil overs in), wheel bearing and where the wheel bearing joins and where the two arms join to one.

Thanks interesting that the Z3M used a 188mm diff, it makes me feel the diff I have may be OK. Will be interesting when it comes apart for an inspection early 2016. Maybe all I need is bigger axles as I've already broken one. Will try and get a photo of it so you can see where it broke.

Thank you guys!

Steve

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