Im looking into a high horsepower mk3 build and was wondering what i would need to do to the rear end (differential axles etc...)
How Strong is the rear end?
- Thread starter Beardman_13
- Start date
While drag racing with Mickey Thompson slicks, I've broke: rearend where the driveshaft bolts to the front of it, driveshaft, transmission, welded the clutch to the fly wheel twice. I've never broke an axle. All this was at 600 rwhp.
Question for suprahero: The DS you broke -- was that a 3" AL driveshaft, 3.5", chromoly, carbon fiber, stocker, or what?
It was the stock front half with an aluminum back half. It broke the welds. I was able to drive it home but it would spin if I gave it any power. As long as I babied it, I was able to creep back to the house. Luckily I only lived about seven minutes from the track.
I now have a 3" aluminum driveshaft, but the track has since closed.
I now have a 3" aluminum driveshaft, but the track has since closed.
I wore out (not broke) my ring and pinion on the dyno at 520hp after 30 pulls in 4 hours. I hadnt checked the fluid in it once and i bought the car 10 years ago with somewhere around 160K on it. It was a grenade with no pin, just waiting to let go. I have since rebuilt another stock rear and i have been giving it plenty of street time on 275/50/15 MT ET street radials with no signs of trouble yet. These rears are pretty stout unless you have a torsen. Torsens dont seem to hold up. Youll run into trouble if you are too hard on the clutch dumps on slicks on sticky tracks with lots of power. If you drive on the street and you dont have 14 inch wide tires, i think you'll be fine. You'll spin before you break the rear. I cant leave on the street with anymore then 3-4 psi on the foot brake. Anything more then that and the boost comes on too hard and it spins like crazy.
You should take a look at the weir upgrades for the mk3 diff. Not so much for durability, but for getting the lsd to work better.
How many high HP guys are still using the pinion crush sleeve? I ask because it is a topic of some debate as to whether it makes any difference.
IMO the pinion preload is the most important part of the rear end setup. If that crush sleeve is compromised in any way the preload will be compromised. If the preload is compromised not only will the bearing life be compromised but the pattern of the gear mesh would also be compromised.
I put a solid spacer in my rear because if that crush sleeve fails not only could the bearings be damaged but the ring and pinion could be damage also. IMO it's too inexpensive to not upgrade. It is a little more complicated to set up but worth, it to me.
I put a solid spacer in my rear because if that crush sleeve fails not only could the bearings be damaged but the ring and pinion could be damage also. IMO it's too inexpensive to not upgrade. It is a little more complicated to set up but worth, it to me.
Marlin's argument seems to be that the sleeve only has any effect during the setup of preload. Once the pinion nut is staked, you could cut the sleeve out and it wouldn't make any difference because the nut and bearings are setting the preload. My confusion would be that if that was the whole story then it would seem the sleeve wouldn't be needed at all.
Yes, IMO that's incorrect. If the spacer was compromised then the torque of the nut would be directly acting on the bearing rollers rather then the inner races and spacer. If the rear was set up and somehow the spacer was removed I would only suspect that the nut would loose all it's torque. Might even cause a massive increase in preload on the bearing. Even though the nut is staked, I think the slight slop would tear things apart.
I would think the torque of the nut is to hold the assembly solid together. The spacer maintains the spacing of the inner pinion bearing races. That spacing determines the preload of the bearing.
In theory with the solid spacer, the torque of the nut could change drastically with zero effect on the bearing preload (obviously barring flex of the spacer and bearing races). This is only possible with a sturdy solid spacer.
I would think the torque of the nut is to hold the assembly solid together. The spacer maintains the spacing of the inner pinion bearing races. That spacing determines the preload of the bearing.
In theory with the solid spacer, the torque of the nut could change drastically with zero effect on the bearing preload (obviously barring flex of the spacer and bearing races). This is only possible with a sturdy solid spacer.
Yes, agreed. Also, the spacer would seem to create a rigid structure that more evenly loads both front and rear bearings for non-rotational loads.
To answer the OP question I think you'd need to state your power goal. 500 whp is considered high power to some, but if you're talking about 900 whp the answer might change.
I can't offer much advise for high power, but I will say that I've run three different LSDs in three different cars from stock boost to around 12 psi on a 50-trim CT. My current LSD came out of a junkyard car with 200k. Assuming that was the original diff from that car, it now has around 240k miles total and it's great. I've been pretty astounded by the reliability of those even after years of abuse above stock power levels.
I can't offer much advise for high power, but I will say that I've run three different LSDs in three different cars from stock boost to around 12 psi on a 50-trim CT. My current LSD came out of a junkyard car with 200k. Assuming that was the original diff from that car, it now has around 240k miles total and it's great. I've been pretty astounded by the reliability of those even after years of abuse above stock power levels.
Yea, While I can't really see a scenario that would put a substantial compressive load on the crush sleeve once installed and finished, I can't see a scenario where a more rigid/sturdy spacer would hurt. It also allows you to increase the torque on the pinion nut. With the crush sleeve your torque value is determined by when bearing preload is attained.
723 whp here, and I use the stock drivetrain since it's production in 1990 MA70 turbo targa model.I just use an ACT HD clutch with a 6 pack disk.
Everything is ok and looks good. I only check and make oil changes with the best and proper brand.
But I never used slicks and never went to the track...
Everything is ok and looks good. I only check and make oil changes with the best and proper brand.
But I never used slicks and never went to the track...