Marx Mcrae

iTrader: (4)

Got a problem with the rear drive of my car...
Whenever I turn a corner at low speeds the inside wheel turns more than what it should causing the wheel to skid/skip.
I've changed both rear driveshafts and the rear diff and the problem is still there??

Anyone got any ideas of what to check next??

ZEN Performance

Sounds like you might have either an aftermaerkt diff in the rear, or a failing standard one, but without knowing what car you're driving it's hard to diagnose. The latest DCCD-A cars tend to skip wheels at low speed due to lock up on slow speed and some reasonable lock (as if you were pulling away from a junction). Does you car have a DCCD centre diff fitted? If so are you using any lock on the diff when you experience the problem?

Jack the rear of the car and see how easy it is to turn one rear wheel relative to the other. An aftermarket diff will be stiff, but allow some slip, possibly accompanied by a slight clonking noise as you do.

Paul

Marx Mcrae

iTrader: (4)

Hi Paul,
Its just a standard diff off another sti 2, non dccd.
I used to have a Type R with the dccd and it does feel like there is some lock on the diff when manouvering at low speeds.
I changed the old diff cos it was also locking/skipping at low speeds, also the old diff was whining alot.
Since fitting this diff the whining has gone but it still locks/skips.
If its not the diff is there anything else that I can check??
Cheers Marcus

ZEN Performance

I would guess that the front and rear diff ratios are not matched. Not knowing either will make it hard, but plenty of cars have had gearboxes or diffs replaced to something non standard. SO you're replacement diff maybe wrong, the old and new diff may be wrong, or it's something else. But until you actually start jacking the car up and feeling what's going on you're not going to know either way.

You can check the rear diff ratio by turning the prop until the wheel does a full revolution, but you don't know the transfer gear ratio or front ratio. You can jack the entire car up, and very slowly drive the wheels with 1st gear, slipping the clutch as necessary. DO this while you have a person at each end of the car counting wheel revolutions (put a generous mark on tyre to do this). YOu should be able to count out about 20 wheel revolutions easily enough, and whatever you get at the front should be repeated at the rear. The open front diff may cause an error (ie one wheel drags and turns less), but you can check the front on both sides and average it if this is the car.

You really need to be sure you know what you're dealling with, so checking the tightness of the diffs is a first step, then checking ratios is the next.

Marx Mcrae

iTrader: (4)

Sorry to sound thick but what do you mean by checking the tightness of the rear diff?? Do you mean is it bolted in place tight enough??

ZEN Performance

Jack the back up, with car in neutral get someone to hold one of the rear wheels, you should be able to turn the other one, or each of you turn a wheel in opposite directions. The LSD in the rear will give some resistance, if the resistance is high, or you can't move the wheels in different directions at all, then the diff is said to be "tight". When you turn the inner wheel is rotating slower due to the shorter path, if the diff is very tight, it will force it to make at the same speed as the outer wheel causing the skipping. BUt the same thing can happen if the rear wheels are forced to move at the same average speed as the front wheels (which go along a longer path again compared to the rear wheels).

I dare say a few miniutes of googling would reveal a nice diagram to explain how it works better than I can explain!

Marx Mcrae

iTrader: (4)

Ok cheers Paul I try and do that asap