Wheel hop
 

If I turn traction control off and accelerate hard in 1st or 2nd gear, the rear wheels spin up as expected but there's a lot of juddering and banging and the gear stick shakes around pretty violently. Apparently this is known as wheel hop or axle tramp. It doesn't do it when drifting, only when trying to accelerate in pretty much a straight line and the wheels are losing grip. Call me immature but sometimes I actually want the wheels to spin up when setting off in a straight line, so this banging and skipping is proving to be quite a pain.

Unfortunately I can't say exactly when this started, but I'm pretty sure it didn't do it when the car was completely stock... but that could just be because there might not have been enough power to spin the wheels up enough to cause this issue (its got a stage 3 AVO turbo now).

So my current setup that's relevant to this issue is as follows:

-- KW V3 coilovers
-- Whiteline rear sub frame bush inserts
-- Primacy stock tyres

Yes I know I could probably switch to better tyres and no longer have this issue, but firstly I don't want to do that because I like sliding around on these tyres, and secondly I don't think that is really solving the problem - if I add enough power to the car so that it spins the wheels up when setting off again then the problem would probably come back.

The KW V3s are currently set pretty soft on the compression and in the middle for rebound. I'll try stiffening them up a bit but I can't really make them a huge amount stiffer as it ends up being a bit much for the bumpy country roads near me, and also I remember still having this issue on track coming out of tight 2nd gear corners when the suspension was set almost as hard as it will go.

I've ordered the Whiteline differential mount bushes (http://www.whiteline.com.au/product_..._number=KDT925) but according to another thread on here that didn't really help the problem much. Will install them anyway and see if it's any better but just wondered if anyone had any other suggestions.

I saw this article: http://www.mc2racing.com/tech/20061012a/ which says:

"assuming your car has reasonably rigid suspension arms, then all you need to look at are the suspension bushings! The wheel can move with respect to the chassis because the bushings flex...especially old, stock rubber bushings" and "The ultimate solution is to use rod ends or spherical bearings at every suspension joint, but that is unreasonable unless your car will never again see public roadways. Anyway, by simply upgrading your bushings, the suspension bushings will not flex as much under strong acceleration"

But I'm not sure exactly which bushing they are referring to when they just say "suspension bushings". Do they mean the bushing between the bottom of the suspension strut and the lower control arm (see image below) ? If so, that came with the KW V3s (which were brand new about a month ago) so I would assume it is stiff enough and in good condition...

Attachment 106707

Wheel hop is bad. On wet sealcoated pavement, my largely stock FR-S is prone to it and I back out of the throttle as quickly as possible. You are making a lot of power and you really should be running a larger rear tire to eliminate wheelspin in the first place. Here's a pretty decent article explaining its cause and what you can do to mitigate it:

http://www.mc2racing.com/tech/20061012a/

From my understanding the wheel hop issue with our car is from the rear subframe moving around. Sure it up with some bushings and braces and it should reduce wheel hop.