I added some braces last year to the car and changed the front ARB. The front of the car feels great while cornering. However on uneven straight roads or hitting drain covers the back of the car feels strange... When the back wheel / wheels go over the bump it feels like the car wobbles / twitches side to side. It's quite annoying.. It gets worse especially when you need new tires on the back!

I had a bit of a moment a few weeks back I hit a large patch of water on the M3 motorway... the car aquaplaned really badly and the side to side sensation from the back-end made it a pant filling moment! I later found out I was down to the wear indicators on the back tyres. The fronts were fine so the rear of the car was aquaplaning on it's own! Obviously some new tires will reduce aquaplaning however I want to get rid of this side to side sensation. Would changing the rear anti roll bar to match the front sort this?

Braces installed;
Strut Brace
Lower Front Brace
Rear Lower Brace
Front anti Roll Bar.

 

Well, I'll be the first to ask........ have you had the geo checked?

Mine did that a lot, but a session at WIM made a big difference.

 

Put your OEM front roll bar back on and post the results

 

I would also add that changing the front ARB without changing the rear to match/compensate could have quite an impact on the balance of the car; however, given the situation you describe (i.e. the suspension not under cornering load) then I suspect that something else (geo) might be causing this...

 

Rear castor angles uneven or wrong, get the geo checked.

 

Rear doesn't have castor, or did you mean camber?

 

When I had just the front ARB you'd feel the rear rolling more than the front, which was odd, and would make me feel a little bit seasick. Better to have both matching IMO, though of course that'll give you more oversteer.

Oh, and have you had the geo checked?

 

I always start to get that sensation when the tyres are below 3-4mm, and at one point it was exacerbated by geo that was on its way out. Change the tyres, then see if it's gone. If not, get the geo done before swapping any parts. In fact, if you've never had the geo done, get it done anyway!

 

Put a rear ARB on to match the front would help no end! You have upset the balance of the car by stiffening the front.

 

That's a fair point. I've got a front tower strut, but nothing at the back. What is the equivalent for the rear?