rear end issues after fitting 19's???, 89GT
04-23-2011, 11:32 AM
#1
Intermediate
Thread Starter
Join Date: Aug 2002
Location: bournemouth,england
Posts: 43
Likes: 0
Received 0 Likes
on
0 Posts
rear end issues after fitting 19's???, 89GT
Hi guys, I bought some second hand carrera BBS ‘lobster forks’, they came with Michelin pilot sports with about 2.5mm left on each tyre, they look to have worn evenly. The fronts 235/35/19 with a 57 offset, the rears are 295/30/19 with 67 offset. Reading many of the posts regarding 19inch wheels I know I should have bought rears with a 67 offset for the rears, to get over this I bought a 15mm spacer. First impressions, the car feels just a little firmer, going from 18’s, not unpleasantly firm as my 928 is not lowered, just feels more like the sports car it is, a very slight rub on the rears, over speed humps but the car looks awesome!
The problem, when cruising the car is fine, not pulling to one side, no tramlining etc, but when I put my foot down from standstill, going through the gears up into about third the back feels unstable, it’s not tramlining, but the best way I can describe it is a wobble, not continuously, but it’s there, I’ve tried this a few times from the lights, without backing off, first second, third, the back does’nt feel planted, every second or so through this process there it is a little wobble from the rear.
On the rear before I was running 265/35/18’s with no issues.
Before I fitted the wheels, we checked they were straight, spun up on a tyre machine, all looked o.k. I did a few miles to let the suspension settle, we all know this takes many miles on a 928! After the ‘wobble’ was apparent I checked the tyre pressures, they were at 37psi which seemed high, I dropped them to 34psi, it seemed to improve a little, then on further advise I dropped them to 30psi on the rears, it is slightly better but still not right. I checked the rear wheels are tight, checked for flex with the wheels bolted on, removed the wheels, to check the spacers are tight to the hub, swapped rear wheels over, the tyres are not directional.
It’s an 89gt, I love these wheels and the slightly firmer ride, is this flex in the spacer? Any ideas please, Rich
The problem, when cruising the car is fine, not pulling to one side, no tramlining etc, but when I put my foot down from standstill, going through the gears up into about third the back feels unstable, it’s not tramlining, but the best way I can describe it is a wobble, not continuously, but it’s there, I’ve tried this a few times from the lights, without backing off, first second, third, the back does’nt feel planted, every second or so through this process there it is a little wobble from the rear.
On the rear before I was running 265/35/18’s with no issues.
Before I fitted the wheels, we checked they were straight, spun up on a tyre machine, all looked o.k. I did a few miles to let the suspension settle, we all know this takes many miles on a 928! After the ‘wobble’ was apparent I checked the tyre pressures, they were at 37psi which seemed high, I dropped them to 34psi, it seemed to improve a little, then on further advise I dropped them to 30psi on the rears, it is slightly better but still not right. I checked the rear wheels are tight, checked for flex with the wheels bolted on, removed the wheels, to check the spacers are tight to the hub, swapped rear wheels over, the tyres are not directional.
It’s an 89gt, I love these wheels and the slightly firmer ride, is this flex in the spacer? Any ideas please, Rich
04-23-2011, 11:38 AM
#2
Do you have any idea on the condition of the rear wheel bearings? Reason I bring this up, on my '88 I had a similar issue, and with new bearings it cleared right up and feels solid.
04-23-2011, 11:41 AM
#3
"the rears are 295/30/19 with 67 offset. Reading many of the posts regarding 19inch wheels I know I should have bought rears with a 67 offset for the rears" - not sure the double reference to 67mm rear offsets is correct, unless I'm misunderstanding.
With respect to your final question about the 15mm spacers, is it possible to put your 18" wheels back on with the spacer and see if the problem remains? Is it possible to run the 19" without the spacer (probably not?) to see if the problem goes away?
With respect to your final question about the 15mm spacers, is it possible to put your 18" wheels back on with the spacer and see if the problem remains? Is it possible to run the 19" without the spacer (probably not?) to see if the problem goes away?
04-23-2011, 03:09 PM
#5
Intermediate
Thread Starter
Join Date: Aug 2002
Location: bournemouth,england
Posts: 43
Likes: 0
Received 0 Likes
on
0 Posts
Sorry forgot to mention, changed nsr wheel bearing a few months back, and yes i made a typo, have 67 offset and i should have bought the same wheels with the correct offset which i think is 51, makes sense 51 + 15mm spacer =66...