Too much camber on GT3 shredding rear tyres?
Discussion
Had a geometry reset done on my GT3 Mk2 about 4000 km ago. Front camber one degree, rear is three degrees - this was set up for fast road/track.
Have since destroyed a set of rear road tyres (ie not used on track): the rear left tyre was shredded on the inside suggesting (a) too much rear camber and (b) the alignment is probably off a little (also the rear is now skipping a bit sideways over bumps).
The shop that does the set up is experienced enough to do the set up for Cup cars, so I won't question their credentials, however should I perhaps be decreasing the camber at the rear and increasing at the front to increase turn in but decrease rear wear? Or have I no idea what I'm talking about and just leave it to them to set it up again?
Have since destroyed a set of rear road tyres (ie not used on track): the rear left tyre was shredded on the inside suggesting (a) too much rear camber and (b) the alignment is probably off a little (also the rear is now skipping a bit sideways over bumps).
The shop that does the set up is experienced enough to do the set up for Cup cars, so I won't question their credentials, however should I perhaps be decreasing the camber at the rear and increasing at the front to increase turn in but decrease rear wear? Or have I no idea what I'm talking about and just leave it to them to set it up again?
Harris_I said:
Had a geometry reset done on my GT3 Mk2 about 4000 km ago. Front camber one degree, rear is three degrees - this was set up for fast road/track.
Have since destroyed a set of rear road tyres (ie not used on track): the rear left tyre was shredded on the inside suggesting (a) too much rear camber and (b) the alignment is probably off a little (also the rear is now skipping a bit sideways over bumps).
The shop that does the set up is experienced enough to do the set up for Cup cars, so I won't question their credentials, however should I perhaps be decreasing the camber at the rear and increasing at the front to increase turn in but decrease rear wear? Or have I no idea what I'm talking about and just leave it to them to set it up again?
This is the downside of a track set up i'm afraid.
Mine do exactly the same, especially if i do too many road miles.
One point to check is that you re-inflate the tyres to road pressures when leaving the track, as
i have been told not doing so, will lead to higher heat build up on the inner edge, causing even faster
wear rate.
Not sure about the skipping part, mine skips over rough surfaces, that's just a GT3.
Get Geometry checked by JZ Machech or Parr.
G
>> Edited by glenn mcmenamin on Thursday 16th February 18:32
>> Edited by glenn mcmenamin on Thursday 16th February 18:33
lol I'd compare notes, but unfortunately JZM don't seem to give out the printouts from the alignment rig! I get the distinct impression that the main GT3 specialists like to keep their settings as confidential as possible.
Not noticed tyre wear problems yet, in fact they wore pretty evenly for me before I had to replace them with a JZM road/track setup (nothing too agressive though). I was religious about getting tyre pressures up sufficiently at the end of track days though. Plenty of stories of people forgetting and trashing their tyres in a few miles once they cool from track temps and go mostly straight on the road. Emphasised by rear road pressures being high 30s with hot track pressures being 32ish. You could end up driving on the road at mid to late 20s if you don't reinflate enough and add a bit extra to account for cool down.
If you aren't happy, have another chat with them or go to JZM who I was impressed with. They should be able to set it up right for your needs, which is likely to be a fair bit less aggressive than a cup car if you aren't trailoring everywhere!
>> Edited by DanH on Thursday 16th February 19:29
Not noticed tyre wear problems yet, in fact they wore pretty evenly for me before I had to replace them with a JZM road/track setup (nothing too agressive though). I was religious about getting tyre pressures up sufficiently at the end of track days though. Plenty of stories of people forgetting and trashing their tyres in a few miles once they cool from track temps and go mostly straight on the road. Emphasised by rear road pressures being high 30s with hot track pressures being 32ish. You could end up driving on the road at mid to late 20s if you don't reinflate enough and add a bit extra to account for cool down.
If you aren't happy, have another chat with them or go to JZM who I was impressed with. They should be able to set it up right for your needs, which is likely to be a fair bit less aggressive than a cup car if you aren't trailoring everywhere!
>> Edited by DanH on Thursday 16th February 19:29
Guys - this is all very helpful. Thank you so much, and lol at suggestion to pop down to Parr! (Although I used to take my '86 Carrera 3.2, and they were superb and not in the least bit snobby, so no doubt I will be doing the same with the GT3 when (if) I return to Blighty).
I will discuss with the shop increasing the front camber a touch and decreasing the rear and see where this gets me.
Of course, the ideal solution would be to have a turbo for the road and a nicely set up GT3 for the track. Now if you'll excuse me, I must sort out those Valentine Day flowers I forgot about...
I will discuss with the shop increasing the front camber a touch and decreasing the rear and see where this gets me.
Of course, the ideal solution would be to have a turbo for the road and a nicely set up GT3 for the track. Now if you'll excuse me, I must sort out those Valentine Day flowers I forgot about...
DanH said:
lol I'd compare notes, but unfortunately JZM don't seem to give out the printouts from the alignment rig! I get the distinct impression that the main GT3 specialists like to keep their settings as confidential as possible.
>> Edited by DanH on Thursday 16th February 19:29
Dan,
I've got all the tools necessary to measure a set up.
I can't see why they would not give out the measurements when its relatively straight forward to check them.
Agreed though if you lazy and don't reinflate your tyres you might see premature wear. I guess it also depends on the type of roads you drive home on, and how you drive!
jpf40 said:
lol I'd compare notes, but unfortunately JZM don't seem to give out the printouts from the alignment rig! I get the distinct impression that the main GT3 specialists like to keep their settings as confidential as possible.
>> Edited by DanH on Thursday 16th February 19:29
Dan,
I've got all the tools necessary to measure a set up.
I can't see why they would not give out the measurements when its relatively straight forward to check them.
Agreed though if you lazy and don't reinflate your tyres you might see premature wear. I guess it also depends on the type of roads you drive home on, and how you drive!
To be fair to JZM, I didn't really press the issue. Not sure what the answer would be though and agree it is a tad off if they are being all secret squirrel on something so easily discoverable. The guys on the US forums publish a couple of recommended setups anyway.
Then again in the UK, Parr & JZM seem to be in healthy competition and have suprisingly different approaches.
that a little 'ballooning' puts a bit more of the centre of the tread on the tarmac....Hi Tim -
Yes Manthey recommend it for their setup so I have followed suit... I have put a couple more pounds in the rear and 4 ish more in the front (as recommended) so I will see how it works. Im running a fairly track biased setup on the standard suspension & I do a number of road miles so I will let you know if it works
Steve M
>> Edited by Merritt on Tuesday 21st February 08:04
Yes Manthey recommend it for their setup so I have followed suit... I have put a couple more pounds in the rear and 4 ish more in the front (as recommended) so I will see how it works. Im running a fairly track biased setup on the standard suspension & I do a number of road miles so I will let you know if it works
Steve M
>> Edited by Merritt on Tuesday 21st February 08:04
gfreeman said:
Hi Tim -
Yes Manthey recommend it
Hi Steve...
Sounds good enough for me.....
Parr this saturday????
Afraid I can't
In the process of trying to sort out the sale / purchase of my everyday driver.. With a bit of luck I should be picking the replacement up on Saturday...
Do you have any PCGB track days booked for April?
Steve
maximu5 said:
When I discussed with Mathey in Germmany how to prevent such wear, they suggested that fitting a Cup dif (with 60% lock) as a measure to reduce wear. Does anybody have experience with this ?
I have a GT3 RSR limited slip diff in my GT3 MK1 it still does not prevent the inside edges of the rear tyres wearing down to the canvas in probably no more than 1500-2000 road miles, I can't see how a diff can help, the problem is on the road at 3 degrees neg camber the inside edge contact patch is probably no more than a few inches add to this a slightly toed in set up on the rear {which JZM do with a track set up} and effectively the tyre is being scrubbed across the road surface which causes excessive heat = wear... never had or heard of the same problem on the front obviously the weight of the engine & torque are factors...
zanzibar said:
When I discussed with Mathey in Germmany how to prevent such wear, they suggested that fitting a Cup dif (with 60% lock) as a measure to reduce wear. Does anybody have experience with this ?
I have a GT3 RSR limited slip diff in my GT3 MK1 it still does not prevent the inside edges of the rear tyres wearing down to the canvas in probably no more than 1500-2000 road miles, I can't see how a diff can help, the problem is on the road at 3 degrees neg camber the inside edge contact patch is probably no more than a few inches add to this a slightly toed in set up on the rear {which JZM do with a track set up} and effectively the tyre is being scrubbed across the road surface which causes excessive heat = wear... never had or heard of the same problem on the front obviously the weight of the engine & torque are factors...
1500 to 2000 miles!! OUCH.... What tyres do you run on the road?
My cars setup must be much less aggressive then as the rear tyres seem to have lasted 4k miles under my ownership, and 5k under the previous owner. Thats with corsa systems, and a JZM setup at 5k. Mixed track and road usage and they wore very evenly until I destroyed them practising limit handling. They had very little grip near the wear bars though, and not sure if that is the compound of if they had just gone off (Corsa apparently only have a shelf life of 6 months at tyre dealers before they cannot be sold).
maximu5 said:
Russell,
when you say you have a GT3 RSR dif, do you mean a Cup dif ? What is the locking factor (60% ?) and how has this affected tye track behaviour ? Did you have to adjust your driving style ?
Tom
Not sure if the diff is the same in the Cup & RSR but Dave at JZM told me it was the RSR diff they fitted, no mention of a different locking factor just that the diff plates are made of a different material ie harder wearing: the standard GT3 diff plates wear after as little as half a dozen track days; causing contamination of the oil in the gearbox with abrasive particles & loss of LSD.
As for on track performance it was very evident after my first outing that my old diff had been totally sh**ged, I have done probably 20 days since and the diff is still working perfectly, they can test the diff by raising the car and measuring the resistance when rotating one wheel with the other.
Russell
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