New tyres causing understeer problem
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 938
Likes: 13
From: Windsor, England
New tyres causing understeer problem
After having a fairly sweet (i thought, and was told) handling c2, i now have a lot of understeer.
I bought the car with cheap tyres. About three months ago i changed the rears (245's x 16) and the handling stayed similar only with more grip under power. On saturday i changed the fronts (205's) and all of a sudden i have lots of understeer. It dosent make sense to me why changing the cheap old fronts for more grippy (toyo proxes) new ones would increase understeer?
I tried filling the tank right up to see if the extra weight would give me a hint more negative camber to aid the problem, but it didnt.
I'm thinking the geometry might need looking at, but the car drives straight, does not vibrate or handle badly at any speed and the old front tyres were fairly evenly worn - maybe a little more worn on the inside lip.
Any ideas?
Edit - hot pressures 38f, 44r - i'm going to go out and try less pressure in the fronts.
I bought the car with cheap tyres. About three months ago i changed the rears (245's x 16) and the handling stayed similar only with more grip under power. On saturday i changed the fronts (205's) and all of a sudden i have lots of understeer. It dosent make sense to me why changing the cheap old fronts for more grippy (toyo proxes) new ones would increase understeer?
I tried filling the tank right up to see if the extra weight would give me a hint more negative camber to aid the problem, but it didnt.
I'm thinking the geometry might need looking at, but the car drives straight, does not vibrate or handle badly at any speed and the old front tyres were fairly evenly worn - maybe a little more worn on the inside lip.
Any ideas?
Edit - hot pressures 38f, 44r - i'm going to go out and try less pressure in the fronts.
Rennlist Member
Joined: Apr 2003
Posts: 2,499
Likes: 6
From: London, UK
Greg - what were the cheap brands?
Secondly, do you now have a set of 4 Toyos?
Thirdly - don't underestimate how long it may take to settle the tyres. JB will agree with this, it having taken CC track day to get his new rears to start gripping!
I'd give them a bit of time to settle...when are you off to the 'ring?
Secondly, do you now have a set of 4 Toyos?
Thirdly - don't underestimate how long it may take to settle the tyres. JB will agree with this, it having taken CC track day to get his new rears to start gripping!
I'd give them a bit of time to settle...when are you off to the 'ring?
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 938
Likes: 13
From: Windsor, England
After some testing, I think tyre pressures was the answer.
I should have experimented before posting, apologies.
My front tyres had cooled to 36psi & I let them down to 34. The rears still felt warm at 41, i inflated them to 43.
After a few roundabouts and hairpins had put more heat in them, the car felt much better. I checked the pressures again when i got back 36f, 44r hot. I still think there may be some of the protective oil on the new fronts - or just a little too much height in the tread, but needless to say, playing with the pressures made a noticable improvement.
Rob,
i have contisportcontacts on the rear (bought for 1/2 price thru a friend at conti - sadly he's now left
). They are wearing faster than i'd guessed so i decided to try toyo's on the front and will replace the rears with toyo's when necessary.
I had Michelin 'Primacy' previously - very average.
Off to the ring first thing on friday morning! Can't wait. I'm hoping to get some good video footage to upload to my site.
I should have experimented before posting, apologies.
My front tyres had cooled to 36psi & I let them down to 34. The rears still felt warm at 41, i inflated them to 43.
After a few roundabouts and hairpins had put more heat in them, the car felt much better. I checked the pressures again when i got back 36f, 44r hot. I still think there may be some of the protective oil on the new fronts - or just a little too much height in the tread, but needless to say, playing with the pressures made a noticable improvement.
Rob,
i have contisportcontacts on the rear (bought for 1/2 price thru a friend at conti - sadly he's now left
). They are wearing faster than i'd guessed so i decided to try toyo's on the front and will replace the rears with toyo's when necessary.I had Michelin 'Primacy' previously - very average.
Off to the ring first thing on friday morning! Can't wait. I'm hoping to get some good video footage to upload to my site.
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 938
Likes: 13
From: Windsor, England
Originally posted by JB
Very true - hundreds of miles needed to establish 'normal' behaivour of the new tyres!
Very true - hundreds of miles needed to establish 'normal' behaivour of the new tyres!
When i changed my rears they felt good after a 10 yard wheelspin out of the tyre place
- on their recommendation!!! Although I guess any sport tyre would have felt better than the "i-cant-sell-the-car-with-bald-tyres-quick-whats-cheap" tyres i previously had.
Racer
Joined: Aug 2002
Posts: 295
Likes: 1
From: Reston, VA
As detailed in my thread below (and based on recommendations I received from the group here), I changed from 205 to 225 fronts (and changed from Pirellis to SO3s) - the larger front size changed my understeering C2 to a wonderfully handling car on the track. I also decreased the tire pressure differential between front and back to 2 lbs. The difference was like night and day. I am running 17 inch wheels, however - don't know about 16 inch wheels but I would assume the principle is the same.
chuck
93 C2
chuck
93 C2
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Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 938
Likes: 13
From: Windsor, England
Originally posted by scupper
As detailed in my thread below (and based on recommendations I received from the group here), I changed from 205 to 225 fronts (and changed from Pirellis to SO3s) - the larger front size changed my understeering C2 to a wonderfully handling car on the track. I also decreased the tire pressure differential between front and back to 2 lbs. The difference was like night and day. I am running 17 inch wheels, however - don't know about 16 inch wheels but I would assume the principle is the same.
chuck
93 C2
As detailed in my thread below (and based on recommendations I received from the group here), I changed from 205 to 225 fronts (and changed from Pirellis to SO3s) - the larger front size changed my understeering C2 to a wonderfully handling car on the track. I also decreased the tire pressure differential between front and back to 2 lbs. The difference was like night and day. I am running 17 inch wheels, however - don't know about 16 inch wheels but I would assume the principle is the same.
chuck
93 C2
Yes i did read your thread, and was not really surprised that the wider fronts gave more grip and therefore less understeer. I read on the boards here that 225 is pushing the limits for a 16 inch wheel, so opted to stay safe and go for 205 - as i'll be hammering them on track.
It is incredible what a small pressure difference between front and rear tyres makes on these cars though !
cheers,
Greg
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Drifting
Joined: Nov 2001
Posts: 2,689
Likes: 5
From: Leeds, where I have run into this many lamp
Must agree with Melvin on this one - mixing tyres gives incredibly noticeable handling problems. I don't know the theory, but the practice was enough to convince me that it is tomfoolery!!
Rennlist Member
Joined: Apr 2003
Posts: 2,499
Likes: 6
From: London, UK
Greg - they're right you know! It's not just whether the front or rear tyres are any good, but the relationship between the 2 brands/axles.
SOunds like you had some success with tyre pressures though, and the 'ring will give you every opportunity to evaluate the tyres properly!
SOunds like you had some success with tyre pressures though, and the 'ring will give you every opportunity to evaluate the tyres properly!
Drifting
Joined: Jun 2002
Posts: 2,464
Likes: 25
From: colchester UK
Hello Melv,
How come it took so long for you to find this place?
Must agree with the sentiment though, mixing tyres is bad news, caused me no end of understeer when I first bought my C2. Horrid.
Kevin
How come it took so long for you to find this place?
Must agree with the sentiment though, mixing tyres is bad news, caused me no end of understeer when I first bought my C2. Horrid.
Kevin
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 938
Likes: 13
From: Windsor, England
I know mixing brands isnt ideal, but surely most important is having the same rubber on each end of each axle. As i said i got a deal on the conti's and wouldn't have chosen them out of choice. I expect to change the rears almost twice as often as the fronts, so i'm opting for Toyo tyres which i believe are far better value than conti's (£112 and £70 respectively for the fronts) and magazine tests have marked the toyo's better all round.
After some pressure tweaking and testing, i'm now happy with the results. I don't think the differences between Z rated sport road tyres are really going to be huge for road and some amateur track use. This is not motorsport.
After some pressure tweaking and testing, i'm now happy with the results. I don't think the differences between Z rated sport road tyres are really going to be huge for road and some amateur track use. This is not motorsport.
Pro
Joined: Aug 2001
Posts: 524
Likes: 1
From: Netherlands
Videoing at the Ring
Originally posted by Greg_L
Off to the ring first thing on friday morning! Can't wait. I'm hoping to get some good video footage to upload to my site.
Off to the ring first thing on friday morning! Can't wait. I'm hoping to get some good video footage to upload to my site.
I look forward to the footage, though
Have fun!
Cheers,
JW