Advice needed on dodgy handling
Discussion
I recently changed the rear tyres from the original SO2's to Toyo TR-1's. This has caused the rear end of the car to be very twitchy. I have done the searches and read the threads concerning 'running' them in (which seems somewhat ridiculous for a modern road tyre) and also the general consensus that Toyos need more pressure.
I have ran them for about 700 miles and tried pressures from 24psi up to 28psi, with no improvement. Under hard acceleration the back end feels like it is about to step out, and the same effect is felt during moderate cornering.
The car still has its original (4mm left) SO2's on the front running at 22psi and all four wheels were geometrical aligned earlier in the year. Is it likely that the car needs aligning again following the tyre swap? Is there anything else I can try? Or do all Toyo's feel like that on a Griff?
Any advice would be much appreciated.
Thanks!
I have ran them for about 700 miles and tried pressures from 24psi up to 28psi, with no improvement. Under hard acceleration the back end feels like it is about to step out, and the same effect is felt during moderate cornering.
The car still has its original (4mm left) SO2's on the front running at 22psi and all four wheels were geometrical aligned earlier in the year. Is it likely that the car needs aligning again following the tyre swap? Is there anything else I can try? Or do all Toyo's feel like that on a Griff?
Any advice would be much appreciated.
Thanks!
SO 2s were really suited to the Griff, good compound and just enough 'give' in the sidewall. The SO 3 was a different animal mainly because of the harder sidewall, some said it was an improvement and a great track tyre but maybe not so good on the road. Maybe this new tyre has the same properties
This is perhaps stating the obvious but new rear tyres with 8mm of tread will "move around" more than old ones, particularly noticeable when you still have old ones on the front. There may of course be more going on in your case but a combination of this and the slipperyness of brand new tyres before they're scrubbed will make it feel like the rear is going to step out. I had a very similar thing a while back when the garage put 32psi in my new rear tyres! The softer sidewalls of the Toyo's will also be moving more (than the SO2s on the front) adding to the experience. Hopefully, it's nothing more than this.
Even between SO2's and T1-R's, there is a hell of a difference. I went from SO2's all round to SO3's on the rear which was ok, but then to T1-R's all round and they were awful. Problem was wrong pressures (too low for the tyre) and that they were new. Pressures are now (30PSI rear / 26 front) and 600 miles later and the T1-R's are great. Still not as good as the SO2's IMHO, but very good nevertheless. Very grippy, but the side walls are still soft compared to the SO2's (even at 30psi I can still push the side wall in with my thumb!!!) and there is still a little flex, but I have got used to them now and cornering is definately quicker. bear with them.
I have a similar prob with my chim.had new shocks,u/j's,track rod ends all set up correctly and the handling was still pants with so-3's all round. i have now been loaned a set of wheels with KUMHO's(budget?) on and it has transformed the car. My dilemma is do I buy a set of kumhos or get toyos bearing in mind when I got SO3's it was because at the time the consensus seemed to be these were the best and now it seems toyos are?????
ray_von said:
I have a similar prob with my chim.had new shocks,u/j's,track rod ends all set up correctly and the handling was still pants with so-3's all round. i have now been loaned a set of wheels with KUMHO's(budget?) on and it has transformed the car. My dilemma is do I buy a set of kumhos or get toyos bearing in mind when I got SO3's it was because at the time the consensus seemed to be these were the best and now it seems toyos are?????
IMHO, consider the Dunlop SP9000.
I've just had them fitted all round for £350 and they are great.
Has anyone experienced Toyos and Dunlops to make a comparison? I am going to give the Toyos another few hundred miles or so and continue experimenting with the pressures, but if they don't get any better I am going to have to look at swapping them is there are any alternatives. The odd movement feeling is just too offputting when trying to use the car's performance to its potential.
Have SO3s on front and rear. Had to renew the rear ones and my mechanic pumped them up to 2.5 bar (don´t know how much that is in psi). however: the car feeled like driving on eggs. talked to auto sautter in starnberg who told me that the tyre pressure with the bridgestone potenza s03 is correct als following:
1.6 bar front
1.8 bar rear
car feels much better now. but simply think that a 4.3 griff with red konis never ever will feel like a modern road car. so be careful driving with more than 220-230 km/h.
has anyone an idea where to get some more "compromised" dumpers from for such a griff ? as i´m not going to trackdays this could improve the "normal" ride on the german bumpy roads.
any idea is appreciated and very wellcome.
kind regards
LastLawyer
1.6 bar front
1.8 bar rear
car feels much better now. but simply think that a 4.3 griff with red konis never ever will feel like a modern road car. so be careful driving with more than 220-230 km/h.
has anyone an idea where to get some more "compromised" dumpers from for such a griff ? as i´m not going to trackdays this could improve the "normal" ride on the german bumpy roads.
any idea is appreciated and very wellcome.
kind regards
LastLawyer
LastLawyer said:
Have SO3s on front and rear. Had to renew the rear ones and my mechanic pumped them up to 2.5 bar (don´t know how much that is in psi). however: the car feeled like driving on eggs. talked to auto sautter in starnberg who told me that the tyre pressure with the bridgestone potenza s03 is correct als following:
1.6 bar front
1.8 bar rear
1.6 bar front
1.8 bar rear
2.5 bar is 36 psi
1.8 bar is 26 psi
1.6 bar is 23 psi
SO3s don't need a lot of pressure, the 'best' pressure will depend on various factors such as tyre size, suspension settings, how hot they're running and how you like the car to handle, but 22psi front / 24 psi rear is a reasonable starting point. For new tyres you would want to drop that by a couple of psi, but bring it back up when they are scrubbed in and cured. 26 psi is too much imo. 36 psi is not just too much, it's way too much, potentially dangerous and anyone letting you drive off with that much pressure in your tyres has no business working on your TVR.
GreenV8S said:
ghouly boy said:
I am going to give the Toyos another few hundred miles or so and continue experimenting with the pressures
Did you notice my comment about heat cycles? Curing the tyres makes a big difference.
I'm not exactly sure what you mean by heat cycles and curing. Could you explain please?
are they the right size?
by that I mean 245/45/16s, make sure they are NOT 245/50/16s. I belive that the rolling diameter of the toyo is slightly larger than the SO2 in any case, and if your car has a greater front/rear rake setting (1/2 inch ideal) then it'll make the rear end feel very light as i can push it up to 3/4 even 1".
roughly measuer it ground to chassis at the outriggers front and rear and see what it is.
you should also have 10-20minutes toe in at the rear.
andy
tvrmonster
by that I mean 245/45/16s, make sure they are NOT 245/50/16s. I belive that the rolling diameter of the toyo is slightly larger than the SO2 in any case, and if your car has a greater front/rear rake setting (1/2 inch ideal) then it'll make the rear end feel very light as i can push it up to 3/4 even 1".
roughly measuer it ground to chassis at the outriggers front and rear and see what it is.
you should also have 10-20minutes toe in at the rear.
andy
tvrmonster
ghouly boy said:
I'm not exactly sure what you mean by heat cycles and curing. Could you explain please?
The rubber that tyres are made from starts off with a consistency like chewing gum, and is hardened by a process called vulcanisation when the tyre is made. Vulcanisation is basically a matter of getting the rubber hot enough for a complicated chemical reaction to occur within the rubber which makes the rubber harder.
Brand new tyres, particularly soft compound high preformance tyres, are still relatively soft and gooey after manufacture. This means that when the tyre is loaded up in cornering/acceleration/braking, the rubber just squidges sideways instead of resisting the load. From the driver's point of view, it feels as if the tyre just won't grip and slides more and more the harder you push it. The natural reaction of you feel the tyre is deflecting too much is to put more air in it. In this case it makes the problem even worse because it reduces the size of the contact patch, increases the sheer stress in the rubber within the contact patch and makes it deflect even further. As a sort of double wammy, this puts a lot of work into the rubber which heats it up and makes it even softer.
Curing tyres is done by driving the car with sustained acceleration, braking and cornering loads which bring the car up to the point of sliding, but without actually sliding. You don't want to squeal the tyres or put rubber down, but you will need to push the car a lot harder than normal, and keep the pressure up for ten minutes or so. Obviously you have to be very careful where you do this so you don't put other people at risk or attract unwanted attention. When you're finished, the surface of the tyre should be at about 50 C, which is painfully hot to the touch but not enough to burn. Let the tyres cool down gradually which will take an hour or so, and they will be significantly harder afterwards. It's worth doing this a couple of times. Each time you get the tyres really hot you'll carry the vulcanisation process on a little more, but it's a case of diminishing returns and the first couple of times makes the big difference.
If you're trying to get the tyres good and hot to cure them, you'll find it helps to increase the pressures by a couple of psi. Let them back to your normal pressure when you're finished.
If you have brand new tyres which haven't been fully cured and you're driving them round trying to get rid of the release compound and buff the surface in, drop the pressure instead to reduce the tread squirm. Again, bring the pressure back to normal once they've been cured.
Cheers for the advice so far. The tyres are definetely the correct size, so the next thing I'll be trying is to cure them as suggested. It just goes to show the depth of knowledge here on PH, as opposed to asking the 'very experienced' tyre fitters who suggested increasing the pressure 5 psi at a time.
Gassing Station | Griffith | Top of Page | What's New | My Stuff