Chimaera Alloys, changing for 18"

[justinbaker]

Hello all, Is there a recommended route to update the dynamics of a Chimaera ?. Looking at the Cebera 18" spider alloys that look superb, has anyone found a 4 stud pattern of the same style and tried these on a chimp?. IE: What do they look like, and what profile tyres fitted. Above all what did the dynamics change like, were they too "Skitish" ?.

Thanks in Advance - Justin Baker

[tvrbob]

justinbaker said:

.....and tried these on a chimp?.

Well this is a chimp and I don't think they have wheels.

[Trefor]

If it's the dynamics you want to change then fit a set of Nitron shocks and better brakes. Makes the Chimaera handle and stop as well as it can get, probably.

If it's the max power look you're after then try a set of 18 inch wheels. You might find some that fit on a local Fiesta ...

[Corin Denton]

I run 17's on my Chimaera and than has made it a bit skittish, it definately drove better on standard rims, 18's must be a horror story!

[tvrbob]

Corin Denton said:

I run 17's on my Chimaera and than has made it a bit skittish

Sounds right. Under heavy cornering I rely on the rear tyre walls deforming. That's how I know it's about to break away. Without this signal it would be much easier to lose it. The SO-3's have a similar effect. Stiffer side walls, so you don't get any warning before they let go.

[Corin Denton]

Very true Bob, the SO3 is so over-rated.

[Nick P]

I have SO-3s and they do not give much warning as to when the grip will go.....when it does....IT DOES..not very progressively

[tvrbob]

Nick P said:

I have SO-3s and they do not give much warning as to when the grip will go.....when it does....IT DOES..not very progressively

Have you reduced the pressures? On standard rims these run best at 20 & 22. That way the walls give a little more on cornering giving a better progressive feel.

[shadowninja]

interesting... how do you know when the walls are deforming? what should it feel like?

I personally like my Avon ZZ1s (no that is definitely not a recommendation)... the rear end is always squirming, even in the dry. "Sir, you'll feel more confident if you use the recommended brand of tyres." said one TVR dealership mechanic to me after a service. "Just cos you can't handle it..." I thought

>> Edited by shadowninja on Sunday 2nd November 12:46

[tvrbob]

shadowninja said:

interesting... how do you know when the walls are deforming? what should it feel like?

Gosh I don't know how best to describe it. Mostly it's seat of the pants I guess. As the rears are pushed to their limit their grip gets progressively worse because the outermost rear tyre is tucking under. Once this happens the car changes orientation, backend kicks out, and the tyre walls straighten up giving grip back. If the tyre doesn’t tuck under then you'll keep full cornering grip for longer but when it does let go you don't get the benefit of the tyre walls straightening up so you end up in a spin. A racing driver would know where the ultimate grip was so would favour no wall movement so maximise cornering grip. Occasional track drivers, like me, like to have the car tell them that they're at the limit by slipping a little before losing grip altogether. Hope that makes sense.

[simpo two]

That seems like a very good description of why my 4.0 with Goodyear Eagles was more 'chuckable' than a 500 with SO2s - thank you for defining it in words!

[Nick P]

tvrbob said:

Nick P said: I have SO-3s and they do not give much warning as to when the grip will go.....when it does....IT DOES..not very progressively Have you reduced the pressures? On standard rims these run best at 20 & 22. That way the walls give a little more on cornering giving a better progressive feel.

I'll try that....when I went around Snetterton earlier in the year, I found that I had a nice amount of understeer (which I like) but then it would snap into oversteer....i'll try the pressures, thanks

[shpub]

Corin Denton said:

I run 17's on my Chimaera and than has made it a bit skittish, it definately drove better on standard rims, 18's must be a horror story!

About 20-30% od the suspension compliance is from the tyres so going to a lower profile will effectively stiffen up the suspension and will rely on the springs to compression. End result is a car that is immensely skittish. It also puts a lot of strain on the suspension components.

[shpub]

shadowninja said:

interesting... how do you know when the walls are deforming? what should it feel like?

On the front it usually causes understeer big time and the more input you give the less actually happens. It effectively limits the speed at which the car can be taken into a corner without resorting to power induced oversteer to compensate. It makes the steering feel very light and as if the car is no longer connected with the outside world. The car feels very squirmy as it moves about on the tyres as they roll off. Another tell tale sign is worn down sidewall lettering....

The problem is that increasing the pressure will cause the tyres to balloon so that the contact patch and grip is reduced. The best solution is to fit wider wheels or go to a tyre with a stronger sidewall.

As for ZZ1.... got them on the Cerbie. The only good think I can say about them is that they are round and black...

[shadowninja]

Thansk for the explanations. I guess I have experienced it then as the sudden self-correction when I'm not pressing on that hard....... guess I'll have to give it more gas next time

[justinbaker]

Trefor said:

If it's the max power look you're after then try a set of 18 inch wheels. You might find some that fit on a local Fiesta ...

Awwww ! Trefor this was my first post too. I was rather after upgrading the look, as this part of the car looks dated (in my option), and after spotting a couple of Cerbera's with spiders on, it was as expected to promote a handling characterises thread. BUT, how about it, can we update the whole geometry, springs shocks, roll bars, and bushes, AND update to "Spider" image ?. I am not suggesting 18" on the front, but 17", and the rears to be 18". Also Folks being a new TVR owner, very very interesting and likewise good to know that there are some knowledgeable people about, unlike eermm excuse the pun "Treved" up Fiesta owners...
Also how do we insert "sensible pictures into the group (if they are allowed that is).

>> Edited by justinbaker on Sunday 2nd November 20:36

>> Edited by justinbaker on Sunday 2nd November 20:39

[simpo two]

justinbaker said:

Also how do we insert "sensible pictures into the group (if they are allowed that is).

Upload the pic to somewhere and then put the following in your post:

[pic]http://(domain name)/(path to filename)/(filename).jpg[/pic]

You can test it by clicking 'preview', which avoids a string of embarrasing posts called 'can you see this?' :O

[bassfiend]

justinbaker said:

Awwww ! Trefor this was my first post too. I was rather after upgrading the look, as this part of the car looks dated (in my option), and after spotting a couple of Cerbera's with spiders on, it was as expected to promote a handling characterises thread. BUT, how about it, can we update the whole geometry, springs shocks, roll bars, and bushes, AND update to "Spider" image ?. I am not suggesting 18" on the front, but 17", and the rears to be 18". Also Folks being a new TVR owner, very very interesting and likewise good to know that there are some knowledgeable people about, unlike eermm excuse the pun "Treved" up Fiesta owners...

Have you looked into the factory spider upgrade?

That looks quite nice without going OTT.

Phil

[shpub]

How much money do you want to spend? Have you checked with your insurers? some can get funny about this.

[kevinday]

Something else to consider is the potential change in the rolling circumference of the wheel/tyre combination. IMHO it is best to keep this difference below about 1.5% for many reasons - gearing, aerodynamics, speedo error etc. If you are going from 15" to 18", or even just a 2" upsizing you could end up with problems of this sort.