Settings and alignment ACB10s / CR500s

[Alba 7]

I'm arranging to get the set up looked at on my VX.

 

I have been running ACB10s for the last year and now have a second set of rims and CR500s that I want to put on, particularly as the weather is going to turn soon. Ideally I would like a set up that suits both the CR500 for winter (and general road use) as well as the ACB10s for summer and very occassional track time.

 

Spec is as follows...

- VX XE with approx 200hp

- Wide track - orange front ARB

- Nitrons with 250 and 175 springs front and back (12 clicks from max hardness)

- Rear ARB disconnected

- 0.25 degree de dion ears

 

Both sets of rims are 13" with unequal front / rear tyre sizes (e.g. CR 500s are 175 / 205)

 

It has been suggested that the current set up is quite "toe out" - which would be supported by the interesting> handling with the ACB10s.

 

What would people recommend as a good compromise set up (assuming that a compromise exists) for toe, camber etc.

 

Thanks for your help,

 

Nick.

[oldbutnotslow]

As you will already know the CR500's are radial and the ACB 10's are X ply so they have a differing set up requirements

 

I have always understood that the Xply set up is 0 degrees Camber whereas I find 2 degrees neg works well on the CR's so a 0.75 or 1 degree neg should be a reasonable compromise

 

I found that the cr's did not work as well on the bolt upright setting and without the adjustable top track control arm that unbolts so that you can change the camber easily it was too much of a fag.

 

As far as toe is concerned I prefer a parallel set up. Some will say a slight toe out but I found that dire on the road with ACB's. It was pick a side of the road to be thrown into - Any side it mattered not as it tram lined so horrendously!

 

In the end I decided to just run CR's as I felt that overall they were a better tyre

 

Have a word with the technical bods at Avon 01225 703101 and ask for Motorsport. They are very helpful.

 

They will tell you that there is little difference between the road holding on the CR's and the ACB10 since they altered the compounds a couple of years ago.

 

Someone will likely contradict or have their own opinions but that’s my view.

If you want something for the track pick up a set of part worn radial slicks Michelin or such like from M Sport Dovenby Hall Cockermouth - Cumbria CA 13 OPN UNITED KINGDOM tel 00 44 19 00 898 912

 

 

Grant Taylor - OBNS Motorsport

😬 1.6K with 183 BHP of Black and 'Stone Chip' excitement. 😬

 

[Stuart Faulds]

This intrigues me - has anyone ever actually tried 0 degrees of camber on *any* tyre?

 

FWIW I'd stick 2 degrees negative on the front, 1.5 on the rear, mid camber, toe to taste and leave it on cr500's all year round, for your proposed use.

[captain chaos]

Stuart,

If it's a track day only Vx running ACB10's or slicks, then is it minimal camber?...what about toe?

 

Canvassing opinion on this one..

[oldbutnotslow]

Stuart I have run X ply slicks on 0 degrees and ACB10's and they were fine. A fairly even heat readings when measured on the outside centre and inside edges of the tyre. I know others who do the same.

 

I agree with you re CR's in the use Nick is putting the car to. I stopped using Xply and now just run CR's for dry and full race wets if its pi$$ing down but then again I use my car only on the track and not the road anymore. However the CR's are very good in the wet on the road.

 

Grant Taylor - OBNS Motorsport

😬 1.6K with 183 BHP of Black and 'Stone Chip' excitement. 😬

 

[captain chaos]

I always felt that ACB's offered just a bit more, especially in warm, dry conditions. My CR's would just overheat and get a bit greasy.

 

Grant, are you saying you don't find that, and, if set up correctly (remember my CR's were running with very little camber) with some camber, that CR500's are as good as ACB10's?

 

Surely, one of the race teams will have some stats on this giving a definative answer rather than seat of the pants opinion...

[SLR No.77]

Nick, I had a similar dilemma here ☹️ Mine was running 1.3º front, 0.25º rear and was bl%%dy aweful on the CR500s (fantastic on ACB-10s!).

I've not yet managed to swap the DeDion ears to the radial (1.5 - 1.75º) versions, but I've changed the camber on the front to 2º negative. This has certainly helped when using the CR500s but I haven't appraised the ACB-10s with the same setting. My fear is it will have deteriorated somewhat. With 1.3º negative, the CR500s understeered and squeeled really badly in semi-damp conditions - I had it suggested that 2.5º negative is really needed to make the CR500s work properly!

 

At the first opportunity I'll be swapping back to Yokos that I ran on my previous car (along with changing the DD ears of course!).

 

Stu.

 

www.superse7ens.co.uk..........the rebuild 😬

 

 

[Mark Durrant]

CR500's will work OK on the road with xply settings and I would suggest you set the tracking to parallel. However, I would not use the xply settings if using the CR500's on track. I used this set up for a couple of years without any problems. Try it and see what you think before going to the trouble of changing De Dion ears etc.

 

Mark D

Comp Sec

 

[Alex Wong1697456877]

CR500's will work OK on the road with xply settings

 

Agree. I use CR500's on the road and X-ply slicks on trackdays, and have the car setup for X-plys. The CR500's work fine like this and wear is not too uneven.

My car is set at 1 deg -ve camber at the front. parallel front tracking, 0.25 -ve camber at the rear.

[captain chaos]

So...

 

What do you think the differences are between..

 

CR500's with decent camber

and

ACB10's run with very little camber

 

Basically, set up both tyres to their optimum, which one offers the best track performance in the dry?

To me it's obvious, but I detect a few feel that it's alot closer...

[Stuart Faulds]

ACB10's are quicker and more stable through a heat range. They both give similar levels of progression and feedback, given your criteria of being setup properly. They are also both useable right down to the wire.

 

Most of my 'hardcore' trackday-only customers use ACB10's, on a range of cars from standard superlights to DLT's monster. For road use with an occasional track foray I'd have the CR500 every single time.

[Alba 7]

Thanks folks (especially the fellow boat anchor users!)

 

I appreciate that what I was after was a compromise (and it seems that at best, that is all it is going to be - a compromise where handling with either set up is not at its optimum).

 

What I didn't want to do was get the set up so wrong that I wore out a set of tyres in an afternoon (as happened this year before I realised that I had 1.75 degree ears rather than 0.25 degree ones ☹️)

 

For the VX users - in particular those with 13" CR500s and a wet sump, how much ground clearance have you got under the sump?

Swapping to the CR500s which appear to have a slightly lower overall diameter, is going to take a few more mm of the clearance which is already pretty darn low (48mm with ACB10s).

 

Thanks again,

Nick.

[captain chaos]

Thanks Stuart..

[oldbutnotslow]

Alba7, I dont have an answer but having had grounding problems with Matt's new VX car we set about changing the suspension bushes. All were somewhere between tired and buggered. The front damper bushes were changed which made a sgnificant diference to theride height. We also changed the lower rears and the tops. Replacing the tops has made a real difference as the lower top, ie the one under the bodywork was about the thickness of a Polo Mint Also the rear A frame bushes were in bits once we took them out!

 

We also moved the front platforms up a notch which gave a +8mm gain without compromising the rake too much

 

Overall its put the car back to where it shoulkd be as standard and amazingly we have gained around 20mm in the process

 

Grant Taylor - OBNS Motorsport

😬 1.6K with 183 BHP of Black and 'Stone Chip' excitement. 😬

 

[anthony1956]

I've read all the above ...

I have up to this year always had CR500's on my road only R500

This year I have ACB10's because I couldn't get CR500's immediately.

 

I have no idea my setup; except was by Hyperion for the track on CR500's as a track only car in its early life for 1800 miles.

 

I noticed the front CR500's were worn unevenly (more worn to one side) and the "tyre fitters" (a race car outfit near Zurich) said it was set up for best road holding and they could change it for tyre life, but then less performance. So I elected to leave it.

 

So, feeling a bit numptyish here with all the tech talk above, still want to compare notes. The ACB10's make more road noise (I was warned about that) - noise hardly being an issue in a 7.

 

At first I reckoned there is more grip, now I'm used to it. Lots of tram lining. I keep looking for wear but can't see any yet (I think that's like trying to see grass grow).

 

13" Anthracite wheels. Original MB's are awaiting fettle.

 

They (ACB10's) were ridiculously expensive, but then so is the exchange rate.

 

I told the fitters to have a care for the weights touching the calipers. Wheels fitted, engine running, gently let clutch out, car glued to spot... balance weights caught on calipers. Why do non 7 types NEVER listen? They suggested the gearbox was seized.... 😬 Anyway, some patience later all was well. I guess it did not help that I did not know my wheel sizes, not a good impression of my car knowledge.. 13" was apparently "not helpful". They wanted the J number written on the inside of the wheel (whose idea was that to put it there!?) Maybe that's why they don't listen. Can't win :-)

 

Anthony