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View Full Version : Changing to slicks, what widths?


CNHSS1
15-10-07, 09:09
im currently running an essentially Mod prod rwd car on sprints and hills but its road legal and runs Kumho V70A soft compound List 1B tyres at the moment (softest 1Bs i can find). im looking to change to slicks and a log book for certain events next year but ive no experience of them at all. car weighs approx 750kgs and is turbocharged and runs 205 fr tyres on 7" split rims and 225s Rr on 8.5" split rims so changing wheel widths is easy enough.
do people run the same compounds F&R?
what widths do you guys suggest? i dont want to 'over-tyre' the car (if thats possible with slicks??)
any tips on compounds? i was looking at Avons as they have a choice of rolling radius too. im prepared for being a set a season.
any other tips such as toe, camber, castor issues over radial 1Bs?
sorry for all the Qs:)

dennis.doyle
15-10-07, 12:45
There was a chap ran a Scimitar like yours in BARC Marque Sports up here about 15 years ago & won the ANWCC with it. Sorry, can't remember name so will have to look up my book of semi-useless facts when I find it. It had a modded turbo & slicks. I didn't pay a lot of attention & memory is faulty, but I reckon he was on 8" & 10" wheels & presumably 7" & 9" Avon slicks. Wings were, of course, jacked out to give some clearance. So I reckon you can't over-tyre it at least up to that extent. Re. compounds, sorry no idea, best give BMTR a ring. They will probably give different advice for sprints & hills & probably suggest you stick to the harder, i.e. sprint, compound for safety if doing both.

CNHSS1
15-10-07, 14:07
you have a good memory! yeah that was the car of Graham Walker (Scimitar dealer) and Kieth Marsden. Graham retired the car many moons ago now and cant remember the tyre compounds. Ive contacted BMTR a while ago and as ever they have been mega helpful, but just like to hear the views of those who use them too (as opposed to those that want to sell me them lol).
with 'normal' road tyres, often too wide a tyre ruins the handling and feel, is the same true of slicks? also will too wide a tyre not heat up as fast as a narrower one?

dennis.doyle
15-10-07, 14:29
It was indeed the Walker/Marsden car. I know what you mean, tramlining etc, with road tyres that are too wide. I can't say I've noticed it on slicks, but then I've only really tried them on cars with limited suspension travel, relativey stiff suspension & little camber change. I rather think even spridgets ran 8's & 10's - anyone with direct experience of that care to comment? While a wider tyre is likely to heat up quicker, it will overheat quicker too & with something relatively powerful & heavy the softer compounds like A40s (or whatever new name is) will definately overheat for you at say Anglesey.

Rob Stevens
15-10-07, 14:29
BMTR are the people tp talk to, as for what size, let BMTR know what wheels you have, they should be able to help.

Cheers Rob

CNHSS1
15-10-07, 15:21
Dennis
cars pretty limited in travel, droop camber change etc already. car weighs circa 750kg plus driver *cough* whos not as light as he used to be *ahem*:) and chucks out 280hp (car, not driver... )
Rob
i will defo contact BMTR again and ask their advice too

dennis.doyle
16-10-07, 11:36
Defo.

Your challenges, should you decide to accept them, are:

Scam (where else :) ) in less than 25.97 which is what that Scimitar did on 13/5/90. BTD going to Joe Ward in the WD8M for a rather swift 23.70.

Or if you prefer the wide open spaces, then how about Aintree in 50.52 with a terminal speed of 134mph which was on 1/9/90.

Of course you may already have cracked these - as I don't have this year's results to hand.

CNHSS1
16-10-07, 12:05
Hi Dennis,
i love a challenge!:) ive never been to scammonden as the scim championship doesnt go there, but last did aintree in april '05 iirc. did a 51.7 126mph iirc on 1Bs, so will have to go there next season to see off the Walker/Marsden time ;)
have you any other results for the car for anywhere else? loton, shelsley, prescott, harewood, 3 sisters, curboro, gurston, wiscombe, MIRA, castle combe etc? the walker/marsden SS1 was replaced by an even more extreme Sabre, a re-bodied prettier version (how could it not be?!:eek:?) that was designed for 750mc racing essentially, although it did run at Loton, curboro etc but i cant find anyone with times for either their SS1 or Sabre. be nice to have more times i can benchmark against.
thanks for your help Sir:)

dennis.doyle
16-10-07, 13:11
Sounds like you are nearly there & the slicks ought to do it.

Suggest you try Scam. It's blah, blah, blah.........................................:D

Sorry, nothing useful in terms of results, but a couple of possibly historical interest:

Harewood (old short course that only went up hill) 43.18 on 1/6/90 which reset the Marque Sports record for cars up to 2.6 litres.

Baitings (now defunct) 29.28 on 6/5/90 when Phil Burton's BTD was 26.89 in his Mallock.

Will try to have a look through adjacent years tonight & see if I have anything for other courses that might be relevant, but I don't think 3-Sisters was doing sprints then, New Brighton has changed, etc. etc. etc.

CNHSS1
16-10-07, 13:49
pic of the walker car

dennis.doyle
16-10-07, 14:10
I'd put up with the looks in return for the effectiveness & VFM.

Another bit of anecdotal evidence on the over-tyreing thing. People used to say Elans' handling was spoilt by putting on wide tyres & I would imagine they were right when talking about driving briskly on the road. However, when it came to going quickly on sprints & hills, I rather think it was those with pretty wide slicks under bubble arches that were fastest. In fairness though, I'd have to admit that the latter feature tended to correlate with having all-steel full-race twin-cams too:). I'd say the Walker car was faster than one of those too, for cars modded to Marque spec at least, on the grounds that it got that Harewood record.

CNHSS1
16-10-07, 15:54
re the looks, it was styled by Ray Charles Guide dog......in the dark:rolleyes:
but they are cheap, RWD, plastic body with a galvanised chassis (no rot) and not overly heavy, with a Nissan turbo'd and inj motor up the front. as a TVR owner too it blows away the Tivs for performance on track and i dont have to wear my chest wig and medallion :D (just a paper bag instead;))

dennis.doyle
17-10-07, 11:54
I had a search, but little to report. It was running in ’89, though less well developed judging by the times. I couldn’t find any results for current venues for it & so the only different venue is again only of historical interest:

Class win at Shap 24/9/89 with a time of 34.84, BTD being the late Tom Hamonds in Quattro in 29.76.

I don’t have any ’91 results as I was between cars at the time & by ’92 it looks like he had moved on as the car is not in any results I’ve got. The Marque class break changed to 2 litre about then & he would have gone into unlimited, probably with no one else to compete with.

iranoff
17-10-07, 19:56
with a galvanised chassis (no rot)

Not the early ones, the sill plates rotted like a peach and cost Reliant a small fortune to rectify. I know because I worked there at the time.

CNHSS1
18-10-07, 08:56
Dennis
thanks for looking, thats very kind.

iranoff
True, but all the production 1800 turbos were only ever galv. As you say tho, the early non galvs are scary. ive bought a couple for pennies to break for panels, trim and suspension components, and when the panels are removed the chassis literally folds up in places :eek:
id love to know more about the car and the development. ive got some pics of the development bucks and mules from '78, but have heard stories of other engines being tried such as the T16 rover turbo and GM 2.5 V6s too. Have you got any info from when you where there?