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> AX setup dilema
grantsfo
post Jan 29 2010, 05:19 PM
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I have a little bit of a temporary dilema. My new slicks fit under rear fender but dont fit under front, stickout about 2 inches. Thing that amazes me is guy in So Cal fit 275 that was 2" taller on same wheel under his Boxster. Guess with lots of negative camber it might have been possible. 16x11" slick fits under the rear fine as I can run it without a spacer. Front requires a 10 mm spacer to clear strut.

So here is dilema. My 15x9 Cantilevers stick out but clear fenders for Autocross in the front as they are short and just a little narrower than the 11" slicks. 16 Slicks are same hieight but they are definitely wider so I think I'll run out of clerence in turns.

I'm thinking maybe put rear 16x11 slick in rear and run canti in front until I get flares on the car? Thoughts? It would look funny as hell sort of like Brits car but certainly would give great traction in rear, concern would be would it cause terrible understeer?

Or should I jest wait months until I get fiberglass fenders to use my 16's? One other suggegestion was to try it and see if it clears at AX but that scares me would hate to crash a crappy boxster fender into expensive race tire.

Here are tires side by side. Current setup on right which is 23x9x15, next the 23x11x16 and finally the 275x45/16 (no longer on wheels)

(IMG:http://www.914club.com/bbs2/uploads/post-433-1264233457_thumb.jpg)

Here is car in turn at AX with canti setup. Can see tire appears to tuck under front fender in turns but just barely. I just dont think I will get away with this with wider tire.
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grantsfo
post Jan 29 2010, 05:25 PM
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Another view of the Canti's in front to show how much they stick out.


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Krote6
post Jan 29 2010, 06:14 PM
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Why dont you make your own flares Grant? metal is metal .. just slice them bend them then reweld them .. just like the old Datsun 510 flares had done

that way you can develope the car with the correct tires this year instead of doing it half way for a year then redoing the car with another set of tires the next year..
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grantsfo
post Jan 29 2010, 06:30 PM
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QUOTE (Krote6 @ Jan 29 2010, 03:14 PM) *
Why dont you make your own flares Grant? metal is metal .. just slice them bend them then reweld them .. just like the old Datsun 510 flares had done

that way you can develope the car with the correct tires this year instead of doing it half way for a year then redoing the car with another set of tires the next year..

Yeah gues I could do that but thats such a commitment. and it still costs money to do that! I dont have facilities or ability to cut thing up like that.
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Mark Garriott
post Jan 29 2010, 06:48 PM
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QUOTE
Thing that amazes me is guy in So Cal fit 275 that was 2" taller on same wheel under his Boxster.


I see 2 possibilities:
The 275s are on a 15" rim -- not 16"
The guy is running an aftermarket strut with a small diameter coil reducing the need for a spacer. If that is the case, it may be easier to make up some different spring perches for the strut rather than bodywork (some people are working on this). (Are you running PSS9s?)
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Borderline
post Jan 29 2010, 07:46 PM
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Please forgive my ignorance, but are all these tires compatible design/construction wise? If they are I would run the little guys up front and the big guys in back. How did the wt distribution turn out? Did all the wt come off the front end? If so, you may find it hard to get the front tires warm. Smaller tires up front would warm up quicker than the big guys. Warm small tires better than cold big tires??
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grantsfo
post Jan 29 2010, 09:43 PM
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QUOTE
Please forgive my ignorance, but are all these tires compatible design/construction wise? If they are I would run the little guys up front and the big guys in back. How did the wt distribution turn out? Did all the wt come off the front end? If so, you may find it hard to get the front tires warm. Smaller tires up front would warm up quicker than the big guys. Warm small tires better than cold big tires??

Both are bias ply construction. Wieght is about 55% rear 45% front I still have lots of firmness settings left in the rear bar. WIth all that tire back there probably could dial in some oversteer and still put down power effectively. I was thinking run low pressures rear and higher up front that way tires all would have similar flex, etc. But then what do I know?

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grantsfo
post Jan 29 2010, 10:31 PM
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QUOTE (Mark Garriott @ Jan 29 2010, 03:48 PM) *
QUOTE
Thing that amazes me is guy in So Cal fit 275 that was 2" taller on same wheel under his Boxster.


I see 2 possibilities:
The 275s are on a 15" rim -- not 16"
The guy is running an aftermarket strut with a small diameter coil reducing the need for a spacer. If that is the case, it may be easier to make up some different spring perches for the strut rather than bodywork (some people are working on this). (Are you running PSS9s?)

Nope these are specific wheels and tires run on his car. He ran PSS9's I believe. Im thinking lots of negative camber helped. I cant do camber as I'm using bias plys. But I'm not even close. I would have loved to see his car with these as it had to have been very tight squeeze.
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crv1
post Jan 30 2010, 03:48 AM
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QUOTE
QUOTE
QUOTE
Thing that amazes me is guy in So Cal fit 275 that was 2" taller on same wheel under his Boxster.


I see 2 possibilities:
The 275s are on a 15" rim -- not 16"
The guy is running an aftermarket strut with a small diameter coil reducing the need for a spacer. If that is the case, it may be easier to make up some different spring perches for the strut rather than bodywork (some people are working on this). (Are you running PSS9s?)

Nope these are specific wheels and tires run on his car. He ran PSS9's I believe. Im thinking lots of negative camber helped. I cant do camber as I'm using bias plys. But I'm not even close. I would have loved to see his car with these as it had to have been very tight squeeze.



just caught this post
I am running the 275 on a 15 x10 with pss9 and stiffer swift springs that I believe are 6 or 7 inches (i think an inch shorter than stock). The perch rides just above the rim and almost rubs the rubber flange portion or the tire. I run about 2.5-2.75 camber. the camber is only from the lower control arms. No camber plates. I also run the 9 x18 stock wheels in the front with 285 710's. If i ran them on a 9.5x18 they would rub the fender.. With the 15's so small diameter. I have a lot of clearance above the tire and have not had any bottoming out of the tire hitting the fender.
As you can see in the picture, the tire just barely sticks out in front. I'm sure its the 11in wheel, plus the lack of camber that are pushing the wheel out that extra inch or two past the fender. You could do the stiffer springs too. I know you prefer not to but may be easier than cutting up the fenders. There is a fabricator down here the does the plastic flares on the Miatas.
Project is looking good! Some day i may join the dark side.
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grantsfo
post Jan 30 2010, 08:27 AM
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Yeah the 275/35/15 is a smaller tire in both section width and hieght than 275/45/16. And 23x11x16 has wider section width than the wider of those two tires by just a little on 16x10. I really wanted to get away from 15 inch wheel because of the lack of caliper clearance both from practical standpoint as I didnt like things getting stuck between wheel and caliper and from brake cooling perspective.

There is a radial Good Year I could go to that is probably perfect but they are very expensive. I will likely go with a flare

Those big tires on the Boxster look great. Do you have any issue getting front tire heated in AX?
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crv1
post Jan 30 2010, 01:46 PM
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No issue with tires getting up to temp. Mine is a lot heavy car. Hoosier said my car is a bit to heavy for the tire. With two drivers all four tires get to much heat (we have to water spray after the second lap) . The miata csp guys running the 275's will sometimes use a tire covers.
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grantsfo
post Jan 30 2010, 04:18 PM
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QUOTE
No issue with tires getting up to temp. Mine is a lot heavy car. Hoosier said my car is a bit to heavy for the tire. With two drivers all four tires get to much heat (we have to water spray after the second lap) . The miata csp guys running the 275's will sometimes use a tire covers.

Being an ex miata guy I know those cars can use big tires in front without much worry. Miatas with motor over front wheels turn great. Problem I see emerging with lightweight Boxster is that most weight comes of the front to mid front of the car. Weight distribution is migrating to rear. Originally I didnt think I would have much issue with front tires heating. Now I'm not sure after seeing new corner weights.

Ideal tire for front would be a bias ply 23x10x16 in a soft compound but those are hard to find. Scary thing is all the soft compounds seem to be disappearing from 17 and up sizes so it really just leaves 23x11x16 or I could think about going with real short 22x10x16 Hoosier in r35 compound. Options are really limited for slicks if you are doing AX and Hillclimbs.

I'm writing to hillclimbers in UK to see i they have any ideas - maybe there is a tire sold there that we cant get.

There is a formula atlantic tire that Good Year guys said they would garuntee would work for me or they would exchange tire. Its a radial and it is a 23x10x16 in a r160 compound. But the tires are $nearly $400 each. Thats a bit expensive for very low treadlife tires. Problen there is I'd need a spare set and that starts getting very expensive.

Well its fun forging new frontier. I prefer experimenting and figuring out what works best. Not many have had to setup a Boxster with 911 like weight distribution.
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ChrisNPDrider
post Jan 31 2010, 11:01 PM
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QUOTE (grantsfo @ Jan 30 2010, 01:18 PM) *
Not many have had to setup a Boxster with 911 like weight distribution.

Then do what the 911s do and use a front wheel 1" skinnier with a staggered setup
(IMG:style_emoticons/default/happy11.gif)
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Evan Fullerton
post Feb 1 2010, 01:17 AM
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Inquiring minds would like to know what the weight distribution is like. I have yet to scale my car but my Dad's 911 is right at 40/60 with almost no weight removal up front and quite a bit off the back. My understanding is that prepared Elise's are right in the 40/60 range as well.
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