Autocross setup help

[dannykao]

Hello, I am completely new to autocrossing a Seven and really have no idea how to set it up. Any suggestion is greatly appreciated and I have a few questions:

I have an old set of R25A from a friend of mine. They are 20.5x7.0-13 and 22.5x7.2-13 used for a Formula Ford. Can I use those tires? Should I use 13x6 or 13x7 rims? What backspacing/offset is correct to use? Where is a good place to get the rims (new or used)?

Can I get an idea on what spring rate to use for front and rear?

The Caterham I have has the standard Zetec 2.0 and not modified and I like to get a little more power. Could I get some suggestions to gain some reliable power?

Thanks in advance and very glad to be part of the 7 group. Danny :driving:

[yellowss7]

So shifter karts weren't fast enough for you?:smilielol5: You can fit alot more rubber than 7 inch on the caterham. Some of us run as much as 10 inch rims.

As for spring rates, the stock springs are 150lbs up front and a variable rate spring in the rear. (i forget the exact numbers) No where as high as you might expect on typical autox cars. I think the next step up on the front is to 225lb springs but then you're going to have to start playing with the anti roll bars front and back.

Do you have a wide track front end? That can be a good first step if you don't.

As for power, I'm not a good driver but with close to 200hp, it's very easy to overdrive the car. I've driven a caterham with 135 hp and it much more controllable. Ask Jack Banha about the difference from his 100 hp to my 200. First time he drove my car he hit about 10 cones. :smilielol5:

As for backspacing, If I recall correctly, I believe it's about 4.5-5 inches on the front and rear. I bought a set of Kodiak three piece rims that are nice and light.

Nice to have another 7 in the Philly Region.

Tom

[JohnCh]

What backspacing/offset is correct to use?

Here is the information I received from RMSC a couple of years ago when I inquired about the factory 13x6 and 13x8 wheels:

13"x6" (front)
.96875" offset (24.6mm positive offset)
4.375" backspacing

13"x8" (rear)
1.53125" offset (38.9mm positive offset)
5.9375" backspacing

-John

[dannykao]

Thanks Tom; thanks John.

The shifter is plenty fast, it's the Evo that is not fast enough.. :D

I don't have the front track option nor LSD. I guess wide front track gives more bite on the turn-in? I figured the first year is just a learning process and try to get used to the car, so finding a cheap set of wheels, some springs and some cheap power become the priority for this coming year, plus learning how to drive.

Doc mentioned that he might be able to help me out with wheels next season, but I am the impatient type and like to run the car at least at the last Philly Event in mid-November. (I would have run it this weekend except I have to pick up my wife at the airport, she would be pissed if I am autocrossing instead) So if I could find the right(cheap) rims set to mount on a set of R25s then it would be great. :driving:

Thanks!

[yellowss7]

Danny, do you have the adjustable spring perches on your car? Are you running front and rear anti sway bars? If so what size at the front?

One of the things that it important in setting up the car is the front to back rake. I believe 15mm higher at the rear is the recommended ratio.

What are your concerns about the current spring rates? The car is pretty well set up with the stock springs, especially if you're going to street it as well. IMO you don't need to play as much with the set up as you would on a normal street car. These things are basically race cars to begin with.

I had my car cornerweighted and set up by George Alderman at Midatlantic Caterham in Del. And I know that Chip (Catracer) at GtClassics in Va. races Caterhams so I'm sure that they can provide good starting points for you.

Tom

[dannykao]

Hi Tom,

Ride height is adjustable, the shock is not. As far as I know it's 100% stock Caterham Roadsport.

I am definitely getting ahead of myself worrying about the spring rate. Afterall I haven't even driven the thing at an autox yet. :(

I was just wondering if there is a baseline setup for the car. It seems like the last few cars that I autocrossed (Evo, Kart, and FF) all have a specific setup formula for autox and it's pretty much well known and shared in the class. I am just trying to avoid to spend unnecessary money for useless mods.

Setting up the Evo was a two year process, and it took me exactly a year to figure out how to set up my kart. I can imagine setting this thing will take quite some time as well. :banghead:

[yellowss7]

This site can provide you with some good starting points.


http://www.blatchat.com/t.asp?id=156943&pn=1&ps=15&c= (http://www.blatchat.com/t.asp?id=156943&pn=1&ps=15&c=)

Tom

[Boxologist]

the baseline setup is that its ready to go for autoX and the track. u'll find very limited adjustability in the base parts. since u have the adjustable spring perches u can get corner weighted. castor is adjustable by washers on teh front of the lower A arm. camber is basically set, which will be fine for the r25s.

as for wheel offsets, my 15" KN prisoner and 10 spokes are both +14 iirc.

as for setup, as wide a tyre as u need and the corresponding wheel width. Lotus/Caterham have been doing this for 50+ years so the formula is pretty solid. The yahoo D/E Mod group is also a good place for info.

Figure out which zetec motor u have, the ZX1/2/3 or SVT. power is not as easy as the EVO, but engine management/tune is a start. building the block and heads is the next step.

if u have 6" wheels, those would be the best for ur tyres. but as tom said, wider is VERY common. his wheel/tyre dimensions are good.

edit: hoping to see a thread in the members rides forum, but there wasn't one. Simplest way to control teh car is with the right foot.

[jwduncan]

Danny,

I'm sure you'll enjoy autoxing your 7. I have an Ultralite S2K so I'm not sure how much of the setup will directly carry over but I run 15x10 wheels with 5.5" backspace. Tires are 23x9.5 R25B which I think are Formula Atlantic fronts so they are easy to find used. I took the inexpensive route and bought a set of Diamond Racing wheels which have worked well.

I'm glad to share more setup info if you'd like but I'd recommend getting as much tire as you can. Even with the 9.5 slicks, the back of the car is easily influenced with some more throttle.

The Cumberland Pumpkin Carve is this weekend if you're looking for a place to try it out.

[dannykao]

Thanks for all the replies!

Fortunately both the shifter and FF requires no lift in the turns, so I hope to be right at home. :-)

I did call Chip and try to get some parts today but wasn't able to reach him. I will try again tomorrow.

Jeff, thanks for your advice. I am trying to slap the old R25s on some cheap 13x6 rims and run it at the next CDC and Philly events first. I will look for Diamond racing to see if they have 13s that will work. I might be able to show up and run Frank Weichold's 85 Reynard FF at Pumpkin Carve. I just got the car last weekend and don't like the way it brakes, and I like to work on a couple of things like check the car over to make sure all the bolts are on tight. As soon as I pass my own "tech" I will be out with it.

Thanks again everybody! :seeya:

[yellowss7]

So Danny, how did the Caterham handle on Sunday? From your times, I suspect you were running on street tires.

Tom

[dannykao]

Hi Tom, I think you gave me too much credit. I am generally pretty slow.:confused:

I ran the tires that came with the car: Avon ZV1 185/60/14s. Here is one of the review I found on the internet on the tire:

"Just to give you an idea of how good the Avon ZV1 tyres are, they are fitted as standard equipment on the Caterham Seven (you know - that tiny English sports car that spanks other sports cars that cost twice as much :) ). I had them fitted to my Seven and I thought they were excellent. Very grippy. ..."

I spun a couple of times, had some entry oversteers, and exit understeers, didn't really brake well. Plus I can't drive - so that's not a good combination. But the car did accelerate nicely in the straights. Doesn't feel underpower at all.

I ordered a front wide track kit, some Diamond Racing wheels to mount a set of take off FF slicks from Jim Garry (Free). Will adjust the toe a little front and rear and try again in two weeks in Frederick, MD. Hopefully I can beat H-Stock time this time.

Trying to resist spending more money that I don't have on Tillett seats and windscreen. Someone please talk me out of it. :willy_nilly:

[Boxologist]

teh ZV1s

SUCK.

14" tyres are now pretty uncommon in the USA. maybe a set of rt-615 can be found. I spun repeatedly on the stockers, granted it was my first season of autoX, but there was tons more traction when I switched to a real summer tyre. Luckily I started w/ the 15" wheels so i had many options.

i'd recomend u trash those next spring an look at getting some RA1/r888 or at a minimum the rt615/ toyo t1r.

u'll find that your understeer/oversteer envelope drastically changes. I bet that those tyres are also way past then end of their life as well.

[yellowss7]

Entry oversteer? When I ran on the Avon CR500's, which came with my car and are pretty sticky, I found that entry Understeer was my problem, probably from entering the turn too hot, so the oversteer you experienced surprises me. Check your Rake front to back as that can easily cause oversteer if it's too high in the back.

That or the right foot can also be the culprit. It's not too hard to induce oversteer with the throttle.

Talk to Mike D. as I think his car is pretty well sorted, unless he changed the set up for his trackday forays. He was the cause of me going to the Hoosiers, I was running the Avons and he let me drive his on the slicks, It felt like it was a slot car the way it turned in. Unbelievable difference.

Tom

[Boxologist]

I take it this you?

http://chrisadolor.smugmug.com/Cars/SCCA-PhiladelphiaSummer-Series/IMG4265-Version-2-Version-2/693004596_kwxwf-M.jpg

http://chrisadolor.smugmug.com/Cars/SCCA-PhiladelphiaSummer-Series/IMG4266-Version-2-Version-2/693004748_dKkk4-M.jpg


http://farm4.static.flickr.com/3583/4044502561_ec956676f6.jpg

and i don't beleive Gebhart has had a sex change in the last 2 months
http://farm3.static.flickr.com/2591/4044504811_09f3f7eb0e.jpg
and how the hell did he end up back in DM? the Beast was turbocharged last time i checked.

[dannykao]

Yes, that is me...

Matt at Philly asked me if I would mind if the "Beast" runs in D-Mod with me. To be quite honest I have no idea what class the Beast should be in. It's 1600+ lbs, 1.6 or 1.8 motor turbo charged. I am not good enough to race anybody in D-Mod anyway so I was glad someone is in the same class to keep me company. I ended up having to leave early and run in an earlier heat.

I should be able to run the old Formula Ford tires at Boeing next weekend, and by next spring I should have the proper setup and the right wheel/tire setup. Hopefully by then I can get a little closer to the Beast. :boxing:

[Silk]

Danny,

Good to meet you and see your car in action in Bowie on Saturday. With the slicks, it looked like it handled quite well. And BTW, that was a nice 360 in the afternoon right at the corner I was working. Very impressive!

Gary

[dannykao]

Hi Gary, it was very nice meeting you on Saturday and Tom on Sunday!

Since I couldn't stop it from spinning, I just let it spin all the way around. :willy_nilly: It was about as entertaining as Sunday when I completely forgot that I have to loop the course around a second time (Sunday's PhillySCCA autox had the same loop around twice before the finish), and instead I made a wrong turn into the finish and ended up drifted sideways the entire steady state by doing an accidental "Scandinavian flick". Both from bad driving but lucky amusing. :ack:

I really didn't have any way of comparing the tire setup since I really have no baseline to compare with. I thought the car was too soft and had too much body roll, and under fast transitions it was a handful to control. But I am not certain it was my bad driving, or not the right tires, or the setup (most likely bad driving). I hope I can figure this out slowly but surely.

I had a lot of fun though. I never thought the 7 will get this much attention and I a lot of my friends and "new friends" want to drive the car and ride along. I think out of the 10 runs I took in this car, I had 9 different passengers.

Thanks again Gary. Hope to see you at Harry Grove in two weeks!

[dannykao]

Sorry for asking some pestering questions, but I have another one:

Has anyone tried a stagger wheel setup with 225/45/13 in the front and 255/40/13 in the rear on the A6s? I understand most folks are running 255s but wondering if anyone tried it.

Thanks! Danny

[Boxologist]

u should be fine. or not. maybe i should test it out for u at an event next year.

[dannykao]

Been to my 3rd autox event in the 7 on Saturday and I am getting more confused (or cleared, not sure which is more).

Thanks to Micheal D's A6, I got to run FF slicks and R-comp.

I also found out my top speed in 2nd gear is 58mph with 225/45/13s and about 63mph with 22.5x10-13s. Tom told me I might have the 3.9x final drive ratio instead of 3.6x, which should give me 5 more mph in the 2nd gear. Does anyone know off hand that Caterham or anyone that carries a pumpkin with lower final drive ratio with LSD built-in?

On stock (not wide track) suspension and 225/13 A6s, the car understeers quite a bit. On Formula Ford slicks with 3.5" backspacing, the car turns-in fine and steady state well; but very lose during transitions. (I was told to report back my findings by Michael D)

[Boxologist]

more camber?

as for the diff, call the Aldermans, Chip Bond, or Ben at CatUSA and get an accurate answer. It may be an interchangable ring gear.

[TheDingo8MyBaby]

I also found out my top speed in 2nd gear is 58mph with 225/45/13s and about 63mph with 22.5x10-13s. Tom told me I might have the 3.9x final drive ratio instead of 3.6x, which should give me 5 more mph in the 2nd gear. Does anyone know off hand that Caterham or anyone that carries a pumpkin with lower final drive ratio with LSD built-in?

Do you have a live axle car or dedion? A higher final drive number will mean better acceleration and therefore you will have LESS speed in a certain gear. (EDIT: I think I read what you said wrong..) Nobody will carry a pumpkin with the LSD and R&P built in. Yes, the ring gear is interchangable. I've been looking for a LSD for a long time but cant seem to find one at a reasonable price. I believe a LSD will really transform the car because the rear end is so light.


Ride height is adjustable, the shock is not.


So you have the bilsteins? Are your swaybars adjustable? Were both the R compounds and FF slicks all the same size? Did you play with tire pressures?

[Boxologist]

Do you have a live axle car or dedion? A higher final drive number will mean better acceleration and therefore you will have LESS speed in a certain gear. Nobody will carry a pumpkin with the LSD and R&P built in. Yes, the ring gear is interchangable. I've been looking for a LSD for a long time but cant seem to find one at a reasonable price. I believe a LSD will really transform the car because the rear end is so light.



So you have the bilsteins? Are your swaybars adjustable? Were both the R compounds and FF slicks all the same size? Did you play with tire pressures?

my secondhand knowledge has told me that the LSD would most benficial on an IRS car. even teh deDion setup doesn't allow the LSD to function well on such a light car, experience w/ the car car breaking loose is going more helpful. since thats what i was told, thats worth less than 2 cents.

maybe the better final drive is desired so he's not cruising at 3500-4000rpm on the highway? i would have suggested building up the engine for a higher redline to increase top speed in gear.

edit: Danny, where was saturday's event? at first I thought u were talking about sunday, but didn't see u listed in teh results.

[TheDingo8MyBaby]

my secondhand knowledge has told me that the LSD would most benficial on an IRS car. even teh deDion setup doesn't allow the LSD to function well on such a light car, experience w/ the car car breaking loose is going more helpful. since thats what i was told, thats worth less than 2 cents.


I have a live axle caterham and it suffers mid corner inside rear tire lift. I can't put what little power I have down. I have no doubt a LSD will help. I have another car with a live axle and adding a LSD was probably the best investment yet...

[dannykao]

I have a DeDion rear. The A6's are the same size front and rear, and the slicks I ran was an FF autox tire setup and are staggered.

Everything is stock right now and I am getting a wide track setup from Chip as well as height adjustable Bilsteins. I picked up some race springs and a adjustable rear bar. Chip is also helped me to get an intake cam, and George helped me with a skid plate for the oil pan which came in handy in the bumpy lot last Saturday.

Most of the parts will be bolted on in the next few weeks. Meanwhile I am finding as many events as I can go before the snow starts.

I was in Philly on Sunday to just take pictures and crew for a friend of mine. (And chitchat with Tom, nice seeing you again Tom.) I ran on Saturday with CDC (Capital Driving Club) at Harry Grove Stadium in Frederick - a very small lot but with a few straightaways. Here is a video of my run for your amusement: :jester:

YouTube - CDC 20091119.mov (http://www.youtube.com/watch?v=5tXUYB77ab0)

I was amazed how much speed I can carry in the Steady state (Probably 7-8 mph more than my Evo) and hit the rev limiter that quickly after the exit, hence the question.

I did call Chip and will try to verify my final drive ratio. If it's indeed 3.9x then Chip will help me out with the swap and source a LSD. Otherwise my other option might be getting a larger set of wheels and tires and butcher the rear fenders.

Oh, I did play with tire pressure and started with 18F/18R and ended up running 18F/15R. I tried to go lower but it got more slippery (Temp was in the high 40s-low 50s). And the entire run should stayed about 3500rpm in the car, at least that's why I was trying to do... :driving:

[yellowss7]

Danny, good seeing you again too. Next year will be fun to run with you. Can't wait. As for slick tire pressures, I run my Hoosiers at around 12-12.5 psi cold. When I ran on the track at Barber, I bumped them up to 15-16 cold. It was still pretty chilly on Sunday around 58 or so, and from past experience, it's almost impossible to get or keep any heat into them when it's that cold out.

I think that next year, once it warms up in the spring/summer, you are going to see what these cars can really do with new rubber.

And if they come up with the next site that they are working on, (a large concrete runway) grip will be incredible.:drool:

Tom

[dannykao]

More stupid questions and observations:

My "heavy duty" rims I got from Diamond Racing came in today. 13x9 and 13x10 and 4x108mm (4x4.25) with 5" backspacing. Both didn't fit well. The fronts will rub with the fender support in my stock 7, and the rear will rub against the edge of the hub mount. So they are for sale. $35 + shipping per rim and that's half price if anyone wants them. It will fit with 3/4 to 1 inch spacers, I just would rather not to mess with them. Next time I will do a better measuring.

Which lead to my stupid question: Anyone ran 13 inch front and 15 inch rear? Hoosier has a 275/35/15 tire that's big enough to give me 65 mph top speed in second gear. (Didn't get a chance to verify the final drive tonight, Chip) 255F/275R sound pretty mean, just wondering if anyone has tried it. It will raise rear ride height by 1 inch.

Thanks.

[Boxologist]

Tom was using 13x8 correct? we was able to get 10" wide tyres on, so the A6 or beyond tyres should be mountable.
Did the 13x9 fit the rear?
If u become a member of the UK club, there is a group buy on Compomotives, or if u can get involved w/ that as non-member(i'd get in too) u can get some good 13x8s. i think at 255/275 u'd be overtyred(sic) and then would be playing catch up on the power end.

[yellowss7]

Box, my street tires and wheels were Avon Cr500's 175x55x13 on I believe 6.5 or 7 inch wheels, at the front and Avon Cr500 205x55x13 on 8.5 inch rims on the rear. I just replaced the Avons with the Toyo R888's. Rears are 205x60x13, fronts I think are 175 or 185x60x13. The wheels are the Mike Barnby 3 piece Magnisium wheels that use to come with the R500's before Caterham switched to their 8 or 10 spoke jobbies. Same ones pictured on Craig Chima's car that's being discussed on another thread.

The Hoosiers are on 10x13 3 piece Kodiak wheels at all four corners. Don't remember the tire size off the top of my head. If needed I can go take a look at them.

Tom

[Boxologist]

i thought the kodiaks were 8" wide as well. were u running a 12" tyre on a 13x10?

[dannykao]

Michael's wheels that he lend me are 13x8 BS4.5 front and 13x9 BS5.5 rear. His A6's are 225/45/13s. The front needs a 5mm spacer to clear the fender support, and the rear is fine except the DeDion hub rubs against the inside of the rim a little.

The slicks that folks are running are 22.5x10-13 rear and 20x9.5-13 front. The track width are 9.8" rear and 9.4" front. If you go to the Hoosier's site, they can be mounted on either 8" thru 10" rims. I went ahead and got 13x10's because that's what the Cashmore is running (SCCA Solo Nats Champ), but since I can't swing th money for lighter rims, I think I will stay with 13x8s with 4 inch backspacing for the rear, and 4 or 3.5 inch backspacing for the front. It should fit OK if I go with that.

BTW, Hoosier is blowing out their old tires (New but old stock) and you can get 22.5x10x13 R25As for $85 a piece with free shipping. Just go to the Hooiser site under discontinued tires and they are on sale now. Unfortunately they don't have the front size, but I bought quite a few rears to last a couple of years.

[yellowss7]

Danny, if by "Dedion hub", you mean the Dedion "Ear" it it a common problem even with the new Caterham 8-10 spoke wheels. A little light maintenance with an angle grinder on the ear will sort that out easily.

Tom

[dannykao]

Thanks Tom! Now I know exactly what you are referring to and I will do that! Thanks for the tip!

[dannykao]

Danny, good seeing you again too. Next year will be fun to run with you.

Hi Tom, Chip is sending the wide track kit and shocks to me next week, and I should have some 255/13 A6s for the rear to run with the 255/13 front from Michael D (who generously lend them too me). Do you want to come out and play (co-drive) at the NJMP winter event event next week? It would be great to get your opinion on the differences between the two cars. Thanks!

[sdca7]

I was running Kumho V710 215/50R13's on Panasport 13x7 rims with backspacing of 4.375" on both front and rear with no clearance issues. This was on a '98 Caterham Superlight. It was pretty well balanced.

I'm soon getting a more high powered Caterham, and will probably go with the following combination for road racing:

CSR wheels. Front 7x13 with 225/45R13 A6's, Rear 9x13 with 255/40R13 A6's.

It is tempting to go wider on the front, but I'm guessing that for road racing I don't want to get too far off the original sizes to avoid bump steer and tramlining. It may even be better to just stay with stock tire sizes (I believe 185 front, 205 or 215 rear on the R500). I think wider pays off on autocross courses, but I'm not sure which would be better for road racing.

I'll have to check and make sure the CSR rear wheels have proper backspacing, as I'm guessing that with the IRS they may have different clearances than the Dedion.

Justin

[yellowss7]

Hi Tom, Do you want to come out and play (co-drive) at the NJMP winter event event next week? It would be great to get your opinion on the differences between the two cars. Thanks!

Danny, thanks, that would be fun, but have you checked the weather forcast for Saturday? 40's rain and possible snow. That's Evo conditions not a Seven's.

Tom