Running 275/35/15s on a 9".
 

I plan to do some autocross this year in XP. My co-driver and I mounted up some 275s on some Avanti S1's. I did a pretty aggressive pull on the rear fenders and have my front fenders spaced out enough so all my outter body work is clearing well. I am a bit worried about rubbing the inner tub sections around the shock towers. Is there anything I can do to clearance the inner tub? I am not extremely aggressive with front camber sitting around -1.8-2.0 with the rear set around -2.0-2.4. I'll probably get another alignment soon but those are about the max numbers this car sees with poly bushings and factory eccentrics.


Factory body work.
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aggressive roll
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They poke out in places around my oversized spats.
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Beef!

Other key take-aways on this car's current setup. 440ish front , 300ish rear springs, ~1950lbs "dry" - 2150lbs "wet". And I highly doubt it will ever see concrete since we don't have any local and unlikely to make it to a tour/prosolo that has concrete.

Pondering on putting a set of spare 700# 6" on the front and moving the 440s to the back and sending it. However it's OTS Bilsteins so not too sure how it will like those rates.

I'd suggest sending them to Whitener to have them revalved. Ben used 600/400 on msm shocks successfully, but they weren't super well behaved always.

We've talked about a revalve but at that point I think I will just sell this setup off and spend the extra $200-400 for Xida's. I never expected that I would get to a point of putting anything other than a street tire on the car. I still think locally the car should be competitive enough. I would just hate to trash a set of tires if there was something I could do to keep the insides from rubbing too much.

You'd want 850/500 for spring rates with those tires. Please dont do what literally everyone else has done when mounting 275s on a miata and destroy your first two sets on the front shock towers due to lazyness. Remove the springs, put the tires on and compress the suspension until the bump stops bind and then turn the wheels. Adjust bump stop length until you can fit a normal sized finger tip between the tire and chassis.

Oh, if a finger tip is all I need then I might be good where I am. However, probably not gonna run rates that high on the car unless I undergo a much larger suspension investment, which is not likely to happen anytime soon. I guess raising the ride height is the only option? I was hoping some offset upper bushings or (enter another idea here) might gain me some inner clearance without taking too much camber. I think making space for the fender isn't a problem.

What math are you using for this? The bilstein setups generally sell for $500-700 used and the Xidas are like $2k. You could have the billies revalved and refreshed for $400.

I love my revalved bilsteins, and run 800/500 with them. It feels like a firm and controlled cloud.

I wouldn't bother raising the ride height, you'd need to run like 7-8" pinch weld heights to not just corner on the bump stops with those tires and rates. Just realize it's going to handle like a more extreme EStock car slamming from bump stop to bump stop as you slalom.

I've been quoted $400 for the revalve +parts. Then I would need new springs as well. I have $800 in my billy setup now with extended top hats.

I also thought Xidas were $1700 for some reason. I've seen them go $1200-1400 used, which is what I would most likely do. I rarely buy new parts.

Sure, which is why I made the thread asking if there were a way to add clearance to the inner tub (shock tower area). I don't mind the car to roll, I'm not competing in some national level events nor does this car make me money. I had access to some local take-offs from an SSM car, the price was good, co-driver offered the wheels and covered some other costs. It's an exercise in having fun while pushing limits on a budget. Not trying to go pass the event horizon on this.

Revalving his bilsteins was the first thing I mentioned awhile back. Good short-term solution, but ultimately Xidas are the answer for this car.

SM cars are supposed to use OTS Bilstein valving along with 700/325, but they also rebuild/revalve often. I know it won't be ideal, but I think running 700f/400r on the OTS Bilsteins will help save some tire life.

SM cars are also on 205 Toyos or SM7s. You have more than an extra tire there.

I mean... if I were running those, I would be running at least 1000/550.

Spring rate most important. Shocks second.

In this case, i'd run the manpants springs even if you don't have the fancy shocks to go with it. That thing is going to be horrifying otherwise.

That would be quite pushy and more spring than you'd want without manly aero.

Nah, hes already got 4 times the spring rate as they ran in E stock, and only 50mm more tire per corner.

Like a big dam, splitter, and a bigass upright nascar style spoiler?

I said manly aero, not that pussy shit.

Damn hater, don't hurt 'em.

I expect it from Leafy. We are going to test it on these rates Sunday and then head back out with 700/400 setup on my OTS valving if more issues pop up. I still think the car is going to do fine locally. Not trying to do some crazy SSM/XP build to sink my life savings into just to dodge some cones in a parking lot.

Truth, but we'll make it work.

BUT WHY NOT?! :rofl:



I'd totally run this car to beat Leafy with :D

:rofl:

Got these from a local SSM guy for cheap enough. Figured I would run them for a thrill in XP. Not looking to smash records or go against the hive mind here, just seeing if there were any easy ways to gain some clearance. I've got a 5mil spacer in the rear and had to clearance my front fender a touch. So far so good but, that's only lightly loading them up. They sound like damn tractor tires going down the street.

I know this sounds like beating a dead horse, but when I was racing on 205 section 200tw tires, 600lbs springs were barely enough to feel fast/good for that setup. With 400lbs fronts and 275 hoosiers the tire will change direction, then the car will try to follow, the shock will bottom out, and the shock of bottoming out will make you way more likely to lose grip if you're driving at the limit of the tires. If you haven't raced on hoosiers yet, the car will take off like you've buttered the wheels once you overwhelm them.

I would run those rates. The ride will be rough since the valving isn't up to par, but I did run 600/400 on OTS Bilsteins and it 'worked'.

So the car did have an issue in the rear with rubbing the tub. I ended up with a 5mm spacer. I also had a bit of clearance issues with my spats. Not sure what happened but on the driver side the spat edge caught the sidewall of the tire and ripped the back of the spat pretty badly. The passenger side had no interference. With that said, on my soft springs and the short course we managed a 3rd and 4th place finish in RAW time. I think we are going to try the 700/440s on the OTS shocks I run and see what happens at the next event. 9's with 275s seem pretty quick overall. Would have liked them to come up to temp faster but hovering in the high 40 to low 50s all day didn't help.

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You can hear it rub occasionally under compression on some bumps:



Boost is fun, got my purple crack fix this month, car is a blast. Improvements to come!

That course gave me aids. So many 135*+ short turns for no reason.