The best setup for autocross on very small tracks

[Fii]

I have a '86 Levin Coupe with broken blue top engine in it (not sure what the problem is yet, but it most likely needs a full rebuild). I would like to build an autocross project car using my AE86 as a base for it. Most of the tracks here in Latvia are very small ones, so most of the time the second gear is used, the third gear is only used in a long straight once a lap. The car will NOT be used as a daily driver, however I should be able to drive it on street if I wanted to.

What would be the best setup for the racing described above?

Chasis
Currently the plan is to take everything apart, reweld the seams and get rid of the rust. Then paint it. Some weight reduction will be done by not putting the rear seats and the trim in the back of the car back in. Also some sport seats will be fitted in the front.

Suspension
I am planning to use the Paradise Racing coilover kit with Tokico blue shocks and Prothane bushing kit.
What spring rates should I choose?
Will I benefit from adjustable links or camber kit?

Engine
I feel that the engine for my target is not the most important factor. But everything else aside I think that low to mid rev torque is the thing that matters. What are the options to maximize the torque? I would like to keep the car NA, so no turbo or supercharging.
I see the following options:
1) Simply rebuild the blue-top
2) Get 7A-FE block and build a 7A-GE out of it (how much torque diference can I expect?)
3) Do the Black-top swap (mostly due to the ITB throttle response and VVT torque curve)

Any comments or suggestions?

[Ivan141]

Hmm... I'm no setup expert, but I can try and give you some views on the parts you mentioned.

First the chassis. Rust removal and seam welding are always a good thing to do. Weight reduction without buying any fibreglass parts is mostly done by stripping interior panels and unneccessary seats. If your going to paint it, remove the sound deadening material on the floorpan, that's good for quite a few kilo's as well.

Suspension: the place where you will need to spend most money.
I have tokico blues myself, they are nice for sporty driving, but I would buy some adjustable koni's, maybe even shortstroke (ae92) shocks.
Especially since you want coilovers, weld the whole thing up nicely.
Spring rates around 6 front and 4 back are very popular for a track car that has to be streetable. Any lower on the front and you will have problems with rubbing tires all the time (which is what I'm experiencing at the moment). The only adjustable link I would get is the panhard rod. All the other ones only take away a bit of slop at the joints, and add some strenght.
Camber plates might be a good idea. being able to adjust the amount of front wheel camber can be very usefull for you to find that ideal setup.

Lastly the engine:
1 if you rebuild the blue-top, maybe use highcomp pistons...
You could make the bluetop more usefull for 2nd and 3rd gear runs by using a shorter final drive gear set. That would give you some faster acceleration.
2: 7AGE seems to be very good for torque, but it will take less of a beating at high rpm than a 4age will.
3 20v is a very nice engine, but I think you would be better of spending the money on your suspension. With a shorter final drive the 4age will propel you just fine around short tracks.

[ZaX]

Agree with Ivan.

use yellow koni shocks, instead of tokico.
springs: Front 8kg, rear 6kg
camber kit is one of best upgrades i've made. worth every cent.
don't mess with 7afe, just rebuild 4a-ge.
black top is to expencive upgrade, also this can affect your car regulations, since you will be running car with different engine.

Have phun!

[robokill]

i have to agree on that.

but

Koni have a less greater rebound i seen on t3 site a full coilover kit which also is very nice (lot more expensive but nice)

the springs zax you say are a bit ..... hard tokico isn't the best solution for track i ahve to agree with ivan nice for sporty driving.

I am looking at rebuilding an engine and to say if you can buy a blacktop for a nice price it would almost cost the same as a good rebuild

20V make the car react totally difrent caus the torque etc is much higher and it revs difrent.

but then again you can buy a whole lot of shit for the 4age 16v for a nice price and for the 20v its alot more expensive.

I think you should check with :arrow: zax and kristians setup and then pick the best of both :-)

[Aico]

Get a real coil-over set with softer springs. For lower speeds you need softer springs and damping. Definatly get the camber plates!

[Ivan141]

'real'coil-over sets are ridiculously expensive, and often just stock struts that are shortened with shorter dampers (ae92 front shocks or sw20 rears) and welded coilover perches.

You can do this yourself if you know how to weld. It may not look as pretty, but it will work the same.
T3 sells this kind of shortstroke with KYB AGX shocks. Koni shocks are perfectly okay for this application as well.

I agree with the softer springs and dampers, but you will need 6kg up front at the least to avoid rubbing (unless you dont lower it offcourse, or use low profile tires). You dont want to roll around the course like a citroen DX like my car did when I took it to slalom last summer.

The loss of dynamic camber gain can be corrected with roll centre adjusters and camber plates for more static camber.


No-one I know on this forum has a car set up for this kind of track, so it's hard to say what works best. Try finding out what the gymkhana guys use, it's one of the few close quarters slalom-like events where ae86's are used a lot.

[NoHachi]

Don't agree with the springs remark. Spring ratio is related to the maximum possible cornering force and the need to controll camber accordingly. Maximum cornering force is related to the tires traction limit not just speed. Professional autoX setups have astronomic rates, starting around 7/4 and upward.
I would start with the std car, then upgrade tires (most important factor by far, a set of 235-45-13 AVON ACB10's is nice). Choose spring rates high enough to controll the tires grip and upgrade the rest when needed.

[Ivan141]

Well, when I said softer, I meant lower than the 8/6 springrates that Zax is using.. Those might be good rates for drifting, but overkill for slalom and other bendy tracks. I'd say you need enough springrate to stop the car from rolling like a pig, but not make it too stiff and twitchy.

[Jan Pedersen]

ZaX Wrote:use yellow koni shocks, instead of tokico.
springs: Front 8kg, rear 6kg

This isnt a great combination... Yellow koni cant handle 8kg/mm springs - Ive tried it...

I might be willing to sell you my springs and dampers, if I choose to buy a new set - they are a bit much for every day use I currently have TRD 8km/mm and matching dampers from TRD Japan...

[NoHachi]

8/6 rates sound pretty good, maybe to much rear bias. Great for drifting, not for fast times. It makes no difference whether its track racing or autoX. The max. G forces are the same, probably bigger in autoX.

Spring rates should be matched to tires. 8/6 is overkill for normal street tires, but semi slicks will need'em. Full slicks need more like 10/6