I don't have the E4 myself but I've had the E3 ever since it came out. Just ran for the first time on those SJT tires. The standard foam tire setup should get you in the right direction. You'll just have to kind of adjust your driving style a bit to compensate. Cuz those rubber tires will never be able to be as grippy as the foam no matter how much you try. All I did really was change my front toe in to 0 degrees, added just a tick of caster and filled the dampening tubes to compensate for the rising grip on the Black Carpet (I usually start out with a higher viscosity in the beginning of the race day and go to a lighter viscosity as the grip comes up) Schumacher includes an excellent section going through each adjustment in the back of their manual. I have never even switched my front springs since building the kit but I do play around with the rear spring a bit. I think the only options that I've got for the E3 was that I bought all of the springs and that's it. Not sure how the E4 is but I can say that the E3 is definitely still a contender out there. Hope this helps.

Oh, almost forgot, One thing that I did do that I've pretty much never done in the past, is not use any traction additive on the front tires. Only sauced up the rear tires. Even with using just a slim part on the front tires is very very twitchy to me. I ran all quals and the main with no sauce on the front tires and it worked great. Qualified second, probably would have finished second also but had a very bad crash that moved the battery and that was it for that race. Just took my car off at that point just to avoid any more issues. Of course this is all subjective, there were a few that used sauce on the front tires, but if they did it was just a little bit. It was just way to twitchy for me to handle.

Ran 17.5 for the first time but I had to file away about 1mm of CFK from the lower pod plate in order to fit a 52t pinion with the 76t spur to get to 90mm rollout.
Luckily the pod plates had enough room to shift the motor in position...
How is the rest doing this??
I saw smaller spurs are available from kawada and I think Xenon but getting them wont be easy.

Same as you already did.

RW makes down to a 63-tooth and should be widely available in Europe.

https://rwracing.co.uk/product/aceta...tal-diff-spurs

Thanks!!

Same, I chucked a router burr style end mill in my drill and clearanced it.

I think imma design a pod plate for 17.5/21.5 guys soon. Got the material to toss on my mill. I couldn’t find a small enough spur in stock.

just got an eclipse 4 to run at amain new track with the crc black carpet. i have a few questions about the gt class on the hub part u4975 rh washer carrier. is that hub for a diff or can u use it on the spool as well. if u use the narrow gt contact tires on a 12th scale does that bring the track width to 165 to run any gt body. does anyone sell the scott jake rubber tires without using paypal. i got the acura body and was wondering if the foam bumper off the atom would fit or are people modifying some other foam. the kit i got had a few issues with missing parts and i,m not sure if the bumper i got is supposed to be countersunk on the bottom where the body posts goes. not sure if i have the right countersink to do it myself or if i should just use a panhead screw instead.

Sorry for the late reply, but in case you didn't get answers to these already....

I've been running my Eclipse 4 extensively in US GT12 trim on CRC black, and I've been very happy with it. I'd be happy to answer any questions you have.

The U4975 is for a diff. If you want to run a spool with the three-screw wheels, Schuie now sells a full kit for that - U8178.
If you want to run a ball diff ( I prefer the diff to a spool with the SJT tires), you'll want U8171.

SidePiece Racing sells the SJT tires now, and they do have a card option. sidepieceracing.com

For the front bumper, the Atom 2 front bumper is a direct fit onto the Eclipse 4, and fits the modern GT12 shells nearly perfectly. I sanded mine just a hair, as it was a tad long for my BittyDesign 720.
As for the screws on the bottom, my front end came the same way, so I'm assuming this is by design. I just ran a countersunk screw in the hole and snugged it down. no issues with dragging.

Hope this helps!
-Jesse

thanks for the reply. i saw your video and put the ball diff in and it's much easier to drive but feels like it's slower or diffing out in the turns and the nut backing off even though it's pretty tight at the start of a run. u say the awesomatic gear diff offset doesn't work but do u know if the xray or arrowmax gear diff could fit.or maybe a different thrust bearing set up like the slapmaster with no bellvue washers but i can't seem to find the slapmaster one. on the front i went with a 1.5 mm spacer in the front and no spacer in the rear should be more than 5 degree caster and was wondering if i could get more ride height if i remove some droop shims from under the hub. i'm down to 40mm front tires and trying to get 3.5mm ride height in the front . now i.m at 3.2 mm ride height just not sure if u can change ride height with droop shims

I have run both the Xray and the Awesomatix gear diff in my eclipse without issues. I have not tried the Arrowmax one as of yet. I will say the Awesomatix one is far superior, in my opinion, to the Xray gear diff. The buid quality is top notch and you can use any spur gears that you want. I am currently running a thin spur like the RW ones mentioned earlier in this thread and they are very good too. You will need to use the appropriate spacers to get the correct width is all. The other thing you need to do is either cut the wheel screws shorter or add shims so that you don't bind the screws onto the end plates of the gear diff.

Out of curiosity does the nut you are using have the little peice of nylon still in the one end? If not that is a possible reason it is loosening off during a run. This was common in the old days when we use to use a plastic 11/32 nut on the diff if you tightened it down just that little too much and stripped it even the slightest.

Yes you can change the ride height with the shims there too if memory serves me right.

Jon

Jon not sure why Jesse couldn't fit his awesomatix gear diff in but maybe your running a lmp body at 172mm track width and the gt bitty 720 body is to narrow in the rear and the tires are gonna stick out at 172mm.Jon how narrow can u get with the gear diff by grinding the wheel screws down. i,m at 6 9/16 in. with a tape measure which is about 166mm and my montech acura body just fits . i think the sjt tire are mounted on jft rims and have a little narrower offset than some brands but not sure. haven't run foams yet because i got no trurer and don't know anyone local that i know that has one

That makes sense then as you said I am running LMP style and not the GT12 style of bodies or tires.

The only reason to grind the wheel screws down was not to make it more narrow but so that when the tire was bolted to the hub it did not hit the gear diff housing and prevent it from turning freely.

I don't have any reference for the SJT rubber tires as I only run on foams for our class locally.

Jon

i guess i'll need a wider body to run a gear diff then if u can't go narrower than 172 track width with the gear diff

My dad sent me pictures of his GT12 spec eclipse 4 yesterday. He had some parts from his previous Atom build he chucked into a lathe and turned down the length to make width with the SJT’s. Whatever’s clever!