im putting this in the FI section because of the power level.. think it will fit better here then in the suspension area.. but what do i know?


505 hp/330 tq on ap1 wheels with good RE71 225 square setup.


getting some chatter and wheel hop in 1st and 2nd. if the tires blow off (like they normally do in 2nd) then its fine but if i get traction i can feel it shutter and hop a little. i know im going to eat a rear end and ive already split many axles and a transmission.. its lowered on some suspension but i cant remember/dont know what, but good quality stuff... just wondering what else i can do thats "very effective" ... ive heard the hasport Diff mounts?. also im at 25-45 degree outside temps - 60-85 IAT so its probably making more than 505 right now...


thanks,

Matt

 

I think you're simply under tired. When I first got my ap2, stock power levels, stock suspension, it would hop like mad if traction broke on take off, like if traction was marginal to begin with.

It turned out to be tires. When the tires that came on the car wore out (some Kumho max summers), replaced with S04, no more issues.

In your case I don't think its the tire construction, rather its size. You got way too much power for the size.

If you can find someone to temporarily swap wheels, you can see if it solves or greatly lessons the issue, before you invest in a wheel and tire package.

 

How do undersized tires in anyway cause wheel hop?

 

Insufficient traction, which results in wheelspin, but which induces a harmonic bouncing of tire such that it gains traction and loses it in quick, rhythmic succession.

The factors that can cause the harmonic are many. But preventing wheelspin prevents the factors that lead to wheelhop.

Prevent the wheelspin, prevent the wheelhop.

 

i also have the 17" ap2 wheels.. but there are some street tires on there and theyre worn... so with them theres absolutly no wheel hop BUT theres also no 1st... 2nd...or 3rd gear, its just right to the limiter.

im planning on running 245/45/R17 RE71's in the spring.. or is there a better tire option??


i guess, then... my question is..


if i keep my hoppy wheel and tire combo, are there other modifications that will greatly help my current issue, or is it strictly a wheel/tire issue?

 

Finally someone running 245/45/17 tire. Very smart. The increase in sidewall height will effectively raise your gearing 3% and the taller tire footprint will help with straightline traction. This is what im getting when my tires wear out. Planning on getting the Michelin Pilot Sport 4S. We are damn lucky they make it in 245/45/17 size. Please post up picture of how the tire size looks on oem rims. Again the taller sidewall will improve ride quality, raise effective gear ratio, and drop rpms on highway cruising this is a must for street driven S2K imo

 

A 275/40/17 or even 315/35/17 if you have the right wheel would be a better option yet. The problem with going with too tall a sidewall is you start running out of tires that are firm enough in their sidewall construction to give you good predictable handling without having the rear end swaying around on you with how quick/sharp the turn is on this car. It can actually be pretty dangerous I've found. And then second point, what would you run up front with this rear 245/45 pairing? Your going to have rubbing issues running that up front, or... your going to run a near normal overall diameter up front which will throw off your handing and brake bias. Your better off sticking to close to OEM overall diameter, increasing the widths and compound to get the best balanced handing and strait line grip. Nitto NT01 and Toyo R888R to name a couple great R comp options that come in the sizes that I mentioned, which are a increase in overall diameter within reason, wile significantly improving contact patch, compound and retaining firm sidewall construction for not giving anything up in handling control.

 

Wheel hop will kill the rear end on this car pretty quick. The weakest link in our rear end is the carrier bearing end caps flex from this abuse, and that in turn separates the ring and pinion gear away from each other, and then you break off the teeth/have a failure. There have been companies in past like Comptech that have offered bolt in carrier bearing end caps that reinforces/stack over oem and in theory increase the stiffness reducing some likely hood of this damage happening. Puddy Dad also can build these diffs in stages offering some level of durability depending on how much you want to spend.

If I were the OP, I would acquire a good used spare diff now in anticipation for a near future failure to either swap in as is or take opportunity to build up some, and then get a different wheel that can accommodate some wider tire options without rubbing to increase your traction in lower gears, and also tune the car for boost by gear so you can actually use 1st and second gear without blowing the tires off or getting wheel hop issues. Stiffer Hasport or the like rear diff mounts will help some as well I'm sure. You will likely want to do all of these things in combination to effectively put down your current power.

A 225 in the rear is just silliness and unsafe.

 

To fend off potential backlash to this totally justified comment if taken out of context, At this sort of power level (OP has >500 whp!), a 225 rear is silliness and unsafe...

 

i have like 400whp and blow off 285 re71s if the tires are cold, ground is even the slightest bit moist or its below 55*. you might want more than 245s and move to something wider yet