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"Throughout the corner, the RX-7's basic trait remains very mild understeer, however, the driver's perception is that of stable neutral steering characteristics"

No, trust me the trained driver's perception is of the reality of understeer...

 

Finding out the geometry is important if you want to make changes using more than expensive guesswork.

I could buy a bunch of different offset wheels to try and find the change I'd like, or I could get down the right road to begin with by doing the math.

It's very easy to go wrong if you don't know what's actually going on. It's very wrong to assume that stock equals good. Stock usually means safe and cheap, rather than optimal.

 

OK, good luck on that!

 

Hey all,

Just accquired some ccw's off a friend's supra. I have not rebored them yet as i wanted to see if they would work for me first before dropping at the machine shop. Here are the specs

F-18x10 +44 with a 7.25" backspacing
R-17X11.5 +51 with a 8.25" backspacing

with a well rolled fender can this be achieved?

 

if you run the 17's in the rear you will probably need a spacer to space it out from the trailing arm. the front should fit easy. perhaps a 10-15mm spacer is what you might want.

 

Thanks for the reply, i'm glad i will be able to use them!

 

Got some Work Emotions D9R in 18x9.5 offset +38 wrapped in Hankooks 255-35-18 all around.
Stock fenders, untouched, no roll no pull! car is in HKS Hipermax IV GT Coilovers, I haven't adjust them, just installed them with HKS presets settings.
No rubbing issues at all, I thought I would need to atleast roll my fenders in the front with this setup but they are fine!
Work Emotions D9R Weight 24Lb.

 

Hello

I was looking to get some help / confirmation with clearance regarding the Brembo BBK in the front (1b1.7010a) and RZ BBK in the rear.

With these rims:
BBS RG-R 18 x 8.5 +40 front and 18 x 9.5 +40 rear.

Any input would be greatly appreciated.

 

I would think you would be ok, as you are running 18s. I have no experience with brembo but am running RZ rear brakes. Only stipulation for them is at least 17" rims. Offset and rim profile (dish) will affect things and it doesn't sound like you are going too extreme.

 

Updating my previous post, I said it didn't rub in the front but after some miles the suspension looks to have settle and now it definitely rubs in the front, not so much but it rubs in the biiiig bumps on the road.

 

anyone running 18x10 +20 or similar up front with wide fenders, without rubbing the front frame? it seems like no matter what it rubs there when turning

 

What size tire?

Where is it rubbing?

 

When does it rub? Full lock? At some point, its going to rub unless you limit the steering angle.

 

285/35/18, rubs just a little before full lock, however its not aligned yet so im not even sure what the caster is at, hoping i can at least get 6 degrees with minimal rubbing. i guess full lock isnt used much other than in U turns

should it be ok?

 

Nope- tire is too tall for the front of an FD if it really is 285/35-18.

25" diameter is the max.

285/30-18 is the correct tire for that width.

Still, as your offset gets further from stock +50 you could start to have problems with wide tires hitting the fender or even the body seam at the rear of the fender well.

 

Full lock is used on the track occasionally... and in drifting.

 

i'm an idiot, its a 265/35/18 R888R. running that size square all around.

sorry!

 

That R888R 265/35-18 is a little too tall at 25.3"

I ran 265/35-18 Federals that were that tall on 18x10.5 +38 and they rubbed the plastic fender liner up front on the inside a bit and the factory mudflap on the rear of the front fender arch as well.
The further from factory +50 offset the less clearance you will have.

To properly implement a wide body front fender on the FD and the resultant lower offset wheels you have to run without the fender liner, cut up the headlight buckets and smash the body seam flat at the rear of the front fender arch.

On the other hand you can fit 295/30-18 on 18x11 +45 on stock rolled front fenders without such issues.as I did.

 

thanks for the info, i'm not running the fender liner right now and the only point of contact seems to be the back of the headlight bucket where that rectangular peice of metal is. tire being too tall would make sense, i will see if i can work it out on the alignment rack, but i guess a slight rub at full lock wont be too bad as im not drifting the car.

 

Aren't you running Hoosier A7 in that size up front as well?

The info from Hoosier says they are 25.3 inches.

Jim and Carter Thompson (and others) are running 315/30/18 in the front, though I have not asked them what was needed other than fenders to make this work. That size is 25.6 inches.

I would like to run those in front if all it required was fenders and wheels.

I would like to also run them in the rear, which can be done with (more) fender rolling and a slight pull

 

No, I haven't manned up and gotten Hoosiers yet.

I ran some used 285/30-18 BFG R1S and some 295/30-18 R888 and those Hankook TDs..

For those taller tires you have to cut the headlight bucket some on the inside front and then pound the body seam flat on the inside rear of the front fender arch.

 

That doesn't sound too bad.

 

Or raise the car ride height. I run 275/35-18 Nittos and similar size Pirelli DH slicks and raised the car about an inch to compensate. Rubs the finder liners to death but no hard metal parts. Not where I'd want it visually, but it works.

 

Sorry to kinda necro, but this seems like the most relevant thread. I'm trying to decide on wheels for my FD. I know I want to run 245s up front and I will probably never bring the car over 350 whp.

I already figured I want to get Rota Grid wheels since my only real other option for something under 20lbs which fits an FD are RPF1s which I don't like the look of. These are available in 3 possibly manageable sizes:
17x9 e42
17x9.5 e30 (seems like the worst fit)
17x10 e50

-The simplest option is 17x9 e42 front and rear with 245/40 up front and 255/40 in the rear.
This is similar to the Spirit R setup in having a slightly larger sized tire compared to the wheel in the rear than the front. Which is probably to give the rear tires a bit more give before they break traction. Except in this case, I'd have both tires stretched in a little bit instead of the front on the larger side and the rear on the maximum recommended side.

-I could do the same, but with a 17x9.5 e30 in the rear... but it's going to poke out a bit. 32mm further than Spirit R stock wheels do, though a bit less for the tire itself than that.

-17x9 e42 245/40 front, and 17x10 e50 265/40 rear
I would worry this could interfere with the rear arms being inset 0.75" over stock, though I have koni yellow coilovers and I'd guess not.
Blue II is running 18x11 e48 with 285 tires so I'd guess I'd be fine and need nothing more than an inner fender lip roll at the worst?
This does have the benefit that I could up to 275/35 tires, but I'm not going to be going up to 400+ horsepower, I don't think.

That said, I guess I'm still leaning toward the 17x9 e42 all around with 245/40 front and 255/40 rear. It's less flexible since I'm stuck with like 265 as the widest rear tire possible to fit, and the rear wheels won't be fitting as flush to the arches, but eh.

 

Careful comparing directly against OEM wheels, USDM or JDM. The factory leaves tons on the table wrt room to move outboard

The 9.5 plus 30 will fit the rear nicely actually if you have any kind of fender roll. With OEM stock fenders it's about 1/4 (6ish mm) out further than is normally recommended, but in the rear you can get away with more---especially with a slightly stretched tire and some negative camber.

You can go 17x9 plus 42 front with a 245/50 and the 9.5 with a 255 and IMO you'll be ok.

Anything I can do to talk you out of mounting Rotas on an FD ?