Correct offset for 1st gen 15" wheels

[cbuzzetti]

I need help, I am building a 1st gen enduro car and plan on using GSL-SE hubs and axles with the 4.5 x 4 pattern. What I need help with is finding the correct offset.
We will be using a 15 x 7 wheel with a 225-45-15 tire.
Anybody have any ideas on the correct offset?

Thanks

Cbuzz

[instigator]

I do not think a 15x7 wheel and tire will fit. The inner fender will rube. The only wheel i have been experimenting with is a 14x7. I am still having inner fender clearance problems.My offset that I use on the 13inch wheels is what I started with and I am aproxx 3/8 of an inch further out and face GCR conflicts.Tire perturding beyond the body work.you may have to use a 15x6.5 wheel to get the clearance you need and try using the existing 13X7 offset .I will remeasure it and give you the number later I don't remeber it off the top of my head.

[Marcus Miller]

I'm pretty sure most people are running 4 inch backspacing on the 13*7 setup....

MM

[lateapex911]

Is this for ITS or ITAA? If A,is using the GSL-SE hub legal? If S, I think the car will face steep odds against doing well...

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Eagle7]

Originally posted by instigator:
... GCR conflicts.Tire perturding beyond the body work...

Remember its the tread on the ground that can't protrude past the body work.

------------------
Marty Doane
ITS RX-7 #13
CenDiv WMR

[cbuzzetti]

Car will be run in NASA Endurance Series as an E1 car.
We have settled on the stock hubs and axles for now (with the large bearings). Testing will determine if we have to go to the bigger axles.
We have run a Pro7 with 14 x 7 wheels and 4" backspacing with 225-50-14 Toyos and have no fitment issues.
The new Toyo 225-45-15 is actually smaller in diameter and about 2/10ths wider. So the thinking is that we should be able to use the same 4" backspacing. Just wondering if anyone has done this yet.

Charles Buzzetti
ITS RX7
E1 1st. gen

[Marcus Miller]

Charlie,

You guys aiming to run the enduro at BRP in April?

If so, I'll see you there with my pro7/PS7/E2 bastard child...

Marcus
http://www.miller-motorsports.com

[cbuzzetti]

Yes we plan to run all the So-cal events and both of the CalClub enduros.
I am partnered up with Shawn Sampson of Sampson Racing Communications.
We should be able to test this car the 3rd weekend of March.

[Marcus Miller]

Cool deal. Who else is driving with you in the Cal Club enduros? I'm on the fence for those, sicne they require three drivers... (atleast the supps last year did)

The third weekend is the dbl reigonal right? We'll be down there for that, My brother is finishing his licensing that weekend.

see ya at the track!
Marcus

[cbuzzetti]

Shawn Sampson (Sampson Racing Comm.) will be my co-driver for all the events.
I think the shorter CalClub Enduros only require 2 drivers. The 6 hr requires 3 I think.
Look us up, we will be in the RV section over by 7's Only.
See you there.

Cbuzz

[[email protected]]

Just an FYI on the tire rim setup. The 15" rims w/ 38mm offset and 1/4" spacers work great.

we ran the NEW Toyo 225x45x15 w/o any rub and it just looks cool!

[instigator]

Hay Shawn, did you get the car down to 5 inch ride hieght?

[cbuzzetti]

We did not check ride height that I know of.
But there was no problems getting the car low. The big problem was the carb. Needs a good cleaning.
Too bad we did not take any pics, it looks awsome.

[ishod]

Hey all. Does anyone have an opinion (what a loaded question) about performance differences between 15" and 13". I think it's important to get the car as low as the rules allow so I wouldn't be an advocate if that was a problem. Maybe 14"? I'm curious about thoughts regarding things like how one size affects HP over the other size. Torque, gearing, etc.

I seems to me that 15" will require more low end power and torque since there is more mass on the outside diameter. Top end speed might improve???

Scott Goble
#33 IT7 MIDIV SCCA
(417) 848-7584

[[email protected]]

Hi Scott-

CBuzzetti and I are turning a Pro7 (1st Gen Rx7)into just a full blown enduro car. The 13" rim with 205 Toyos is the same size as the 15" rims w/ the new 225x45 Toyos. Unsprung weight is more but we felt that a longer lasting tire (for what we are doing) would be better.