Shell Valley Ride Height / Backspacing

blykins · #1 (**permalink**) 10-15-2003, 04:17 PM

Guys...

I'm getting ready to purchase some wheels for my SVC. I really don't think the backspacing they specify looks correct...plus I think there's too much room between the tires and the back fender lip.

Is this easily corrected by just ordering wheels with a different offset to just tuck the wheels in a little more...and then tightening the coilovers up to get the ride height down?

It seems as though it would be this simple, but I'm just asking for expert opinions.

ravedemon · #2 (**permalink**) 10-15-2003, 06:27 PM

i'm dieing to know that myself............i plan on putting 17" wheels with 315-35-17 tires and still have no idea what size wheel to ask for.........as soon as you know for sure please let me know....
thanks
Jason

blykins · #3 (**permalink**) 10-15-2003, 06:35 PM

Well for now I'm concentrating on the rear...and I know I wanna go with a 15x10. Shell Valley specifies what backspacing to use, but I don't think it looks right at all. They stick out too much. I think they should probably be shoved in about another inch or so. That shouldn't be much of a problem.

Actually I'll probably follow Team III's advice on figuring offset...just pull a wheel and tire off of another vehicle (in this case my Mustang GT), stick it on there....then measure how far you want the tire to move each way. Then measure the front and rear spacing of the mock wheel and add/subtract as needed. I think we have plenty of room to do what we want...and I don't think an inch is gonna hurt much. I wanna tuck the tire in just enough so that I can lower the car a little bit without the tire getting into the fender lip. Ah....the joys of doing it yourself.....

Jack21 · #4 (**permalink**) 10-15-2003, 06:43 PM

Actually, it's not that simple, given all the variables.

And given that you're going to be spending at least $1,200 - $1,500 on wheels; $400 - $800 on tires. We should get this one right the first time.

What backspacing does SV recommend, F, R, using what size wheels and tires? Do you intend to use this size wheels and tires?
Does SV offer a "Factory" wheel? What is its' size and backspacing?

What front suspension are you using? MII stock? MII aftermarket tubular w/coil overs? What front brakes are you using?

What differential are you using? '80's and early '90's Mustang 8.8's are one width. From about '95 up, they get wider requiring more backspacing. Other FoMoCo 8.8's off Continentals are wider requiring more backspacing.

Case in point. I have a Classic Roadsters (CR), not an SV. But they are similar.

Plus sizing to a larger tire/wheel. Some like the originality of a 15" wheel/tire. And with due respect, 15" wheels/tires were the performance tires of the mid '60's and '70's. Grocery getters were running mostly 14" tires, and some econo-boxes 13"ers. That was then. Today, the performance tires are at least 17", requiring a 17" wheel. Going from a 235/60R15 to a 235/45ZR17 tire will give you a tire that is the same diameter (roughly 25"), and a narrower sidewall because there is no sidewall bulge. Tires are less likely to rub the fenderwells at the sidewall bulge. Backspacing should only change if you go to a (substantially) wider tire and wheel.

My CR front is aftermarket MII with 11" brakes. Factory (CR, not Ford) wheels were Cragar 15" x 8" w/4" backspacing. Factory tires were 235/60R15. I plus sized to 17" wheels and tires. Wheels were 17" x 8", tires were 235/45ZR17. Backspacing remained the same at 4".

Rear is '84 Mustang 8.8. Brakes are SVO Mustang rear disk brake conversion kit which uses T-Bird Turbo Coupe 10" rotors. No dimensional changes from original drum brakes. (But some disk brake conversions do have dimensional changes, in, or out.) Factory (CR, not Ford) wheels were same as front; 15" x 8" Cragars with 4" backspacing. Tires were 255/60R15's.

I plus sized, and plus width'd to 275/40ZR17 tires, and used a 17" x 9 1/2" wide wheel. Ideally, the backspacing should put the wheel centerline directly on the the wheel mounting flange centerline, or 1/2 wheel width. I measured the tire to inner fenderwell clearance, and outer fenderwel clearance and found them about the same. My ideal backspacing should be 1/2 wheel width, or 4 3/4". But if my eyeball calibration is off and additional clearance was needed, would it be easier to shim the wheel out a smidgen, or in a smidgen. I ordered my rear wheels with a 5" backspacing thinking I could shim the wheel out a smidgen if necessary. It wasn't necessary. Everything fits, and everything works.

Ride height. Assuming your front and rear ride height can be adjusted, here's what I've found to be the determining criteria.

First, find out what the lowest point between your car and the ground is. This will likely be the "Chin" portion of the frame, the oil pan, the bellhousing, or the trans. The softer your front shocks and springs are, the greater this distance should be. 5" - 6" should be the absolute minimum for street ground clearance. And this will determine your front ride height.

Rear ride height is a little more flexible because car parts should not be in danger of scraping the pavement due to speed bumps. Once front ride height has been set, look at the rear. You want the top of the rear tires, and the bottom of the rear fenderwell to be apart by 1" - 2". If you have to do a lot of adjusting at the rear, you might have to readjust your front.

Now roadtest it. No rubbing anyplace? Now go to an alignment shop and have the front end alignment dialed in. Yeah, they look at you and say, "We don't do those here!" Be persistant, explaining that the front end is a '76 - '78 MII. This the front end shop has alignment spec's for.

blykins · #5 (**permalink**) 10-15-2003, 06:43 PM

If you look at this picture of CSX-4039, you'll see what I wanna accomplish. I think if the tire was moved in about an inch from the current SV spec...it would be fine. It just takes a little tongue-in-cheek work with some mock-up tires/wheels.

blykins · #6 (**permalink**) 10-15-2003, 06:51 PM

Jack, thanks for your post...here's a few answers for you.

I wanna go with the original 15" wheels. I'll probably be going with the Team III wheels. I have a Mustang II front suspension with coilovers...and a 9" rear with coilovers.

SV recommends a 15x7 in the front with a 3.5" backspacing....and a 15x10 in the rear with a 4.5" backspacing.

However, I don't think this looks right at all...and if I can change it, I want to. I will be going with the tires they recommend though.....295's on the hindend and 235's up front.

I've attached another file....it's off of SV's webpage. You can see what I'm talking about. It looks like you can just get out, lock in the front hubs and go four-wheeling. The back tires need to be pushed in...and the hindend needs to be dropped. Again, my feeling is that I just need to find the correct offset on the wheel, and I should be fine.

ACC427US · #7 (**permalink**) 10-15-2003, 07:08 PM

I got really wrapped around the axle trying to get my front end off the tires and teh 427 off teh ground! When I finnally took the car to a real shop, they tested the springs which were only 350#. They measured the shocks and found the shaft length was too short. They scrapped the coil overs and the shocks I got from SV and got some that are about an 1 1/2 inches longer and it works great.

Bottom line: Be careful or you can really get yourself upside down.

ROMANBUILT · #8 (**permalink**) 10-15-2003, 07:18 PM

I bought the 15" Team III wheels with the recommended spacing and sizing from Shell Valley. Personally I think they look great, and fit the wheelwells perfectly. However, I will be the first to admit they do not have that original look because the original wheels and tires did not fit the wells as well as these do, they are set back from the edge of the wells. Then again, from the pictures I have seen I dont believe the original tires were as wide as the new ones. It all comes down to personal taste.

Good luck with it.

RB

Jack21 · #9 (**permalink**) 10-15-2003, 07:54 PM

Went with TeamIII's on my CR. They're 17", and a great wheel. Absolutely no problems with the wheels subsequent to installation. Tires mounted right up, wheels balanced right up, and no problemswith nearly 15,000 miles on 'em.

If you've shopped around, Team III is about the least expensive "Halibrand" look alike on the market. $300 vs $500 apiece from Compomotive. Granted, the Compomotive is a beefier, and bulkier wheel compared to the Team III, but for street use the Team III has worked out just fine. They're a small shop so be patient with them (OK, be extremely patient with them). They're a quality product and worth the wait.

If you're using a MII front suspension, you probably want to use a 15" x 8" wheel with a 4" backspacing.

Assuming your diff is the same width as a stock mid-80's Mustang 8.8 (better check this), you can split the backspacing (1/2 wheel width). I think Team III offers wheel widths in 8", 9 1/2", and 11", you're going to have to go narrower (9 1/2"), or wider (11") with the wheels.

My gut for a 295 rear tire would be the 9 1/2", with a 4 3/4" or 5" backspacing.

Are you sure we can't talk you into considering the 17" wheel/tire alternative????? Man, this was a big one for me. The purists saying 15", and the Factory (BFG, Pirelli, Bridgestone, Falken, etc) telling me, "Man, You want 17's if you want performance.

"I don't want what looks like forklift truck tires (17") on my Cobra. Tough, tough, tough decision. Sprung for the 17's, and once driven on, never looked back. They look factory, but the traction has got to be experienced to be appreciated. Most guys on this forum won't drive their 15" tired Cobras in the rain. The car behaves like a Hockey Puck. Wet road traction with 17's is as good as dry road traction.

Just consider your options before you plunk down your $$$$.

blykins · #10 (**permalink**) 10-16-2003, 03:43 AM

Well, what I like about Team III, is they say they can custom build any offset due to the fact that they are welded 2-piece wheels. So if I want a backspace at 4.375....I suppose they could build it right?

red99z · #11 (**permalink**) 10-16-2003, 04:18 AM

Look at my SV cobra.... I have the recommended wheel sizes. I think they look good. (click on the camera by my user name)

McCobra · #12 (**permalink**) 10-16-2003, 06:11 AM

Jack 21,

I would like to see a picture of your wheel and tire setup on your Classic if you have one available.
Thanks, McCobra

blykins · #13 (**permalink**) 10-16-2003, 06:55 AM

Red99z

Your car does look right...I wonder what the difference is? You're using the backspacings given by SVC? What sizes are your wheels and tires? And are you using the stock coilovers? Your ride height looks good too.

Let me know your secrets... :-)

red99z · #14 (**permalink**) 10-16-2003, 09:53 AM

Blykin,

15X10 rear 15X7 front... on one the bake spacing was off by 1/4 inch (i forget which one... I think the rears though) so actually the tire sticks out 1/4 inch further then the recommended ones. they are the stock coilovers buuutttttt the engine is not in the car in those pix. I now have the engine in and need to adjust the coil to the height that I like.

blykins · #15 (**permalink**) 10-16-2003, 09:57 AM

So you are using 295's in the rear and 235's in the front, right?

Would you happen to have the info on the wheels you used? Since I am a fellow Shell Valley owner, I'm hoping you'll hook me up. Your car looks very good. I wished I were that far along.

Any info you can give me would be helpful. Even front face and rear face measurements....or you could give me the brand and model of the wheel and I could call and get them myself. :-)

Jack21 · #16 (**permalink**) 10-16-2003, 10:38 AM

McCobra, send e-mail to jwalsh21@ix.netcom.com and I'll return shots of car with 17" TeamIII wheel & tire setup.

red99z · #17 (**permalink**) 10-16-2003, 10:40 AM

295's on back 235's up front... I'll have to get the wheel info from home (i'm at work right now). I'll do what i can for ya.

RED

Junket · #18 (**permalink**) 10-16-2003, 02:06 PM

I am runing BFG G Force TA with tread ware of 200 17X 91/2 W/5 1/2 BS 275-40 rear 17X8 W/3 1/2 BS on 225-45 wish I had 7 1/2 on the front the tire sticks out about 1/2" to far. Had to adjust the coilovers 3-4 times after things settled in. Don't remember what Dana told me would work but this is not it.
I like the G Force they hook hard
Ken

McCobra · #19 (**permalink**) 10-16-2003, 04:46 PM

Everyone,
Here is a great TIRE dimension calculator that I ran accross.
Hope it helps with your tire/wheel changes.

http://discounttire.com/dtc/brochure/info/tireMath.jsp