Backspacing advice on year one rims

[xlarshn]

Been quite awhile since I have logged into the forum, have a 1980 Olds Cutlass (originally a Calais) that I brought out of storage this last summer after being in storage for the last 12 years. I'd like to solicit anyone's experience or recommendation on the Year One 17 inch Super Stock II rims, specifically the backspacing. Year one website says the rims come with 4.5" backspacing, however everything I've read says I need to stay within the 3.5 to 4.0" range. My factory Olds 14x6 ralleyes have 3.5, and my set of 15x7 ralleyes have 4.0" of backspacing. Seems like the 4.5" might be to much?

I recently tore up the factory 7.5" 10 bolt rearend (sheared 3 teeth off the ring gear), that has spawned a 9" ford upgrade from Quick Performance with disk brakes, which is going to require a rim size change to clear the disk brakes. One thing continues to lead to another.

 

[565bbchevy]

I recently tore up the factory 7.5" 10 bolt rearend (sheared 3 teeth off the ring gear), that has spawned a 9" ford upgrade from Quick Performance with disk brakes, which is going to require a rim size change to clear the disk brakes. One thing continues to lead to another.

If you haven't ordered your rear housing yet and those are the rims you want to use, then you could do some "mock ups" on your 7.5" and if you need less backspace QP can add to the length of the rear to accommodate at no extra charge.

 

[xlarshn]

Originally I was set on using my 15x7 ralleyes, but was informed be QP that because of how the stock olds ralleyes are made (regardless of 14 or 15 inch rim) that they would not clear the disk brake setup on the rear. So I test fitted one of my 15 inch rims on another ford 9 inch with willwood disks and sure enough they interfered. Talked with a local "SME" and he confirmed that in order to use the factory olds rims I would have to try to find a 10 or 10.5 inch disk brake setup.

So I would take recommendations on either backspace for the Year One rims or alternate disk brake setups. I do need to go and try to mock up the Year One rims on my current 7.5" as I haven't ordered my QP rear yet.

 

[565bbchevy]

I was referring to doing mock ups with the Year One rims if those are what you want and if 4.50" BS makes them too close to the frame you could have QP make the rear wider maybe a 1/2" on each side which would theoretically bring your rims down to 4" BS compared to being on a stock width rear.
I don't know about your stock rims but on my Monte I have Wilwood rear disc on my 9" with a 2.36" offset and it clears my 15" rims with a 12.19" rotor.

 

[xlarshn]

I knew what you meant on the mock ups relative to the year one rims, my response probably could have been clearer.

Regarding the olds rims, where the outer hoop of the rim and center section of the rim are welded together there is a reduction in overall diameter that isn't on other factory ralley rims (Chevy) or aftermarket 15 inch rims. It is that reduction in diameter that is interfering with the disk brake caliper

.

 

[xlarshn]

I don't know about your stock rims but on my Monte I have Wilwood rear disc on my 9" with a 2.36" offset and it clears my 15" rims with a 12.19" rotor.

Out of curiosity, who manufactured your 9" ford? QP uses big bearing new ford (torino) flange ends with a 2.5 offset.

 

[565bbchevy]

Sorry, I thought this was about h

Out of curiosity, who manufactured your 9" ford? QP uses big bearing new ford (torino) flange ends with a 2.5 offset.

Mine is a Moser with old style big Ford, you can get the QP with whatever ends you want on it you just want to make sure your brakes are compatible with what you choose.

 

[scoti]

Been quite awhile since I have logged into the forum, have a 1980 Olds Cutlass (originally a Calais) that I brought out of storage this last summer after being in storage for the last 12 years. I'd like to solicit anyone's experience or recommendation on the Year One 17 inch Super Stock II rims, specifically the backspacing. Year one website says the rims come with 4.5" backspacing, however everything I've read says I need to stay within the 3.5 to 4.0" range. My factory Olds 14x6 ralleyes have 3.5, and my set of 15x7 ralleyes have 4.0" of backspacing. Seems like the 4.5" might be to much?

I recently tore up the factory 7.5" 10 bolt rearend (sheared 3 teeth off the ring gear), that has spawned a 9" ford upgrade from Quick Performance with disk brakes, which is going to require a rim size change to clear the disk brakes. One thing continues to lead to another.

Your quoted numbers are for a 6" & 7" wheel respectively. I'm pretty sure the Year One SS-II wheels are 8" wide so that's simply adding .5" inside & out vs your 15x7 dimension.
You should be fine.

 

[Ribbedroof]

Some will depend on desired tire width.

A 4.5" b/s fits fine to the frame, the tire is going to be the determining factor. 245s and 255s are fine, beyond that I have no personal data

 

[carnutjw]

I have 17x8 front and 17x9 rear cast aluminum (AR-VN501) rims on my 79 Cutlass, both zero offset, so 4.5" and 5" Backspacing. Rear 255/45 tires have a little room to the frame (1/4"-5/16") at static position, but apparently rub slightly in a bind based on the rub marks on the frame rail. Front 8" rims just barely clear C5 Vette 12.8" rotors with C6 two piston caliper, surely the QP rear discs aren't any bigger.