Hi Folks,
Just spent a ton of money on 4 new wheels & tires for my 68’ 442 rag. It has the factory 4 piston disc brakes up front. I was told everything would fit with no issues etc. The trouble is, the outside of the caliper is contacting the inside of the wheel preventing the wheel from turning/spinning freely. This is a bummer. Do I need to swap out the 68’ four piston calipers and rotors to the newer style single piston caliper used on 1969 to 72’ cars? Will that work? Thanks in advance for your assistance!

 

It works, and is what I have.

 

How much room do you need? If you only need 1/16" - 1/8", I might try to clearance the caliper first. Remember that the 67-68 4 piston calipers are solid mointed not floating like the 69 up, so they should not move around much once you get good clearence. If they are the original date coded calipers for the car, you might want to get a new pair of calipers rather than grinding on your origianls.

 

I would have thought that with the move from 14s to 15s the old 4-piston setup would work. Was this factory equipment or was your car retrofitted?

 

I had a similar interference problem and found that putting large OD, 0.015-thick hardened washers on each wheel stud gave the wheel enough clearance to spin freely.

 

Yes- all original / unmolested. Calipers are the original GM 68' calipers and rotors for 1968. I thought about wheel spacers but am not certain that would look great. Additionally, it may compromise the front end somewhat by extending the front wheels away from the car- not sure what impact that might have on things. I suppose washers would be the poor mans approach to things and allow me to slowly build up the required height that I need to push the wheel away from the rotors. I get grinding the surface of the contact area on the caliper but can't bring myself to mar the finish of an original set of GM four piston calipers that we pay so much for nowadays. I just wish the folks at Wheel Vintiques would have disclosed this PRIOR to me spending good money. Surely I can't be the first one to bring this to their attention??

 

They are happy to cash your check and let you deal with any issues.

 

The issue isn't the 14" or 15" wheel hoop. It's the center. They're ALL the same size in the centers whether 14" or 15" hoops. So even with 15", they both meet in the middle at the same locations.

It sounds to me it may either a backspacing issue that wheel vintiques never will admit to being wrong, but the tape measure doesn't lie, or the hoop design on the inside. The lips and drops and ledges and overall shape could be different than the originals that actually fit. They did it all over the place on the SSIII rims they used to sell. Knowing them, the 15" hoop they use on the SSI would likely be the same hoop, thus the backspacing would likely be a tad deeper. The SSIIIs would clear the single piston brakes, but not sure of the quads, even with a 1/4" extra backspacing than factory.

 

The originals didn't actually fit though. You couldn't get SS I's with disc brakes in '68, which is actually the origin of OP's problem.

Good call on the centers v. rims -- I never really stopped to think that one out.

 

Maybe not the SSI, but there was SOME original wheel that actually fit. And that clearance is what needs to be investigated further and compared to what the desired wheel setup is. If it's only a slight rub, I'd agree with shaving down the caliper a bit for clearance, but if it's going to need something like a 1/4" spacer or something, I'd probably opt for a different wheel. JMO.

 

The four piston calipers came from the factory with 14" wheels.

 

WVI-52-5734438
Wheel, Oldsmobile SS1, Steel, Chrome, 15 in.x 7 in., 5 x 4.75 in. Bolt Circle, 4.375 in. Backspace, Each
(Mfr. #: 52-5734438).

Did you order this part number? 8 years ago I upgraded my 68 to 15" SS1s to replace the 14" SS2s. The above part number is what I ordered from Summit.

I upgraded the car ~35 years ago to the single-piston disc brake design. I used 72 Cutlass spindles, calipers, caliper brackets, rotors, and flex line frame brackets.
(Still running the 72 rotors with the wear groove in the middle! How's that for USA Delco iron).

Not sure if the 69 & up calipers will bolt up to the dual piston spindle? At a minimum, you will need the single-piston caliper bracket, the caliper, and possibly the flex line. The frame bracket for the disc brake flex line may be different too?? I know the drum flex line uses a different frame bracket vs the disc. I believe the disc bracket is reproduced. Worst case you'll need spindles too.

I'm not trying to be rude (we don't need any more of it here or in this world), but who put the unsightly weights on the outside of the rim? That's a BIG no-no. It will compromise the chrome and encourage rust.

Bust the tires off (with a touchless tire changing machine) and coat the whole wheel with good paste wax, including the bead area. WD-40 the gap between the hoop & the center (B4 wax) to thwart rust.
Then take them to a competent shop w/a touchless machine and use the appropriate stick-on weights on the backside. Wax & WD-40 them annually and they will last.

Do you plan on installing chrome lug nuts? If so make sure they are not chineasium junk, for safety, correct profile & longevity.
Make sure they are the correct profile taper to match the OEM shaped hole.

You spent a lot of $$ don't want to see them get damaged by the weights or the wrong lug nuts.

 

Not SS I's, though.

 

Which was entirely due to the design of the early SS I wheels, since the early SS I wheels didn't clear the single piston calipers either.

 

Ok, so, the answer is, it depends. There's multiple SSI's. Some of them fit disc brakes, some don't and this has nothing to do with the SSI center, but the hoop.

66-69 all chrome 14x6: does not fit oem disc
Certain 69 all chrome 14x6: does fit oem disc
70-72 trim ring 14x6: does fit oem disc.
72 all chrome 14x7: does fit oem disc.

Those repro rims, it depends what hoop geometry they were using. I have two sets of 69 SSI all chrome 14x6 oem wheels and 69-72 caliper disc brake take off spindles set, assembled. I have put one of the wheels on it and spun it. Please also remember all SSIIs clear oem disc; the same hoop was used, just with different center.

See Joe's picture.

 

i would try an 1/8" spacer, you seem to have plenty of threads sticking out of the lug nut.

 

+1. Problem solved.