My next mini-project is going to be converting the power drums on my 56 Olds Holiday 98 to power discs up front. The bracket kits that I'm finding from reputable sources say I will need to use 15" "disc brake wheels" in lieu of the standard 15" wheels that work fine with the drums. Obviously I understand the reason why, that the shape of these wheels will not interfere with the caliper. I get that part. My question is, specifically, what year or model wheels will work for this application? Is there an aftermarket supplier of these wheels where I can just buy new ones? Will I be able to continue to use my stock caps, and are there specific versions that will work better for retaining the caps? A little help here would be appreciated
I converted a 58 T bird to discs and had to use 69 mustang wheels .The 58 hubcaps worked on the new rims.
Youre going to be 5 x 5” PCD aren’t you. So for factory steels that came on disc equipped cars it’ll be big GM stuff like C10s I’d have thought.
Its probably the center hub hole interference, similar to Fords. I mean isnt this similar conversion to Tri-5 chevys?
Disc brakes became increasingly common on American cars around 1966 - 1967. After that they were for all intents and purposes universally available at least as an option for all but the lightest economy cars.
It's also the rim profile, as the back of the drum brake wheels are a tapered funnel shape, not the cylindrical shape needed for discs.
I think the term disk brake wheels also indicated the addition, or enlargement, of cooling slots or vents to provide better air circulation around the brakes.
My apologies to the Ford guys............. A bit OT but if you have a 67 Nova with factory disc brakes (read that as RARE), and your plan is for 14" rally wheels, the only one that will fit, is the "DA" coded wheel, in 14x5", again, RARE. Many years back I had three full sets of them.
A drum brake is flat at the wheel mounting surface. A caliper extends past this plane. Wheel must have clearance for this. Labeled overhang here. As said American cars started getting discs in the mid to late 60s. Those of the late 60s tend to be narrower than the 70s and often restorers will create demand for them. So narrow and harder to find and more expensive or wider and likely easier and cheaper to find. Most will not accept old center caps. Full wheel covers may or may not fit. A very deep style like the 50s Caddy probably will not.
It's got nothing to do with cooling, and everything to do with clearance. For instance, try to run a stock wheel from my '64 GTO on a later A body with factory discs, and the inside of the wheel scrubs on the caliper.
^THIS^ I tried it when I was a teenager. '73 Chevelle w/ a flat. Put an earlier "drum brake" wheel on it. The wheel wouldn't turn. Clearance issues. A lot of the GM ones have a flat area that the lugs bolt through. The drum wheels weren't flat there. If you need 5X5, look at big GM cars from the '70s-'90s.
Done numerous disc brake conversions and never bought any wheels labeled as "disc brake wheels". Simply do the conversion, and check the wheel fitment to see it clears the caliper.
Some years/versions (police package) of Caprice had the 5 on 5" bolt pattern you need. Otherwise you'd probably be looking for C10/van wheels. 15x7/8 half ton wheels would probably be the most plentiful. The wheel cover should fit just fine, the difference is in caliper clearance on the back, both in open diameter on the rear side of the wheel and clear distance from the wheel mounting surface. I've tried drum brake Impala wheels on a disc brake front end to see how they interfered. If you buy an aftermarket wheel from a brand like Wheel Vintiques, US Wheel, Wheelsmith, etc., they are all disc brake compatible.
For the big GM cars in that age range not all have the right bolt pattern. 71-76 Caprices had a 5 on 5" pattern 77-90 Caprices had a 5 x 4.75" pattern UNLESS it had the 9C1 (police) package, then it was 5 on 5" 91-96 Caprices had a 5 on 5" pattern, but some (not all) had aluminum wheels 2WD Chevy trucks/vans had 15" 5 on 5" steel wheels that are typically easy to find
The American Torque Thrust D wheel was created to clear the caliper. The curved spoke sets it apart from the original Torque Thrust.
Looks like some of the BS artists showed up again. "disk brake wheels started with the advent of disk brakes and the extra clearance needed for the calipers. It;s the shape of the inner side of the rim and nothing else. Easy to see when yo you have a drum brake wheel and a disk brake wheel side by side but I don't think I have a drum brake wheel on the place for show and tell photos. The standard trick in the early 70's when you bought a 71/72 Chevelle with disk brakes was to use a "disk brake spacer" to space your older custom wheels off the hub enough to clear the calipers. Any 73/mid 80's full size rear wheel drive caprice, Buick , Pontiac or Olds with 5 on 5 lug bolt pattern should have the right wheels/ On Chevy and Olds you have to watch because they could come with either 5 on 4/3/4 with 7/16 studs and nuts that took a 3/4 lug wrench or 5 on 5 that had 1/2 inch studs with nuts that normally take a 13/16 lug wrench. Center hole register I am not positive but that is where you take your calipers wheel hunting. 71/80 something C 10 should work but many of those run wider stock rims.
Sooo very simple - Disc brake wheels have a "pentagon" shaped center hole, the hoop tapers out from the wheel center on the backside. Use chalk on the top of the calipers to check for slight clearance issues - usually burs on the tabs that attach the centers to the hoops.
Thanks for the input fellas. I agree that it mainly has to do with clearance for the caliper, as @RodStRace points out with the diagram posted. A buddy saw this post and reached out that he has a set, so hopefully that's the case. I'm looking to gather all the necessary parts and tools to do this job and then just attack it all at once. Thanks for the help guys, this makes a lot of sense
I have Torq Thrust TTO's which are built like old style Torq Thrust and they have plenty of clearance for my disc brakes. Mine are 15"x5" size.
Not all cars are created equal but more importantly they have changed the TTO design (from its 1963 spec) to clear disc brakes. The D was originally a magnesium race wheel and the curved spoke allowed them to keep the strength (without just making the spoke cross section thicker/heavier) that would have been lost by merely cutting the spoke for clearance. The strength of aluminum is higher allowing them to cast in caliper clearance. They were on the 65 GT350 R Model so maybe developed in late 64 - AI says they were on the Corvette Grand Sport (63/4) but that is an error those cars had an oddball pin drive wheel. They were probably used on Vettes when they became available and were maybe needed to clear the rear disc brakes when they were added to the Vette in 1966. The "D" Signifies Disc Brake Clearance: Released 1965 the 'D' variant was a direct response to the adoption of disc brakes on mid-year Corvettes and other performance cars, which required more room than the original straight-spoked Torque Thrust permitted. Design Evolution: While the original Torq Thrust (1963) had straight spokes, the Torq Thrust D featured curved spokes to clear calipers.
I never had a car with disks until sometime in the '70s, so there's a big blank spot in my '50s and '60s wheel education. But there were times in the '60s, when I was drag racing "muscle cars", I needed 15" wheels to mount slicks for the track and big ol' Mickey Thomsons for the streets. The common problem at the time was the 15" stock steel wheels on the "big" GM cars, like the Olds 98s, had a different bolt pattern than the 14" stock steel wheels on the GM (ie: mid-size cars). My solution was to buy the 15" Corvette steel wheels to mount my slicks and 'Mickeys'. The 15" Corvette wheels had the same bolt pattern as the 14" GM wheels. Although I didn't have disks, I'm sure the Corvette steels could clear disk calipers.
I started with Speedway's small brake kit on my J. MII sized rotors and GM metric calipers. 14" Sears Radar wheels fit fine but I though I needed more pad contact with the rotors. I went up to 11" rotors and made brackets to fit the metric calipers and then the Radars wouldn't fit. Went with 15" Torque Thrust Ds. All good now. Gary
Its probably because the disc brake kit uses 12'' rotors. the majority of disc brake conversions use an 11'' rotor note its nothing to do with 'i'll just wang on a 11'' rotor from 75 gm 75 ford - 75 mopar its more to do with @I BET@ the chosen rotor best matches the original cars hub face and wheel mounting position or geometry. one thing to note is with an aluminium wheel, the thickness is about 1/2'' at the tyre bead on a steel wheel its 1/8'' gm cars get discs in 1970, the same disc is used to 77 1968 sees a federal law in the us and a which says you cannot sell a car with riveted steel wheels anymore and they have to be welded - -its because , you would get a puncture in your inner tube, the air would leak out of the rivet holes the 1968 federal law also stipulates the switch to wheel rims requiring a snap bead or bead locks or what ever you call them - -clinchers as there is a transition to tubeless tyres. what may have been happening was, the 65 mustang - -65 porker and 65 bmw are the first cars in the world to have factory fitted aloominoominoom wheels of which you cannot run a inner tube in - -something like that and so you could if you like buy a tyre that didn't need a tube and physically fit it to a leaky rusty rim without a bead lock and the tyre would leave the chat before the first turn. I am of the op onion that the aftermarket wheel business owes its existence to peaople knowing this in 1970 . BUT you can go out now and spend 250 bucks on a 16'' steel wheel thinking it will take a 175 75 16 commercial van tyre only to find it is designed to run a tube and early tyre.
To answer your question about where top buy them, I recommend WheelSmith. They may be able to make what you need so you can put your caps on, I've used them and the quality of their wheels is very good, give then a call.
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