47-55.1 Unexpected disk brake - wheel problem

[TX3100Guy]

A month or so ago, I installed four disk brakes on my 1953 Chevy truck. The manufacturer of the rotors/calipers claimed that they worked with 15 inch wheels. I also purchased a set of chrome "Smoothie" wheels from US Wheels and installed them after the brakes were already done and on the old wheels.

While working on my leaf springs, I tried to rotate one of the rear wheels when the rear axle was off the ground. I found the rear wheels unable to rotate. Removal of the wheel/tire proved that the rotors and axle were able to rotate on their own. Further investigation showed that the wheels contacts the outer edge of the caliper, preventing it from rotating.

The chrome wheels are 15 inch by 6 inch wheels with an offset of 6 and backspace of 3.75. In contacting the brake manufacturer, they indicate that they designed the rotor/caliper to works with "factory stock wheels". which is not what I currently have.

Interestingly, the front wheels/tires have no issue with rotating. Which means at a minimum I'm stuck with two brand new wheels and new tires that don't work properly with the rear brakes. Even more confounding is, I don't know what size or backspace of wheel to use on the rears now. Any helpful suggestions will be appreciated.

[leegreen]

Put some washers onto the wheel studs to space the wheel out until it turns, then measure the washers?
You may just need a wheel spacer, or at least you will have some idea how much different offset you need.

Avoid the temptation to drive with the washers in there.

[TX3100Guy]

Originally Posted by leegreen

Put some washers onto the wheel studs to space the wheel out until it turns, then measure the washers?
You may just need a wheel spacer, or at least you will have some idea how much different offset you need.

Avoid the temptation to drive with the washers in there.

In the stuff the previous owner had in a box were two wheel spacers of about 1/4 inch thickness. I did try those, but given the construction of the inner wheel, they forced the wheel to be pushed out nearly 1/2 inch and as a result the lug bolts were too short to even get one thread of the lug nuts on.

I will try washers tomorrow to see if that makes a difference. Thats a good plan, thanks.

[mr48chev]

This used to be real common when putting non factory wheels on disk brake cars in the early 70's or after we started swapping disk brakes to our trucks in the late 70's early 80's.

I've taken a grinder to the high spots on the caliper and rounded them off more than once, I have a pair of those same spacers hanging in the garage that were on the disk brakes on my 48 when I had it subframed. That means those are 41 years old.

The good thing is that all you need to have is enough clearance that the wheel doesn't hit the caliper, As the pads wear the caliper will move away from the wheel.

First step is follow Leegreens's advice and figure out how much space you need.

[dsraven]

I have done both of the aforementioned things with new disc brakes or new wheels or both. the other thing I am curious about is whether you have the steering connected to the spindles. I ask because the next problem you may encounter is that the outer tie rods may rub the wheels on their back side. if the wheels are aluminum they tend to be thicker that the steel wheels, for strength, so those thicker wheels are sometimes just thick enough to interfere with the tie rod joint.
I usually try to set things up so I can use a wheel with some common size and back space, that way you can find some cheap wheels and tires to use when working on the vehicle. no worries about getting welding slag burnt in or oversprayed with paint or primer. since building doesn't usually happen in a week sometimes guys that buy new wheels and tires when they start the build find that by the time the project is complete those new wheels are out of vogue and the tires are outdated, so possibly need replacing. We all start with good intentions but then life gets in the way.

[dsraven]

some steel wheels are also made with a deeper "groove" or recessed are in the center of the donut. this smaller diameter area is sometimes what rubs the brakes.maybe you can find a wheel with a larger diameter center section?

[_Ogre]

Originally Posted by mr48chev

I've taken a grinder to the high spots on the caliper and rounded them off more than once, I have a pair of those same spacers hanging in the garage that were on the disk brakes on my 48 when I had it subframed. That means those are 41 years old.

this. grind it

[57tailgater]

Did you get the kit for 5 or 6 lug wheels? The 5 lug will have rotors off a 70's Camaro with a smaller diameter rotor than the 6 lug kit which uses parts originally for 16" wheels and a larger diameter rotor. Even though the 6 lug kit says can be used with 15" wheels it can be tight depending on the wheels like you have found out. I have a 6 lug kit and with the wheels I am going to use it will take some grinding on the calipers, a spacer and no wheel weights on the area where the caliper is near the wheel.

[TX3100Guy]

Originally Posted by 57tailgater

Did you get the kit for 5 or 6 lug wheels? The 5 lug will have rotors off a 70's Camaro with a smaller diameter rotor than the 6 lug kit which uses parts originally for 16" wheels and a larger diameter rotor. Even though the 6 lug kit says can be used with 15" wheels it can be tight depending on the wheels like you have found out. I have a 6 lug kit and with the wheels I am going to use it will take some grinding on the calipers, a spacer and no wheel weights on the area where the caliper is near the wheel.

6 lug axle with 15 inch wheels. As I mentioned, the fronts are free and clear. The rear are binding on the outside rear edge of the caliper.

I just tried the spacer again and managed to get the lugs to catch by a thread or two. With the spacer and the gap that exists between the spacer and the chrome wheel due to its configuration (looks stamped) it adds about 5/16 of an inch, the caliper just clears, but not by much.

I need a quick study of offset versus backspace to determine what is needed to make this work. I'm tempted to try a 16 inch wheel, but that has a big financial penalty given I already own new 15 inch wheels and tires.

[TX3100Guy]

Originally Posted by TX3100Guy

I need a quick study of offset versus backspace to determine what is needed to make this work. I'm tempted to try a 16 inch wheel, but that has a big financial penalty given I already own new 15 inch wheels and tires.

So I just did a quick study of offset versus backspace. It appears to me that my issue is related to offset. My current wheels are 15 inch by 6 inch wheel, with an offset of 6 and backspace of 3.75.

The wheel is set back to far on the axle, allowing the inside edge of the rim to rub against the outside edge of the caliper. If the offset were 0 or negative, the wheel would be moved outward and away from binding on the caliper.

I went to the US Wheel website where I purchased the Chrome "Smoothies" and see that there is a 15 inch by 7 inch wheel available that has a "0" offset and a 4.0 backspace. By moving the wheel 6 millimeters outward I think my binding issue would go away.

Thoughts?

[57tailgater]

Sounds like you may have a somewhat easy solution. Just make sure you have fender clearance and sufficient thread engagement on the wheel studs for the lug nuts.

[mr48chev]

Wrong way, you need a 3 to 3.5 inch back space. 4 puts the inside rim closer to the caliper yet. Most likely you won't even be able to get a 4 inch backspace wheel on the hub with the caliper on.

[mr48chev]

This link that I snagged those images off does a fairly decent explanaiton.

https://www.roughcountry.com/blog/wh...explained.html


This may explain it a bit simpler Again 4x4 site but your problem now is too much backspacing and more backspacing will increase the problem. https://ok4wd.com/blog/the-differenc...d-backspacing/

[TX3100Guy]

Originally Posted by mr48chev

This link that I snagged those images off does a fairly decent explanation.


This may explain it a bit simpler Again 4x4 site but your problem now is too much backspacing and more backspacing will increase the problem. https://ok4wd.com/blog/the-differenc...d-backspacing/

I get it now. I need a wheel with a negative offset.

As for the trick with the washers, I stacked three 1/2 washers on each stud after measuring their thickness with my caliper. They were 9/32 of an inch or about 7 mm. Which is darn close to measurement of the other 15 inch wheel that I mentioned. While it fit and the wheel turned, the caliper was only clear by the finest measurement known to man (as my Dad used to say). It's unfortunately clear, that simply buying a 15 by 7 inch wheel with 0 offset and 4 backspace will not work and as you mentioned, is moving in the wrong direction.

Should I just consider moving to a 16 inch wheel with -6 offset and 3.75 backspace?

[TX3100Guy]

Maybe a good question for the group is, what size wheel and tires do you run on your truck? 15, 16, 17, 18 inch wheels? Tire size? Same tire size front and rear?

[_Ogre]

15x9 rims from wheelvintiques 4 wheel disc brakes, 4" bs

[TX3100Guy]

Originally Posted by _Ogre

15x9 rims from wheelvintiques 4 wheel disc brakes, 4" bs

Power steering? How does it steer with 9 inches up front?

[mr48chev]

I've run 14-7 on the front since around 1975 and used to run 14-8-1/4 Crager Mach 8's on the rear, Since around 1990 it has had Enkie 32's 14x7 on the front and 15x8 on the rear with 195-60 14 on the front and 255-60-15 on the rear. That for a staggered hot rod look with the percentage of sidewall to wheel on the fronts pretty close to the precentage of sidewall to wheel on the rear being fairly equial Per what Boyd Coddington suggested in the late 80's. Most of his earlier builds had a larger diameter wheel on the back than on the front and had that balance between front and rear.

Back when it still had the Crager Mach 8s on it.


Still and I know that some might get tired of me saying it, Wheel and tire choice have to match your total build theme and have to be a working and contributiting component of the total look. They shouldn't overpower the truck and turn it into a background for a wheel add but on the other hand they shouldn't look settled for as most white spoke wheels scream on old trucks. When you look at a vehicle your eyes should not pick out one specific component before they take in the whole vehicle as a total package. That is any part of the rig unless you are specifically looking for that part. If you scroll down the page or flip pages or are walking though a show and your eye picks out a component before you see the whole rig as a unit that component is wrong for that truck.

[TX3100Guy]

Originally Posted by mr48chev

I've run 14-7 on the front since around 1975 and used to run 14-8-1/4 Crager Mach 8's on the rear, Since around 1990 it has had Enkie 32's 14x7 on the front and 15x8 on the rear with 195-60 14 on the front and 255-60-15 on the rear. That for a staggered hot rod look with the percentage of sidewall to wheel on the fronts pretty close to the precentage of sidewall to wheel on the rear being fairly equial Per what Boyd Coddington suggested in the late 80's. Most of his earlier builds had a larger diameter wheel on the back than on the front and had that balance between front and rear.

Back when it still had the Crager Mach 8s on it.


Still and I know that some might get tired of me saying it, Wheel and tire choice have to match your total build theme and have to be a working and contributiting component of the total look. They shouldn't overpower the truck and turn it into a background for a wheel add but on the other hand they shouldn't look settled for as most white spoke wheels scream on old trucks. When you look at a vehicle your eyes should not pick out one specific component before they take in the whole vehicle as a total package. That is any part of the rig unless you are specifically looking for that part. If you scroll down the page or flip pages or are walking though a show and your eye picks out a component before you see the whole rig as a unit that component is wrong for that truck.

I pretty much agree with you. Given the pedigree of this truck (was a pusher truck on the Bonneville salt flats), a 1959 261cu/in inline six engine with a McCulloch supercharger, a vertex magneto, and a Hallibrand quick change diff. I'm definitely going for more of a hot rod look than a low rider.

While I have 15 inch wheels, I did have slightly different sizes 215/75/15 front and 235/75/15 rear. I'm really torn on what to do to correct my disk/caliper issue. It seems that when I find a wheel size that has the appropriate offset (negative) it seems too wide for the brand spanking new tires I already own.

[TX3100Guy]

Originally Posted by mr48chev

I've run 14-7 on the front since around 1975 and used to run 14-8-1/4 Crager Mach 8's on the rear, Since around 1990 it has had Enkie 32's 14x7 on the front and 15x8 on the rear with 195-60 14 on the front and 255-60-15 on the rear. That for a staggered hot rod look with the percentage of sidewall to wheel on the fronts pretty close to the precentage of sidewall to wheel on the rear being fairly equial Per what Boyd Coddington suggested in the late 80's. Most of his earlier builds had a larger diameter wheel on the back than on the front and had that balance between front and rear.

Back when it still had the Crager Mach 8s on it.


Still and I know that some might get tired of me saying it, Wheel and tire choice have to match your total build theme and have to be a working and contributiting component of the total look. They shouldn't overpower the truck and turn it into a background for a wheel add but on the other hand they shouldn't look settled for as most white spoke wheels scream on old trucks. When you look at a vehicle your eyes should not pick out one specific component before they take in the whole vehicle as a total package. That is any part of the rig unless you are specifically looking for that part. If you scroll down the page or flip pages or are walking though a show and your eye picks out a component before you see the whole rig as a unit that component is wrong for that truck.

I pretty much agree with you. Given the pedigree of this truck (was a pusher truck on the Bonneville salt flats), a 1959 261cu/in inline six engine with a McCulloch supercharger, a vertex magneto, and a Hallibrand quick change diff. I'm definitely going for more of a hot rod look than a low rider.

While I have 15 inch wheels, I did have slightly different sizes 215/75/15 front and 235/75/15 rear. I'm really torn on what to do to correct my disk/caliper issue. It seems that when I find a wheel size that has the appropriate offset (negative) it seems too wide for the brand spanking new tires I already own.

[geezer#99]

Use your spacers, grind a tiny bit more clearance on the calliper and install some longer wheel studs.
For those who think the spacers are the weak point, I’ve used them for years on trucks/cars with way more power and torque than your set up produces.
JMHO

[mr48chev]

When I took that photo in 1982 At the Chevy-GMC Truckin Nationals in Ogden I had a 68 Camaro Subframe with 72 Monte Carlo disk brakes on the front and a 66 Impala 12 bolt posi under the rear. That is after I did have to use spacers and had to grind on one corner of the caliper for clearance.

Still I have to believe that you can get by with just a bit of a spacer. get a hand full of flat washers and go one layer at a time until you have clearance and the measure the stack. Don't forget that it isn't very hard or expensive to swap out the lug bolts for longer lug bolts. That is under 20 bucks a side if you do it yourself.

I'd add that I think your choice of simple chrome wheels and those tires do give it that all business push truck look. I might go as far as actually build a push bar for it. If you drove it to Bonneville for speed week that sure would one up those posers who paint drag car classes on their rust buckets and pretend that they are old land speed cars hoping someone will take a photo of it.

[TX3100Guy]

Originally Posted by geezer#99

Use your spacers, grind a tiny bit more clearance on the calliper and install some longer wheel studs.
For those who think the spacers are the weak point, I’ve used them for years on trucks/cars with way more power and torque than your set up produces.
JMHO

My reply from Post #14 above -

As for the trick with the washers, I stacked three 1/2 washers on each stud after measuring their thickness with my caliper. They were 9/32 of an inch or about 7 mm. Which is darn close to measurement of the other 15 inch wheel that I mentioned. While it fit and the wheel turned, the caliper was only clear by the finest measurement known to man (as my Dad used to say).

[TX3100Guy]

Two question.

1) Does anyone know the backspace/offset dimensions of the stock factory 15 inch rims?

2) For those of you without power steering, what is the size of the tires you are running up front?

[leegreen]

I could measure a factory 16 in a day or so if that helps.
I seen online sources saying the base tire for 1/2 tons was 15 and 16. At least around here all the trucks I found back in the day were 16s.....I wanted 15s with the factory shape to the centre and cap clips and never found any.

I have 15x8 aluminum slots, 235/70 on rear and 215/60 front, I like that look.

I've driven other trucks with 235/75/ front and no power steering and it was not a problem.