47-55.1 Unexpected disk brake - wheel problem

[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

[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).

[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]

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.

[TX3100Guy]

Originally Posted by 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.

Thanks Lee. I'm trying to salvage my investment in the 215/75/15 and 235/75/15 tires. Given that I'll need to sell the 15" chrome smoothies that I bought, I'm thinking of moving to a wider 7" Cragar wheel. It has -6 offset, which is a full 12 mm difference from the +6 I have now. Hopefully, that'd be enough to clear the calipers.

[joedoh]

Originally Posted by TX3100Guy

I'm thinking of moving to a wider 7" Cragar wheel. It has -6 offset, which is a full 12 mm difference from the +6 I have now.

no, thats only going to be an additional 6mm. thats why i tried to explain the difference in offset and backspacing but i guess I did it poorly.


when you make the wheel wider, the extra width is spread equally over the front and back halves of the wheel. so a 7" vs a 6" will have an extra 1/2 inch on the front half of the wheel (wheel mounting surface to the front lip) and 1/2" on the back half of the wheel (wheel mounting surface to the rear).

so going from a +6 to -6 will be a 12mm (1/2") difference in the mounting surface to the center of the wheel, but the actual gain in backspace is only going to be:

8/2 -1/4 (-6mm) = 3.75 backspace
and

7/2 + 1/4 (+6mm) = 3.75 backspace

zero. there will be no difference in the backspace, all the extra inch of the wheel width change will be on the front side of the rim, 1/2 inch that was already on the front side + 1/2 inch in offset change.

also, and this is kind of important to put all the way down here at the bottom but cest la vie, if the caliper right now is hitting the CENTER of the wheel, a different offset will not fix it, only a spacer will. if the caliper is hitting the rim portion of the wheel, a different offset may fix it. a different style wheel with a different center shape may fix it too.

and finally its worth mentioning, if you have the room for the extra 1" wider wheel to have the extra width all the way on the front side.... just get some 1.25" spacers and dont worry about new studs, it will move the wheel center out away from the caliper for about $50.

[mr48chev]

Stock 16 inch 4-1/2 inch wide wheels on a 53 had/have 0 offset. 15- 5.5 have 0 offset. That should give about a 2-1/4 inch backspace.

I've got what I think is a 15 inch AD wheel out here and if I can find it in the snow tomorrow I'll measure the backspacing.

This from page 155 of the GM Heritage 53 truck pfd https://www.gm.com/content/dam/compa...olet-Truck.pdf

[geezer#99]

Do you have the box and fenders on the truck?
I’d hate to see you finally figure out a rim/tire that fits your discs only to have the tire contact the fender.

[TX3100Guy]

Originally Posted by geezer#99

Do you have the box and fenders on the truck?
I’d hate to see you finally figure out a rim/tire that fits your discs only to have the tire contact the fender.

That is a really good question. The bed was on but not the fenders. To ensure that the spacer I purchased was going to work, I remounted one side and took measurements. There is another 2 inches from the current wheel/tire to the outside edge of the wheel well. The 1 1/4" spacer should work out fine. Also, the bottom edge of the wheel well is about an inch above the top of the tire, so I should be fine. Thanks for the heads up!

[geezer#99]

Originally Posted by TX3100Guy

That is a really good question. The bed was on but not the fenders. To ensure that the spacer I purchased was going to work, I remounted one side and took measurements. There is another 2 inches from the current wheel/tire to the outside edge of the wheel well. The 1 1/4" spacer should work out fine. Also, the bottom edge of the wheel well is about an inch above the top of the tire, so I should be fine. Thanks for the heads up!

I looked up your smoothies on their website.
They certainly ain’t cheap.
A 16x7 would be the way to go but still not a gaurentee they’d fit either. Sometimes the wheel is designed different when you swap to larger sizes.
And if you changed to a different rim style like the cragars, still no gaurentee they’d fit.

[mr48chev]

Originally Posted by geezer#99

Do you have the box and fenders on the truck?
I’d hate to see you finally figure out a rim/tire that fits your discs only to have the tire contact the fender.

He won't have any trouble with fender clearance with 7 inch wheels unless his axle is way too wide as 64 inche wms to wms. His whole problem is that he hasn't quite figured out that more back spacing puts the rim closer to the caliper and less back spacing puts it further away to the caliper. We have explained the problem and have given him the fix but it takes him longer to figure it out.

He could have popped a lug stud out, run to the parts house and found some matching lug studs that were 1/4 or more longer and put the spacers on and done but he has to do everything the hard way and make old man Davison cringe. fiy Mr 48 = old man Davison or Rob Davison in some groups.

[TX3100Guy]

Originally Posted by mr48chev

He could have popped a lug stud out, run to the parts house and found some matching lug studs that were 1/4 or more longer and put the spacers on and done but he has to do everything the hard way and make old man Davison cringe. fiy Mr 48 = old man Davison or Rob Davison in some groups.

Despite your belief that I "could have popped a lug stud out" which sounds so incredibly easy which must be case on the factory axle. But as I've pointed out several times, I have an aftermarket axle that would require removal of the caliper, rotors, mounting brackets, and axle shaft. Then taking the 1/2 axle to my press to just pop out the lug stud. All of that just to see if that idea is workable.

Instead, I chose to purchase a wheel adapter to see if that remedies the problem. If it does, then I can continue with my build and decide at a later date if I change my wheels and tires.

By the way, I did try washers and the 1/4" spacer with the existing lugs and it just barely worked, which is why I purchased the 1 1/4" spacer/adapter that Lee suggested, which seemed like a more constructive suggestion than critical.

[_Ogre]

why haven't you ground the interference off yet???
yeah a 1/4" less back space would have done it

and why did you mount tires on bare steel rims?
you need to dismount the tires to powder coat or paint rims
you can't tape it to keep the rust out of the crack

fyi i powder coated my steelies with an eastwood pc setup in an old oven
to avoid handling the powder, i dusted them right on the oven rack
and carefully slid the rack in
i made a rotisserie out of wood and a bearing to rotate the rim
yeah it smoked a bit but never affected the pc

[TX3100Guy]

Originally Posted by _Ogre

why haven't you ground the interference off yet???
yeah a 1/4" less back space would have done it

and why did you mount tires on bare steel rims?
you need to dismount the tires to powder coat or paint rims
you can't tape it to keep the rust out of the crack

fyi i powder coated my steelies with an eastwood pc setup in an old oven
to avoid handling the powder, i dusted them right on the oven rack
and carefully slid the rack in
i made a rotisserie out of wood and a bearing to rotate the rim
yeah it smoked a bit but never affected the pc

They are chrome rims, didn't think they needed powder coated. I'm reluctant to grind away at a brand new caliper, I'd rather fix the wheel issue.

[_Ogre]

Originally Posted by TX3100Guy

They are chrome rims, didn't think they needed powder coated. I'm reluctant to grind away at a brand new caliper, I'd rather fix the wheel issue.

My bad! The back of a chrome wheel sometimes doesn't look smooth

[TX3100Guy]

Originally Posted by _Ogre

My bad! The back of a chrome wheel sometimes doesn't look smooth

No worries, I love your idea on powder coating. Now if I could just convince my wife to let me powder coat in the kitchen......LOL

[geezer#99]

Originally Posted by TX3100Guy

No worries, I love your idea on powder coating. Now if I could just convince my wife to let me powder coat in the kitchen......LOL

That’s easy!
Buy her a new stove for Xmas and use the old one in the shop.

[geezer#99]

Now you got it figured!
Do you have a link to the 1 1/4 spacers you bought?

[TX3100Guy]

Originally Posted by geezer#99

Now you got it figured!
Do you have a link to the 1 1/4 spacers you bought?

I bought them on eBay since I couldn't find 7/16-20 studs with a 6 by 5.5 bolt pattern (to match my lugs) on Speedway or Summit.....they may have them but they made it hard to find.

Here is a link to what I bought - https://www.ebay.com/itm/262252146185

Originally Posted by geezer#99

I looked up your smoothies on their website.
They certainly ain’t cheap.
A 16x7 would be the way to go but still not a guarantee they’d fit either. Sometimes the wheel is designed different when you swap to larger sizes.
And if you changed to a different rim style like the cragars, still no guarantee they’d fit.

Yeah, #1 reason I was disappointed given what I spent for them and the tires. I'd prefer the ones I bought, so the spacer/adapter should allow me to save my current investment.

Thanks!

[mr48chev]

Originally Posted by TX3100Guy

I bought them on eBay since I couldn't find 7/16-20 studs with a 6 by 5.5 bolt pattern (to match my lugs) on Speedway or Summit.....they may have them but they made it hard to find.

Here is a link to what I bought - https://www.ebay.com/itm/262252146185

Attachment 2235484



Yeah, #1 reason I was disappointed given what I spent for them and the tires. I'd prefer the ones I bought, so the spacer/adapter should allow me to save my current investment.

Thanks!

You Buy longer studs at the local NAPA not through Summet or Speedway.

They have 16 pages of 7/16 lug studs listed. https://www.napaonline.com/en/search...%20&referer=v2

[leegreen]

geezer#99, How can you tell the spacers are hub centric? They look like they have tapered seats. The link does not appear to say specifically. Maybe there is a visual clue I am missing, but I have not had much to do with spacers.
I think I need hub rings for my wheels before I drive it so I want to learn more.

the wheels are not hub centric? - if this is the wheel in question https://www.summitracing.com/parts/usw-52-5660n

Mr48: he said he had trouble finding spacers with the right thread, not longer lugs

[TX3100Guy]

Originally Posted by leegreen

the wheels are not hub centric? - if this is the wheel in question https://www.summitracing.com/parts/usw-52-5660n

That is indeed the wheel, luckily I must have bought them before the latest inflationary price increase/gouging. I've had them for several months and paid less than that price, thankfully.

[TX3100Guy]

Originally Posted by mr48chev

You Buy longer studs at the local NAPA not through Summet or Speedway.

They have 16 pages of 7/16 lug studs listed. https://www.napaonline.com/en/search...%20&referer=v2

Actually, if you filter the 16 pages down to just studs that are 7/16-20 there are sixteen choices of varying lengths and knurl sizings. If I decide to throw out the spacers/adapters that I just bought and remove the calipers, rotors, brackets, and axle shafts to use the press to punch out six studs (on each side), so that I can press in six new longer studs and then reassemble everything so that I can use a different spacer and/or washers, I'll head to Napa.

[geezer#99]

Maybe!
Sorry to complicate things but best to be safe.
They’ll work to get you a roller for around the shop but possibly not safe to be driven on the road.
From your pic, your axles are lug centric. Your wheels are hub centric.
Your wheel adaptors are hub centric.
The wheel design is different for a lug versus hub centric rim.
Here’s a link to help with that.


https://lmr.com/products/hub-centric-vs-lug-centric