Truck rallys and disc brakes problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

howzzzit · 08-04-2024, 01:31 AM

I know there are several posts about this subject, but here we go again. I have a set of 15x8 truck rallys with 4 inch backspacing. They will not mount over the original brake calipers. Truck is original and original ride height with no modifications. It's been stated this type of wheel is compatible with disc brakes as long as they aren't larger aftermarket calipers. I have a 72 C10 with disc front/drum rear. What gives? I haven't tried them on the rear drums, but if they won't fit the front they are useless to me. Bought these at a swap meet and a lesson learned. Any thoughts? (other than I'm screwed) Thanks
One thing I notice is a slight inward taper of the rim toward the hub. Normal?

PowerdbyChevy79 · 08-04-2024, 03:49 AM

Quote:

Originally Posted by howzzzit

I know there are several posts about this subject, but here we go again. I have a set of 15x8 truck rallys with 4 inch backspacing. They will not mount over the original brake calipers. Truck is original and original ride height with no modifications. It's been stated this type of wheel is compatible with disc brakes as long as they aren't larger aftermarket calipers. I have a 72 C10 with disc front/drum rear. What gives? I haven't tried them on the rear drums, but if they won't fit the front they are useless to me. Bought these at a swap meet and a lesson learned. Any thoughts? (other than I'm screwed) Thanks
One thing I notice is a slight inward taper of the rim toward the hub. Normal?

What is keeping them from fitting? 15x8 rallys should fit with no problem on a 72 c10. Do you have any pics of the wheels?

**jerry moss** · 08-04-2024, 11:27 AM

Quote:

Originally Posted by PowerdbyChevy79

What is keeping them from fitting? 15x8 rallys should fit with no problem on a 72 c10. Do you have any pics of the wheels?

are you sure they are truck rallys, factory truck rallys weren't available until a few years after disc brakes became standard equipment on all GM light duty trucks. post some pics so we can see where the problem is.

howzzzit · 08-04-2024, 02:28 PM

Thanks. I'll send pics asap. Won't go through it says a security token missing. That's a new one.

**dmjlambert** · 08-04-2024, 03:27 PM

I have encountered that and fixed it by reducing the picture size to 2000 pixels wide and add the pictures one at a time. You can still compose a post with 5 pictures, but just upload them one at a time.

howzzzit · 08-04-2024, 03:48 PM

Thanks DJ. It worked.

**Rust_never_sleeps** · 08-04-2024, 04:16 PM

I have no insights to offer, but maybe slap some painter's tape on the inside of the rim to show you where it's rubbing(without marking the metal). Maybe a blobby weld, or something you can clean up.

**too much stuff** · 08-04-2024, 09:30 PM

They should fit without issue. Are they stamped 15x8jj or something similar? My only thought is maybe aftermarket but even those SHOULD fit.

**Smitty** · 08-04-2024, 11:27 PM

Can't remember for sure. But when I went with the 115x8's on my '71 the issue wasn't with the calipers. But the problem was because of the dropped spindles that were interfering. Had to grind a small amount of material off to get the needed clearance. So take a look at this area instead of the calipers. It's been 20+ years ago, so can't remember exactly where the rub was. But in that era I think this was somewhat a problem often encountered. Best of luck.

howzzzit · 08-05-2024, 12:46 AM

Quote:

Originally Posted by Smitty

Can't remember for sure. But when I went with the 115x8's on my '71 the issue wasn't with the calipers. But the problem was because of the dropped spindles that were interfering. Had to grind a small amount of material off to get the needed clearance. So take a look at this area instead of the calipers. It's been 20+ years ago, so can't remember exactly where the rub was. But in that era I think this was somewhat a problem often encountered. Best of luck.

Smitty it's stock suspension. I'm gonna mess with it tomorrow or the next day. Been too hot. Thanks for the reply.

PowerdbyChevy79 · 08-05-2024, 01:16 AM

Quote:

Originally Posted by howzzzit

Smitty it's stock suspension. I'm gonna mess with it tomorrow or the next day. Been too hot. Thanks for the reply.

Those look like regular rallys... the should fit with no issues … especially with stock suspension.

SCOTI · 08-05-2024, 09:19 AM

Post an image of the truck as well as one of the front suspension & spindle.

GASoline71 · 08-05-2024, 04:17 PM

I had some raised areas on the casting line on the backs of the disc brake calipers on my '72. I had to take a grinder and smooth out the backs of the calipers for them to not rub on the 15x8 slot mags I used up front.

Gary

**jaros44sr** · 08-05-2024, 06:31 PM

image by [url=https://www.flickr.com/photos/97391199@N06

If I couldn’t run my 6lug slotted steel wheels,I’d be hard pressed to choose something else

No problem bolting them on with suspension or calipers, but it’s 4WD………

SCOTI · 08-06-2024, 12:05 PM

Quote:

Originally Posted by jaros44sr

If I couldn’t run my 6lug slotted steel wheels,I’d be hard pressed to choose something else

No problem bolting them on with suspension or calipers, but it’s 4WD………

6-lug car 'Rallys' are definitely aftermarket vs an OE 15x8" truck 'Rally'.

howzzzit · 08-06-2024, 02:03 PM

Quote:

Originally Posted by howzzzit

I know there are several posts about this subject, but here we go again. I have a set of 15x8 truck rallys with 4 inch backspacing. They will not mount over the original brake calipers. Truck is original and original ride height with no modifications. It's been stated this type of wheel is compatible with disc brakes as long as they aren't larger aftermarket calipers. I have a 72 C10 with disc front/drum rear. What gives? I haven't tried them on the rear drums, but if they won't fit the front they are useless to me. Bought these at a swap meet and a lesson learned. Any thoughts? (other than I'm screwed) Thanks
One thing I notice is a slight inward taper of the rim toward the hub. Normal?

OK I'm a dumb a__. The rims weren't hitting the calipers like I first thought. The wheels Have been powder coated. In fact, twice. Wrong color the first time. Anyway the problem was the wheel center. Just enough powder coat buildup to keep the rim from seating. I used a drum sander on all four wheels and now they all fit perfectly. Didn't take off much, but it worked. Thanks for everyone's replies. Maybe this will help somebody down the line. I can now sleep tonight.

68Gold/white · 08-06-2024, 04:27 PM

Festus, if you rode a horse like everyone else, instead of that mule, you might not have these problems!!!!!!

**jerry moss** · 08-06-2024, 05:02 PM

Quote:

Originally Posted by 68Gold/white

Festus, if you rode a horse like everyone else, instead of that mule, you might not have these problems!!!!!!

08-04-2024, 01:31 AM	#1
howzzzit Registered User Join Date: Dec 2005 Location: Kalifornia Posts: 351	Truck rallys and disc brakes problems I know there are several posts about this subject, but here we go again. I have a set of 15x8 truck rallys with 4 inch backspacing. They will not mount over the original brake calipers. Truck is original and original ride height with no modifications. It's been stated this type of wheel is compatible with disc brakes as long as they aren't larger aftermarket calipers. I have a 72 C10 with disc front/drum rear. What gives? I haven't tried them on the rear drums, but if they won't fit the front they are useless to me. Bought these at a swap meet and a lesson learned. Any thoughts? (other than I'm screwed) Thanks One thing I notice is a slight inward taper of the rim toward the hub. Normal?

08-04-2024, 02:28 PM	#4
howzzzit Registered User Join Date: Dec 2005 Location: Kalifornia Posts: 351	Re: Truck rallys and disc brakes problems Thanks. I'll send pics asap. Won't go through it says a security token missing. That's a new one.

08-04-2024, 03:27 PM	#5
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,816	Re: Truck rallys and disc brakes problems I have encountered that and fixed it by reducing the picture size to 2000 pixels wide and add the pictures one at a time. You can still compose a post with 5 pictures, but just upload them one at a time.

08-04-2024, 03:48 PM	#6
howzzzit Registered User Join Date: Dec 2005 Location: Kalifornia Posts: 351	Re: Truck rallys and disc brakes problems Thanks DJ. It worked. Attached Images

08-04-2024, 04:16 PM	#7
Rust_never_sleeps Senior Member Join Date: Jun 2022 Location: San Ramon,CA Posts: 570	Re: Truck rallys and disc brakes problems I have no insights to offer, but maybe slap some painter's tape on the inside of the rim to show you where it's rubbing(without marking the metal). Maybe a blobby weld, or something you can clean up. __________________ 1970 C10 Custom longbed 350/350

08-04-2024, 09:30 PM	#8
too much stuff Roadtrip! Join Date: Feb 2003 Location: Grand Rapids MN Posts: 13,773	Re: Truck rallys and disc brakes problems They should fit without issue. Are they stamped 15x8jj or something similar? My only thought is maybe aftermarket but even those SHOULD fit. __________________ 67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto

08-04-2024, 11:27 PM	#9
Smitty Senior Member Join Date: Dec 1999 Location: Spring Valley, Ca. Posts: 1,134	Re: Truck rallys and disc brakes problems Can't remember for sure. But when I went with the 115x8's on my '71 the issue wasn't with the calipers. But the problem was because of the dropped spindles that were interfering. Had to grind a small amount of material off to get the needed clearance. So take a look at this area instead of the calipers. It's been 20+ years ago, so can't remember exactly where the rub was. But in that era I think this was somewhat a problem often encountered. Best of luck. __________________ Smitty '71 Short Fleetside Spring Valley, Ca.

08-05-2024, 09:19 AM	#12
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 22,041	Re: Truck rallys and disc brakes problems Post an image of the truck as well as one of the front suspension & spindle. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

08-05-2024, 06:31 PM	#14
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,713	Re: Truck rallys and disc brakes problems image by [url=https://www.flickr.com/photos/97391199@N06 If I couldn’t run my 6lug slotted steel wheels,I’d be hard pressed to choose something else No problem bolting them on with suspension or calipers, but it’s 4WD……… __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

08-06-2024, 04:27 PM	#17
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,393	Re: Truck rallys and disc brakes problems Festus, if you rode a horse like everyone else, instead of that mule, you might not have these problems!!!!!!

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