Help with wheels after disc conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

macdaddy70 · 06-20-2021, 04:04 PM

I have done searches and cant find what I am looking for. 1970 LWB GMC with original 15" wheels. Recently had all new MOOG suspension and CPP disc brakes/booster/mc/prop valve installed.
Wheels are in place, but had to add washers to clear calipers. Backspace of original wheel is about 3 7/8". Approx 1/2 inch of washers had to be added for clearance. Does that mean that I need to look for a wheel with roughly 4.5" backspace?
I wanted to stay with stock look, but going to aftermarket aluminum, dont want to use a spacer.
Pics meant to show space from rotor to back of rim and clearance from caliper to inside of rim.

**Grumpy old man** · 06-20-2021, 04:43 PM

I sure hope your not driving it like that ? those wheels are destroyed .

gmc684x4 · 06-20-2021, 05:37 PM

Drum brake wheels do not fit with disc brakes
The inside area hits the caliper

Mike C · 06-20-2021, 05:43 PM

You kept it 6 lug? If so 71-87 6 lug 4x4 rims should work just fine.

macdaddy70 · 06-20-2021, 05:48 PM

No I am not driving, but want too. Looking for wheel info so i can get the right fit on the first try.

geezer#99 · 06-20-2021, 05:59 PM

Try this.

https://www.hotrod.com/articles/ccrp...heels-fitment/

**BigBird05** · 06-21-2021, 04:13 AM

Its not the back spacing that is the problem. Its the design of the rim where it curves up. The rims were redesigned for more clearance when the trucks went to disc brakes.

**lolife99** · 06-21-2021, 12:31 PM

Look at this thread,...
http://67-72chevytrucks.com/vboard/s...d.php?t=560599

**lolife99** · 06-21-2021, 12:35 PM

Quote:

Originally Posted by macdaddy70

I have done searches and cant find what I am looking for. 1970 LWB GMC with original 15" wheels. Recently had all new MOOG suspension and CPP disc brakes/booster/mc/prop valve installed.
Wheels are in place, but had to add washers to clear calipers. Backspace of original wheel is about 3 7/8". Approx 1/2 inch of washers had to be added for clearance. Does that mean that I need to look for a wheel with roughly 4.5" backspace?
I wanted to stay with stock look, but going to aftermarket aluminum, dont want to use a spacer.
Pics meant to show space from rotor to back of rim and clearance from caliper to inside of rim.

Also do a search about backspacing.
Backspacing is the measurement taken on the BACK SIDE of the wheel.
With 15” wheels you want no more than 3.5”-4” of backspacing.
Even then with drop spindles you may need to grind a little clearance on the lower control arm.

**MikeB** · 06-21-2021, 12:48 PM

CPP strikes again! On my 69 C10 I used 73-87 spindles, rotors, and calipers with 73-87 8-inch rally wheels. Zero issues. Had a shop re-drill the rear axles for 5-on-5.

Too bad Early Classic Enterprises is gone. They sold stuff that actually fit!

Did you call CPP?

**lolife99** · 06-21-2021, 01:01 PM

Quote:

Originally Posted by MikeB

CPP strikes again! On my 69 C10 I used 73-87 spindles, rotors, and calipers with 73-87 8-inch rally wheels. Zero issues. Had a shop re-drill the rear axles for 5-on-5.

Too bad Early Classic Enterprises is gone. They sold stuff that actually fit!

Did you call CPP?

This isn’t a CPP problem.
The proble is trying to fit drum brake (pre-71) steel wheels on a disc brake rotor.

67C10Step · 06-21-2021, 03:09 PM

Quote:

Originally Posted by lolife99

This isn’t a CPP problem.
The proble is trying to fit drum brake (pre-71) steel wheels on a disc brake rotor.

Agree. All my CPP stuff fit perfectly but I knew my original 67 wheels would not fit. Went with 15x8 rally's with the correct back spacing. All fit fine with no rubbing issues anywhere.

**MikeB** · 06-21-2021, 03:28 PM

Quote:

Originally Posted by lolife99

This isn’t a CPP problem.
The proble is trying to fit drum brake (pre-71) steel wheels on a disc brake rotor.

I stand corrected. I'm just too quick to jump on CPP, having dealt with them in the past.

macdaddy70 · 06-21-2021, 07:15 PM

Thanks for responses. I ordered a couple of wheels today that should fit after doing more research. Will know for sure in a few days.

**lolife99** · 06-21-2021, 08:46 PM

Quote:

Originally Posted by MikeB

I stand corrected. I'm just too quick to jump on CPP, having dealt with them in the past.

I also hate to defend CPP because I’ve had issue with them also.
Summit Racing seems to take the guess work out of buying CPP products.
I would never buy directly from CPP.

06-20-2021, 04:04 PM	#1
macdaddy70 Registered User Join Date: Aug 2013 Location: Gluckstadt, MS Posts: 71	Help with wheels after disc conversion I have done searches and cant find what I am looking for. 1970 LWB GMC with original 15" wheels. Recently had all new MOOG suspension and CPP disc brakes/booster/mc/prop valve installed. Wheels are in place, but had to add washers to clear calipers. Backspace of original wheel is about 3 7/8". Approx 1/2 inch of washers had to be added for clearance. Does that mean that I need to look for a wheel with roughly 4.5" backspace? I wanted to stay with stock look, but going to aftermarket aluminum, dont want to use a spacer. Pics meant to show space from rotor to back of rim and clearance from caliper to inside of rim. Attached Images

06-20-2021, 04:43 PM	#2
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: Help with wheels after disc conversion I sure hope your not driving it like that ? those wheels are destroyed . __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop

06-20-2021, 05:37 PM	#3
gmc684x4 Registered User Join Date: Jul 2012 Location: Whitehorse yukon Posts: 1,218	Re: Help with wheels after disc conversion Drum brake wheels do not fit with disc brakes The inside area hits the caliper

06-20-2021, 05:43 PM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	Re: Help with wheels after disc conversion You kept it 6 lug? If so 71-87 6 lug 4x4 rims should work just fine. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-20-2021, 05:48 PM	#5
macdaddy70 Registered User Join Date: Aug 2013 Location: Gluckstadt, MS Posts: 71	Re: Help with wheels after disc conversion No I am not driving, but want too. Looking for wheel info so i can get the right fit on the first try.

06-20-2021, 05:59 PM	#6
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Help with wheels after disc conversion Try this. https://www.hotrod.com/articles/ccrp...heels-fitment/

06-21-2021, 04:13 AM	#7
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Help with wheels after disc conversion Its not the back spacing that is the problem. Its the design of the rim where it curves up. The rims were redesigned for more clearance when the trucks went to disc brakes.

06-21-2021, 12:31 PM	#8
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,681	Re: Help with wheels after disc conversion Look at this thread,... http://67-72chevytrucks.com/vboard/s...d.php?t=560599 __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823

06-21-2021, 12:48 PM	#10
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,422	Re: Help with wheels after disc conversion CPP strikes again! On my 69 C10 I used 73-87 spindles, rotors, and calipers with 73-87 8-inch rally wheels. Zero issues. Had a shop re-drill the rear axles for 5-on-5. Too bad Early Classic Enterprises is gone. They sold stuff that actually fit! Did you call CPP? __________________ Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 23 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

06-21-2021, 07:15 PM	#14
macdaddy70 Registered User Join Date: Aug 2013 Location: Gluckstadt, MS Posts: 71	Re: Help with wheels after disc conversion Thanks for responses. I ordered a couple of wheels today that should fit after doing more research. Will know for sure in a few days.



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