front brakes: 1" vs 1.25" - The 1947 - Present Chevrolet & GMC Truck Message Board Network

swb85 · 08-10-2010, 10:01 PM

What all is different in the front brake system between the 1" and 1.25" rotors? Is it just the rotors and spindle or are the calipers and pads different too? I've got 1.25" rotors on my truck and want to swap to the 1" setup to fit the new lowering spindles I picked up. What all parts do I need?

texasfunk · 08-10-2010, 10:06 PM

You will indeed need the rotors (of course) and calipers as well, and with that I believe pads, but can't quote me on that.

booger69 · 08-11-2010, 02:52 AM

i did this same swap the pads are the same you will need calipers rotors and brake lines for the 11x2" brake set up

swb85 · 08-11-2010, 09:03 AM

The rubber brake lines are different too?

**lolife99** · 08-11-2010, 09:41 AM

Quote:

Originally Posted by swb85

The rubber brake lines are different too?

No.
EDIT:
I stand corrected by post below.

booger69 · 08-11-2010, 12:13 PM

yes the ends that go on the calibers are different first pic is for 1.25" set up and second is for 1"

westofb · 08-12-2010, 01:37 AM

Are the wheel bearings, races, and grease seals the same....not that it matters to me but the original poster will probably need to know this.

booger69 · 08-12-2010, 01:52 AM

forgot that part but yes they are different

swb85 · 08-12-2010, 10:17 AM

Thanks guys, yet another parts store run tonight I guess!
This budget lowering job (shackles/hangers/spindles) has now cost me over twice as much as I planned on, and about 5x as much time.

I need a new (cheaper) hobby.....

LONGHAIR · 08-12-2010, 07:48 PM

Quote:

Originally Posted by swb85

This budget lowering job has now cost me over twice as much as I planned on, and about 5x as much time.

That's why the kits only "seem" expensive........Trying tp "piece" things together can be costly and still not be "better" in any way, usually a compromise at best.
A well engineered kit is far easier to deal with and generally pretty predictable. (lowering or lifting)

swb85 · 08-13-2010, 10:40 AM

Quote:

Originally Posted by LONGHAIR

That's why the kits only "seem" expensive........Trying tp "piece" things together can be costly and still not be "better" in any way, usually a compromise at best.
A well engineered kit is far easier to deal with and generally pretty predictable. (lowering or lifting)

I actually bought a nice "kit" with shackles/hangers & spindles. What bit me is that my truck originally came with 1" brakes, so I ordered spindles for 1" brakes without measuring my rotors......but it turns out at some point before I got the truck, someone put 1.25" brakes on it and I didn't find out until I got in there. I couldn't return the spindles, so I had to replace the rotors/hubs, wheel bearings, calipers and brake lines just to make the spindles work! On top of that, my ball joints and tie rods were trashed when I got in there, so I had to rebuild most of the front end. On the back end, the 4" drop made my drive shaft too long so I had to have it shortened and rebalanced. Moral of the story, don't ASSume anything and measure EVERYTHING first.

shimp · 08-13-2010, 10:50 AM

Quote:

Originally Posted by swb85

I actually bought a nice "kit" with shackles/hangers & spindles. What bit me is that my truck originally came with 1" brakes, so I ordered spindles for 1" brakes without measuring my rotors......but it turns out at some point before I got the truck, someone put 1.25" brakes on it and I didn't find out until I got in there. I couldn't return the spindles, so I had to replace the rotors/hubs, wheel bearings, calipers and brake lines just to make the spindles work! On top of that, my ball joints and tie rods were trashed when I got in there, so I had to rebuild most of the front end. On the back end, the 4" drop made my drive shaft too long so I had to have it shortened and rebalanced. Moral of the story, don't ASSume anything and measure EVERYTHING first.

I used to lower a lot of trucks, and this is a typical issue. Most all C10's have 1.25" brakes in my experience. I think the only C10's with 1" brakes would have to have been the 6 cyl trucks. I guess there should be a "lowering FAQ" here on the forum that has information like "be sure to actually measure your brake rotors before orderering drop spindles" might save someone some headache.

shimp · 08-13-2010, 10:52 AM

Never had an issue with Driveshaft length though. You must have put a manual trans in your truck, most came with an Auto? I never had issues with Drive shaft length when lowering a standard amount, like 2,4,6 inch drop kits for rear.

kevinr1970 · 08-13-2010, 04:37 PM

Potential dumb question, but the 1" vs. 1.25" refers to the thickness of the rotors right?

LONGHAIR · 08-13-2010, 05:34 PM

Quote:

Originally Posted by swb85

I actually bought a nice "kit" with shackles/hangers & spindles. I couldn't return the spindles, so I had to replace the rotors/hubs, wheel bearings, calipers and brake lines just to make the spindles work!

Seems like a shakey vendor situation there. That seems like a simple thing for them to fix, even if they made you send the wrong ones back to them first.

Quote:

Originally Posted by kevinr1970

Potential dumb question, but the 1" vs. 1.25" refers to the thickness of the rotors right?

Yes, not so dumb either. Someone else wanted to know too....they just didn't ask.

swb85 · 08-14-2010, 09:15 AM

Quote:

Originally Posted by LONGHAIR

Seems like a shakey vendor situation there. That seems like a simple thing for them to fix, even if they made you send the wrong ones back to them first.

Guess I should have worded that differently. They would have let me return them like you say (send old ones back first, I pay shipping), but this truck is my daily driver and I couldn't afford to be w/out a vehicle for 2 weeks while I sent the 1" spindles back and waited on new spindles to be shipped/delivered. The option I chose was a little more expensive, but it was WAY faster and now I know that everything in my front end is in good shape.

shimp: Yes I swapped the M21 into my truck and the drive shaft isn't the original. I don't remember what I got it from, but it fit so I used it! Was just an inch too long after dropping the truck 4".

Chlsnk · 08-14-2010, 11:11 AM

Quote:

Originally Posted by shimp

I used to lower a lot of trucks, and this is a typical issue. Most all C10's have 1.25" brakes in my experience. I think the only C10's with 1" brakes would have to have been the 6 cyl trucks. I guess there should be a "lowering FAQ" here on the forum that has information like "be sure to actually measure your brake rotors before orderering drop spindles" might save someone some headache.

This post really got me parinoid I just ordered drop spindles for my truck with 1" rotors

.

rocket_customz · 02-03-2017, 11:35 AM

Sorry to resurrect a dead post but does anyone have part numbers for the 1.25 calipers, lines, etc..?
My parts catalog just lists RPO codes and I'm having trouble finding which is which

thanks

bbbc10 · 02-03-2017, 03:44 PM

Any auto parts store should have that info on their website they ask u what brakes u have when y buy then in person

Sinisterv10 · 04-24-2017, 11:35 PM

Hello everyone,
Not wanting to take over this post, but i figure it was the most appropriate and recent post.

I've been reading many of the posts on here, and i have a 1960 that i already swapped in a 1985 front suspension. however my front suspension doesn't have the rotors for me to measure. I want to use the 91 camaro rotor so i can have the 5 on 4.75 bolt pattern as i already have some skinnies for the front and its not a DD so the thinner rotor is no big deal. Like i said, i read several post but my question is how do i know what spindle i have, i know i need the spindle for 1" rotor to be able to use the camaro rotors. These are the measurements i got so far.

2.0" at the base of the spindle where the bearing sits
1.37" where the inner bearing sits
0.84" where the outer bearing sits

If anyone has the measurement for the 1" and 1 1/4" rotor spindle that would help me out.

bbbc10 · 04-25-2017, 01:05 AM

pretty sure u have the 1" spindle don't think they had that option in later years think it stopped in 82

Sinisterv10 · 04-25-2017, 02:02 AM

Quote:

Originally Posted by bbbc10

pretty sure u have the 1" spindle don't think they had that option in later years think it stopped in 82

That would be sweet. I guess i'' pick up a camaro rotor and bearings tomorrow and see if it fits.

Keith Seymore · 04-25-2017, 07:29 AM

Here's the brake release chart for '87 (should be the same for '85 - I just happened to have this one handy).

The 1" rotor goes on the manual brake applications (JB1), and the lightest duty power system (JB3). The majority of the vehicles were built with the 1.25 rotor (JB5 system).

K

SCOTI · 04-25-2017, 08:27 AM

The difference in spindles (Which ones do I have?) can be verified by checking what wheel bearings fit since the 1" brake rotors use different (inner?) bearings.

Sinisterv10 · 04-26-2017, 01:55 AM

Well i picked up some bearings from the parts store and apparently i have the spindles that go with the 1.25" rotors so the camaro rotor swap is out unless i get aftermarket lowering spindles or stock 1" spindles. Since the truck is not a DD im having the rotors drilled for now while decide. Thanks for the info.

08-10-2010, 10:01 PM	#1
swb85 On a budget like Fred Sanford Join Date: Oct 2005 Location: Topeka, KS Posts: 2,031	front brakes: 1" vs 1.25" What all is different in the front brake system between the 1" and 1.25" rotors? Is it just the rotors and spindle or are the calipers and pads different too? I've got 1.25" rotors on my truck and want to swap to the 1" setup to fit the new lowering spindles I picked up. What all parts do I need? __________________ '85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

08-10-2010, 10:06 PM	#2
texasfunk Registered User Join Date: Jun 2009 Location: Lubbock, TX Posts: 1,671	Re: front brakes: 1" vs 1.25" You will indeed need the rotors (of course) and calipers as well, and with that I believe pads, but can't quote me on that. __________________ 2006 GMC Sierra CCSB, 6.0 swap 2000 Chevy C3500 Crew Cab shortbed dually 1999 Chevy c2500 Crew Cab shortbed 1982 El Camino 350/350 1979 K5 2wd blazer bagged/bodied 1986 Monte Carlo SS 1991 Chevy CK SWB-67 clip and tailgate, bagged 350/700r4 1955 Chevy Bel Air 2014 Chevy Silverado ccsb

08-11-2010, 02:52 AM	#3
booger69 Registered User Join Date: Mar 2009 Location: pueblo CO Posts: 86	Re: front brakes: 1" vs 1.25" i did this same swap the pads are the same you will need calipers rotors and brake lines for the 11x2" brake set up

08-11-2010, 09:03 AM	#4
swb85 On a budget like Fred Sanford Join Date: Oct 2005 Location: Topeka, KS Posts: 2,031	Re: front brakes: 1" vs 1.25" The rubber brake lines are different too? __________________ '85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

08-11-2010, 12:13 PM	#6
booger69 Registered User Join Date: Mar 2009 Location: pueblo CO Posts: 86	Re: front brakes: 1" vs 1.25" yes the ends that go on the calibers are different first pic is for 1.25" set up and second is for 1" Attached Images

08-12-2010, 01:37 AM	#7
westofb I really hate wet sanding! Join Date: Dec 2008 Location: Brookfield, MO Posts: 601	Re: front brakes: 1" vs 1.25" Are the wheel bearings, races, and grease seals the same....not that it matters to me but the original poster will probably need to know this. __________________ Jeff, 68 C-10 75 C-20, now a C-10! 10 F-150

08-12-2010, 01:52 AM	#8
booger69 Registered User Join Date: Mar 2009 Location: pueblo CO Posts: 86	Re: front brakes: 1" vs 1.25" forgot that part but yes they are different

08-12-2010, 10:17 AM	#9
swb85 On a budget like Fred Sanford Join Date: Oct 2005 Location: Topeka, KS Posts: 2,031	Re: front brakes: 1" vs 1.25" Thanks guys, yet another parts store run tonight I guess! This budget lowering job (shackles/hangers/spindles) has now cost me over twice as much as I planned on, and about 5x as much time. I need a new (cheaper) hobby..... __________________ '85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD

08-13-2010, 10:52 AM	#13
shimp Registered User Join Date: Dec 2003 Location: Waller, TX Posts: 57	Re: front brakes: 1" vs 1.25" Never had an issue with Driveshaft length though. You must have put a manual trans in your truck, most came with an Auto? I never had issues with Drive shaft length when lowering a standard amount, like 2,4,6 inch drop kits for rear. __________________ 2004 Chevy Silverado 1500 RCSB 4.8v8 5 speed 2002 GMC Sierra 1500 RCSB 4.8v8 auto (wifes truck) 1986 Chevy Caprice 5.0 auto (like driving a couch down the road) 1982 Chevy C30 Crew Cab 2wd LWB - Beater Truck (I have more!) Too many to list!

08-13-2010, 04:37 PM	#14
kevinr1970 Senior Member Join Date: Aug 2004 Location: Everett, WA Posts: 2,316	Re: front brakes: 1" vs 1.25" Potential dumb question, but the 1" vs. 1.25" refers to the thickness of the rotors right? __________________ 2009 Honda Fit CfC (bsf 44.9 mpg) 2000 Tahoe Limited 1991 GMC CrewCab Dually 2wd, will end up swb, not dually and replace CCswb below 1991 GMC CrewCab Dually 4x4, just going to fix things up for now 1982/1989 K5/GMC Jimmy 2wd 1987 GMC 1/2 ton swb 2wd Crew (sold)

02-03-2017, 11:35 AM	#18
rocket_customz Registered User Join Date: Apr 2015 Location: Heber city, Utah Posts: 28	Re: front brakes: 1" vs 1.25" Sorry to resurrect a dead post but does anyone have part numbers for the 1.25 calipers, lines, etc..? My parts catalog just lists RPO codes and I'm having trouble finding which is which thanks Last edited by rocket_customz; 02-03-2017 at 11:51 AM.

02-03-2017, 03:44 PM	#19
bbbc10 Diggin The SquareLife Join Date: Dec 2010 Location: garland,tx Posts: 1,933	Re: front brakes: 1" vs 1.25" Any auto parts store should have that info on their website they ask u what brakes u have when y buy then in person

04-24-2017, 11:35 PM	#20
Sinisterv10 Registered User Join Date: Nov 2016 Location: El Paso, TX Posts: 10	Re: front brakes: 1" vs 1.25" Hello everyone, Not wanting to take over this post, but i figure it was the most appropriate and recent post. I've been reading many of the posts on here, and i have a 1960 that i already swapped in a 1985 front suspension. however my front suspension doesn't have the rotors for me to measure. I want to use the 91 camaro rotor so i can have the 5 on 4.75 bolt pattern as i already have some skinnies for the front and its not a DD so the thinner rotor is no big deal. Like i said, i read several post but my question is how do i know what spindle i have, i know i need the spindle for 1" rotor to be able to use the camaro rotors. These are the measurements i got so far. 2.0" at the base of the spindle where the bearing sits 1.37" where the inner bearing sits 0.84" where the outer bearing sits If anyone has the measurement for the 1" and 1 1/4" rotor spindle that would help me out.

04-25-2017, 01:05 AM	#21
bbbc10 Diggin The SquareLife Join Date: Dec 2010 Location: garland,tx Posts: 1,933	Re: front brakes: 1" vs 1.25" pretty sure u have the 1" spindle don't think they had that option in later years think it stopped in 82

04-25-2017, 07:29 AM	#23
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,149	Re: front brakes: 1" vs 1.25" Here's the brake release chart for '87 (should be the same for '85 - I just happened to have this one handy). The 1" rotor goes on the manual brake applications (JB1), and the lightest duty power system (JB3). The majority of the vehicles were built with the 1.25 rotor (JB5 system). K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/



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04-25-2017, 08:27 AM	#24
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 21,910	Re: front brakes: 1" vs 1.25" The difference in spindles (Which ones do I have?) can be verified by checking what wheel bearings fit since the 1" brake rotors use different (inner?) bearings. __________________ 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.*

04-26-2017, 01:55 AM	#25
Sinisterv10 Registered User Join Date: Nov 2016 Location: El Paso, TX Posts: 10	Re: front brakes: 1" vs 1.25" Well i picked up some bearings from the parts store and apparently i have the spindles that go with the 1.25" rotors so the camaro rotor swap is out unless i get aftermarket lowering spindles or stock 1" spindles. Since the truck is not a DD im having the rotors drilled for now while decide. Thanks for the info.

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