Disc brake conversion? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

krue · 12-01-2003, 09:13 PM

What do I need to get off a 71/72 to put disc brakes on my 70 GMC?

Where do I measure my rear end to see if I can use later model axles in my rear end?

Thanks, Krue.

frogsmakr · 12-01-2003, 09:33 PM

i would (and have) used 73-87 parts. The brake hoses are more available, calipers are cheeper ..........git it all: crossmember, brake lines all the way to master cyl, master cyl, prop valve, booster,booster bracket, rod to brake pedal, rear brake line to the coupling

JimKshortstep4x4 · 12-01-2003, 09:53 PM

71-72 five lug rear ends measure 57" between the backing plates. The shorter axles measure 30 1/4" and the 71-72 longer axles measure 31".

Jim

Hooter · 12-01-2003, 10:42 PM

well you need spindles, ball joints, calipers, rotors, proportioning valve, master cylinder, tools, band aids and beer

Cat Fuzz · 12-02-2003, 01:59 AM

Lots of Band-aids and beer.

68c10owner · 12-02-2003, 04:22 AM

don`t forget that the ball joints are a different size on 71 and up. i`ve heard some people have done the swap without changing anything and others say you need diferent ball joints,tierod end,drag link ect. not sure who is right but i`m getting stuff from a 71 up truck to make sure everything fits my 68.

Injected68LS1 · 12-02-2003, 05:06 AM

The ball joints on a 71-72 are sized different than the earlier ones. Same with the tie rod ends. I pretty sure you need the drag link changed too. The good news is that the ball joints are a direct replacement in the older control arms. Or you can just change out the whole control arms with the ball joints. Then you don't have to worry about pressing the lower ball joint out.

Southpa · 12-02-2003, 06:57 AM

Better yet is if you can find a complete front end assembly off a 71 or 72 thats in better shape than your own. Its well worth it if your ball joints etc. are on their way out anyway. A very quick and easy swap too! Just be aware that pitmans from power steering and non-power steering have different size spline holes for the steering box shaft.

TEXAS 68 · 12-02-2003, 10:50 AM

I just did my 68 and used every thing from 85 including swaybar ps and draglink,tie rod ends with no trouble.

FRANKIEPOTATAS · 12-02-2003, 11:08 AM

I even pulled the crossmember out of the front disc brake donor so that I maintained the correct brake line holders for the discs (my drum brake lines went around the front of the crossmember and the disc lines went around the back)

krue · 12-03-2003, 08:07 AM

Thanks guys!

12-01-2003, 09:13 PM	#1
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Disc brake conversion? What do I need to get off a 71/72 to put disc brakes on my 70 GMC? Where do I measure my rear end to see if I can use later model axles in my rear end? Thanks, Krue. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

12-01-2003, 09:33 PM	#2
frogsmakr Registered User Join Date: Feb 2000 Location: Sherwood AR Posts: 553	i would (and have) used 73-87 parts. The brake hoses are more available, calipers are cheeper ..........git it all: crossmember, brake lines all the way to master cyl, master cyl, prop valve, booster,booster bracket, rod to brake pedal, rear brake line to the coupling __________________ 67 C-10 shortwide '06 Triumph Thruxton '09 Harley 'Lectra Glide '95 Z-71 two door Tahoe

12-01-2003, 10:42 PM	#4
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,083	well you need spindles, ball joints, calipers, rotors, proportioning valve, master cylinder, tools, band aids and beer __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

12-02-2003, 04:22 AM	#6
68c10owner Registered User Join Date: Oct 2003 Location: Carmichael, California Posts: 3,006	don`t forget that the ball joints are a different size on 71 and up. i`ve heard some people have done the swap without changing anything and others say you need diferent ball joints,tierod end,drag link ect. not sure who is right but i`m getting stuff from a 71 up truck to make sure everything fits my 68. __________________ Anthony

12-02-2003, 05:06 AM	#7
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	The ball joints on a 71-72 are sized different than the earlier ones. Same with the tie rod ends. I pretty sure you need the drag link changed too. The good news is that the ball joints are a direct replacement in the older control arms. Or you can just change out the whole control arms with the ball joints. Then you don't have to worry about pressing the lower ball joint out. __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

12-01-2003, 09:53 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	71-72 five lug rear ends measure 57" between the backing plates. The shorter axles measure 30 1/4" and the 71-72 longer axles measure 31". Jim

12-02-2003, 01:59 AM	#5
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	Lots of Band-aids and beer.

12-02-2003, 06:57 AM	#8
Southpa Registered User Join Date: May 2000 Location: Victoria, BC, Canada Posts: 2,410	Better yet is if you can find a complete front end assembly off a 71 or 72 thats in better shape than your own. Its well worth it if your ball joints etc. are on their way out anyway. A very quick and easy swap too! Just be aware that pitmans from power steering and non-power steering have different size spline holes for the steering box shaft. __________________ 1970 GMC 1500 Custom Original 350/TH350 Victoria, BC, Canada You can wish in one hand and crap in the other. See which one gets filled first. Last edited by Southpa; 12-02-2003 at 07:02 AM.

12-02-2003, 10:50 AM	#9
TEXAS 68 Vortec in the works Join Date: Nov 2003 Location: Spring,Texas Posts: 735	I just did my 68 and used every thing from 85 including swaybar ps and draglink,tie rod ends with no trouble. __________________ 68? It's all figured out untill you get it apart. Is it Sunday yet??? 68 Project 68 SWB frame off/98 Vortec with stock FI/power everything. 95 ECLB 2500 with 346,000 on the clock(the original HD) 99 Lesabre-wifes ride 08 Crew Cab LTZ-All Mine 89 SWB 5/7 drop-Son's first ride.

12-02-2003, 11:08 AM	#10
FRANKIEPOTATAS Registered User Join Date: Oct 2003 Location: San Francisco Bay Area Posts: 63	I even pulled the crossmember out of the front disc brake donor so that I maintained the correct brake line holders for the discs (my drum brake lines went around the front of the crossmember and the disc lines went around the back)

12-03-2003, 08:07 AM	#11
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Thanks guys! __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"



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