Brake Puzzle (1982 GMC Sierra 3500 with a 2006 14-Bolt Axle Rear-Disc Brakes!!)

[GMCbigblock]

The Truck is 1982 GMC Sierra, 3500 Series, with a GM Hi-Perf. 502 (ported Heads tuned to 540 HP). Manual 5-spd. The original 'Brake Hydo-Booster' was replaced with a late-model power-assited unit (like those found on the 1990's Yokun's). It worked fine with the original 14-Bolt Rear (with the huge-drums). However, after replacing the Axle with newer one (to gain better and safer braking-power), I almost lost the rear-braking functionality. Note that I fixed a new brake controller/distribution-unit (located underneath the engine).

Am here asking for the maximum info-sharing and earliest assistance of the 'brake-experts' to help me fixing the 'rear-brake' to make it properly and safely operational (now, it's very weak when the brake-pedal is fully depressed). For trial-n-error, I noted that it greatly improved after fixing late model Brake-Clyinder (about 2006), but the hood wouldn't close!! Appreciate your help. Thanks.

 

[tlape4965]

Have you changed the proportioning valve?

 

[tlape4965]

There is a different part number. If you replaced it with the OE it's wrong. The OE is for drum to drum. There is an aftermarket one for disc to disc. I will try to find the part number.

 

[TheBeast_88K5]

There is a different part number. If you replaced it with the OE it's wrong. The OE is for drum to drum. There is an aftermarket one for disc to disc. I will try to find the part number.

Interested in this part #.

 

[tlape4965]

Go to LMCtruck dot com pick your vehicle or enter the part # 37-8546 in the search.
Upper R/H corner of the page is the valve you will need. It will look just like your OE valve; however, the guts are configured for a disc to disc set up. You can also do a search for adjustable proportioning valves. That way you can manually adjust your brakes. part# 37-8546 should work for your year.

 

[GMCbigblock]

tlape4965,

I just placed the order with LMC and hope it will close this chapter. Highly appreciate your attention and valuable advice. This is an asset for this Site.

 

[GMCbigblock]

One more query (easy, I guess) if anyone can help, from which particular year I can easily swap the air-booster and the brake-cylinder to fit into this my truck (noting that am no longer using the Hydo-Booster unit - as explained in the Thread). My intention is to renew the current brake-system using OEM late-model replacement-parts as much as possible as they are more available at the local dealer and junk-yards. Thanks!

 

[tlape4965]

The latest model that will work for your vehicle with no modification is 89-91 3/4 ton suburban JB7 brake system.

 

[GMCbigblock]

The latest model that will work for your vehicle with no modification is 89-91 3/4 ton suburban JB7 brake system.

Noted and thanks for this valuable info.

 

[GMCbigblock]

Hi, I fixed the proportioning valve (disc to disc) from LMC and still the brake pedals seems very soft with a moderate braking!! Am suspecting the rear center small distribution block, or else the brake pipes may need to match with the increased pressure.

How about fixing latest model Master Cylinder coupled with its corresponding Brake Booster? Has any gone thru this and if so, can I have the Parts numbers and brand please!! Am dying for a safe good braking to avoid harming people and myself as well, thanks buddies.