brake adj. problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chucks70 · 04-07-2002, 08:14 PM

Have a 4X4 and just changed front drums to disc. Now the brakes don't engage until the peddle is almost on the floor. I noticed the Power boost rod had a threaded shaft for adjustment, could this need lengthened? Also a light on the dash now comes on that says "tandem lock". Any ideas what this means, I thought maybe the brake light wired wrong or is this it? Any input would be appreciated.

Longhorn Man · 04-07-2002, 08:50 PM

The tandem lock should be reading brake...it is in the lower left on your gas guage isn't it? This set up is out of a larger truck.
Go and try pumping the brakes and see if it helps, could just be a low level or air. (the light coing on says that to me)

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

70shortnphat · 04-07-2002, 09:03 PM

It is possible that the plunger on the booster needs adjusted like you said.But if you over adjust this you may get brake drag or full blown brake lock!

chucks70 · 04-07-2002, 09:16 PM

Cab is not original so may be off of bigger truck. Will try re-bleeding tomorrow. Am I right that you have to hold in the button on the end of the prop valve when doing the rear brakes? Pumping brake did not help much.

blue72stepside · 04-07-2002, 10:28 PM

you mentioned u change from drum to disk. don't you have to change the master cylinder
disk brakes take more fluid than drums. i have never heard of holding prop valve to adjust the rear brakes. the light might just be i the wrong hole in the back of the dash. the light might of came on because pressure is not building up on front brakes.

[This message has been edited by blue72stepside (edited April 07, 2002).]

chucks70 · 04-08-2002, 07:33 PM

When I changed I swapped in disc master cylinder and prop valve. Everything now off of an 85 3/4 ton 4X4. Pretty much a bolt up except for changing some brake lines. Didn't get to look at it tonight, got home too late and the moon isn't real bright tonight!!

04-07-2002, 08:14 PM	#1
chucks70 Registered User Join Date: Feb 2002 Location: Cadiz, OH Posts: 628	brake adj. problem Have a 4X4 and just changed front drums to disc. Now the brakes don't engage until the peddle is almost on the floor. I noticed the Power boost rod had a threaded shaft for adjustment, could this need lengthened? Also a light on the dash now comes on that says "tandem lock". Any ideas what this means, I thought maybe the brake light wired wrong or is this it? Any input would be appreciated. __________________ 68 1 ton dually 292, 2001 Sebring, 2004 Trailblazer, 11 Camaro Convertible.

04-07-2002, 09:03 PM	#3
70shortnphat "See the U.S.A....." Join Date: Apr 2002 Location: Richmond TX. Posts: 269	It is possible that the plunger on the booster needs adjusted like you said.But if you over adjust this you may get brake drag or full blown brake lock! __________________ 1970 short bed fleetside 1949 all origional chevy 3600 1974 camaro Richmond , Texas(just S.W.of Houston)

04-07-2002, 09:16 PM	#4
chucks70 Registered User Join Date: Feb 2002 Location: Cadiz, OH Posts: 628	Cab is not original so may be off of bigger truck. Will try re-bleeding tomorrow. Am I right that you have to hold in the button on the end of the prop valve when doing the rear brakes? Pumping brake did not help much. __________________ 68 1 ton dually 292, 2001 Sebring, 2004 Trailblazer, 11 Camaro Convertible.

04-07-2002, 10:28 PM	#5
blue72stepside Registered User Join Date: Aug 2001 Location: Morgan Hill, California Posts: 309	you mentioned u change from drum to disk. don't you have to change the master cylinder disk brakes take more fluid than drums. i have never heard of holding prop valve to adjust the rear brakes. the light might just be i the wrong hole in the back of the dash. the light might of came on because pressure is not building up on front brakes. [This message has been edited by blue72stepside (edited April 07, 2002).] __________________ 72 Cheyenne Stepside 357/TH350 3.07 Posi 379HP@5500 412FT#@4000 96 1500 Work Truck 88 Chevy Van 3/4 97 Tahoe 8.5 Lift (Sons) 00 1500 LT 4x4 (Sons) 98 Ford Cobra (Wifes Car)

04-08-2002, 07:33 PM	#6
chucks70 Registered User Join Date: Feb 2002 Location: Cadiz, OH Posts: 628	When I changed I swapped in disc master cylinder and prop valve. Everything now off of an 85 3/4 ton 4X4. Pretty much a bolt up except for changing some brake lines. Didn't get to look at it tonight, got home too late and the moon isn't real bright tonight!! __________________ 68 1 ton dually 292, 2001 Sebring, 2004 Trailblazer, 11 Camaro Convertible.

04-07-2002, 08:50 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	The tandem lock should be reading brake...it is in the lower left on your gas guage isn't it? This set up is out of a larger truck. Go and try pumping the brakes and see if it helps, could just be a low level or air. (the light coing on says that to me) ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio



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