soft brake pedal...help!!!

[shodid]

(1) I have had my 96 tahoe over 3 years replaced front and rear brakes and blead them in sequence:right rear,left rear,right front,left front...and still my pedal goes down a lil past half way...i dont understand why my pedal feels like that? anyone knows the cure? im thinking brake booster? and yes my fluid is full!!

(2) and also does anyone know why a tahoe,yukon etc. gives a bunk,jerk when you pull off from a dead stop...its like its coming from the rear end or u-joint...I've notice when I took my tranny out and replaced it...the bunk,jerk went away but came back in bout a week...any know what that can be? my cousin has a 98 yukon and her truck does the same thing!!

[exwldr]

i would start at the brake master cyl. unbolt it from the brake booster and look to see if it's wet at the end . this tells you the master cyl. is leaking & needs to be replaced.. have you checked the rear wheel cylinders to see if they are leaking you must pull back the outer seal & look inside to the piston cup for any leakage.. if they are more than 5 yrs old i would replace them anyway. also i would remove all the old brake fluid and replace i with a D.O.T.3 SYNTHETIC BRAKE FLUID .they do not break down & retain water like conventional fluid. i use this in all my vehicles... walmart sells a good D.O.T.3 Brake FLUID Prestone Synthetic brake fluid and its at a good price .SEE IF DOING THIS DOESN'T SOLVE YOUR PROBLEM.... exwldr....

[exwldr]

as far as the other problem i would look very closely at all the u-joints as they are usually the culprit......exwldr

[sprucegoose]

Originally Posted by shodid

(1)

(2) and also does anyone know why a tahoe,yukon etc. gives a bunk,jerk when you pull off from a dead stop...its like its coming from the rear end or u-joint...I've notice when I took my tranny out and replaced it...the bunk,jerk went away but came back in bout a week...any know what that can be? my cousin has a 98 yukon and her truck does the same thing!!

This is caused by slip/stick in the driveshaft yoke going into the transfer case... Ton's of info out there on this, but the best fix (workled for me) is to make sure you put the blue synthetic GM fluid in the transfer case. It is called Autotrac II ($7 qt.!) and you can only get it from a GM dealer. It takes two quarts... Give it a shot, you'd be surprised!

[wafrederick]

Look for rusted out brake lines too,look for wet spots.The brake lines do rust out and leak overtime due to age of the vehicle.I have seen this happen when the master cylinder is still full.

[jonnik]

GM anti-lock brakes can be tricky to bleed-you must follow a specific procedure to do it. This really helped me:
http://www.automotiveforums.com/vbul...d.php?t=373282
I eventually replaced both the rotors and calipers. The truck stops well, but both my '97 Tahoe and '98 Cheyanne brakes feel flimsy.

[shodid]

(1)Shodid...well thanx for everyone response...I forgot my truck was in a wreck on my drivers side...my computer and abs was tossed around and my brake line is bent on the master cylinder!! so I believe imma solved tthat problem at the salvage yard...lucky me its the line from the master cylinder to the abs!!

(2) As for thejerk in my rearend/yolk,u-joint....my truck is a 2wd not a 4wd so I dont have an transfer case...so im still confuse on that!!

[ukrkoz]

Originally Posted by sprucegoose

This is caused by slip/stick in the driveshaft yoke going into the transfer case... Ton's of info out there on this, but the best fix (workled for me) is to make sure you put the blue synthetic GM fluid in the transfer case. It is called Autotrac II ($7 qt.!) and you can only get it from a GM dealer. It takes two quarts... Give it a shot, you'd be surprised!

though diagnosis is correct, treatment is not the best. GM recommends "exercising" the yoke with their magic grease only on the 1st run, then - replace it with nickel plated one. it does not rust as the substandard original does. i think it's about $700 dealership. i just keep driving, got used to it.

as of the 1st question let me ask you this: ARE THE BRAKES ADEQUATE? if so, just get used to it. it's the way it's made - spongy feel. matter of fact, try your parking brake. isn't it going all the way to the floor with little resistance? once again, GM geniouses will tell you that it's "normal".

[j cAT]

(2) As for thejerk in my rearend/yolk,u-joint....my truck is a 2wd not a 4wd so I dont have an transfer case...so im still confuse on that!![/quote]

on your clunk / jerk I would look at the engine and transmission mounts,and if you have a U joint problem it will start to tweet/squeek...since this is very old the transmission tail shaft bushing could be worn check for lateral movement with rear wheels off the ground..

[ukrkoz]

yoke is part of driveshaft. it is a rod with splines that goes into transmission on 2wd and transfer case on 4wd models. wheelllbase length changes as truck moves, and yoke "slips" or slides back and forth in transmission output shaft to accomodate. when rusted, it binds and gives pronounced thud when taking of, sometimes feels like wheels are lagging behind.
of course, on a post-accident truck everything is possible...... slight bend or kink here and there will result in all kindas of rubs and thuds and thumps...