1991 Chevy Blazer brake help

[blazer88]

Just bought a 91 Blazer, 350 k5, with the 4l60 tranny, drove it home 400 miles drives great, just got it aligned, only had it for about a week, and their is a weird lurching feeling when you brake. previous owner said it has done this for the five years he owned it, have what looks to be a 4 inch procomp lift, blocks in the rear, springs up front, procomp shocks all the way around, running 33x12.5's under it.

when you come to a complete stop vehicle seem to lift/lurch forward from the rear, and then settle down, with noticable noise inside, had a friend listen to it outside and it is not noticable on the outside. i noticed that the rear leaf springs almost seem to be missing a leaf, the brackets that hold them have a lot of space, it looks like an extra leaf should be there, i had an 88 blazer that i put a 3 inch lift on, but i do not remember what the rear spring were like, was curious if that could be the problem? any and all help is greatly appreciated.

 

[apache]

Hard to diagnose sounds over the net etc but id start with possible warped rotors or out of round brake drums. The rotors can be checked on the truck with a dial indicator,the rears can be turned/checked pretty inexpensively at Napa auto or a good brake shop.

 

[blazer88]

brakes all check out good, redone recently, the problem only happens in drive when moving forward, if you are reversing and brake, the noise does not happen.

 

[BGKYK5]

Where exactly do you see the extra space? In the leaf pack clamps at either end?

Does it sound like something is banging or thumping around under the rear while it is lurching? You may be running out of yoke clearance at the rear diff when the pinion rotates down under braking. You should be able to see where the yokes are hitting if you crawl under and take a look. If so, a little grinding for additional clearance should clear it up. A four inch lift is about the limit for the stock rear driveshaft, and blocks will increase axle wrap (even during braking).

 

[michaelgilitiuk]

i hade the same problem so i threw away my old blocks and got some rear leafs and it helped alot.

 

[blazer88]

yeah there is space on both ends of the clamps, so what area do i need to grind for more clearance?

 

[BGKYK5]

Grind the yoke where the screw heads are contacting it (you may need to grind the screw heads a bit too) Make nice smooth transitions so you don't create stress risers. I ground off a little, hit it with some spray paint, and drove it around a bit. The spray paint helps you see where it is still making contact, then grind again and repeat.

 

[blazer88]

checked the yoke and everything checks out okay, no indications of rubbing or anything like that, you suppose that it just might be axle wrap?

 

[BGKYK5]

Describe the sound and lurching in more detail, maybe that would help.

 

[blazer88]

as you are coming to a stop, in drive, and when you come to a complete stop, the vehicle seems to lurch forward, like normal, but as all the momentum stops, and the vehicle settles back down, there are several clunks, they all come from the back of the vehicle, in the leaf spring and rear axle area, the noises are only heard inside the vehicle, they are not audible outside the vehicle. it is around five clunks, or creaks, in close succesion, if you california stop, the sound does not occur, nor does it happen when you come to a stop in reverse, and if you come to a really slow stop it usually might not happen, it usually happens when there is a considerable amount of nose dive, and if you stop fast and take of fast it also happens then when you take off

i drove the vehicle home over 400 miles and it drove great without any problems, so i dont think it would be the rearend, i just lowered the transfer case an inch, and greased the rear ujoint, which took alot of grease, and i have checked all of the suspension components, all the nuts, bolts, u bolts, everything is tight, the last owner said that this noise has occured the whole time he had the vehicle, and he had it for five years, so i dont think it is a big issue, i just would like to solve it

all help is greatly appreciated.

 

[BGKYK5]

Dunno

A late 2-1 downshift? Prolly not, a mis-adjusted TV cable would have killed the trans by now.

Wear in the slip yoke in the t-case?

I'm just throwing darts in the dark now, maybe somebody else can help.

 

[blazer88]

its when you are in first gear, i will have to get back in and do some driving, and try to document things better

thanks for the help

 

[cuervo]

Take some photos of the under carrage so we can look around. Get the end of the transfer case, the tranny, the drive shaft, rearend, and body mounting points.

 

[chulisohombre]

maybe spring bushings are worn out.and the creaking is the shackle settling back in place where the bushings are worn out.it more sounds like a axle wrap issue as was said thoug.the driveshaft is binding as the nose dives and twists the pinion up.the stock springs are pretty beat up now that they are almost 20 years old.then on top of that there is a 4 inch block puting more tortional force on the whole axle as you brake and take off.new 4 inch lift springs and new shackle bushings at the same time would help a lot with that.my blocks eventually fell apart and i almost lost my axle out fro under my truck.i do not suggest keeping blocks to anyone that has a lift.they are unsafe in my opinion.a 4 inch spring will ride a lot better and still give more than enough flex to get over obstacles.

 

[blazer88]

okay problem update for everybody, talked to a fellow hot rodder and car nut, and he gave me the idea to come to a stop in nuetral. i did that and there is absolutely no problem, he thought the problem could be in the yoke, transfer case area, but the sound still sounds like it is coming from the rearend, i ahd a friend tell me to cut the driveshaft and sleeve it, to make it longer, sounds great in theory, not sure how it would go in practice or if it would help the problem, if the pinion is binding, as said in an earlier post, what am i to do to solve this problem? would a longer drive shaft solve the problem, i have not yet looked at the pinion gears, will dive into that on my next day off, can post pictures if needed.

 

[BGKYK5]

Neutral in the trans or in the T-case?

 

[blazer88]

in the tranny