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Jul 8, 2016, 1:45 PM

Post #1 of 15 (906 views)
rear brakes Sign In

I have a 1989 jimmy s15 4x4

It was shuddering real bad. The shake was in the steering wheel and it shook real bad when I slowed down at 70.

I replaced the rotors and pads and now the steering wheel shudder is gone.

At 70 mph I still have a problem though. I seems to be coming from the rear end. You can feel it through the pedal. You can feel the shoes engage but after they engage it feels like the shoes aren't staying applied evenly to the drum. I have to think it is because ithe drums are probably warped. The the drag on the drums seems to pulse. At slower speeds they stop fine.

Should I replace the drums and should I also replace the shoes even if they are not worn out.

(This post was edited by jackx on Jul 8, 2016, 1:49 PM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 8, 2016, 2:01 PM

Post #2 of 15 (900 views)
Re: rear brakes Sign In

Are you now talking about just doing up rear drum brakes on this and fronts are all set now? Pads mean for disc brakes, shoes mean for drum brakes which are rears as you subject line says.

Rear drum brakes are actually more tricky than the fronts now on these. They are both your service brake AND your parking brakes use the same parts just by cables known to stick and mess up the show.

That alone is very fussy if they are a problem to replace and adjust properly or will be the problem if all wrong.

Drums should be cheap as well as a hardware kit so do it all. Wheel cylinders highly suggested as well. They can have leaking gear oil from rear axles either.

It's all doable and nothing out of control expensive but getting them and parking brake cables and adjustment just right is even hard to explain.

For now if and when you go for this do one side at a time to use other for reference first time. They are "asymmetrically opposite" and need to define the word - means mirror images of each other like your hands are left and right so are drum brakes.

Some tools will really help and not too expensive either. Doable and yes do drums but be warned about parking brake cables and adjustments of all and understand it or it will screw it up,

kev2 profile image

Jul 8, 2016, 2:04 PM

Post #3 of 15 (898 views)
Re: rear brakes Sign In

As you are doing the work..
do some math - rear brake shoes and 2 drums*.... and then a complete new brakes.
less than 200$ more likely 125$ just pay attention to quality


Jul 8, 2016, 7:41 PM

Post #4 of 15 (888 views)
Re: rear brakes Sign In

Well the front rotors and new pads fixed the front.

I will go ahead and put new brake drums on the rear along with new shoes. I replaced one brake cylinder last month and the old one crumbled in my hands. So, I'll go ahead and replace the other brake cylinder too.

It will cost me about a hundred bucks if I buy rabestos. I think they are probably ok. they are $26.79 on rockauto. ACdelco are $27.79. I may get them. I know they are ok.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 8, 2016, 11:38 PM

Post #5 of 15 (882 views)
Re: rear brakes Sign In

! A wheel cylinder crumbled in your hands? You must mean rust and suggests you can't fake anything with this job - do it all. Wheel cylinders are still only about 1/3rd the prices you just mentioned for this but can and usually twist up the brake line (rust issue vehicles or just age) on this.
Is rust a real factor with this? Backing plates may not be any good and the list goes on. As parts go brakes on this are not that expensive. Fussy as said to get it all right.

You didn't say but is parking brake and cables totally free moving now? Could be or could need them all quite possibly still OE lengths ready to use if needed totally suggested as make your own always available is just a ton of time and work.

Other: You don't just replace one side of things with brakes you do in pairs per axle.

Still said all doable just think hard where each part goes back on and how adjusted. This is not a good place to buy parts off the web IMO the last of choices. Cheap drums can be fine and may require machining new vs higher end ones just cleaning first if much at all should say in packaging. Water is common on most new now if cleaning drums vs brake cleaner required stuff put of parts to prevent rust in plain storage till sold.

I'm still harping on the parking brake. It will ruin the job if you don't have that right and I'll add you really can't adjust new cable parts till the service brakes are done and perfectly adjusted first or they be trouble right away or later.

The order of things done counts critically with drum brakes. Great concept for ages still viable and tolerant for certain conditions, intolerant of others,



Jul 9, 2016, 7:33 AM

Post #6 of 15 (866 views)
Re: rear brakes Sign In

Tom that brake cylinder came apart when I pushed on the brakes after I had installed the new

I pulled the drum off and it appeared the brakes shoes
were not self adjusting because the cylinder piston pushed
the shoes as far apart as it could and then
the cylinder came apart.

When I was cleaning up the mess the rubber seals on the
wheel cylinder just crumbed in my hands. I replaced it. It
did appear that the self adjuster hangs up on the bottom
spring that is connected to both springs.
The spring gets into the notches on the self adjuster.

I will have to look at it again and see if I can figure out
how to connect the spring so it does not get into the
adjuster notches. I did adjusted the shoes
with the drum off until I could just barely get the drum
back on so I could drive the vehicle. So far so good.

I am thinking I may need to try to flip the spring around
next time so the spring coils will be on the end where the
adjuster notches are or I may have to bend it. I will go to
the wrecking yard to see how the spring goes on.

if I can't figure it out. That spring getting into the adjus
t notch makes it impossible to adjust the brakes manually
with the drum on.

If there is a trick to installing the spring I am all ears.

I used to replace brake shoes before they were self
adjusting and I have heard they don't work very well. I
have to put them back right though even though
they seem to be a PITA.

I have read they adjust when you back up or apply the
emergency brake. I have not got a clue how they work.
It would be nice if I could figure out what makes them
self adjust.

There is no rust and the parking brake works fine.

(This post was edited by jackx on Jul 9, 2016, 8:14 AM)

Hammer Time
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Jul 9, 2016, 8:18 AM

Post #7 of 15 (857 views)
Re: rear brakes Sign In

I pulled the drum off and it appeared the brakes shoes
were not self adjusting because the cylinder piston pushed
the shoes as far apart as it could and then
the cylinder came apart.

Working on brakes 101...................... Never step on the brake pedal with no drum on the car.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 9, 2016, 8:37 AM

Post #8 of 15 (855 views)
Re: rear brakes Sign In

Hard read but understood. You can't have rear drum OFF and push the brake pedal or wheel cylinders will just push against no stop via shoes on the drum and can fall out - some will lock and not fall out - varies.

They are wrecked IMO if they do that and if on even new linings (shoes) soaked with brake fluid hard to impossible to make friction coefficient the correct amount again so those get trashed.

The reason lower spring is hitting star adjuster it's called is you have the wrong ones or they are on the wrong side of the vehicles. They are mirror images as said and only left can go on left and right go on the right side.
Access to manually adjust requires punching out a stamped hole in drum or backing plate then a tool used called a brake spoon to adjust brakes tight while drum is on and tight by lug nuts then with a smaller tool (#1 screwdriver can work) hold back the one way lever and back off till shoes don't rub drum.

I told you to do only one side at a time so you can look at the other for a first time. It will confuse you to death to figure it out if just a pile of springs, clips, hold down springs and pins, the parking brake bar with spring in correct position and nothing sticking holding anything up.

Backing plate can wear, frequently from where shoes rub such that shoes get stuck and have trouble to move to apply or can't retract via return springs.

Hate to say this stuff is the most unbelievable silly mechanical mess of springs and adjustments you actually have to pay total attention or it fails. It's easy once you've done it or seen it done forever more.

This is all any vehicles ever had for fronts or rear for mega decades still used with slight changes in style of the same concept.

These never self adjusted long unless you assertively took out self adjuster and re- lubed it periodically or it froze. You can buy new ones separately but those too are left or right side. Get that wrong and brake will self adjust till it locks solid driving forward and applying brakes not reverse and applying brakes.

Places you can get in trouble seriously! If you over adjust brakes or they fail and can't get drums off you may have to force them off wrecking parts, bending parts.

You could end up needing special tools to work with or even a chance at removing a parking brake cable if good you'll wreck it taking one out of a backing plate. There's a holding spring tool so you can re-attach it inside or fight with a couple needle nose vice grips - all was common bull and said still in use just not on many passenger cars/vehicles.

OK - I'm an old Phart so this I can do blindfolded with one arm and hand. Doesn't help you much and explaining it is a book and then some. A video would fall short of the assorted problems you need to know exist or not like worn backing plates and what to do.
You are fighting with some lack of tools probably. Return spring or called brake pliers. Hold down spring tool and tools to remove and replace parking cable if needed or replace if needed plus correct brake "spoon" for star adjuster. Holes for access are not punched out when new you do that or by now someone should have already.

Hardware kits come with assorted extra springs and parts so you match up correct ones for your specific job. A rubber plug for the slot you adjust thru needed or not if punched out or not. New drums you don't need to adjust with the wheel on and shouldn't really later - take drums off and at least dump out the brake dust at tire rotation time or dust will be a problem.

They got rid of this style brake for good reasons. They aren't passive - you actually should pull drums and look at them periodically and people just hate anything to do other than changing oil so forget this style. They also don't sling off water so don't stop for crap if soaked till you drag them dry or quite some time as they aren't totally exposed but water can get in.

I doubt you know if parking brake is fine. Makes this a total novel and still could be an inch thick on paper for all details. Parking brake cable at wheel if you can pull it out more that it's spring pushes it is junk now but could work with the worn brakes and ruin the new ones.
Quick look didn't show me exact fit new ones so the generic make your own stinks and another whole novel.

Your brake springs - almost all are "asymmetrically" opposite. Some hardware kits have two of the same by mistake. Several new cars/trucks were built new with wrong bottom springs or some used clips and other crap wrong from new. It's too old to have worked if it wasn't right at some point.

Tell you what: This is just a ton to explain as you can see. Look for a YouTube on GM rear drum brakes - the total replacement of all parts which may be an hour or more long or target one problem area at a time you can run into. I'll look for one or two and post if any are any good.

It's an oxymoron to say these are so simple once you just know what to check and adjust when and how much without thinking about it but first time really silly stuff will mess you all up.

The good news is the parts are cheap compared to lots of other things. I still can't see how parts for some things not purchased in person matched to old parts is going to be so easy. Catch any wrong items right at a counter not by surprise by blind mail order if stuff was free,



Jul 9, 2016, 10:12 AM

Post #9 of 15 (849 views)
Re: rear brakes Sign In

I must have said something to make you think I pushed on the
brakes with the drums off. I did not do that.

The drums were on. I just assumed that the
brake cylinder pushed itself apart because the shoes were
out of adjustment because that is the only way I could see
it could happen.

I did not take the other side off so the spring I took of was the
one that was on that side when I took it apart. I did attempt
to pull the drum off the other side but it hung up and I blew off
trying to get it off. Its brake cylinder was not giving me the
problem anyway. Since it was so tight I could not get it off
I figured it had to be adjusting. I figured it just had a lip on it
that was hanging the drum up when I tried to remove it.

I think maybe whoever last worked on it may have switched
the springs. I don't know until I get the struck drum off. It is
stuck because of a lip I can probably get it off and who knows
I may even be able to get it to adjust so it will be easy to
move the shoes in and get it off.

The backing plates already have the adjusting holes punched
out. You can't take a screw driver and push the adjusting arm
back off the adjuster notches so you can use brake spoon
because the spring is also wedged into the adjuster notches.

Nice to know that the spring should not end up in the adjuster
notches and that there are springs somewhere I can get my
hands one that will work right. I will go to autozone and see what
they have. If not I guess I can go to the wrecking yard.

Thanks for your help.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 9, 2016, 10:31 AM

Post #10 of 15 (848 views)
Re: rear brakes Sign In

If you can't remove that drum with shoes as they are you could just chisle off the back side of "the nail" pin for the hold-down springs and shoes and all would come off with the drum just the parking brake cable would sill hang onto one shoe.

I think it's all going to go for new so not much to lose just get it to where you can work on putting new stuff in.

Kits and parts should be same day at a place like Autozone - or similar places if closer for you. Truck parts seem available much more likely and quickly than plain car parts,

PS: Google out an image of a GM brake drum left then right intact to go by if everything all in pieces would probably help with where things go,



Jul 10, 2016, 10:45 AM

Post #11 of 15 (841 views)
Re: rear brakes Sign In

I found some used drums in a pile out back that had no
run out.

I pulled them of a rear end I put in my Blazer a few years
ago and i had just forgot about them.

I put them on and fixed the spring. Got rid of the pulsing
brakes at 70 and all the out of balance shake that I had
figured was due to my tires. Killed two birds with one stone.

The drums were covered with a thick coat of rust that came
right off after I soaked them a hour or so in white vinegar.
I could tell the old warped drums I removed had been
turned down a few times.I think I am good to go now.

Next week I will replace the brake cylinder and put the

Thanks for you help.
pads off the Blazer on the Jimmy. They are better shoes
than what is on the Jimmy and even have rivets. Just too
hot to do today.

(This post was edited by jackx on Jul 10, 2016, 10:46 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 10, 2016, 11:24 AM

Post #12 of 15 (837 views)
Re: rear brakes Sign In

I can't stop you but used brake parts area no, no to another vehicle.
Just FYI - I don't "machine" rotors or drums on stuff this light duty ever or any cars. There isn't enough extra metal and they are marked the legal limit. Fine - but the thinner the more apt to warp for rotors mostly. For drums the exact diameter new is set only once for new shoes. Cutting then changes where a shoe will then touch and wear into in time on some but isn't suggested.

You have stuff back together now and truth is rear brakes in a seriously hard stop only account for maybe 30% of power to stop a vehicle as weight shifts forward.

Still need those to fit and be right or you lose brake pedal feel and sureness of pressure for fronts to some degree. Put a shoe in a drum and see where it fits and will touch just to understand that. Under force shoe will flex just some but not much.

In short, hack brake word you are really fooling yourself. Fine for a yard vehicle but you share the roads with other people and have a responsibility to know you can control your vehicles as best as it can and jeopardized that so don't approve of what you did at all,



Jul 10, 2016, 1:50 PM

Post #13 of 15 (831 views)
Re: rear brakes Sign In

I would never put parts from one vehicle on another vehicle without
throughly checking them out.

I checked and the shoes are interchangeable. This means they will work
with either drum. So, from the lugs back to the inner edge of the shoes the
drums are the same. I did get stats on the Drums. They are almost
identical as(the normal dia, max. dia, friction surface bolt pattern on the
drums are the same) The only difference is the outer dia . On the blazer
the outer dia is 11.97 and the 89 Jimmy is 11.81.

To summarize they are the same except the blazer is .16 inch thicker. They
may fit further back over the backing plate. I also looked into and discovered
why the blazer drum is .16 inch thicker. I discovered:

The blazer axle is 29.28 inches and the 89 Jimmy is 29.03 inches. That pretty
much accounts for why the blazer drum is thicker

Since they don't rub anywhere I went ahead and put them on just to make
sure that when I buy some new ones for the Jimmy I am not wasting my
money. I now know by putting these on that the Drums were indeed the root
of my problem. They are 45 bucks at autozone and I can get ac delco
for about half that on Rockauto.

I did not want to waste my money.

Next week, I will look closely to make sure that the pads are fitting ok
and that everything associated with the pads working right is in order
and I will also make sure the additional .16 inches width is not causing
a problem with the backing plate. I intend to look at this real close as
that .16 inch of additional drum should it seems to me should be rubbing
on the backing plate and its not. So, the additional .16 inch must be
fitting over the backing plate. If so that is ok.

If everything is ok then I may consider
continuing using the drums.

I agree using different parts from different vehicles is not the route if
I was you that I would recommend. So, I can not expect you to
agree with me doing that. If eveyone did that we all would be in trouble.

I intend once it cools off around her to pull them back off and finish putting
on a new wheel cylinder. I have looked and those are not interchangeable.

It does appear that the additional width of .16 is comprised of just an
additional outer lip that fits back over the backing plate that the old drum
did not have. That 1/8 of an inch is not very much and the outer lip does
not even come close to the backing plate.

Thanks again for helping me. I could not be happier. I actually believe if I
had to I could lock up all 4 brakes on that old truck. Believe me it has not
stopped as smoothly as it does now in a long long time.

(This post was edited by jackx on Jul 10, 2016, 2:16 PM)


Jul 13, 2016, 7:41 PM

Post #14 of 15 (795 views)
Re: rear brakes Sign In

Well after putting new shoes on it I found the blazer drums did not fit right afterall
I also found some things that had to be changed about how the shoes were installed
and I put the old drums back on and every things seems to be find now. Proves that
you really should not expect any drum but the one that is for the vehicle to work
right. got the oportunity do drill out the hold down pegs and had to hammer the back of
the blazer drums to get them to come off. I found that the actual lug hole is sliightly
smaler than the what the 89 Jimmy drum has and that causes it to seize up plus the
new pads were so thick that I could not get the adjustement to allow the new shoes
to be used with the blazer drums without dragging. They work fine with the old 89 jimmy drums.

Just wanted to get back and say you advice to not use anything but what is supposed
to fit on a vehicle is good advice. I found out the hard way but that sometimes is the
best way to learn something..

Thanks for putting up with me. I only did it to avoid spending what I consider a lot of
cash on new drrums. Since the old ones are working fine I still avoided buying new
drums. so all is good.

(This post was edited by jackx on Jul 13, 2016, 7:44 PM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 13, 2016, 10:59 PM

Post #15 of 15 (788 views)
Re: rear brakes Sign In

OK - I'm putting up with you if YOU can put up with me - deal?
Some parts work and don't look the same some do. Knowing that is its own thing.

Removing a drum that has a rust ring that is loose from the hub and can't retract the star adjuster is a pest. IDK - assorted ways up to just sacrifice the hold-down springs and cut off the pins from the back and take it off shoes, springs and all as most we be tossed for new anyway.

The whole spring kit for both wheels is less than $10 bucks - check out there. Add a new star adjuster and adjustment arm if needed if you expect it to self adjust properly for more than a few years or perhaps 40,000 miles is about all I expect for them to work or work again properly for another round of brakes.

Parts are not that costly vs most other types or vehicles. Tools aren't that extensive or costly either as things go - easy for me to say having 2 or 3 of each thing needed on hand but have to if time is any issue as if anything fails you can't always stop and go get another of something.

Drums and rotors for the most part I don't believe in machining any more as already said the metal thickness is just getting thinner, warps easily and with drums the show isn't the same arc as the new size of the drum for many miles even if in close spec legal size still. They make so much dust right away you just plan on going right back and clean it all out and set it all right when broken in which you could do but isn't something a customer is going to want to hear about.

I STILL WANT YOU TO KNOW PARKING BRAKE CABLES ARE ALL FREE AS A BIRD! If not nothing is going to stay right for long - they will stick and shoes not return to where they should be, drag, warp drums up to total failure.

Cables are fussy as said. Some tools make them a lot easier to cut off bad ones. Getting the initial adjustment perfect is tricky and if not new drums and shoes about impossible to get right.

Stinks for most but about every normal oil change you should remove drums and dump out brake dust and check them out and probably rotate tires every oil change on a 4X4 or FWD vehicle which most are now plus drum brakes at all are about gone for all but HD vehicle use - something good or bad for each style for the long run and what it will be doing.

Where are we now. Just new drums coming to finish this up or what? Just get new return springs - the set. One was already installed wrong or wrong side so that one isn't any good or I don't trust it now.

Hey - easy for me to say as after untold hundreds I did save the extra new springs that come with many and have new singles right now for this vehicle if I went hunting for it. Nobody would do that normally and you wouldn't be seeing assorted problems off hours or the same type or even exact brake again and again. Done with all but my own and still have all the junk kicking around now finding it is the problem.

Let's get this finished. It's all doable just pay attention. I want you to look at the backing plate as well. Look for the areas where shoes ride on it for wear. If worn in to the crooked spot of the shoes they may have to go or shoes will hang up, drag and we'll be doing these brakes forever.

All parts should still be available for this especially same day or quickly as it's a truck in essence. Personal but like brick and mortar places to acquire parts bargain or not you can know then and there if parts are right not the shipping game back and forth over just drum brakes or any for that matter.

Let's roll,


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