Surge when stop/rear drum adjustment

[a049701]

I have a theory on the surge when stopped issue that keeps popping up on this forum and would like any feedback on it that anyone might have. My 2002 SR5 2WD with 97K occasionally does it depending on how I stop. I am very easy on it having had my share of "hard" driving in my younger days. A few weeks ago I ordered all parts for the timing belt/water pump replacement job and figured with 97K it would probably need brakes all around so ordered them too. After the timing belt/water pump replacement job was complete, I checked the front pads and they still had about .120" of pad left, Toyota says minimum is .060". Since they start out about .400", I figured they would have gone another 12-15K but I changed them out anyway. I then removed the rear drums and to my surprise they showed almost no wear at all. I did not replace them at this time. I got to reading up in the official Toyota manual and best I can tell the action of the emergency brake engagement keeps the rear drum brakes adjusted. Well, I almost never use my emergency brake and am wondering if this has anything to do with the lack of wear on my shoes. I activated and released the emergency brake about 50 times and they did tighten up some obvious by a couple of threads showing on the adjustment screws without crud on them. To my theory, I have always felt that the surge we disuss was caused by the rear brakes making a crude sloppy release in some way, just due to the feel and sound when it happens. I drove my truck a couple times after this rear brake adjustment and the surge is not there (however, it may come back), when I stop and then go it feels much smoother at the point where the surge usually occurs. By the way, I just checked my driveline a couple days ago and it appears perfect, no slop, spline not sticking in tranny, etc. I do not buy that as the cause of MY surge, anyway. Has this been investigated by anyone else?

[BAD BONEZ BJ]

Originally Posted by a049701

......... To my theory, I have always felt that the surge we disuss was caused by the rear brakes making a crude sloppy release in some way, just due to the feel and sound when it happens. .............By the way, I just checked my driveline a couple days ago and it appears perfect, no slop, spline not sticking in tranny, etc. I do not buy that as the cause of MY surge, anyway. Has this been investigated by anyone else?

I occaisionally have that surge and as did you, I thought the rear brakes. Doesn't feel like the driveline at all. I'll be pulling my rear drums apart soon for annual cleaning and adjustment. Will see what that does.

In the meantime, I'll crawl under the truck and fill all the zirks with new grease (been putting this off on my truck but did help Tundradinalin do his).

Doing both of these procedures should get rid of that surge for sure. While under there I think I'll do the rear spring squeak fix too, since that just recently started.

[sr5mike]

This topic was beat up on the tacoma board. I had a 99 taco prior to my tundra purchase. I get the surge once in a while with my tundra. The tacoma was awful for that it was happening almost every stop. I think it is axle wrap. During hard or somewhat hard braking the axle rotates slightly. When you let off the brake it releases. Making it feel as if someone just tapped the back of your truck. I think the soft springs of the toyota trucks are to blame.

[Burger Steak & Eggs]

Originally Posted by a049701

I then removed the rear drums and to my surprise they showed almost no wear at all. I did not replace them at this time.

Most of the braking force is placed on the front brakes, hence the rears last longer.

[a049701]

Yes, I am aware most of the braking force is handled by the front pads, but again, 97,000 miles and the rear shoes look almost new...? I would have thought they would have considerable wear on them with that milage...but then, as I stated in previous posts, most of my miles are highway miles across Tennessee's I-40 back and forth from one end of state to the other (350 miles each way) a couple times a month, that does add up with minimal use of brakes.

[Burger Steak & Eggs]

I usually equalize wear at the rear with several trips to the dragstrip each year.

[sr5mike]

Maybe the Guys with the AAL can answer if that helped any.

[DJ]

My '00 Access Cab with 111,xxx miles on it shows almost no wear on the rear brake shoes or drums. My brother's '97 Chevy truck went about 200,000 miles, after which the rear shoes and drums showed almost no wear.

The rear brakes do contribute to braking, but Hunter Engineering's brake tester shows that 75-90% of the braking is done by the front brakes. Less braking means less wear, but the wear is not proportional to the use, i.e. if the rear brakes provided half the force that the front brakes applied, they'd have much less than half the wear over the same duration of use. So, they last and last and last. That's normal.

[ejsharp]

I've heard that rear shoes can last the life of the truck. I suppose the rear brakes get more action and wear if the rear of the truck is loaded down.

The important and really simple thing to do, is to get on the back sides of the rear wheels and adjust the rear brakes with a brake spoon (you have to raise wheel off the ground to do the adjustment so you can spin the tire and feel the grab of the shoes as you adjust the star wheel).

[Hi Volt]

I have had this issue occasionally and have come across apparent different causes, at least the symptoms always felt very similar. The thump in the butt feel upon stopping and the occasional thump on starting off can be caused by the rear-most u-joint starting to go bad. I have had this issue twice before and it has always gone away after the change. Recently I noticed it again, and very regular, and again assuming it was a u-joint issue again did the routine change. Upon inspection I did notice some very light needle bearing impressions in the journals, but not as bad a previous times ( comes from hard driving ). These impression will cause binding in the joint under load ( not noticeable if the u-joint is articulated by hand ). Well after the re+re the problem still persisted which was very discouraging and annoying. I started to think it may be a brake issue so I did a simple test. I first placed the park brake on 1 click and went for a drive, this has the effect of tightening up the brake adjustment a little. ( note: The closer the pads are to the drums the less fluid is required to move them the rest of the way and the more responsive the brakes feel ( as they actually are ). Rear brakes use return springs to pull the shoes back from the drums, however as the shoes wear this gap gets larger. Disc brakes on the other hand always maintain light contact when released so they always stay adjusted.)

Anyway, there wasn't enough improvement to be conclusive so I did the same test with 2 clicks and then 3. With the brake on 3 clicks the problem was gone and the brakes also had more grab, but were not dragging. My rear brakes were in need of adjustment as it took about 5 clicks before I could feel drag while driving. Regular use of the park brake is supposed to adjust the rear brakes but it doesn't do as good a job as a real "hands on" brake adjustment in my opinion. I usually keep my rear brakes adjusted because the brakes simply work so much better and the fronts won't warp, but I guess it just got away from me this time. Anyway they are adjusted now and problem gone.

So within a few minutes you can do the park brake test I did and see if that helps, if so, crawl under and do a proper brake adjustment (or service if you are due).

Hope this helps out

P.S. Here is an adjustment tip I use - When doing the adjustment there is a distincive "ting" noise after each click ( noise through the backing plate ). Listen carefully for a pitch change to a destinctive deeper "tong" sound. This is the point I stop the adjustment and it seems good. I prefer this to trying to feel for the same amount of drag side to side by spinning the wheels ( a method I used to use).

[BAD BONEZ BJ]

I haven't opened the rear drum yet but did grease the one sliding yoke on the diveshaft and my clunk went away. Don't know about the surge yet.

BJ

[MEvang]

Well you are all on to the cause of this. This is a fundamental engineering problem with trucks and common on many brands. As with many problems like this there are many things going on to cause the problem. Rear shoes can become more aggressive or"sticky".
When the rear axle "wraps" during a stop, as soon as you let up on the pressure the axle will snap back and you feel it. If the drive shaft slider is sticky you feel it more. If the shoes don't slide loose and abruptly let go, you feel it more.
Rear brake shoes last on these truck not only because of the proportioning of the brake system but because of the material formulation of the shoes. Just like brake pads, ceramic and metallic formulations have made shoes last a long time. The dust from these shoes can also contribute to the shoes becoming more aggressive "sticky". I suggest a good cleaning, and a light sanding of the shoes and drum surface when you adjust the brakes, at lest once to twice a year. This will help the shoes slide lose from the drum instead of breaking loose aggressively.
This year Dodge has fixed this problem on their light duty trucks. They have gone to coil spring rear suspension. No more spring wrapping. Now these truck can no longer carry the load a leaf spring truck can, but comfort will be much better.
Keep you shoes cleaned and adjusted and the slider lubed and this problem is very minimized.
Mike