Funny rear brake question

both sides are the emergency brake. the cable from the cab connects to the passenger side run but when it's pulled it pulls the driver's side cable to offset equal amount.

 

Call me crazy, but i still don't think your axle, seals, or bearings have ANYTHING to do with your brake issue. I believe you have a bad cylinder and a ton of air in the system. Does your reservoir get low?

There is no gear oil in the drum, indicating that the brakes are not being compromised by oil.

Three brake components were shiny clean, indicating they have never even engaged. Oil wouldn't cause them to not engage, it would simply cause them to be less effective. There would be oil everywhere inside with groom and nasty brake dust. Regardless it this just started or has been long term, this would be true.

We know air was in the line. We know the cylinder moved less then normal. We know the shoes are not engaging the drums, and we know there isn't a ton of oil inside. Nothing here points to any type of seal failure what so ever.

 

I think you need to read post #6 and you'll probably rethink what you wrote.

 

You make a great point. It's still WAYYY too clean in there in my opinion and we saw how much air was in the lines and also the limited movement of the cylinder. Ill accept that their may be a little gear oil on the shoes, but i also think there is another issue. Just my .02 though

 

Well, I reckon he has 2 problems.

 

How did you Jack up the truck? Jack stands under frame? The perportioning valve will be almost completely bypassed when the axle is sagging.

 

Nah, jack stands were under the shock spring brackets; axle supported. Still though, I had no idea there was such a valve, something I'll have to look into.

I agree. And so here's the UPDATE for now: I drove it 750 miles since I flushed and re-bled the system (and recall, I do feel like an abnormal amount of air came out of that drivers side rear brake line when I did the flush. Much more air than the other brakes). So currently when I take the drum off, there is a new wear pattern to the brake. Now in drum/shoe life, 750 miles is nothing at all, but I'm pretty damn sure that the wear pattern is much increased. It was like-new when I took it off the first time, now at least there are score/wear marks on the outer edges of the shoes. Actually it looks like what people refer to as "seating" when talking about new pad/shoes

Also, with regards the wheel cylinder, I had a helper, and now with a 6' iron cheater bar put between lug nuts fitted to the exposed drum, he couldn't move the axle with the brake applied, so I believe the wheel cylinder is functioning. We did also take the drums off both sides and apply the brakes (gently), and they appeared to be moving equally on both sides.

And yes, I do. Getting more familiar with the drums/axles back there, I've realized there is a oily residue on the lower half of the drivers side just under where the axle meets the brake assembly. It's not pronounced or impressive, but there's a residue there. The axle seals are definitely failed.

Overall my next steps/new plan is to drive it about 5,000 more miles and then re-check the wear pattern back there, and then to fit new brake shoes/re-surface the drums just to equal things out, plus/minus new wheel cylinders and axle seal repair, depending on how things look and how much time/money I have.

 

Update here about my rear brake question after driving for an additional 8,000 miles: As some of you first suggested, seems like the problem was likely and axle seal (possibly compounded by a small amount of air in the system that needed to be bled). See here the updated pix, with much more oily residue evident than before, and still hardly any wear on the braking surface:

And more:


It's too bad, as seals are a much more involved repair than a wheel cylinder, but I guess I've known that since getting feedback on the thread. On a positive side note, I went back down to stock tire size from my 285s, and the brakes work tons better with the shorter radius regardless of this seal leak. I'll probably delay fixing the seals until I get some other things finished first, such as getting the timing belt done, which is due. Thanks for all the comments and suggestions on the issue above.

 

You've got your priorities wrong in my opinion. Right now, you have a problem staring you straight in the face that is affecting the safety of your vehicle. Also, if you put other things in front of taking care of your axle seal problem, you are going to have to keep a close eye on your rear differential oil level until you get it fixed. With gear oil getting past the seal, it's now surrounding the bearing and slowly washing out the grease from the bearing. Once there's very little grease left, it's the gear oil from the differential that's keeping the bearing lubricated and not overheating. If you don't watch the oil level close enough and it drops down to a level that isn't lubricating the bearing sufficiently anymore, and you go for a long enough drive, the bearing will overheat and completely disintegrate ruining your axle, damaging the inside of your axle housing and leaving you stranded wherever it happens. How do I know this? This exact thing happened to a guy who drove from Auburn California to my house in San Jose California for a party I was throwing for our channel subscribers. Luckily for him, he made it to my house barely. Unfortunately for me, I spent a good part of the day working on this kid's rig because he ignored his leaking rear axle seal for too long.

Your timing belt being "Due" is not more important than fixing your rear axle seal. Timing belts can last much much longer than we think, 200k miles and more. Is it smart to replace the timing belt and related wear components at a regular interval like every 100k? Sure it is. But, your preventative maintenance timing belt replacement shouldn't take priority over something that is affecting the proper braking of your vehicle and that could ultimately cause you a catastrophic failure if the bearing fails. It's your truck and your life but it's obvious to me and probably most others that you should take care of the issue that's staring you straight in the face. My two and a half cents.

 

I had a leaky seal on my '97 4Runner which probably is the same setup as your 2002 Tacoma. Actually with the differential oil getting into the drum the rear brake shoe it bound hard and would lock the wheel. I put in a new seal, topped off the differential oil, brake cleanered the entire drum assembly, verified the piston wasn't leaking, wire brushed all the components, put in new brake shoes, put everything back dry except for a little high temp grease on the star wheel thread, and it brakes perfectly.

 

Thanks for the response. I've thought about it, and you're right. I'll get on the seals and prioritize them, thanks again.

This is good to know, I'm going to get into it.

I'm not really sure what causes it. My truck has about 180k miles, quite a bit of time in desert sands, deep/prolonged beach sand driving, with 140k of those miles using tires with around 17% greater circumference and much greater weight. Maybe that's why?

 

This is what happens if you drive too long on a bad wheel seal/bearing.


Had a catastrophic seal failure (no previous leaks, but potentially a slowly failing bearing) about 400 miles from home. Drove back being careful to keep the diff topped up and to not use the brakes (gear oil swells brake shoes causing them to hang up on the drum) but found this when pulling it apart.

If you have a failing seal, it's possible that your bearing is also on the way out. One failure mode of the seals is due to excessive axle movement caused by a bad bearing. While it's a lot more work to replace the bearing than just the seal, it's probably worthwhile to ensure you're not setting yourself up for another seal failure down the road.

 

Put the drum in have someone step I
I’m the brake and see if you can turn the drum by hand.
Someone may have put new parts on. It never seated the adjuster properly into the slot where the shoe is. I did that to myself when I rebuilt the rear brakes on mine.

 

Wow, that's good to know. Thanks for the pictures. I just got my new seals/bearings in the mail, so I'll be getting into this soon. I think you guys are totally right that fixing this needs to be top priority.

 

Just an update here on my seal leak issue...

Seal/bearing have been replaced, and have about 175 miles on it since the replacement.

All seems good so far, and I've already got more wear for this side than the previous several thousand miles. Not having gear oil on the shoes works wonders:



And while it's not many miles yet, so far everything is nice and dry. Drums were turned, and I used new shoes (Raybestos).

Interesting thing that I wished I had known going into it, is that while I don't have ABS on my truck at all, I do have an ABS rear end, and all the internal axle hardware is set up for ABS. See this picture for where the ABS sensor would go if I had one:


So I should have known better, but I just figured my axle would be configured like non-ABS on the inside. Significance of this being that I hadn't ordered enough parts prior to starting the project. In addition to a new bearing, I needed Two retention clips and a speed ring, instead of just a single retention clip and no speed ring.

It also makes the procedure a little more difficult because you need to be more careful with the measurements of the inner retention clip. A bonus though was that since I don't actually have ABS, I decided to not put a new speed control ring on the axle, since as far as I can tell it serves no purpose if there's no sensor attached to it. I saved some on that as they're $70 a piece at the dealership.

Here's my last grease test prior to moving it 3 mm further down the axle, and installed it with no speed ring (I actually didn't do another grease test after moving it the last 3 mm, as it was getting late and I was tired):

Since I had plenty of room to move the clip around to exactly the right depth without a speed ring, I didn't switch the bevel backwards as many people are doing.

Overall, I'm happy with the outcome so far. I am learning this stuff as I go though, and it wouldn't surprise me if something were not to work out the way I hoped. I welcome any comments/questions about what I've done so far, and I'll update if there are any changes/problems coming up.

Oh, one final note: There's a video on youtube of a guy doing a Toyota rear axle bearing/seal replacement with No press. I was optimistic and thought maybe his technique would work out for me. After trying it myself, IMHO it is a very bad idea. I ended up paying a local shop to help with the press work (charged me $117, but worth every penny). I did tap the final retention clip on with a pipe though, measurements being 1-3/4 ID, 2-1/16 OD if that helps anyone. I also used a Honda A02 oil filter to tap in the new seal. The Taco filter would have worked top-first, but I thought the A02 was a little better for it as it went in base-first.