Sharp Brake Engagement

About a month ago, I took my Taco in to the dealership for a pretty loud braking squeal in the driver rear drum. The tech "cleaned and adjusted" the rear brakes. I drove the truck off with no issues. About 2 weeks ago, I noticed the braking had changed. Instead of smooth, gradual stopping/braking, when the brakes would engage, I got a sudden, sharp brake grab and a very noticeable nose dive until I came to a stop. For a passenger, it feels as if I'm hitting the brake really hard, although I'm barely stepping on the pedal. It happens at slow speeds, but is much more obvious at faster speeds. I get the concepts of inertia and momentum, but this is extreme compared to previous braking. For a few days, I "babied" the pedal to minimize the "grabbiness," but recognized this was not cool and was potentially unsafe. I went back to the dealership, and the tech said the shoes were adjusted too tightly and the drums were glazed. Again, they cleaned and readjusted the brakes. And again, I drove off with no issues...until 2 days ago. I have the same issues: instead of gradual stopping, the brakes "grab" and the nose "dives." No lights or any other indications of issues.

I've researched all the forums I could about this and am at a loss. Beyond pulling the wheels and drums off, and adjusting them myself, I'm not sure what else to do...considering I'm still under warranty. That said, I have just enough room in my garage to change my oil, but not to remove wheels, etc. My 2 concerns: the fact that the braking has changed AND the glazing.

What I've done:

- I've tried the semi-mythical "self-adjustment" method of hitting the brake/e-brake while in reverse, but no change. If they're really tight, I'm sure this can only make it worse.
- I've disconnected the battery to see if the issue is electrical, as opposed to mechanical, but no change.
- I've got ANOTHER appointment tomorrow at the dealership.

The symptoms are identical as last time, so I'm assuming the shoes are once again too tight (explains the glazing)...but it seems to me that "loose" shoes would make the front dive, too. Is it possible these rear brakes are self-adjusting to a notch that's just too tight right now (even though the tech loosened them), until they wear a bit? Any other recommendations for what to check before I kill at least another 3-4 hours tomorrow?

Thanks!

 

A 'nose dive' condition usually means you have TOO MUCH braking in the front and not enough braking power going to the rear. A 'dragging rear brake shoe' or an overly adjusted rear brake (too tight) will not cause a nose dive in the front.

The glazing could explain there's TOO MUCH braking in the front.

If you're still under warranty, keep going back to the dealership and keep pushing the issue. It sounds like there could be a 'proportioning valve' or even a master cylinder issue.

 

Oh, I am...lol. They know me.

Yeah, the fact that the nose dives tells me the back's not pulling its weight, sts. Of course, I wasn't back in the shop when the tech saw what he saw and did what he did. However, he did say the drums were glazed...that seems to support the fact that they were possibly dragging due to tight adjustment (or even a seized cylinder, etc.). While it's possible there's a master cylinder or proportioning valve issue, it's extremely ironic either would go out while the brakes were being adjusted.

The really weird part is that immediately after each visit to the d-ship, everything was fine, for a couple weeks, then about 2 days. It seems as though something is losing adjustment. I'm going to bring everything up to them tomorrow...we'll see.

 

I think there is a proportioning valve, you might want to have them check that too...

 

Yeah, I ended up going down 6 clicks on the star wheel, but no dice...guess I was being hopeful. When I actually drove the truck, it was the same. I'll def ask them to check the valve.

 

They found nothing wrong with her, except the work I did to tighten the shoes. The dealership "initiated a ticket" to reveal whether this is a shared issue. I don't think it is. if it readjusts again, I may just have to adapt to it, until the shoes wear a bit and eventually mellow out...lol.

 

You missed the point of Jansters post.

The truck is nose diving when you brake.

The problem is in the Front Brakes Not the Rear Brakes.

You could lock up the rear brakes and it will not cause a nose dive.

Look at the Front Brakes for your problem.

 

No, I get it...just no obvious issues. The d'ship honed in on the drums because that's what was originally adjusted and cleaned for a squeal. What's strange is that they adjusted the drums, and the symptoms were gone...then reappeared.

 

As they adjust the shoes in, the problem disappears. As the shoes self-adjust (to a tighter position), the issue returns. No lights or anything like that...may eventually work itself out.