Brakes Mystery

My brakes were terrible, now they are awesome. I don't know why!
My story:
1. About 4 months ago the brakes were fine.
2. I replaced the LH axle seal (seal blown due to plugged breather which I fixed).
3. During axle seal replacement I replaced shoes on that drum because the existing were saturated from the blown axle seal.
4. Reassembled axle and bled brakes as per spec.
5. Test drive: Not good. the beginning of the brake issue.
6. The brake issue: One mushy push then fair braking. Have to cycle through one mushy push before adequate braking... every stinkin time!
7. Numerous bleeds by me and a couple by shops. I replaced master seal. Nothing changed. Nothing.
8. This was months ago and I've been living with it ever since... I got used to it.
Now the mystery part....
9. I did an abusive offroad trail (about 25 miles worth) and wasn't shy on the skinny pedal. My suspension is built for it and... it's a HELL of a lot of fun.
10. After returning to the HWY from this abuse... my brakes are working perfectly! And I mean PERFECTLY. Like better than when I got the truck.
Beating the shit out of the truck actually fixed my brakes?
WHAT????? Any ideas on this mystery fix? I'm perplexed, but in a good way.

 

Did you replace both sets of rear brake shoes? or just one side? How old were the rear brake shoes?

 

I only replaced that side and adjusted them as per spec at that time. The shoes on the RH side were still pretty new.

 

Would there have been residue on the drums you didn’t get off after changing the shoes again? The off road exercise may have worn it off?

 

No way. I completely sterilized that drum and components before reassembly.

 

Your double pump issue is exactly the same issue I have. I can pump the pedal once(mushy), then the 2nd time it's firm. What I suspect, based on feedback from other members such as @NUDRAT is that I have air trapped in my ABS line/module. Nudrat had the same issue and his mechanic fixed it by engaging ABS several times and then immediately bleeding the brakes. The last time I found gravel and engaged ABS a lot, my pedal felt great for a few days before returning to mush. What I should have done is bleed the brakes.

I think this may be the clue. Did your ABS engage a lot while on this trail? It's possible the rough trail freed up the air from its hiding spot. Don't be surprised if the pedal returns to mush. You may want to bleed them again.

 

Entirely possible. They are working so great right now that I don't dare fiddle with bleeding them again... like the 6th time.

 

The theory is that ABS engaging will burp the air from the hiding place. In my case, it worked until it settled back in it's home. I think the double pump thing can only be because we're compressing the air the first time. I haven't found another explanation for why I can get a firm pedal after 2 pumps. I believe you also replaced your master cylinder around the same time I did mine so it's not like our master is failing.

 

I recommend going for a violent drive up a big rocky mtn.
It's all I know.

 

Most have reported properly bedded and adjusted rear brakes is the key to great braking. Something must have settled into favorable position post off-road exercise. My brakes always feel great after I readjust the rears to have some slight drag. Just wish they would stay adjusted. I'm a parking brake fanatic. I hear there is an updated starwheel adjuster for these drums, more teeth or less teeth or some crap that fixes the not self adjusting feature of these brakes.

 

Putting my truck up on jack stands and manually clicking the adjuster with a screw driver till the wheel has a little drag when spun by hand really helps my truck with the “double pump”. The parking brake should do this but if it’s not the rear brakes don’t adjust and then as they wear you get a gap. You then have to push the brake pad to the drum with the first pump.

 

Please report back in a few weeks and let me know if the brakes are still great. If they return to mush then we'll know.

 

I will definitely do this. It's been a couple of days and about 200 miles so far.