Poor brake pedal feel

7Mboost

7M Powered
Aug 15, 2006
2,201
0
0
Gainesville, FL
Poodles;1437250 said:
Nope, as long as the booster isn't damaged they usually don't fail (hence their cost). Damage from a leaking MC is usually why they fail, hence why I asked if there was rust or brake fluid in the bore.

The adjusting rod may be the issue, but I can't say for sure.

It was adjusted correctly, I checked it through TSRM spec.
 

87nasupra

Scotty's Garage
Mar 2, 2006
993
0
0
Jacksonville, FLORIDA !
My car did the same thing, but I actually had a bad ABS solenoid. One of the solenoids was sticking open causeing a soft/spongy pedal when braking. I replaced each one from a donor booster and found the bad one was the RR. IT stopped 10x better and had a much better feel and stiffer pedal too.
 

Asterix

Lurker of Power
Mar 31, 2005
463
32
28
Vienna, VA
Thanks, 87nasupra. I was afraid it's the ABS unit. It has to be, by process of elimination.

Yesterday, I swapped out my booster for a slightly newer one. Neither are rebuilt units. With both out, I compared the freeplay in them, and they were both the same. The input shaft (pedal side) moves about 1/16" before the output shaft moves. That certainly isn't enough for the amount of dead travel my pedal has. The output shaft of the replacement booster was 0.025" longer than my old one, but I had to go with it because the adjustment nub wouldn't turn.

I guess I look for a new ABS unit next.

Aren't there 3 solenoids in the ABS unit? Which is RR? That suggests "right rear" to me, but both rear brakes are controlled together.

Asterix
 

Satan

Supramania Contributor
Mar 31, 2005
1,594
0
36
Tampa
I have had similar issues in the 90 I recently sold. I also included a full set of new brake lines. This issue was driving me nuts. Still had the issue after replacing the brake master cyl. and bleeding 'til the fluid's very clear (I am sure I bled more than 20 times).

I have another brake booster that I was going to use on it, but never got around to it. I do not think it was the booster and was going to start with the proportioning valve that sits on the driver's side of the engine bay (near the steering shaft/column).

That's where I'd suggest you try next, instead of the ABS unit.
 

Asterix

Lurker of Power
Mar 31, 2005
463
32
28
Vienna, VA
The proportioning valve isn't a bad idea except my front and rear brakes are wearing at pretty much the same rate (with the same pad material). At least it's still proportioning properly. It is a cheaper thing to try first, since the valve is a mere $274 from Toyota, rather than $1300 for the ABS unit.

If you try another valve Satan, I'd like to know now it turns out.

Edit: The TSRM to the rescue! (...should've looked a while ago...)
This page tells me there is something wrong with the ABS actuator. The actuator checker SST is only $178, if it's still available.

Asterix
 
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Satan

Supramania Contributor
Mar 31, 2005
1,594
0
36
Tampa
The SST to check the actuator is $178? You can probably get a used actuator from another member for cheap... Like $20.

Instead of all that other work, swap the actuator and see if the problem is resolved. If it is not, then you are out $20 and have a spare actuator. Then, you can put the time/money you saved, towards finding the real issue.
 

adampecush

Regular Supramaniac
May 11, 2006
2,118
3
38
Edmonton
87nasupra;1455572 said:
My car did the same thing, but I actually had a bad ABS solenoid. One of the solenoids was sticking open causeing a soft/spongy pedal when braking. I replaced each one from a donor booster and found the bad one was the RR. IT stopped 10x better and had a much better feel and stiffer pedal too.

Was it the actual solenoid (actuator) or the relay?

What I guess I'm asking is was the problem electrical, or did it require disassembly of the ABS unit?

I ask this as I'm experiencing the same sort of problem as others, although my pedal dead-travel distance seems to be inconsistent from stop-to-stop.

Edit: Upon review of the EPC, i see one relay and one solenoid...i guess that answers my question.
 

87nasupra

Scotty's Garage
Mar 2, 2006
993
0
0
Jacksonville, FLORIDA !
It was the solenoid itself...was sticking and you have no idea on how much crap was stuck in the lines! I cleaned everything out and the supra stopped better then it ever did with the new one installed.