Power Brake Booster Push Rod tool or alternatives. (1 Viewer)

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Red Merle

Red Merle

Joined
Jul 7, 2016
Threads
47
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3,079
Location
Twin Ports of Superior, WI and Duluth, MN
Alright, I am still trying to get my brakes figured out. So far, I have replaced all of the calipers and pads, installed a new master cylinder and deleted both the LSPV and the ABS. Everything is bled now and there doesn't seem to be any air in the lines now, but I may check that again. I have been using one of those pneumatic bleeders in conjunction with leaving the bleeder run while I pump the brakes in hopes of driving any air out and then getting out and tightening the bleeder valves.

I am still not getting good results and I think my booster might be shot. I have a hard pedal and the truck will stop, but the booster seems to do nothing. I tried adjusting the push rod a bit using the dab of grease method to see if I would get a dot on the plunger of the MC, which I did. There is good vacuum coming from the intake manifold to the booster, but again, the booster doesn't seem to work right. Of course this is the most expensive part of the job, so I want to be sure that is the issue and that when I put the new one in, that I actually get good brakes and I am sure that I won't burn an exhaust valve by having the push rod sticking out too far.

So what are some alternatives to the SST 09737-00010 tool that the FSM recommends? I did some searching on google and that tool seems to be discontinued and the ones that seemingly replace it are like $300, which is nuts for what the thing actually does.

My concern with the grease method is that I don't know if it is pushing too far on the plunger since the tolerance they are calling for in the FSM is literally 0 mm. It has to be just barely touching the plunger, but not pushing it. I did see something about using old fashioned carbon paper, but I don't like that idea for two reasons. 1) I am not sure how I could get the paper to stick to the plunger or the push rod without using something that would have a thickness and 2) the paper itself has a thickness. The FSM goes so far to say that you should put the new gasket between the MC and the booster on before you use the SST, which means that thickness matters.

So how do people do this without the tool? From my google search, it looks like there are millions of Toyota's out there across many models and years that use this system. I can't believe every little brake shop and garage out there just tells anyone with this type of booster to pound sand.

Any thoughts?
 
I used a flat bar of aluminum (what I had) to bridge the holes and a vernier caliper as a depth gauge. You just have to do a little math. I think the procedure was in my FSM with illustrations and how to add/subtract measurements. I didn't have the FSM in my hand when I did it, so I just thought about what I was measuring and what I was trying to compare. The gasket will push the master cylinder a little further away from the end of the pushrod, so that needs to be taken into account.
 
OK, so I tried the math method and used a vernier gauge and a flat bar. The push rod doesn't even seem long enough to make up the distance needed. I loosened all the way out and threaded it back on just for the first few threads and it appears to still be shy of what I measured. The new MC seems to have the same depth as the old one.

Is the recessed push rod a symptom that my booster is shot? It just doesn't seem likely that I should have had to loosen it as far as I did.
 
There are tests for the booster in the FSM. I don't remember exactly what they are. My booster failed at least one of the tests long before it failed completely. No tools needed for the booster test. You might try that.
 
Tedward said:
There are tests for the booster in the FSM. I don't remember exactly what they are. My booster failed at least one of the tests long before it failed completely. No tools needed for the booster test. You might try that.
Click to expand...


It seems to fail the tests in the FSM, but if the push rod somehow moved and doesn't even make contact with the MC plunger, then how would I know if it was functioning or not?

I guess I will just have to buy a new one and see where I end up.
 
GDA62/100 said:
I used a flat bar of aluminum (what I had) to bridge the holes and a vernier caliper as a depth gauge. You just have to do a little math. I think the procedure was in my FSM with illustrations and how to add/subtract measurements. I didn't have the FSM in my hand when I did it, so I just thought about what I was measuring and what I was trying to compare. The gasket will push the master cylinder a little further away from the end of the pushrod, so that needs to be taken into account.
Click to expand...
Do any of you have a copy of those pages in the FSM? Mine is a 1994 and the FSM for my year does not seem to have those details and I would like to double check my methods before I assume the booster is shot.
 
GDA62/100 said:
My mistake. It's not in the FSM. It's a Toyota Technical training course, Toyota Brake Systems Course 552. It has diagrams and a worksheet. It's here:
http://www.testroete.com/car/Toyota/mr2 spyder/References/Technical Training/05 - Brake Systems/10.pdf
Click to expand...
Thanks for this. I followed the instructions but I am still having brake issues. The only thing I can think of is the way I read the measurment on the push rod. When the booster is not installed, there is a slight bit of play in it on the bench. When I measured, I pulled it out gently and then took the reading. Should I have pushed it in gently? This is the only thing I could see that I might have screwed up enough for the brakes to be as poor as they are now.

Neither the FSM or these instructions you've posted are clear on this, but I am thinking that if the booster has a vacuum, then maybe the push rod gets pulled in back into the booster and I should have measured from there. Does that sound right? I didn't want the push rod to push too far or be constantly pushing on the MC, so I did it the way that I did it, but now that I am thinking about it, maybe that was wrong.

Any thoughts?
 
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I'm in the same boat considering the play in the booster push rod. There is no mention of it in the FSM or technical training.
Originally, I just swapped the master cylinder and I adjusted the booster push rod out a little since the replacement master cylinder measured a little deeper to the piston and excessive pedal free play was part of the original problem. Work had been done on the brake system before I bought it and it probably wasn't adjusted properly--that would be on par with the other work done in the past on this rig.
The brakes still weren't stellar and with the truck being 25 years old and 162k miles, so I followed @beno's advice and replaced the booster, too (although, I suspect it had been replaced once already). The replacement booster's push rod measured the same (within 0.03 mm or so) as the previous, so I left the adjustment alone.
I measured with the push rod pushed in. There was push rod slack in both the old and the new boosters.
In my case, after installation, free play at the pedal is now as it should be. I still need to bleed the system again and road test it, but so far, so good. I think the intent is that the booster push rod is not pushing on the master cylinder all the time resulting in brake drag. I may put it on stands and make sure the brakes aren't dragging.

The original issue that led to this was that there was way too much free play in the brake pedal, the brakes weren't applied until way too far in the pedal stroke, and the feel wasn't right. There were no leaks, the brake lines looked good, and the calipers, pistons, and mechanisms were working. The booster tests seemed okay other than the pedal didn't build up while pumping with the engine not running. Oddly, each pedal stroke was the same, but the pedal did drop when the engine was started. Replacing the master cylinder and proper installation made progress, but after installing a fresh booster, everything works better. But, a good, complete bleeding is essential for optimum braking performance. Of course, the brake system on my 91 is significantly simpler than on your 94.
 
GDA62/100 said:
I'm in the same boat considering the play in the booster push rod. There is no mention of it in the FSM or technical training.
Originally, I just swapped the master cylinder and I adjusted the booster push rod out a little since the replacement master cylinder measured a little deeper to the piston and excessive pedal free play was part of the original problem. Work had been done on the brake system before I bought it and it probably wasn't adjusted properly--that would be on par with the other work done in the past on this rig.
The brakes still weren't stellar and with the truck being 25 years old and 162k miles, so I followed @beno's advice and replaced the booster, too (although, I suspect it had been replaced once already). The replacement booster's push rod measured the same (within 0.03 mm or so) as the previous, so I left the adjustment alone.
I measured with the push rod pushed in. There was push rod slack in both the old and the new boosters.
In my case, after installation, free play at the pedal is now as it should be. I still need to bleed the system again and road test it, but so far, so good. I think the intent is that the booster push rod is not pushing on the master cylinder all the time resulting in brake drag. I may put it on stands and make sure the brakes aren't dragging.

The original issue that led to this was that there was way too much free play in the brake pedal, the brakes weren't applied until way too far in the pedal stroke, and the feel wasn't right. There were no leaks, the brake lines looked good, and the calipers, pistons, and mechanisms were working. The booster tests seemed okay other than the pedal didn't build up while pumping with the engine not running. Oddly, each pedal stroke was the same, but the pedal did drop when the engine was started. Replacing the master cylinder and proper installation made progress, but after installing a fresh booster, everything works better. But, a good, complete bleeding is essential for optimum braking performance. Of course, the brake system on my 91 is significantly simpler than on your 94.
Click to expand...
Thanks for the response. So, I adjusted the push rod out to match the measurements and I did it with the rod pushed in. That helped, but things are still not the way they should be. I am giving up. I took it to a place that claims to be a brake specialist. I am still not sure about my bleed job as I did it alone and I really don't have anyone that can help me during daylight hours.

I do hope that by deleting the ABS and the LSPV that my system is about as complicated as yours is now and that will help. I am also hoping they have the SST to check the push rod as I am still worried about having it cause slight brake drag which I understand is a good way to burn a valve in the motor.

At this point, the only things left to replace would be the lines and I am not even going to think about trying to do that without having a lift. Rolling around on a creeper is OK for some things, but I don't feel like doing the lines that way.

I will let you know how it ends up.

Thanks again for the tech notes, those were really helpful, much more so than the FSM.

Edit: I just wanted to be clear that I did install a new booster. I can hear it hissing which might mean the check valve is bad and the new booster didn't come with one.
 
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Pumping the pedal while the bleeder is open may suck air in to the system.

You never did say what is wrong with the brakes, other than you don't like them.
 
Pin_Head said:
Pumping the pedal while the bleeder is open may suck air in to the system.

You never did say what is wrong with the brakes, other than you don't like them.
Click to expand...
If I knew what was wrong, we wouldn't be this far into it. The thing that started it was that I was driving the truck before I rebuilt the front axle and I went to press the pedal and it wasn't there. I knew I was going to replace the pads, calipers and front rotors as part of my process, but I never did figure out what caused the pedal to go like that. I could pump it up, at first and then that just stopped being an option and as I replaced and deleted things, I never did get it right. Now everything is new and there is nothing beyond the lines themselves to be replaced.

Air may have very well gotten into the system, but I don't have another person to pump and hold the way you would if you were bleeding the brakes. I bought one of those air bleeders and I thought the vacuum that created might be enough to keep a good draw on the bleed valve when I pumped the pedal to press more fluid through.

Something is f'ed, there is no question about it. The brakes should be better than they are.
 
No pedal with all new parts is most likely air in the system, especially if your pedal pumps up and holds firm. Pumping with no pressure sounds like the master isn't even pumping. Maybe you got a bad one. You really need to get somebody to help even if you have to buy the guy hanging out in back of the liquor store another bottle of wine. A wife or girl friend or significant other would be good. A school child would work too.

Don't worry about adjusting the booster rod until you get some brakes. I use a BB size ball of plumber's putty to check the clearance. It's not rocket science.
 
I gravity bleed the brakes, you can do this by yourself, hook tube to the bleeder in the other end of the tube in bucket with brake fluid then open bleeder have the line higher then the caliper and it will pull fluid out, let it run for while while keeping eye on master cylinder keeping it topped off, do all the calipers, then go smack the caliper few times with rubber mallet this will knock the air up to bleeder and repeat till no bubbles, this is the best way to do cruiser brakes in my experimnce , you'll pull all the air out and get firm pedal
 
I appreciate the thoughts. I could try again and have my GF sit in the truck, but at this point, I want to see what the shop thinks. If it's just a confirmed good bleed, there is value in having them do it. I may have missed something and I really want to be sure the push rod is adjusted right. I just got done rebuilding the entire top of the motor and I do not want to cause any issues with that.
 
ajax1 said:
I gravity bleed the brakes, you can do this by yourself, hook tube to the bleeder in the other end of the tube in bucket with brake fluid then open bleeder have the line higher then the caliper and it will pull fluid out, let it run for while while keeping eye on master cylinder keeping it topped off, do all the calipers, then go smack the caliper few times with rubber mallet this will knock the air up to bleeder and repeat till no bubbles, this is the best way to do cruiser brakes in my experimnce , you'll pull all the air out and get firm pedal
Click to expand...
This is good info. I have been bleeding per the FSM and I got creative on the MC bench bleed when it wouldn't stop bubbling. I tipped it up a bit and got it to cooperate when I went back to level that way. I have not bled since I replaced the MC, it seems like that union is tight and there is no reason to re-bleed every time I take the MC off the booster.
 
Alright, I got the truck back from the brake shop. They were able to determine that the new booster wasn't holding any vacuum, which would explain the hissing sounds that I heard right after I installed it. I am sending this one back and will wait until I get the new, new one in before I start over. At least I feel good about the fact that it didn't seem like I did anything wrong when I installed the last one.
 
Bring up this thread again, I have about the same thing, brake pedal goes down about 3/4th the way down before it feels like I get any brakes. I have replaced all the pads, rotors, slave cylinders are in good shape, and both Brake Masters, Brakes Plus, and the Dealer have had the car and no one has said this is out of the ordinary. I did have Brake Masters bleed and replace the fluid, which made no difference. Booster has been replaced twice. The only thing I am thinking is that I have not replaced the Master, nor have I adjusted the push rod yet. Wanted to get others opinion before I proceed. Thanks,
 
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