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I swapped in a brake booster from a '88 22RE equiped truck. Its about an inch in diameter bigger than the one that was on my '85 truck. I don't know what booster you'd have on your 4Runner? My guess would be the smaller one. Or maybe the big booster came with EFI?

Anyway, that would be an easy upgrade.

If you are going to rear disks then you might get a FJ80 MC and the aforementioned big booster. That ought to work well.
 

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When we put the Chevy master in my brother in law's '91 4runner, I realized that it already had the dual diaphragm booster.

So I guess T100's aren't the only ones with them. :D
 

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ErikB said:
When we put the Chevy master in my brother in law's '91 4runner, I realized that it already had the dual diaphragm booster.

So I guess T100's aren't the only ones with them. :D
do you think that maybe automatic pickups and runners got the dual diaphram booster to make up for their lack of compresion braking by the engine? :confused: Just a thought.
 

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ErikB:

Thanks for the great page man! All that info saved me tons of time on the T100/Chevy/Wilwood swap. It was nice to have all the part numbers, harder for the counter-monkeys at the stores around here to screw it up. :D
 

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4RnrRick said:
Any Dims on those boosters?????

Did you read ErikB's site?

The T100 booster upgrade is very straight forward. The booster I used was from a '96-98 or so T100 xtracab 4x4 without ABS. It bolts right in place of the old stock booster, but is about 1" thicker (due to the dual-diaphragm design). Be sure to re-check your push-rod distance.
So it's the same diameter, 1" thicker. From my own "eyeballing" measurements, that is exactly the case. So just find a thick one. I also noticed that both ErikB and myself have a different vacuum connection from the stock one. The new one appears to be connected to the body of the booster somehow and is a different color. The stock unit is cast or welded into the booster housing and is black. As you can see in this pic of ErikB's...



The booster I used came from a 95 T100 without ABS. I suspect it's a rather common part. ErikB mentioned he has seen them on 4runners before as well.

You're making this more complicated then it needs to be. Just go get one that is 1" thicker than yours and bolt the biatch in.
 

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ErikB said:
When we put the Chevy master in my brother in law's '91 4runner, I realized that it already had the dual diaphragm booster.

So I guess T100's aren't the only ones with them. :D
ErikB did you happen to notice if there was any spacers between the booster and firewall?
 

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Discussion Starter · #13 · (Edited)
Yeah I did read the site but I must of missed that. I was just wanting a good comparision between the two (single diapharm verses the dual.

I pulled these comparision pictures off of www.NapaOnline.com (very cool site if you haven't been there.

85 22RE 4runner Booster (Single)
90 V6 4Runner Booster (looks like a dual)
97 T100 Booster (looks like a dual)




also found this on another post

the diameter on the old one (I think thisis refering to a 83 booster) was about 8 1/2" and 4"thick with 2 1/2" long studs fork is 7 1/4 from the base

the T100 booster is 10" diameter 5" thick and the studs are 1 1/4 " with 6" long fork the fork length appears to adjustable
 

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thankyou for all of the info, making it easy on a newb, the problem i have in my 85 truck is that after the lift the proportioning was basically of no use, and after swaping new calipers up front, for some reason my passenger caliper does nothing until the petal is all the way to the floor, so i only have the driverside caliper working and i have a heavy pull! im working on getting the parts together to do this swap of the bigger master and brake booster, the lines have been bleed numerous times, but still no luck, could this be a faulty master cyl? also my petal is mush all the way to the floor, at the very end the brake will engage...help me out before i wreck!!!
 

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One side working differently than the other is definitely a problem at the wheel (caliper, pads, etc.), not the MC or air in the lines.

Mushy pedal could be a MC problem or air.
Did you bleed the prop. valve?

Fix your prop. valve rod back up to match your lift or raise it all the way up so that you at least have rear brakes again.

Also, you could have a wheel bearing problem. Loose bearings will let the rotor wobble and push the pads/pistons back into the bores so that the pedal will go to the floor when you try to press it and/or it may need two pumps. That would only happen when moving though.
 

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i havent tried bleeding it at the prop vlave, i will tomorrow, im not too worried about the rears cause im going to disk soon, the caliper is new with new pads, the petal is never hard until the very end, so im ruling out a wheel bearin, i went to a flat rock field the other day and tested the brakes so that i could see the results, at a meduim press after being all the way to the floor only the driverside locks up and pulls very hard, at a full stomp both fronts will lcok except the pass side looked like it was doing very little and only locked at the end of the stop. if there is air in the prop valve could this cause the pass to not work like it should? if so why is the drivers working fine? should i replace the caliper? should i maybe try switching the lines and seeing if the pass side picks up? or should i rule out the MC?
 

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Every time I consider doing this and/or swapping in the larger bore Master... I keep remembering I can get a rebuilt mid-80s F-350 master for about 20 bucks. I think I'm gonna try running that and ditching vacuum brakes all together, whenever I FINALLY get around to going to rear disks.
 
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