Master Cylinder Swap Specifics - 3 questions

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Randy88FJ62

Randy88FJ62

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UPDATED: SEE POST #14

My SOA build is nearing completion as shocks are almost finished. My attention is now on brakes. The parts truck I bought came with SSBC front calipers and Chevy S-10 rear floating calipers. Due to the increased volume in brake fluid caused by the switch to disk brakes in the rear I am looking at a master cylinder upgrade. The few threads I have gone through during search show a lot of different approaches. I want to stick with a Toyota MC and am leaning towards an FJ80 MC or a T100 MC. Is there a MC that bolts directly up? I want to do the swap with as little modifications as possible. So, who can tell me which, if any model bolts directly up and will have a larger volume to accommodate the rear pistons on the Chevy S-10 calipers. The Chevy S-10 calipers look very similar to El Dorado calipers used by others and have the added benefit of using stock Toyota pads.

Second Question:
Assuming I can get a MC that bolts up, do I need to consider the bore and stroke of certain MC’s in order to keep the same pedal feel?

Third Question:
What is the benefit of keeping the LSPV? I can’t see any problems with taking it out other than skidding the rear tires during an emergency stop. This is normal to me and must be watched anyway as early 60 series had no ABS.
 
Last edited:
Randy88FJ62 said:
My SOA build is nearing completion as shocks are almost finished. My attention is now on brakes. The parts truck I bought came with SSBC front calipers and Chevy S-10 rear floating calipers. Due to the increased volume in brake fluid caused by the switch to disk brakes in the rear I am looking at a master cylinder upgrade. The few threads I have gone through during search show a lot of different approaches. I want to stick with a Toyota MC and am leaning towards an FJ80 MC or a T100 MC. Is there a MC that bolts directly up? I want to do the swap with as little modifications as possible. So, who can tell me which, if any model bolts directly up and will have a larger volume to accommodate the rear pistons on the Chevy S-10 calipers. The Chevy S-10 calipers look very similar to El Dorado calipers used by others and have the added benefit of using stock Toyota pads.

Second Question:
Assuming I can get a MC that bolts up, do I need to consider the bore and stroke of certain MC’s in order to keep the same pedal feel?

Third Question:
What is the benefit of keeping the LSPV? I can’t see any problems with taking it out other than skidding the rear tires during an emergency stop. This is normal to me and must be watched anyway as early 60 series had no ABS.
Click to expand...


1) the 80 series and T100 will both bolt up. it is all the same pattern.

2) Yes. you need a bigger bore. It is hard to tell what you need without the specifics. Read ntsq's threads here, he really knows about brakes.

3) Rear tires blocking before the fronts is a huge problem. You'll spin out under slippery conditions and you get much worse braking efficiency in general. Frankly, the rear;s should NEVER block before the fronts. So yes, you absolutely need some sort of proportioning valve. The stock one will most likely not do it, considering the mongrel brake system you have on the truck.
BTW, a functioning brake system on an early 60 will NOT lead to the rears blocking up before the fronts. If they do you have bad wheel cylinders, dirty shoes or a bad master.
J
 
The part number for the T100/early 80 non ABS MC should be in my build thread.

Get rid of the LSPV, buy an adjustable proportioning valve from wilwood or somewhere and adjust it such that the rear brakes will not lock up before the fronts. From what I understand, adjusting the proportioning valve is a trial and error type of operation requiring a bit of driving around. That's what I've read works well with rear discs.

I run the 1" bore MC on my 60 and it stops the truck very well.
 
Now that I have confirmation that MC of an FJ80 or a T100 are bolt in, which year and or model is best? Are there different bore / stroke combinations that are preferable? I plan on ordering directly from Toyota and getting a new MC.
 
I'll have to disagree on which should lock first. If the fronts lock first you have no steering. If the rears lock first they're like throwing out an anchor, but you still have directional control (barring ice or slime kinds of situations). The goal is to get the system balanced so that at the extreme the rears lock *very slightly* before the fronts. Just enough before that they give you some warning that the fronts are next.

I've NEVER heard of a GM caliper that used Toyota pads. The pad retention systems are totally different.

All of the "metric" GM calipers (Eldo rears, S-10, late Monte Carlo, etc.) use the D154 pad and are nominally a 2.5" OD single piston. Assuming a 0.015" pad knock-back/retraction distance (a std., usually close to real, number) you'll need 0.147 cubic inches of brake fluid just to move the pads into contact with the rotor. (Assumes that the Eldo calipers are in adjustment - BIG assumption.)
If that volume is significantly different than what the fronts need then the axle with the least volumetric need will start to stop first.
 
I got mixed up. The rear pads are stock Chevy S-10 pads. The diameter of the floating caliper is about 2.5" as you mentioned. I wonder if the SSBC dual piston front has more volume that the single piston rear.

Any other suggestions on stock Toyota MC's? I'm curious what others have used and why?

Wasn't the 1990 SR5 V6 truck smaller than the landcruiser? I feel that the master cylinder wouldn't be a good match for the 60 series since the SR5 looks like a lighter vehicle.
 
I read some where that the T100 MC are 1" bore and the 80's Non ABS are 7/8" bore.
Or viseversa, but cant seem to find the link....
I used the 80's series reman.
 
MANUCHAO said:
I read some where that the T100 MC are 1" bore and the 80's Non ABS are 7/8" bore.
Or viseversa, but cant seem to find the link....
I used the 80's series reman.
Click to expand...

Th e T-100, 4-runner and FJ-80 w/o ABS all call for the same part number if you use Napa's online information. The resevoirs may be different, but that is all. They are 1" bores. FWIW, your fronts should lock just before the rears. It is just plain scary trying to descend an ice-covered hill with too much rear brake. Proportioning valves are readily available and don't cost much.
 
I called Northridge Toyota and they said the first year they have for the T100’s in 1993 and the P/N is 4720134020. The cost to me would be $280 new after our 4x4 club discount. Can anyone confirm this is the correct MC? Does the price sound about right for a new MC?
 
That is way too much money. I would not spend that on a MC. Get a new aftermarket unit. It will be way less than 1/2 the cost and live almost as long.

Dynosoar:zilla:
 
Dynosoar said:
That is way too much money. I would not spend that on a MC. Get a new aftermarket unit. It will be way less than 1/2 the cost and live almost as long.

Dynosoar:zilla:
Click to expand...

Any specific part number suggestions or manufacturers? I know MAN A FRE sells one. Does summitt racing have a specific one? Any help sourcing would be appreciated as I don't want to order the wrong one.
 
Background:
Over the weekend I went to my local pick your parts and grabbed a 1995 T100 Master Cylinder for $40. I immeditely went back to my truck and removed my old one only to find that it doesn't exaclty fit. Bolt pattern is fine but the actual piston is about 1/8" lower on the bolt pattern and doesn't go into the firewall. A little trimming and it should go in.

Question:
What are the extra two wires coming out of the side of this T100 master cylinder reservoir?
P3050010.jpg


Looking at the FSM wiring diagram I see only two wires which trigger a warning light if the fluid level gets too low. These wires and switch are not the ones coming out of the side. The factory switch is integrated into the top cover. Both my old top and the new top I grabbed off a FJ80 in the junk yard broke as seen in the below picture.
P3050012.jpg


Can anyone explain the wiring and extra switch in the 1995 T100 reservoir?

Can I somehow not use the top stock switch since I broke it or do I really need to get a replacement to be safe?

More Pics:

T100 Master Cylinder Part Number
P3050004.jpg


Obvious volume increase between cylinders
P3050002.jpg


Another View
P3050001.jpg
 
The master cylinder will bolt up to the booster ( black base ) no problem. You'll have to bend the outer brake line slightly to make it fit but you shouldn't need a tool to do so. Bending slightly by hand is fine.
 
GLTHFJ60 said:
The master cylinder will bolt up to the booster ( black base ) no problem. You'll have to bend the outer brake line slightly to make it fit but you shouldn't need a tool to do so. Bending slightly by hand is fine.
Click to expand...

When I unbolt and reinstall the new master cylinder with the old booster are there any innards that are hard to reinstall or is it a simple bolt on swap?

While we're talking master cylinders; anyone know what this brand is? It's on the side of the casted T100 master cylinder:
P3050009.jpg
 
Simple bolt on. Took 5 minutes to do. Make sure to bench bleed the MC before you put it on.
 
GLTHFJ60 said:
Simple bolt on. Took 5 minutes to do. Make sure to bench bleed the MC before you put it on.
Click to expand...

Spikestrip mentioned he did that too. How do you do it? Add fluid to reservoir and then pull fluid through the two ports on the cylinder?
 
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