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3g Brake Booster & MC

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Nekid

10+ Year Contributor
128
0
Aug 17, 2012
Saskatoon, SK_Canada
I have found a few threads which indicate that the 3g brake booster is a direct bolt-on for the 2g. However, when I went looking for the 3g brake booster, two different part numbers are listed. One refers to a 3g with traction control, the other to a 3g without traction control. For reference, the top trim model, GTS, came with traction control and in these discussion, is the only trim mentioned.

Which one is the bigger brake booster? Which one is the bigger MC?
 
When I used the 3g MC on my 1g I was asked that same question about traction control,so I dont think the booster is the part that would be the difference with or without traction control.I think it has more to do with the MC. I went with non traction on mine.
 
I know that the traction control won't affect the configuration of the brake booster or the MC, however, because of the different part numbers, I'm assuming there is two different sizes of brake boosters and MCs, either the one with TC gets the bigger parts or the one with no TC gets the bigger parts.

If you could list the size of your 3g MC it would be a starting point. I'm going to see what other information I can dig up.
 
I'd like to know about this as well. I'm going to be doing this swap soon.
 
Well, I can't say which model to buy because honestly I don't remember, but you could call up Paul at JNZ Tuning and ask him which one John Freund (me) bought. I do remember there were two part variants and Paul ordered me both, and he couldn't tell the difference so we just guessed and the one I received did work. I use it on my track car.

The reason for this "upgrade", in case it's not clear to folks stumbling into this thread, is to properly match your master cylinder to the brake caliper piston volume. 2g calipers are matched to the 2g master cylinder (which I think is 7/8" bore, right?), but if you move to calipers like an Evos that is normally matched to a 1 1/16" bore master cylinder your pedal play will be greatly increased (you have to push more to get the same fluid volume moved). In my case I moved to evo rear calipers only and my pedal play difference was pretty huge on the race track, enough that I couldn't even do the "heel-toe" (more like toe-heel on a DSM) and it was really screwing up my driving having to go so deep into the brakes. Arguably a preference thing more than performance, but it just really unnerved me going so deep in the pedal every time. By moving to the 3g master cylinder, which is 1 1/16", my pedal play is pretty much back to "normal", or at least matching what it was with a 2g matched brake set and I'm much more comfortable driving. I can't imagine what it would have been like with evo calipers on front AND rear... I imagine that might be borderline dangerous.

Hope that helps.
 
Going through ASA, here is what I have:

Master Cylinders:
MR475973
MR375431

Brake Booster:
MR475433 - Replaced by MR527042
MR475434 - Replaced by MR527043

And I'll be damned if I can find any difference between them.

All MCs seem to be 17/16" and all boosters are 8" + 9". Going to have to find a junkyard with a few to see if there is actually any difference.
 
Well, I can't say which model to buy because honestly I don't remember, but you could call up Paul at JNZ Tuning and ask him which one John Freund (me) bought. I do remember there were two part variants and Paul ordered me both, and he couldn't tell the difference so we just guessed and the one I received did work. I use it on my track car.

The reason for this "upgrade", in case it's not clear to folks stumbling into this thread, is to properly match your master cylinder to the brake caliper piston volume. 2g calipers are matched to the 2g master cylinder (which I think is 7/8" bore, right?), but if you move to calipers like an Evos that is normally matched to a 1 1/16" bore master cylinder your pedal play will be greatly increased (you have to push more to get the same fluid volume moved). In my case I moved to evo rear calipers only and my pedal play difference was pretty huge on the race track, enough that I couldn't even do the "heel-toe" (more like toe-heel on a DSM) and it was really screwing up my driving having to go so deep into the brakes. Arguably a preference thing more than performance, but it just really unnerved me going so deep in the pedal every time. By moving to the 3g master cylinder, which is 1 1/16", my pedal play is pretty much back to "normal", or at least matching what it was with a 2g matched brake set and I'm much more comfortable driving. I can't imagine what it would have been like with evo calipers on front AND rear... I imagine that might be borderline dangerous.

Hope that helps.

Glad you explained this, was quite confused and well still kind of am. I guess i don't understand why you would need to do this in the first place. Mine feels right... I guess i just don't understand how it could truly benefit me, cant you just get use to what you have and perfect your speed from there?
 
It is all about pedal effort. When going to a bigger brake setup, you can regain proper feel by adjusting the MC size.

For me, I went to bigger brakes and also cherish the idea of having the reservoir on the MC instead of attached with hoses up in the air. Since I have SS front lines, it isn't a huge issue to adjust for the new port directions.
 
Well, I can't say which model to buy because honestly I don't remember, but you could call up Paul at JNZ Tuning and ask him which one John Freund (me) bought. I do remember there were two part variants and Paul ordered me both, and he couldn't tell the difference so we just guessed and the one I received did work. I use it on my track car.

The reason for this "upgrade", in case it's not clear to folks stumbling into this thread, is to properly match your master cylinder to the brake caliper piston volume. 2g calipers are matched to the 2g master cylinder (which I think is 7/8" bore, right?), but if you move to calipers like an Evos that is normally matched to a 1 1/16" bore master cylinder your pedal play will be greatly increased (you have to push more to get the same fluid volume moved). In my case I moved to evo rear calipers only and my pedal play difference was pretty huge on the race track, enough that I couldn't even do the "heel-toe" (more like toe-heel on a DSM) and it was really screwing up my driving having to go so deep into the brakes. Arguably a preference thing more than performance, but it just really unnerved me going so deep in the pedal every time. By moving to the 3g master cylinder, which is 1 1/16", my pedal play is pretty much back to "normal", or at least matching what it was with a 2g matched brake set and I'm much more comfortable driving. I can't imagine what it would have been like with evo calipers on front AND rear... I imagine that might be borderline dangerous.

Hope that helps.

We used MR475431 for your car John. Glad it is working out well for you!
 
Going through ASA, here is what I have:

Master Cylinders:
MR475973
MR475431

Brake Booster:
MR475433 - Replaced by MR527042
MR475434 - Replaced by MR527043

And I'll be damned if I can find any difference between them.

All MCs seem to be 17/16" and all boosters are 8" + 9". Going to have to find a junkyard with a few to see if there is actually any difference.

Can anybody help me with this problem, I can not figure out what the difference is. I want to buy a brand new OEM 3g master cylinder but not a brand new booster, so how can I determine which junk yard booster I will need to match the MR475973 master cylinder which in the non ABS that JNZ now sells and seems to be the correct part even though there above post says they sold the customer the MR475431 part #?
 
I'd guess one of those part numbers could be a superceded version and the other one is old. Could be referring to different parts manufacturers that make the same part.
 
Iirc, and its been a while, the differences for the two master cylinders should be the rod length going between the actual master actually pedal assembly. One is longer than the other, i believe the non-traction control equipped unit is longer/different.

They should have the same 1 and 1/16" bore between the two. I wouldn't recommend doing this swap without a caliper upgrade, but If you already have dual piston calipers up front, you should be alright.

I'm using a 3g mc/booster with outlander brakes and 2 piston calipers, and my brakes are very good, and can stop hard if needed. If i can find one, ill look for the p/n on my units to see what I have exactly.
 
OK, cool that makes sense, then can we get an explanation for why there are two different boosters as well. I know people say that they want the MR527042, the one with the 42 sticker on it, which came on all 5 spd cars but brake master MR475973 (non abs) is not the corresponding brakes master cylinder number that was on all 5 spd cars, that part is brake master cyl part # MR475431.

Unless that 42 sticker on the booster was coincidence that was the last 2 numbers in the part #.

I know that no 5spd 3gs came with traction control which was controlled via the ABS, but I'm not sure if you could get ABS despite not having traction control.

????? So confused
 
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