Master Cylinder Replacement/Upgrade

[mtb_rider]

So my master cylinder is starting to go and is in need of a replacement. I know of the 4Runner caliper upgrade, and that to get optimal performance you should upgrade the MC as well. In this case I am working a little backwards. My brakes are fine, and in fact aren't terribly old. I was thinking on putting the upgraded MC on now, so that it is already done for a future caliper swap. What I am not sure of is if a Runner or T100 MC will work without issue with my stock calipers. And about that, I have searched and read the FAQ and have read many threads on the brake upgrade, and see people have used both. Pros/Cons? As always, TIA.

 

[ntsqd]

If you like the way the brakes perform and behave now, why change?
I'd stick with the stock part.

 

[DirtyLittleSecret]

"upgrading" the MC with the 4Runner calipers is controvercial at best. I think a good lot of people would counter argue the "upgrade".

 

[worshhim]

I run 33" BFG on my 88FJ62, I have considered the upgrade, but ever since I put DBA drilled/slotted rotors on, my brakes are beautiful.

 

[Cruzerman]

I run the 4runner calipers in the front with the stock MC. I'd go with the stock MC. Even if you do the 4runner upgrade in the future, you'll still be just fine.

 

[GLTHFJ60]

Isn't the T100 MC a little larger than the stock 60 MC? Considering that the 4runner calipers have a much larger second pot makes me want to have a MC that is a little larger as well.

I can tell you that after driving kevinmrowland's 60 with the T100 and 4runner calipers, that's the route I'm going to go. They're very firm and have much better stopping power compared to my stock brakes.

 

[ntsqd]

The 4rnnr caliper increases hydraulic leverage. A larger bore master decreases leverage.

IH8MUD Forums - View Single Post - Comments on brakes

IH8MUD Forums - View Single Post - Comments on brakes

 

[GLTHFJ60]

In your second post, you say that decreasing leverage increases the pedal's firmness, and when you increase the leverage it decreases the pedal's firmness. So if you put the larger 4runner calipers on with the larger MC, then you should get a pedal feel that is pretty close to stock with better performance, right?

 

[ntsqd]

And end up with braking effectiveness that is also pretty close to stock. If that's where you're going to end up, why change anything for stock?

 

[GLTHFJ60]

And end up with braking effectiveness that is also pretty close to stock. If that's where you're going to end up, why change anything for stock?

Better performance with the same feel. Two large pistons instead of one large and one small piston in the caliper.

 

[mtb_rider]

Thanks for the input. I definately would like to upgrade the brakes in the future. However, like most people, I am on a budget right now so price point was a concern. We also have some incliment weather on the way here in the next few days and need to get the brakes fixed up and working safely again. I would prefer to go with a new MC, but was able to get a reman from NAPA for 54 bucks. That will at least get me safely back on the road for the time being. I can look back into the swap later on, though it looks as though it may not be needed.

 

[Bret]

I think what ntsqd is saying is that if you change only the calipers you gain mechanical (hydraulic) advantage over the stock calipers(but more travel at the pedal), but when you change the master from 15/16" to 1" you lose the mechanical advantage you just gained(larger master less travel). So if you increase the caliper surface area and the master area you end up with a wash, or close to it.

Some of the newer masters are aluminum so they won't rust which could be considered better.

 

[FJ40_68_Nick]

Its a wash at the pedal... you have the same pedal "feel".... you're pushing more fluid to more surface area though.

 

[ntsqd]

I think what ntsqd is saying is that if you change only the calipers you gain mechanical (hydraulic) advantage over the stock calipers(but more travel at the pedal), but when you change the master from 15/16" to 1" you lose the mechanical advantage you just gained(larger master less travel). So if you increase the caliper surface area and the master area you end up with a wash, or close to it.

Some of the newer masters are aluminum so they won't rust which could be considered better.

Exactly.
If you increase the caliper piston area, regardless of what the individual piston area composition is (i.e. a big and a small piston or two of the same size, or anything else), by some random percentage - say 15% - and then you also increase the master bore size by, say - 12% - then you really haven't done much. Except that now none of the replacement parts are stock.