Mr2 brake upgrade

[hsmidy]

hey

as it suggests can anyone suggest a primo brake upgrade for a sw20 mr2 or where ya can pick one up from in chch,

cheers

[soopachargen]

have you done the basics?? checked discs, pads, fluid etc for quality, upgraded to better pads and fluid?

http://forums.toyspeed.org.nz/viewtopic.php?t=53729&highlight=

this is the thread on an ae92 brake upgrade.... may pay to read that too

anything more just ask

[hsmidy]

yeah nar the discs and calipers are gunna get scrapped its in aticapation of a engine convesion coming up, and the standard discs and calipers wont do so its time for new stuff, wilwood etc, cheers for the link

[fivebob]

What year is it?

If it's a made before Dec '91 (chassis # < 59266) then just upgrade to the later model brakes. If you need more than that, and I seriously doubt you do, then you're in for an expensive and frustrating experience trying to get the brake balance correct, and retaining the handbrake

[2jayzgte]

Another option is putting JZA 80 4-pots and big rotors up front that will definitely do the job.I no of a place Wgtn that is selling the rotors and callipers brand new out of Toyota for $750..

[fivebob]

Another option is putting JZA 80 4-pots and big rotors up front that will definitely do the job.I no of a place Wgtn that is selling the rotors and callipers brand new out of Toyota for $750..

then you're in for an expensive and frustrating experience trying to get the brake balance correct

Also they don't fit without a lot of modification

[2jayzgte]

Another option is putting JZA 80 4-pots and big rotors up front that will definitely do the job.I no of a place Wgtn that is selling the rotors and callipers brand new out of Toyota for $750..

then you're in for an expensive and frustrating experience trying to get the brake balance correct

Also they don't fit without a lot of modification

I've seen a few owners with MR-2s in Japan with this mod and they absolutely rave about it..

[fivebob]

I've seen a few owners with MR-2s in Japan with this mod and they absolutely rave about it..

Is that your only basis for recommending this upgrade?

How much did it cost?

What had to be modified?

What were the results of the braking bias change?

In my experience upgrading the front brakes on a '92 onwards SW20 for the street in a pointless waste of time. All you get is a car that will lock the front end continously, unless you upgrade the rear at the same time, or fit some form of brake bias adjustment.

Either option is expensive and frustrating to get right. Simple proportioning valves don't work, and you end up having to replace the master cylinder with an adjustable twin cylinder arrangement, which in turn requires the removal of the brake booster . That's ok for the track, but not for the street.

Upgrading to a set of later model brakes for a '89-'91 car, and changing the pads, is all that is needed to eliminate brake fade on these cars. Before I did this my '90 SW20 would have the brakes smoking on a quick trip through the twisties, afterwards all I managed to do was turn the brake discs blue

[Dell'Orto]

Another option is putting JZA 80 4-pots and big rotors up front that will definitely do the job.I no of a place Wgtn that is selling the rotors and callipers brand new out of Toyota for $750..

then you're in for an expensive and frustrating experience trying to get the brake balance correct

Also they don't fit without a lot of modification

I've seen a few owners with MR-2s in Japan with this mod and they absolutely rave about it..

Just think about it...massive front locking capability + large mass at the opposite end of the car

[Boosted_162]

Just out of interest (i don't even know if it's possible), if you put JZA80 brakes all around, what would happen to the bias then? Are you able to transfer one complete brake setup (proportion valves etc) from one car to another?

[Mr Revhead]

ok, see if you can work it out for your self

think about the weight distribution differences between the 2 cars

[Boosted_162]

Obviously less weight in front = lockup? What effect would large rear brakes with more rear bias do to the braking?

[Dell'Orto]

My guess is Supras will have more front bias than an MR2....got pirouette?

[fivebob]

My guess is Supras will have more front bias than an MR2....got pirouette?

Actually you tend to pirouette more when the rear locks up...Lock up = less braking force, therefore more push/pull from the end that locks up.

What you do get however is less braking overall in an emergency situation, because the ABS takes over.

[sergei]

My theory (just speculation) is:
obviously supra callipers have much more volume of fluid than stock MR2 calipers, so to get same movement it will require more movement of the pedal -> which will result more force at the rear (which will result of rear lock up). Although the force which supra calipers can provide with same pedal movement would be higher than stock caliper on MR2 the brake pad area is bigger aswell. The only difference would be in leverage - rotor diameter. The supra rotor would have more leverage. But if you are using just supra calipers on MR2 rotors I see no advatnage using them (as the most gain you will get is by increasing rotor diameter - which increases contact surface area, also increases leverage, and also increases the radiating area).

[fivebob]

My theory (just speculation) is:
obviously supra callipers have much more volume of fluid than stock MR2 calipers, so to get same movement it will require more movement of the pedal -> which will result more force at the rear (which will result of rear lock up).

No, the pedal travel is longer to get the same pressure so the rears won't lock easier. In fact because there is more force applied to the front pads (bigger pistons/more of them), the front will lock up sooner.

[sergei]

Arent the front and rear almost separate system? I am thinking of that because there are 2 seals in master cylinder which feed 2 different tubes? And in fact there is a spring between rear and front shaft in the master cylinder so the rear would activate first then when the spring is compressed the rear shaft pushes front which applies pressure to front circuit?
Please correct me if I am wrong. I am drawing these conclusions from liteace van master cylinder which I dissasembled (and reasembled) a while ago...

[fivebob]

Arent the front and rear almost separate system? I am thinking of that because there are 2 seals in master cylinder which feed 2 different tubes? And in fact there is a spring between rear and front shaft in the master cylinder so the rear would activate first then when the spring is compressed the rear shaft pushes front which applies pressure to front circuit?
Please correct me if I am wrong. I am drawing these conclusions from liteace van master cylinder which I dissasembled (and reasembled) a while ago...

Don't know about the liteace system, but the SW20 has a single master cylinder with a fixed proportioning valve. So the rear sees a fixed % of the pressure that is applied by the master cylinder.

[sergei]

On the same topic: how does the proprtion valve works: is it just a restriction or has a diaphragm(speling?) or a piston with a spring that properly regulates the pressure?

[2jayzgte]

It is just a option I am not saying you should go ahead and do it.It is just another option to look at as I think no one else in NZ has done it.But I figured if it has been done in Japan and worked well it must be fairly safe to assume it could be a worth while upgrade..