Smeagol

iTrader: (1)

Alrighty, I thought I would ask you guys about this brake issue I've noticed on the RX-3 I picked up a couple weeks ago.

the brakes work, but the pedal doesn't have the same resistance as my other 1st gen. RX-7s or RX-2. Sometimes the pedal will even go all the way to the floor. The car will stop, but it's not very comforting if an emergency situation comes up, it sort of just 'coasts' to a stop -- impossible to lock up the brakes how it is right now. Also, pumping the brake pedal doesn't seem to increase the resistance any.

anyway, the car has a shortened ford 9" rear end with GSL-SE disc brakes, stock discs in the front. Originally I was thinking it was just air in the system, so we bled the brakes.. no noticeable air, although the fluid did appear old (yellow). I'm perplexed as to what else it could be.

The only other thing I can think of is either the brake booster isn't working right, or the brake junction block isn't correct for a rear disc setup. As far as I can tell it's the stock junction block, but there's an odd sensor coming off it I've never seen on an old school rotor before. I'll get some pics of it up here in the next few days.

Any ideas? Could it possibly be a bad brake master cylinder? I'm not really sure what to try next, but I definitely want to fix this as it's scary to drive it this way.

Thanks,
Mike

13B-RX3

iTrader: (2)

Oh man, it sound bad REAL BAD. I think the car is a goner. You should probably just go ahead and give it to me.

But seriously, if the pedal is going to the floor but not every time and you are not losing any fluid the master is internally bypassing. The brake booster will not cause this. Your looking at a bad master cylinder.

Smeagol

iTrader: (1)

Heh, ok..

well, I guess technically it would go to the floor every time if I hit the pedal enough. I just tend to brake way in advance with the car the way it is.

Apparently the master cylinder was recently changed, but I'll have to double check with the previous owner.

Mike

smurfy RX3

Hey Mike,

If the brake master cylinder was recently changed I would be willing to bet money that it wasn't bled when installed, which would cause the symptoms you're describing.
To bleed it, remove the lines and bleed the MC until fluid comes out in a stream. Then reconnect the lines and bleed all around. The brakes should get nice and firm.... don't ask me how I know about this. LOL

Smeagol

iTrader: (1)

Thanks, I'll try that. I hope that's it, as changing the booster or junction block itself seems more involved.

Anyone know offhand if that junction needs to be modified in any way when converting the rear end to disc? IE enlarging the rear line holes, etc. I thought I remembered reading something about that in the past.

Anyway, I'll try bleeding the master itself and let ya know how it goes.

Thanks,
Mike

rxtasy3

iTrader: (2)

u might want to ask the previous owner if when he replaced the master cylinder, did he use one for rear disc. there IS a difference ya know.

Smeagol

iTrader: (1)

what's the difference?

I don't think any RX-3s came with rear discs, so that might be a hard to find item. Maybe a RX-7 one will bolt up, anyone know for sure?

Mike

Siraniko

iTrader: (13)

nope...too close to the side wall.