Serious safety issue! -Master cylinder mods (1 Viewer)

[lostmarbles]

Sorry should have made this clearer, that setup was on ebay and stated it was of a 40 series with factory disks (not sure what model exactly). Here's a pic of my MC. I have drums at the front but am going to be converting to disks. The fitting of a later series bigger booster with a spacer isn't going to be an option to me from what I can see as there's not much clearance between the MC and the air filter, ok for an FJ but not a BJ.

Well if you're ever getting rid of that booster let me know and I'll buy it off you for a spare

 

[rockcrawler]

It's yours for the price of postage when I do Tom. Still trying to figure out just what sort of MC/booster I need for a front disk system. After seeing yours perhaps that one on ebay was a drum one on a 40 that was retrofitted with disks and the seller just assumed it was original??

 

[numby]

You guys have me a little freaked so I thought I'd throw this in.

This is supposedly a 78 era U.S. spec master cylinder (FJ40 - front disc/rear drum) that I installed some years ago. It came in a Toyota box but there were no identifying marks so it could be aftermarket. The previous master and booster were apparently out of a Celica so I had nothing to compare to. All lines hooked right up without modification so in it went. Notice that the brake lines come straight out of the master and there doesn't seem to be any residual/metering valves or even provisions for such. The proportioning valve is bolted to the booster.

Even with freshly adjusted rears and tight steering I've never been entirely happy with the panic braking. Seems to require a lot of steering input (gol durn deer) even without lock-up.

What think the learned?

 

[lostmarbles]

.... Notice that the brake lines come straight out of the master and there doesn't seem to be any residual/metering valves or even provisions for such....

If your drum wheel-cylinders don't "weep" (and you regularly check fluid levels) then I wouldn't worry about the apparently-missing residual valves.

...Even with freshly adjusted rears and tight steering I've never been entirely happy with the panic braking. Seems to require a lot of steering input (gol durn deer) even without lock-up.

What think the learned?

I don't classify myself as "learned" but the "bottom line" must be that you must end up with "safe braking" (and a safe vehicle).

Sounds like your steering is pulling to the right or left while braking. This is not safe.

I had a lot of trouble with that - especially when towing and coming down long steep gradients. It took me years to find out that it was caused by my "underseal".

I used to spray a mixture of fishoilene and bitumous paint EVERYWHERE underneath for rust-prevention. I have a completely rust-free underbody as a result but the underseal on the outside of the brake backing-plate used to weep oil that somehow found its way into my brake drums under "extremely hot" conditions (such as the almost-continuous braking down a long steep gradient in summer-time).

Once I removed that underseal from my brake backing plates and kept that area free of "swivel grease" - No further problems!!!

But I suggest doing the usual checks for leaking or seized cylinders/pistons etc too (on your front callipers) of course.