Master Cylinder

My brakes have been pretty weird lately. When driving my brakes are really good when you are aggressive with them but when you are soft on the brake pedal you have no power/pressure until you reach the floor and then it locks up. I also have brake fluid leaking from the cap of one reservoir (the one closest to the back of the vehicle. And the reservoir closest to the front of the vehicle keeps needing to be topped up.

Is this just a result of the master cylinder needing to be changed? My guess is it’s from 77.

Yes. That sounds like the master cylinder is failing. It would be worthwhile to get it repaired before it causes a wreck.

Working on it just tough finding parts for this thing. Thanks for the quick reply.

The front reservoir on the master cylinder is for the rear brakes.

If you have to keep filling the front reservoir, there’s a leak in the rear brake system.


Yeah, the fluid is bypassing the seal around the MC piston and getting pushed out the cap when the piston returns instead of pushing the caliper piston and staying in the system. You definitely need a new MC.

So tell us, what year Huppmobile is it? Or is that a secret?

Huppmobile? haha what does that mean?

No, no secret. 1977 Toyota Dolphin. It’s a little camper that I use for working in bush camps during the summer.

Thanks for all the help guys. I freakin love this site haha.

Attached are images of Huppmobiles.
When you neglected to tell us what it was, that left us guessing. I figure if I gotta guess, I might as well make it fun.

Assuming Toyota did not change the brake system from the pickup that the Dolphin is based on, you can find a new MC for it here.

Toyota Dolphins were built on Toyota Hilux chassis. They didn’t have independent rear suspension but they had independent front suspension. A semi-floating solid rear axle with spring-under leaf suspension was found in the rear. A common upgrade is to replace the semi-float 5-lug rear axle with a full-floating, 6-lug axle from a later Toyota 1-ton chassis but if you’re removing the camper part, the 5-lug semi-float axle should be sufficient. Toyota offered at least two different frame lengths on their cab-chassis trucks in the 80s. The earlier ones may have only come in one length. You can look at the original brochures here:

Urmpfh. In that case, OP may be out of luck, at least as far as getting an OEM part goes.

So I ordered a Brake master cylinder (Centric) and the brake lines go in on the bottom of the brake MC rather than the side. My brake lines are set up to go in on the side. So I guess now my only two options are to send the MC back or to buy new brake lines right? Are brake lines something that most places will stock or is this something I am going to have to source out on the internet again?

Same vehicle.
1977 Toyota Hi Lux/Dolphin

ALSO! There is a second component to brake MC on the vehicle now. I am not sure what it is, you guys probably will. After the brake line leaves the MC it goes about 6 inches and then goes through another small metal piece attached to the brake booster then another brake line comes out the other side. Both sides of this “small metal piece” have similar connections to MC. Anyone have an idea or should I take some pictures to show everyone?

send it back, it seems they sent you the wrong brake master

If they claim it’s correct, it means their information database is wrong

Not to be too pessimistic, but I don’t think there’s anybody stocking brake lines for a 1977 Hilux

But there’s plenty of guys that will fabricate a new set

“There is a second component to brake MC on the vehicle now. I am not sure what it is…”

Proportioning valve? It balances front vs rear brake force.

From what I’ve been able to dig up, which isn’t much, the proportioning valve was definitely different on the Dolphin than on the regular Hilux. Wouldn’t surprise me if the MC was too - they’d have had to beef up the brakes to haul the coach assembly around.