Unbreak my Brakes

[orttauq]

OK. I will replace and give that a try. I have a power bleeder but it just does not work too well with the LX.

 

[tacosupreme]

Why would a larger piston be any better? It'd just require more force at the pedal for the same clamping force at the caliper. Stock MC works great when it isn't leaking.



Sounds fair.. but, leaks are more likely at other fittings. The MC uses the short fittings, so a long one will fit there without bottoming out. My issue was in one of the steel elbows further along the braking system. I put one of the short fitting lines that went from the MC to the ABS module into the steel elbow and that is where I had a leak.

Either way.. if it were a leaking line/fitting you'd see brake fluid dripping somewhere. If you aren't losing any fluid it strongly suggests master cylinder, as there is a second seal on the shaft and this often keeps the fluid within the MC bore when you release pressure. Usually if a cylinder is leaking it doesn't have the ability to push the fluid back past the seal when you release.. so the fluid will be visible on the brake and level will drop in the reservoir.

A common swap on mini trucks is the FJ80 master. The mini trucks are 7/8" bore, ours are 1", no noticeable difference in pedal pressure but much better braking performance. Maybe more pedal travel? I'm having trouble finding a non-ABS master for my 1991 FJ80, just wondered if the ABS was "better" or if there is a common upgrade like for the mini trucks.

 

[Squash]

Sorry,
You need to keep the res. full at all times otherwise you will allow air into the system.
Best to invert a bottle of brake fluid and monitor.

 

[orttauq]

Got the BeckArnley from Amazon and it is AISIN (cast in the body)...hope to install today.

 

[alia176]

Got the BeckArnley from Amazon and it is AISIN (cast in the body)...hope to install today.

Please upload the picture in this thread so that we have it for future record.

 

[orttauq]

 

[alia176]

EXCELLENT pics, thank you for uploading directly to this site vs using a photo sharing site. I hope your brakes work much better now.

 

[orttauq]

Installing a new master cylinder did not fix the issue. Pedal still moves down slowly after I pump up the brakes, engine running. I also have about an inch or more of travel before I get any braking when driving. Bled the system twice.

Looking at calipers now--does anyone make NEW other than Toyota? At around $300 each this project will get spendy fast.

 

[orttauq]

Well I wanted to go OEM but NAPA has remanufactured calipers in stock for ~$60 each...hard to spend $240 more per corner.
Ordered Hawk pads and am going to replace all 4 hoses as well then do the gravity bled trick mention by @bloc.

Wish the reservoir had a screw top like German cars. I bought a pressure bleeder years ago that screwed on and used a few pounds of air pressure to push the fluid through. Works perfect. I now have to use a vacuum

bleeder that just sucks air around the bleeder so hard to tell if any air left in the line.

Rant off

 

[orttauq]

Anyone know the part number for this?

Maybe 90313-93003

 

[DARKNESS]

I don't think calipers are causing this. Did you bench bleed the new master? It sounds like air in the lines still or the new master is bad (I have heard of them being bad out of the box more than once).

I'd also check the booster pushrod depth. Unfortunately the master has to come off for that. It can also cause excess travel before braking if its set too short.

 

[BlueCruiser84]

***Disregard below. I went back and read the first post. Looks like all that stuff has been removed. I don't know what to tell you.

I would just keep bleeding. There are some lines that are higher than the master cylinder that can hold air bubbles.




The ABS pump can get air in it. You might need to go out and cycle the ABS on a wet or gravel road then re-bleed. Keep doing that until you get a good pedal. Try bleeding the LSPV too. 80s are notoriously hard to bleed.

Or, if you aren't in love with ABS, just pull the whole shebang out.

 

[orttauq]

Agreed that it is not the calipers but they are off the truck now. I knew I needed rotors due to a shake on braking plus the bearings/seals/etc in the front were a complete mess.

Yes, the ABS was removed a while ago and made massive improvements on braking. Hell it would not really stop at all before

I checked the pushrod on the master cylinder side but maybe the pedal side needs adjustment.

Thanks All

 

[bloc]

Wish the reservoir had a screw top like German cars. I bought a pressure bleeder years ago that screwed on and used a few pounds of air pressure to push the fluid through. Works perfect. I now have to use a vacuum bleeder that just sucks air around the bleeder so hard to tell if any air left in the line.

Put thick silicon grease around the bleeder threads and it'll stop pulling air in.

Alternately, you can cobble together an adapter that will work on toyota master cylinders. I'm (far) away from home but basically you need a flange or something large enough to cover the hole and stiff enough not to deform, some gasket material, some long machine screws, and a bit of chain. You use the screws on either side and wrap the chain around the bottom of the MC. This holds the cap on and you can apply a few PSi just like the german pressure bleeders.

Basically a homemade version of the parts in the right of this pic:

Anyone know the part number for this?
Maybe 90313-93003

that's the number I found.

 

[JeepinPete]

I have the motive bleeder, and can state that it works well on the LC. Dropping brake pedal is generally not air, but a leak or bypass of fluid. If you are not losing fluid, you do not have a leak. I have replaced many "rebuilt" master cylinders that were bad out of the box, but have had great luck with new parts.

I wonder if you booster has a pinhole leak? Easy enough to check. Does the pedal continue its trip to the floor when the engine is off? Does it do so once all vacuum has been released from the booster (by pressing the pedal several times until it get hard to push)?

FWIW, I replaced all four caliper with remanufactured, new pads, removed ABS,LSPV. I can now lock up the front on dry asphalt running 37" tires. Takes a lot of leg, but it can now be done. Much better than when I bought the truck. Keep at it!

 

[orttauq]

Thanks...I like the idea of the chains around the master cylinder. I think I can adapt what I have. @bloc

I am waiting on parts now since this went into a full axle rebuild.

I do need help on brake lines...SS or just OEM? Slee and Iron Pig Off-road are out of stock for the caliper lines. Any other sources?

 

[DARKNESS]

Get OEM brake lines.

 

[orttauq]

Get OEM brake lines.

Agreed

I have found the 4 caliper hoses:
90947-02614 RR
90947-02615 LR
90947-02A16 x 2 Front

For the 3 frame to axle extended lines:
96940-34605 x1
96940-34705 x1
90947-A2016 x1

 

[jstigler]

A leak in the brake booster can cause an odd feeling in the pedal. Your description does not sound like the booster. I will second the air in the lines that DARKNESS mentioned or a bad MC. If a MC is not bench bled it can take a long long time to get the air out.
A few people have stated this already but I just wanted to add that I have seen quite a few rebuilt MCs bad out of the box.

Edit:
To add - Clamp off the lines to the calipers and then hit the brakes. If this firms up the pedal you know its the calipers, you can unclamp each individually until the pedal drop returns to find the culprit.

 

[alia176]

To add - Clamp off the lines to the calipers and then hit the brakes. If this firms up the pedal you know its the calipers, you can unclamp each individually until the pedal drop returns to find the culprit.

This is good info and a good thing to try before opening up the brake system. I wonder if you can do this with the SS brake lines that some of us has migrated to?