Weak Brake Master? ETC...

TJDIV

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After about an hour straight of driving today, the brakes on the 40 seem incredibly weak. Needed serious down-shiftage to stop. The clutch rubber is dry rotted and that's the reason it's weak shifting...

But the brake master looks really clean, holds fluid, etc. But the fxxxer is weak ONLY after it gets hot, etc.

Just wondering is the wheel cylinders could get old/hot and be weak, etc. Or the brake master/booster?

Brake guys? Get on it. Thanks. :bounce2:
 

tornadoalleycruiser

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YEar? All disks? all drums?
Replaced the flex lines in the system?
Checked the booster to see if it's fully functional? (the hose clear and the test sequence for the booster?)
 
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I'd check the flex lines for cracking and other signs of aging. Hot rubber lines are less likely to hold pressure well. If the brake fluid is dark, I'd replace and bleed the lines until clear, and I might bleed it even if it is clear in case you have some air in there. If you have bubbles they might get bigger in the heat and deteriorate your brake function, maybe? I think the wheel cylinders can get grimey and seize from rusting up. But I don't think that getting hot would make them worse. I'd check to make sure all of them are working. Only 4 of the 8 were functional when I got my FJ40.
 

TJDIV

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I'm 110% certain this thing needs some brake work.

Fact is I've got half a mind to order up all 8 cyls. and the brake master/clutch/slave and just do it all.


It's a 75 FJ40. I'll PM FSU to see what all he's done to it in the last few years.....

Thanks guys. Thought of the lines, but have never fxxxed with a brake booster before...
 

Mace

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sometimes when it is really hot the fluid for the clutch master gets close to boiling.. So on long trips I actually can lose clutch availability..
 
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Dump the drums and go with disks. Replacing all the cylinders and master with LC parts will be expensive. For the same cost you can do front disks. Rears can be done for around $400. The fronts first wait a awhile then do the rears if you want to spread the cost out a bit.
 
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I would adjust and bleed your drums, and if you desire more switch to front disks and rebuild the rear drums.

I love this setup on my 40. Front late cruiser disks and all new rear drums.
 
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