Master Cylinder Question

Muspos · 04-23-08, 09:09 AM

I have a 78 40 with the 30 year old stock braking system on it and I was preparing for a trip this weekend after it had sat for most of the winter without being run. I noticed the reservoir for the rear brakes was low so I filled it up and figured life is good. I came out the next morning to find a puddle under the cruiser and all of the fluid had leaked out. It is not leaking from the reservoirs but where the master cyl bolts onto the brake booster. I have never replaced the master cylinder and do not know what it would take, 4 bolts? But I wanted to see if anyone could help me diagnose the problem.

Thanks!

PabloCruise · 04-23-08, 10:09 AM

Sounds like you are leaking out the back.

I replaced my '78 MC w/ one from Toyota - Cruiser Dan at American Toyota.

You can do a bench bleed, I didn't.

4 bolts and two line fittings and two electrical connections.

Bleed the brakes and you are good to go!

Some people get an early 80 series MC. I think these are a different bore size, so I cannot remember if pedal effort goes up or down...

Anyone comment on the 80 series MC's?

Muspos · 04-23-08, 10:12 AM

Thank you once again Pablo. I will get a kit or remain on it's way!

ohrly? · 04-23-08, 07:28 PM

You need to try to find a rebuilt one. I found one for $120, with $50 off if I gave them the core out of my old one. I purchased this one from NAPA - about $70 when I gave them the core out of mine.

Fast Eddy · 04-23-08, 07:50 PM

Quote:

Originally Posted by ohrly?

You need to try to find a rebuilt one.

I totally disagree. I'd go with a new OEM unit from Cruiser Dan.

Lots of times when they leak fluid out the back it will get into the booster and ruin that too.

Check to see if it will hold vacuum.

04-23-08, 09:09 AM	#1
Muspos IH8MUD Junior Join Date: Sep 2005 Location: Monticello, UT Posts: 80	Master Cylinder Question I have a 78 40 with the 30 year old stock braking system on it and I was preparing for a trip this weekend after it had sat for most of the winter without being run. I noticed the reservoir for the rear brakes was low so I filled it up and figured life is good. I came out the next morning to find a puddle under the cruiser and all of the fluid had leaked out. It is not leaking from the reservoirs but where the master cyl bolts onto the brake booster. I have never replaced the master cylinder and do not know what it would take, 4 bolts? But I wanted to see if anyone could help me diagnose the problem. Thanks!

04-23-08, 10:09 AM	#2
PabloCruise IH8MUD Lifer Join Date: Jun 2004 Location: Northern Colorado TLCA# 10713 Posts: 4,702	Sounds like you are leaking out the back. I replaced my '78 MC w/ one from Toyota - Cruiser Dan at American Toyota. You can do a bench bleed, I didn't. 4 bolts and two line fittings and two electrical connections. Bleed the brakes and you are good to go! Some people get an early 80 series MC. I think these are a different bore size, so I cannot remember if pedal effort goes up or down... Anyone comment on the 80 series MC's? __________________ TJS -- 1978 FJ-40 1974 FJ-55 w/ 3FE CO/WY - Horsetooth 4 Wheelers Cruiser Club <<CLICK HERE>> for my Tech Threads

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04-23-08, 10:12 AM	#3
Muspos IH8MUD Junior Join Date: Sep 2005 Location: Monticello, UT Posts: 80	Thank you once again Pablo. I will get a kit or remain on it's way!

04-23-08, 07:28 PM	#4
ohrly? IH8MUD Regular Join Date: Nov 2007 Posts: 263	You need to try to find a rebuilt one. I found one for $120, with $50 off if I gave them the core out of my old one. I purchased this one from NAPA - about $70 when I gave them the core out of mine.