Chevota clutch master question

[bikersmurf]

I've got a 7/74 40 with a Toyota 4 speed and a 350. The conversion used a Downey belhousing and a LUK clutch.

I've had no issues with the clutch since I rebuilt the clutch master 12 years ago. I think it's starting to go as it isn't always fully disengaging. It improved after bleeding the system... But seems variable.

Specs would indicate that the master is 3/4" bore and the slave is also 3/4".

I'm consider going to a 1" master. To those who've done it, how much heavier is the clutch pedal?

Could a rebuild be enough? My left knee is in rough shape and I don't want to make it harder to shift. Any thoughts?


With next to no free play at the bearing the pedal is almost 1/3 of the way down befor there is significant resistance.

 

[Rockets2000]

When was the last time you replaced the clutch? If you've already adjusted the slave shaft length, I don't see how increasing the volume of fluid will help.

 

[Lake Rat]

Seems I have the same set up a 40 that I bought, it does have the Downey bell housing. If nothing is leaking, it may be a pressure plate, if that's O.K., check the adjustment of the rod between clutch pedal and master...maybe?......

 

[Radd Cruisers]

I've got a 7/74 40 with a Toyota 4 speed and a 350. The conversion used a Downey belhousing and a LUK clutch.

I've had no issues with the clutch since I rebuilt the clutch master 12 years ago. I think it's starting to go as it isn't always fully disengaging. It improved after bleeding the system... But seems variable.

Specs would indicate that the master is 3/4" bore and the slave is also 3/4".

I'm consider going to a 1" master. To those who've done it, how much heavier is the clutch pedal?

Could a rebuild be enough? My left knee is in rough shape and I don't want to make it harder to shift. Any thoughts?

With next to no free play at the bearing the pedal is almost 1/3 of the way down befor there is significant resistance.

If you got 12 years from a rebuilt cylinder in our climate, you're really doing something right. Most cylinders, even new ones, won't usually last anywhere near that long.

It's probably time to put in a new unit, check the pushrod clearances at the pedal and at the release arm, and then see how it is.

~John

 

[bikersmurf]

If you got 12 years from a rebuilt cylinder in our climate, you're really doing something right. Most cylinders, even new ones, won't usually last anywhere near that long.

It's probably time to put in a new unit, check the pushrod clearances at the pedal and at the release arm, and then see how it is.

~John

I've checked the pushrod clearance... only 2-3 millimeters.

I think it needs a rebuild, and a good flush (even though it's not leaking).

I've noticed that if I pump the clutch a few times, I get good feel and engages higer up. If it sits for a while the pedal seems softer again and engages just off the floor.

If it was the pressure plate, I think it would be more consistent or slipping. I'm not getting any slipping or clutch shudder. But... it does have 30,000 miles + on it.

 

[bikersmurf]

When was the last time you replaced the clutch? If you've already adjusted the slave shaft length, I don't see how increasing the volume of fluid will help.

More volume of fluid will allow the arm to move a little farther thereby increasing movement at pressure plate. The trade off is a heavier pedal for my bum knee... but somewhat less movement.

Crunching some numbers I come up with a surprising 60%+ increase in pressure required to depress the clutch pedal if I step up to a 1" bore from the 3/4" that I currently am running.

 

[77TPIFJ]

what master would have a 1" bore ? just for future reference

 

[bikersmurf]

58-62 Clutch Master per SOR site.

pre 72 single circuit brake master.

 

[bikersmurf]

Well, the clutch slave puked out all the fluid... guess I've got my answer.

I've got a new slave on order for $34 and a rebuild kit for the clutch master for $15. It's jobber stuff, but I don't like Toyota's prices or "no returns" policy.

 

[Rockets2000]

Glad you got it figured out. At least you know it's a cheap quick fix.

 

[bikersmurf]

I'm glad I know how to drive without a clutch. Probably saved me an hour, and a $150 tow bill.

With a strong starter who needs a clutch.

 

[bikersmurf]

Rebuilt the clutch, installed new slave, adjusted, and bled.

We seem to be back in buisness. Time for a test drive.

 

[Bennett]

Just a fyi.. I use a pre 69 brake master for the clutch master( yes brake master cylinder) fpr my sbc behind a toy 4 speed.
I flat out needed more throw. The brake master is a bolt in where the clutch master goes and is about 10-20% stiffer. A pre 69 brake master is a 1" bore and gave me about 7/8"" more throw on the 3/4"slave.

I did a few post's about it.. I credit Mark whatley with the info given to me
years ago on teh tlc forum.

 

[bikersmurf]

Just a fyi.. I use a pre 69 brake master for the clutch master( yes brake master cylinder) fpr my sbc behind a toy 4 speed.
I flat out needed more throw. The brake master is a bolt in where the clutch master goes and is about 10-20% stiffer. A pre 69 brake master is a 1" bore and gave me about 7/8"" more throw on the 3/4"slave.

I did a few post's about it.. I credit Mark whatley with the info given to me
years ago on teh tlc forum.

Which year of slave did you use? Pre 74 is 3/4" and 75 up is 13/16".

With the 3/4" master and 3/4" slave I've got 1 1/2" - 2" of free play and the clutch engages about half way up... I've got plenty of travel with my Luk clutch.

 

[Bennett]

Which year of slave did you use? Pre 74 is 3/4" and 75 up is 13/16".

I used a stock 76 I thought it was 3/4" ..maybe its 13/16 ?

 

[bikersmurf]

Which year of slave did you use? Pre 74 is 3/4" and 75 up is 13/16".

I used a stock 76 I thought it was 3/4" ..maybe its 13/16 ?

Per SOR... 13/16" from Aug 74 to ??
Specter Off-Road Land Cruiser Parts - Search On 018-06

 

[bikersmurf]

I'm looking to source a new clutch slave for my July '74 40. It has a 3/4" bore, and it appears that a lot of the replacements are switching over to an "equivalent" 13/16" slave. This, however, will reduce travel. Aisin ones seem to be discontinued on many sites... does anyone have a current part number?

I'll be checking the Jobbers in town soon, as it appears mine are failing. Given the slave was replaced and master rebulit 10+ years ago, they are due again... which I'm sure is why the clutch doesn't stay released if I hold it for long.