Clutch Master Cylinders (which one for mixed parts)
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Clutch Master Cylinders (which one for mixed parts)
As the attached picture shows, there are some options with choosing a clutch master cylinder. My chassis is a 1980, which as I understand it has a different thread pitch than the FB models. My transmission is from a 1984 GSL. I assume the 84 slave would be fine but not sure what master to use. The 81-83 or the 84-85.
Thanks!
Thanks!
If you use a 1984 slave, I'd go with the 84/85 master. I'm not sure your current master/slave hardline is course or fine.
The RockAuto master and slave cylinders are dirt cheap.
The RockAuto master and slave cylinders are dirt cheap.
Last edited by KansasCityREPU; Dec 20, 2016 at 06:40 PM.
Old [Sch|F]ool
Joined: May 2001
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From: Cleveland, Ohio, USA
They are all functionally interchangeable with the only real difference being the hydraulic line pitch that you've already noted. Some of the later ones have some sort of valve on the outlet, I've never felt any difference in clutch feel between those and the non-valved ones.
Something to be careful of - the last three master cylinders i installed came with studs that had a too-long unthreaded portion. When you install it, the nuts bottom out on the studs before they tighten down against the firewall. Compare the new studs vs. the old ones and if the unthreaded part is longer, you'll have to swap them.
I only use NAPA brand masters, they last the longest IME.
The slave cylinders are where you have to watch. There are basically three types, coarse pitch, normal pitch, and normal pitch with a different shape because the beehive oil cooler is in the way. That should be enough of a clue to know what to watch for
The '83-85 12A slave works fine on the earlier models (save pitch of course) but going the other way is a Bad Idea if you want to actually bleed the system.
Something to be careful of - the last three master cylinders i installed came with studs that had a too-long unthreaded portion. When you install it, the nuts bottom out on the studs before they tighten down against the firewall. Compare the new studs vs. the old ones and if the unthreaded part is longer, you'll have to swap them.
I only use NAPA brand masters, they last the longest IME.
The slave cylinders are where you have to watch. There are basically three types, coarse pitch, normal pitch, and normal pitch with a different shape because the beehive oil cooler is in the way. That should be enough of a clue to know what to watch for
The '83-85 12A slave works fine on the earlier models (save pitch of course) but going the other way is a Bad Idea if you want to actually bleed the system.
Last edited by peejay; Dec 20, 2016 at 06:56 PM.
Thread pitches aside, I'd check your hard line if you go with an SA master. There are two different styles of SA clutch master cylinders as per the illustration from the black dragon catalog. One attaches the hard line from the firewall 90 degrees straight down, the other is at a 45 degree angle. You might need to fabricate your own line to make what ever pieces you are mixing and matching go together.
Old [Sch|F]ool
Joined: May 2001
Posts: 12,870
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From: Cleveland, Ohio, USA
Or just bend it to the correct shape with your fingers.
It looks like the oddball master is for early '79 anyway, which were oddballs no matter what. Hood prop on the right side of the engine bay, dogs and cats living together, mass hysteria!
It looks like the oddball master is for early '79 anyway, which were oddballs no matter what. Hood prop on the right side of the engine bay, dogs and cats living together, mass hysteria!
