MY6 clutch.. which size?

[Geektrucker]

I've got an 81 SB with an Inline 6 250 and the MY6 3 speed w/ OD manual tranny. Need to replace the clutch as it's slipping badly! Looking around the usual parts places, they want to know if I have an 11" or a 12" clutch. I have no clue...any advice? Do I need to get in there first and measure what I have now? I plan on buying the entire kit and probably also the flywheel while I'm at it to make sure that's all good...

Any help (soon!) is appreciated... This is my daily, so I have to get it done on my next weekend (Mon-Wed) so have to order by this Friday.

Thanks!

 

[CSFJ]

I think the only different part is the clutch disk. If I remember correctly these took the same clutches as the m465. With those, the normal application got the 11" and anything heavier, got the 12".

 

[DoubleDingo]

With yours being a 2500, it's probably a 12".

 

[DoubleDingo]

You may not need the new flywheel. Not sure what you'rs looks like, but it may just a resurface. Of course with this being your daily driver and you needing to get it done quickly, if you by chance have access to second vehicle or a ride to machine shop, you could have resurfaced there. Or, if it's not in bad condition, just get a sanding block and use coarse to medium to fine emery cloth and then 320 wet sandpaper for a polished smooth surface, and go around and around and around to keep it from getting uneven spots.

I just did this and it turned out well. These pics were taken before the 320 was done to it.

 

[Geektrucker]

With yours being a 2500, it's probably a 12".

I had forgotten to update my profile... it's NOT a 2500, it's (now / new truck) an 81 C10...

According to LMC it appears it should be the 11" and from the responses so far that's what I'm going to order.

Regarding the flywheel... for the $75 I figure I'll KNOW I have a good flywheel when I put it back together.. unless by some miracle the existing one is pristine when I take the tranny out... in which case I'll just return the new one.

 

[Geektrucker]

I finally got a chance to climb under the truck this morning.. looking to see if I could adjust the clutch at all.. what I found was the bolt holding the "bellcrank" (according to LMC) is very loose and just spins with the bushing. The bushing appears to have worn considerably, when you step on the pedal, the bellcrank moves forward a good half inch or more. I tried tightening it, but as I said, it just spins with bushing.

So.. my questions are now:
Is the clutch really slipping, or is the bellcrank maybe moving enough to not fully engage / disengage the clutch?

How do I tighten up that bolt? The other end is attached to the block...

How do I replace that bushing? Do I have to remove the inner fender as it appears I do?

 

[Geektrucker]

Can anyone tell me if the bolt that goes into that bellcrank (I've also heard it called a "Z-bar"?) is one long one into the block or what the (dis)assembly is? I've got the clutch kit and flywheel waiting for pickup at the local parts place, but I really want to address that bellcrank bolt while I'm under there.

TIA

 

[DoubleDingo]

I'm guessing you mean number 7 in the lMC Truck catalog, I cannot upload a photo right now, for some reason my phone wont let me. there should be a nut that helps you with adjustment that threads through the piece that goes into the Z bar once I get to work I'll chime in unless someone else does before

 

[Geektrucker]

I'm guessing you mean number 7 in the lMC Truck catalog, I cannot upload a photo right now, for some reason my phone wont let me. there should be a nut that helps you with adjustment that threads through the piece that goes into the Z bar once I get to work I'll chime in unless someone else does before

No, actually I mean #14 from that same page. It shows the bellcrank, but no bolt? The bolt on mine is way super loose / bushing is shot (?) as it won't tighten up, just spins the bushing and is creating a huge amount of slop when the clutch is engaged. I'm thinking that's part of the problem of why my clutch is slipping so bad? First standard trans SB I've had, I've always had autos so not sure how it mounts.

I can see it attached to the block on the other end, but I'm wondering if it's one long bolt, or if there is an "ear" the bellcrank slides onto, then a short bold to tighten it down? From trying to tighten it yesterday, there's ZERO clearance to get a socket on it (up against the inner fender, and there's only space for a 1/4 turn on a wrench), so I'm not sure how the bolt comes out without removing the fenders.

Thanks

 

[DoubleDingo]

The slop in the components won't cause the clutch to slip. They will cause it to not disengage completely if out of adjustment bad enough. The z-bar (bell crank) rides on a ball stud bolted to the block and slips into a piece on the frame and that is the pivot point. You don't need to remove that replace a clutch. You should only need to remove #7 as shown in the LMC catalog. And is just a pressure fit from what I recall. Press the fork towards the back of the truck and it should cause enough of a gap to remove get the rod out of the fork. From there you should be ready to pull everything off the bellhousing and then the bellhousing from the block.

 

[DoubleDingo]

The z-bar linkage setup are old school but they work pretty well. The only issue I've had with them is stuff wearing out.

 

[Geektrucker]

The slop in the components won't cause the clutch to slip. They will cause it to not disengage completely if out of adjustment bad enough. The z-bar (bell crank) rides on a ball stud bolted to the block and slips into a piece on the frame and that is the pivot point. You don't need to remove that replace a clutch. You should only need to remove #7 as shown in the LMC catalog. And is just a pressure fit from what I recall. Press the fork towards the back of the truck and it should cause enough of a gap to remove get the rod out of the fork. From there you should be ready to pull everything off the bellhousing and then the bellhousing from the block.

Okay... we're close to the same page now! I know that removing the bell crank isn't needed for a clutch job, but my concern is that the bushing (?) inside, where the bolt connects to, is so worn out. When you push the clutch in, there's a ton of slop taken up by the bell crank before the clutch fork even thinks of moving (I'm guessing about half the clutch pedal travel?).

I just double-checked, the bolt that goes into the end (thru the "tab" off the frame) will not tighten up, just spins that bushing. So the next question is.. IS that a bushing of some sort in there, or is my bell crank broken?

 

[DoubleDingo]

Some pics would help. But let me see if I am visualizing this correctly. By bushing I am thinking you're talking about the piece with a cotter pin that goes on the z-bar and the threaded rod threads into and there is a nut to lock the the adjustment rod in place. If that's what you're meaning by bushing, then #7 from LMC can replace it, except you get the whole thing. It will remove the slop from that though.

The part that is on the frame side is like a bolt that has been ground on two sides to make flat spots. Those flat spots slide into a slot on the piece riveted to the frame. Once it slides in the slot it the nut will tighten. Unless the slot is somehow wollered out. The only way to check that is to get the frame side of the z-bar off the riveted piece to inspect the slot and flat spots on the engine side of the nut that you're trying to tighten.

 

[Geektrucker]

Some pics would help. But let me see if I am visualizing this correctly. By bushing I am thinking you're talking about the piece with a cotter pin that goes on the z-bar and the threaded rod threads into and there is a nut to lock the the adjustment rod in place. If that's what you're meaning by bushing, then #7 from LMC can replace it, except you get the whole thing. It will remove the slop from that though.

The part that is on the frame side is like a bolt that has been ground on two sides to make flat spots. Those flat spots slide into a slot on the piece riveted to the frame. Once it slides in the slot it the nut will tighten. Unless the slot is somehow wollered out. The only way to check that is to get the frame side of the z-bar off the riveted piece to inspect the slot and flat spots on the engine side of the nut that you're trying to tighten.

I'm definitely not talking about the adjuster / block side, I'm looking at the frame side. On mine, the z-bar is in-board of that tab, with a bolt going thru the tab into the z-bar. There appears to be some kind of insert into the end of the z-bar... When I try to tighten that bolt, the insert and bolt just spin.

I work mids and am waaay past my bed time.. I'll get some photos / video when I get up later tonight and post.

Thanks for the help so far!

Sent from my LG-v410 using Tapatalk

 

[Geektrucker]

Not the best of videos (the sun angle is wrong this early in the morning, but you get the idea). Looking at it this morning, I can see it's NOT a bolt into the frame end like I thought, but a rusted nut.. so the question is, how do I fix it?

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