Clutch Slipping

[leversole]

I was told that I have a dual disk clutch. Is there a way to "tighten" it up? It slips pretty good in high gear...The pedal linkage is not holding it off so I think the adjustment there is okay.

Is there a way to increase the pressure?

Thanks

[HK Trucking]

I was told that I have a dual disk clutch. Is there a way to "tighten" it up? It slips pretty good in high gear...The pedal linkage is not holding it off so I think the adjustment there is okay.

Is there a way to increase the pressure?

Thanks

In a B model that double disc would be a push type, as opposed to the more modern pull type double disc clutches.

First off, does the pedal have 1 to 2" of free travel at the beginning before you feel resistance? If not, then adjust the linkage at the clutch release shaft on the side of the bellhousing. It will have a 3/4 hex jam nut and a square head adjusting bolt. Loosen the jam nut and back off the adj. bolt til you have the proper free travel in the pedal, then tighten the jam nut.

If the pedal already has free travel and the clutch is slipping, then you can take out the shims between the pressure plate & flywheel to get some more life out of a worn clutch. Take out the floorboard, take off the inspection cover on top of the bellhousing, and remove the pressure plate attaching bolts one at a time and take the shim out (the shims are washers with a tab that has a hole in it where you can hook a piece of mechanics wire while removing, so you don't drop a shim into the clutch or bellhousing), then replace the bolt Do not fully tighten any of the bolts until you have rotated the flywheel 360 degrees and removed all the shims, then go around one more time and tighten all the pressure plate attaching bolts.

After removing the shims you will have to re adjust the clutch as I described previously.

If you find that the shims have already been removed and the clutch is properly adjusted and still slipping, or, you cannot get a good adjustment, then the clutch is history and needs to be replaced.

.

[theakerstwo]

In a B model that double disc would be a push type, as opposed to the more modern pull type double disc clutches.

First off, does the pedal have 1 to 2" of free travel at the beginning before you feel resistance? If not, then adjust the linkage at the clutch release shaft on the side of the bellhousing. It will have a 3/4 hex jam nut and a square head adjusting bolt. Loosen the jam nut and back off the adj. bolt til you have the proper free travel in the pedal, then tighten the jam nut.

If the pedal already has free travel and the clutch is slipping, then you can take out the shims between the pressure plate & flywheel to get some more life out of a worn clutch. Take out the floorboard, take off the inspection cover on top of the bellhousing, and remove the pressure plate attaching bolts one at a time and take the shim out (the shims are washers with a tab that has a hole in it where you can hook a piece of mechanics wire while removing, so you don't drop a shim into the clutch or bellhousing), then replace the bolt Do not fully tighten any of the bolts until you have rotated the flywheel 360 degrees and removed all the shims, then go around one more time and tighten all the pressure plate attaching bolts.

After removing the shims you will have to re adjust the clutch as I described previously.

If you find that the shims have already been removed and the clutch is properly adjusted and still slipping, or, you cannot get a good adjustment, then the clutch is history and needs to be replaced.

.

You must be as old as dirt. Not many guys remenber or have seen them.Something i have forgot is have you ever seen a pull clutch in a quadplex?I think they came up into the R models with them but can not remenber for sure.

[leversole]

In a B model that double disc would be a push type, as opposed to the more modern pull type double disc clutches.

First off, does the pedal have 1 to 2" of free travel at the beginning before you feel resistance? If not, then adjust the linkage at the clutch release shaft on the side of the bellhousing. It will have a 3/4 hex jam nut and a square head adjusting bolt. Loosen the jam nut and back off the adj. bolt til you have the proper free travel in the pedal, then tighten the jam nut.

If the pedal already has free travel and the clutch is slipping, then you can take out the shims between the pressure plate & flywheel to get some more life out of a worn clutch. Take out the floorboard, take off the inspection cover on top of the bellhousing, and remove the pressure plate attaching bolts one at a time and take the shim out (the shims are washers with a tab that has a hole in it where you can hook a piece of mechanics wire while removing, so you don't drop a shim into the clutch or bellhousing), then replace the bolt Do not fully tighten any of the bolts until you have rotated the flywheel 360 degrees and removed all the shims, then go around one more time and tighten all the pressure plate attaching bolts.

After removing the shims you will have to re adjust the clutch as I described previously.

If you find that the shims have already been removed and the clutch is properly adjusted and still slipping, or, you cannot get a good adjustment, then the clutch is history and needs to be replaced.

.

I know the motor is a later model, and the transmission is not the original, can you tell from this photo if it is a puch type for sure?

Thanks

[HK Trucking]

I know the motor is a later model, and the transmission is not the original, can you tell from this photo if it is a puch type for sure?

Thanks

Yes it's a push type. The release shaft is below the centerline of the trans, and the rod pulls on the arm, which causes the fork to push on the throwout bearing.

It's definitely a double disc because the mounting bosses where the bolts attach the trans bellhousing to the flywheel housing are about an inch long. On a single disc bellhousing those bosses would be nearly flat.

Also in that pic is the adjusting bolt with jam nut that I was referring to earlier, but yours must have been replaced with a conventional 3/4 hex head bolt at some point..

[leversole]

Yes it's a push type. The release shaft is below the centerline of the trans, and the rod pulls on the arm, which causes the fork to push on the throwout bearing.

It's definitely a double disc because the mounting bosses where the bolts attach the trans bellhousing to the flywheel housing are about an inch long. On a single disc bellhousing those bosses would be nearly flat.

Also in that pic is the adjusting bolt with jam nut that I was referring to earlier, but yours must have been replaced with a conventional 3/4 hex head bolt at some point..

Looks like I will be trying to get the floor out tomorrow! Dosent look very easy, as there are several smaller plates and EVERYTHING is rusted shut! I just hoper there are lots of shims!

Thanks

[HK Trucking]

You must be as old as dirt. Not many guys remenber or have seen them.Something i have forgot is have you ever seen a pull clutch in a quadplex?I think they came up into the R models with them but can not remenber for sure.

Glenn, the last one of those push type clutches that I "unshimmed" was on a hot August day in 1981, in my B613T5466 single axle dump truck that I had at the time. I can remember it like it was yesterday.

Yes, I have seen numerous TRQ7220 Quadruplex transmissions with the 14" angle spring pull type double disc clutch, the ones I dealt with were in DM611SX dump trucks.

Oh, BTW, I'm "only" 54!!!!!!!

.

[Superdog]

When I pulled the shims out on my B83 wrecker,I done it from the underside,PITA but I didn't have to pull the floorboard out.

[HK Trucking]

Looks like I will be trying to get the floor out tomorrow! Dosent look very easy, as there are several smaller plates and EVERYTHING is rusted shut! I just hoper there are lots of shims!

Thanks

I was just thinking: With the push type double disc clutch, Mack used a clutch brake on the countershaft. Assuming it is still in there, you'll have to re adjust that clutch brake too after this is all said & done. If you look up thru the bottom inspection hole you'll see it, there's a 15/16 head adjusting bolt & jam nut on it. Adjust the bolt as necessary to squeeze the clutch brake at the bottom 1 inch of clutch pedal travel, then tighten the jam nut.

.

[leversole]

Still trying to get the floor out! Looks like a homemade firewall...have to get that out before I can pull the floor...firewall looks homemade, like they had to do it because of the engine change?!? I can't believe the brake pedal is not mounted to something more substational than some thin sheetmetal...

The floor is already cut and damaged, I may just cut out an access for the top of the clutch, and put a nice piece of metal with stiffeners in to replace...

[Bobby Covert]

THE ADJUSTMENT YOU SEEK TO DO MAY BE FIXABLE FROM UNDER THE TRUCK AND NOT THE FLOOR PLAN DOWN.I TRY NEVER TO MESS WITH SOMETHING Unless Iam ready to redo the entire thing. Remember these are old trucks and parts may be brittle and ready to break. You might as well go to walmart and buy a case of spray lubricant. I have fooled with so many frozen bolts and nuts the I give up immediately and grab the lubricant.

[leversole]

Is this the spacer?!? I sure can't get it from the top?!? I will try again tomorrow from the bottom...the journey continues!

[HK Trucking]

Yup. That's a spacer.