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Moparmike

2000 mack rd 688 clutch adjustment help

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Ok guys my truck has a fuller 8ll Trans..I have adjusted the clutch in my freightliner before but the mack is a little different so I thought I would ask before I do..the clutch is releasing at the top not much free pedal..I took the cover off butthe release bearing is different from my other it looks as if it rides on the cross shaft my other truck is just the bearing this truck has a cable with a couple different points looks like to adjust other is a rod either top or bottom..so please guide me on this ..thanks in advance 

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Mack release bearing is upside down compared to other trucks. The grease fitting is on top, with a hose kit installed so you can access with the grease gun. Clutch free play adjustment is the same as any other truck, with the lock ring on the pressure plate. The linkage only gets adjusted during initial setup, or if you have clutch brake issues.

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Thank you I just didn't won't to mess things up figured I would ask first..new to make but loving mine so far ..

20170216_144007.jpg

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Once you go Mack, you'll never go back!

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Find the adjusting bolt on the face of the pressure plate,with the. Peddle depressed push n on the locking ring with a 5/8 box wrench and turn the bolt clockwise for more free pedal.Very important to measure inbeetween the clutch brake and the throw out bearing,has to be 1/2 to 9/16 inch. Do a search on here some has the whole procedure outlined.

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there are a few different style clutches out there that don't all adjust the same way but the majority are the way macks described.

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we find setting the gap at 7'16ths _1/2" and the set the free travel at 1/1/2 instead of 2" give better clutch brake engagement in r models ,thats with eaton easy pedal clutches 

 

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really more gap with less free play should give you more break squeeze. 1/2 + gap with 2" free play would give more clutch break squeeze than 7/16's with 2 inch free play. 

 

i normally setup my clutch's for closer to 2.5 inches of free play with right around a 1/2 gap and always have plenty of break squeeze. after your first setup of the clutch though you should never have to touch the linkage unless someone else has monkey'd with it. neither adjustment is terribly critical as long as they are close on the bearing clearance and free play is in range the clutch will work good. 

 

the biggest problem i have run across is people not knowing what there doing and adjusting the linkage every time they are running out of free play. then by the time you measure the bearing clearance and set it where its supposed to be you have 5 inches of free play. 

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