jimbo40

Ok, here's the situation. She's broken and got a full rebuild. Syncros shot, a 2 inch shaft broke. Most in the back box but up front didn't look good either. Must be a super tough trans because it worked really well all the way around until it didn't. 4500 plus clutch and flywheel. 6k

I had a shop pull the trans to do the clutch and rear main seal, as well as go over the trans to see the problem and If i should just do a full rebuild. Question on oil. I know a trucking company that says they use 80-90w gear oil in all their 8ll trans, eaton says ps-386 synthetic. He said he doesn't use the synthetic and has no trans issues at all. Does anyone else use 80-90w? I would rather use that and not have a 400 to $1000 5gal bucket of oil.

This 8ll has the 5 bolt cover with 2 pistons 1 large and 1 small. The larger piston looks as if it is in about a 1/2" from its resting position, because you can see the slide marks in the cylinder walls

There was no rust. Instead of just removing the cover, can I pull the cylinder off too and try to manipulate that piston manually to see if it is just stuck?

I've exhausted everything superficial that I can think of and the suggestions from the group. I'm going into that secondary section on Monday, pull it off and take to to the trans shop. I pulled it once before about 12 years ago, I remember it not being to hard to do, but I would welcome any tips important steps you want to pass along. Thanks for the help so far.

Thanks for the manual, its just such a trip that there was no noise, or snap, or bang indicating a failure.

Nothing in high range, I can feel the gears spinning through the shift handle but nothing make it through to output. 10 years ago that box blew up on me, we pulled it but I can't remember how difficult it was, I'm rememberKing not to hard, but now it seems hard.

I pulled it and the nuts are tight, pistons looked good. Reg is putting out 61psi

Hello everyone, I'm new here and came to where the Mack folks hang out because I have an issue with my 8LL. I have been running Macks for 43 years in the dirt. This problem is in a quad axle, 97 Mack cl700 I'm an owner operator and know evey clunk and odd sound and pay attention to it, and fix it myself usually. The other day I took a load into a soft dump site, this is the first time out in the spring for this truck. The backin was showing some stress so I stopped put it in low low, and drove right out, maybe half throttle max. Back in for a flat dump and the pulled out no problems about 70000 was the haul. I've been in much worst with this truck. Read to roll back for another load and pu it in direct, but nothing, neutral. Back in LL and it drives fine all gears and reverse, no strange sounds but main stage and high are neutral. Drove it 3 blocks back to my shop at about 10mph and began to work on anything obvious. No air leaks, checked reg /filter, pulled the splitter valve and clean it and checked orings. I can hear all the clunking when shifting the stages, and if I sit at 1000 rpm in direct low, (not low low) with it in 1st gear it is just neutral but every once in a while it will grumble and slightly move like it's trying to connect. But still LL seems to work fine. Obvious I won't work this way. 1000 a day down time. They've been so good i had never had to do much to them, I'm a good mechanic but don't have any time with these 8LL All tech advice welcome. And thank you. Also, I away follow up with final result to help others with the same problems