Tranny or rear end problem?

[bryanhes]

This MC7 8V-71 Spicer 4 speed I had been looking at in the storage yard. The engine sounds good but there is a problem  . You put it in first and in about 5-10 feet it acts like it slips out of gear or off teeth in the rear end. When it does this you can put it in reverse and it will back up about the same distance as it went forward then the same thing. When it gets to this point you can let the clutch out but it sounds like gears not meshing and just rolling off of each other.

Any Ideas?

Thanks,
Bryan

[bevans6]

It could be either.  First and reverse are both driven from the layshaft, power comes in the transmission on the input gear, then to the layshaft, then to the change gears, so while first and reverse don't share an actual gear, they do have things in common.  They also share the sliding gear.  And of course the ring gear could have shed some teeth.

Briian

[bryanhes]

Brian,

If it is the layshaft should it pull ok in second on up? I am not sure what could have happened with it sitting for 5 years. It was driven into the storage and parked?

Bryan

[luvrbus]

Bryan, if it moves 5 or 10 feet it is the ring gear in the differential.
Check with RD Bishop on the board here he may have a extra from his gear change he did on his 7  


good luck

[bryanhes]

I Have been thinking ring or pinion gear as it will pretty much go the same distance either forward or reverse. I wonder how they drove it in that way? 

Bryan

[JackConrad]

Watch the driveshaft as someone tries to move the bus (should be able to see it through the passenger side engine compartment door).  If driveshart turns, rear end is the problem, if driveshaft stops turning, you have a tranny problem.  Jack

[bryanhes]

Jack,

I thought that would be the easiest way. I did not have anyone there with me to look. Maybe I can try today.

Bryan

[Busted Knuckle]

I Have been thinking ring or pinion gear as it will pretty much go the same distance either forward or reverse. I wonder how they drove it in that way?

Bryan

Lots of jerking, crunching and banging!
It's probably why they put it in storage!
It will probably keep going if you were to get some momentum built up before hitting that spot. But it would be very noisy and jerky! I have seen one driven all the way to New Orleans, LA from Union City, TN and back that way after the driver took out 5 teeth on the ring gear and several on the pinion by "banging gears" because he had never driven a stick shift bus and didn't tell the boss he couldn't because he was afraid they'd send someone else on the trip. Then he brought it back and parked it with out telling anyone about it! When confronted about it he said "It was fine when I parked it, must of been whoever drove it after me!"
Only after I almost knocked him out and drug him across the parking lot did he say "hey, OK it was like that almost all the way there and back, but it drove ok!" (I was the last one to drive it before him & first after him and worked on them too)
  BK 

[bryanhes]

BK,

No it does not jerk, crunch or bang. Once it gets to the spot it's as it is just barely rubbing teeth. If a person was to get into the throttle from the start it might do that but I let the clutch out easy to just a roll when it kind of banged a little (ok maybe there is a little bang, lol). I did not want to cause more damage by racing it through what I thought might be a bad spot.

Bryan

[Chopper Scott]

The good part is if you are after the tranny and it's the rear end having a problem you have a lot of negotiating room in your favor as to buying the bus. The bad part is whoever was in charge of checking the rearend oil probably also was in charge of checking the tranny!!

[gus]

Bryan,

It could be the driveshaft slip joint, happened to me.

All the splines were so rounded off you couldn't tell they were ever square, how they held I'll never know!!

[bryanhes]

Gus,

Would it move a few feet then slip out?

Bryan

[gus]

No, but it would make a big clicking sound. The truck mechanic who discovered it couldn't figure out why it didn't slip long ago. It may have but I didn't notice. I did notice it vibrated a bit. Small wonder!!

The reason I mentioned this is that it is very easy to check. Just get under the shaft and see if there is any up and down or twisting relative motion between the two shaft halves (Obviously with the bus out of gear). They shouldn't move except back and forth. You may need help to do this, get all the muscle you can find since the shaft is pretty heavy.

Since the drive shaft is far easier to remove than any of your other choices I sure hope this is your only problem.

[rdbishop]

Bryan, the next time you mess with the bus, back it up till it falls out of gear, then put it in 2nd gear, ride the clutch a little to get it moving and see what that does. If it keeps going, thats how the drove it in, and the problem will be 1st an reverse gear.

Richard

[bryanhes]

Richard,

I will try that. Bill from Pacesetter is supposed to be there Monday sometime, maybe. Don't know with this blizzard 

Bryan