Tranny Problems

[rip]

I have an Allison 748 with a 8v92 and the tranny has been running great until yesterday.I was coming into Rapid City when I had to climb a short hill at least 10% grade when the tranny started to slip.I made it up the hill,unhooked my toad then had to go uphill to turn around so I could park.The tranny work fine and shifted with no problems.After getting parked I checked my tranny fluid and it was a dark color but did not smell burnt.I have not looked for a repair shop yet. Any ideas of what's going on. Does anyone know of a good shop around here? I guess it's a good thing I plan to be here for three weeks.
          Don

[buswarrior]

Hello Don,

Not wanting to be impolite,

Have you driven the coach up such a steep incline in that manner before and got different results?

If you point the nose of a bus at the sky, there will be whole lot of hydraulic going on and very little forward motion. Not your father's Oldsmobile? 

Seeking service far from home for a transmission that is rare, when you aren't sure what is wrong...well, you are at the mercy....

One way or another, the fluid should be more pink than dark, so a fluid and filter change sometime soon would not be money poorly spent.

I would drive it a little more, and if it seems ok, take it to trusted service back home.

happy coaching!
buswarrior

[Utahclaimjumper]

Don, I would change the filter and add Lucas additive, then drive it, no sence
to be in a hurry to get out your wallet.>>>Dan

[TomC]

Don't take this the wrong way-the Allison fluid level is checked just like your cars-with the transmission at running temperature, engine running and in neutral.  I almost sounds like you were just low on fluid.  With the bus transmissions, it is vital to keep a sharp eye on the fluid level since most of the automatics have low profile oil pans that don't give much leeway for low fluid levels.  I'd also advise changing the fluid and the filter and try driving it again.  If it does slip in one gear, try slowing down and down shift to the next lower gear.  If it also slips in that gear, most likely your forward clutch is gone, translated transmission overhaul time.  If it only slips in one gear and not the other gears, then that one gear clutch is worn-you could probably drive it for a while longer-not gassing it in that gear that slips.  Good Luck, TomC

[rip]

Thanks for the info.This is the first time it has ever slipped and only in first gear.I try and check my fluids often.It was checked about 2000 miles ago.I also have an external filter,but I assume you guys are talking about the one inside the tranny.Is that correct.I can't get the rear to high but I assume the pan has to come off to change the filter.
Again thanks for the info,and no I would never get insulted on your  guys advice. This board is a great place
  Don

[Busted Knuckle]

Don you are less than an hour away from a good friend of mine's place! His family owns;
Dakota Trailways /  Dakota Bus
631 South 32nd Street  Spearfish, SD. 57783
Tel: (605) 642-2353
Fax: (605) 642-7707
After Hours Emergencies: (605) 641-2353
Office hours: Monday thru Friday 7:00 am - 5:00 pm.  Saturday by appointment only.

Try to talk to Travis Ladson tell him Bryce from TN told you to call.
They have a good shop man! (I don't recall his name but I do know Travis brags about him)
I think they'll do you right! FWIW   BK 

[pvcces]

Don, I don't know which setup you have other than it is a T-drive.

Don't rely on the assumption that you have to pull the pan to change the filter; a lot of heavy duty equipment has a remote mounted filter that is very easy to change.

One of the things that should be done if the filter is replaced is to cut it open and see what contaminants have collected in it. If it's very clean, that's one thing. If it's full of metal or fiber, that's another.

This should guide you in your choices regarding repairs.

For what it's worth.

Tom Caffrey

[rip]

After I bought the bus it was converted form a stick an auto.When it was installed the shop installed an external filter.Without pulling the pan how to I tell if it also has an internal filter or do I assume it only has one.The guy installed it is not around to ask.
   Don

[TomC]

Allisons typically do not have an internal filter that is accessed by removing the pan.  The older Allisons had remote mounted filters. The World transmissions have the two filters built into the pan-but changing them does not allow all the oil to drain out of the pan-just have to replace the oil that was lost with the filter.  Good Luck, TomC

[Busted Knuckle]

Don, I don't know which setup you have other than it is a T-drive.

Don't rely on the assumption that you have to pull the pan to change the filter; a lot of heavy duty equipment has a remote mounted filter that is very easy to change.

One of the things that should be done if the filter is replaced is to cut it open and see what contaminants have collected in it. If it's very clean, that's one thing. If it's full of metal or fiber, that's another.

This should guide you in your choices regarding repairs.

For what it's worth.

Tom Caffrey

Tom you are correct but I have also found that many of these ALSO still have a filter in the pan that is usually never changed or even check because of the fact there is a remote filter! I honestly believe that they should atleast be checked every so often even if not changed as they can get clogged and hamper performance and are seldom ever suspected, checked and many time known about! FWIW my 2 cents! BK

[Sammy]

BK, you are absolutely correct. it is called a suction filter. It mounts on top of the control module (valve body) in the B500.It filters the fluid BEFORE it gets to the pump. You'd be quite surprised to see all the crap it catches,in a unit with some mileage on it.
The control module must be removed to gain access to it. It's inside an aluminum housing, and secured with 2 bolts. New one looks identical, you don't remove the filter from the aluminum housing.

[rip]

I just went to Allison web site and if I read it right,the 700 series comes with an external filter.The internal filter and screen  should only be changed when the tranny is rebuilt.   Don

[luvrbus]

BK that must be the reason when i got a rebuilt transmission they installed another filter on the suction or return side i now have 2 filters