Hi all,

On a trip over the mountains through W.VA a couple weeks ago, I
experienced for the first time what I think is trans clutch slippage. I'm in
a 330 cat / Allison 3000 MH, XC chassis pulling a 2005
Ford Explorer (about 4500 lbs). Going up the steep 6 to 7% grades, I'm
getting a significant oscillating (in and out like) vibration. Engine rpm stays flat, but
speed drops in steps. I equate trans slip with engine rpm going up too, but
this is not happening. Fluid in the trans looks OK although I'm due
for a filter change at 75000 mi I believe (71100 now). I check and it does not seem burnt to me, level on the stick is right on. I ran the dia mode on the trans when at a stop to cool and get fuel - ok on fluid and no code registered in the 5 memory positions. Has my fluid gone bad now?
I called local FL dealer and says that fluid change is not required
till 100K miles. But clearly I feel a slippage. Running on flat or
moderate grade there is no problem. Let me know your ideas. I don't
have an ECM monitor.

This week, I had to drive about 5 miles into the hilly Adirondack mnts to get
to our camp site and it is happening again. Definitely an
oscillating shudder in the trans pulling my heavy Explorer up the
grades. Unfortunately, I was dealt with an major hill before the park
here that must have been 8+% and had to go down to 2nd to get up
it. Fortunately, it was not too long of a hill. Will have to have
it looked at when I get to a city. It could be getting worse,
although on flat lands the trans runs just fine, and on interstate
hills shifting into 5 or 4 manually before the trans decides to
downshift, prevents the shudder in most cases. Reading the forums here, it sounds like a
clutch plate is slipping in the trans.

I have not found much on the forum of others having this issue under towing or over heated trans situation. Is that what I did? Overheat the trans 1st, and now the clutch slipping will require a repair? I will change fluid and filters asap, but middle of an RV trip at the moment.

Thanks, Jeff.

That description sounds like torque convertor slippage. If that is the problem, metal particles from the T/C will get pumped throughout the trans, which means a total rebuild most times.
The Allison computer should put the transmission into "limp mode" if it detects slippage above the parameters.
What is the tow rating for your MH? GCVWR? What are your actual weights? The shudder could be the result of exceeding your MH capabilities.

Had same problem with my cummins sometimes, mostly at start on a uphill grade. Checked out at allison two years ago and problem was unverisal joint out of time,180 out. Allison timed and problem disappeared. Allison said that some tow truck operators didn't know you could put a unversal joint together wrong, niether did I. Have you ever been towed?

Hope this helps.

Had same problem with my cummins sometimes, mostly at start on a uphill grade. Checked out at allison two y

quote:

Originally posted by Ray,IN:
That description sounds like torque convertor slippage. If that is the problem, metal particles from the T/C will get pumped throughout the trans, which means a total rebuild most times.
The Allison computer should put the transmission into "limp mode" if it detects slippage above the parameters.
What is the tow rating for your MH? GCVWR? What are your actual weights? The shudder could be the result of exceeding your MH capabilities.

The 2002 34HD has a 10K Lbs tow rating. Empty I'm 21000 Lbs, and has a 5500 lbs carring capacity. I'm carring about 2000 lbs. Total MH + toad is 36K lbs rated. I'm well under the weights although I have not put in on scales yet.

I would hope the filters are picking up the metal. I think the slip is still below parameter and therefore trans still allowed to run. But I can't do the rocky's now till fixed.

I think you are right about the torque convertor slip.

Thanks, Jeff.

quote:

Originally posted by beejay25:
Had same problem with my cummins sometimes, mostly at start on a uphill grade. Checked out at allison two years ago and problem was unverisal joint out of time,180 out. Allison timed and problem disappeared. Allison said that some tow truck operators didn't know you could put a unversal joint together wrong, niether did I. Have you ever been towed?

Hope this helps.

This is my 1st long distance tow, up to that I towed my boat to the local lakes without issue, and the boat weights about 1000 lbs more than the Xpl.

What is the relationship between u joint and the trans timing?

Thanks, Jeff.

I don't know, just what Allison told me. But it worked.