Inspecting Allison clutches

[Mark Rinker]

I have put my 2001 through some extreme towing conditions this summer, and am soon to put the snowplow on for the winter.

So we don't end up broken down in the middle of a snowstorm, I'd like to examine the Allison clutch packs and see how they are fairing under this continual heavy duty use, at 150K+ miles on the stock transmission.

Is this something that can be done with the tranny in the truck, or does it have to be removed? If so, how many hours effort would you estimate (in and out) - and wouldn't this be a good time to simply replace the clutch packs if they are scorched and/or worn?

[ronniejoe]

That requires a complete teardown. Experienced techs can do it in a day with all the right tools.

One thing you might do is pull the pan and look for sludge. If clutches are wearing heavily, you'll see a buildup of friction material particles in the pan.

[Mark Rinker]

Good thoughts - and an easy check before tearing into it further. If it appears that there is significant clutch wear, I may opt for a lower mile takeout tranny and apply the mods, rather than start with a well worked 150K tranny anyway. (Truck #4 below.)

The pan will be dropped next service. Really, the only issues I have had are the occasional limp when I have the 1) power turned up (fuel+propane), 2) HEAVY loads (>14K GTrailerW), and 3) cruise control.

These three add up to unexpected and harsh downshifts on hills that push the transmission past its slip point, sets the code, and limps. If I don't use cruise, even under these conditions, it rarely happens. Have also set the MSD to pull propane over 20lbs boost, so it will usually cut the power quick enough under downshifts to avoid slippage...

[BMDMAX]

With the spin-on filter on the Ally I doubt you will find too much in the pan. I have never found too much in the pan on any of my six Allison tear-downs and I have thrown a wee bit of HP & heat in the clutches....

[JohnC]

I agree there won't be much in the pan, but, you can always cut the filter open and it'll all be there!

[SoTxPollock]

BMDMAX, why six teardowns? I assume that was before the Suncoast?

[BMDMAX]

Two trucks. One build was taking my LLY to a Stage V. The others have always been done on my LB7. The first one was to get my LB7 to a Stage IV. That one ran great for about two years until I decided to upgrade it to a Stage V.

Then working with Mr. Kennedy we decided to see just how hard we could push it and started to find some limitations pretty quickly. Suncoast has fixed all the issues every time and along the way they have been able to custom tailor a converter that really works in my 2WD application.

[Mark Rinker]

For any of you that have burned/glazed clutches - what were your first driveability symptoms that something was amiss?