Transmission Shudder at Startup

MasterChief · 09-28-2009, 07:15 AM

I have a problem with the initial engagement of my transmission on my 2004 Allegro Bus that has a Freightliner XC Chassis, a 330 Cat, and an Allison 6 speed 3000MH transmission.

This occurs on initial startup after the motorhome has been sitting idle for 24 to 36 hours. Starting procedure: key on, check gauges, start engine, air pressure builds up to normal, all alarms off, idle speed 700 rpm, all gauges normal, foot brake held on while emergency brake is released, gear selector pad pressed from neutral to drive - the motorhome will shudder for a second or two.

After that, is it runs smooth as always. All starts after that are normal - no shuddering on start (until the motorhome sits again for a day or more)

The transmission control unit has been changed and reprogrammed twice. The transmission has been changed, and the motorhome still has the same problem.

This first started happening at about 30,000 miles.

Has anyone else experienced this or know what this problem might be?

wagon217 · 10-01-2009, 09:48 AM

Kinda interested to see what anyone had to say about your problem. Sure sounds like a drive train problem but must not be in the transmission. Look at universal joints and get the differential checked out. That's my two cents.

Good luck!

Cruzer · 10-01-2009, 02:32 PM

I had an '04 Bus/Freightliner. I never really had that kind of shudder but the brakes would howl like a pig when I first got going. The Freightliner brake shoes are known to be quick to glaze and when you combine that with drums that have rusted a bit overnight they grab and squeel at first.

Is it possible that your shudder is the brakes chattering when you first throw it into gear? Do the wheels turn ever so slightly when the shuddering happens until the brakes bite into the drum?

wa8yxm · 10-01-2009, 06:50 PM

Well I thought I had an idea (If the fluid is low or the filters are dirty it can take a while for the torque converter to properly engage, and shudder can happen when it is trying)

But when you changed the transmission.. they would have taken care of all that.