2008 LMM shakes/floor rumble's climbing hills

jmkat · Aug 15, 2022

LMM 3500 dually 280,000 set #2 EFI. Pulling 16,000 toyhaluer fifth wheel. cursing 68-70 MPH. when climbing hills, tach jumps 200 rpm. than some times/not every time. The shakes/ floor rumble's. Am concerned of what's going to fall apart. Changed trans fluid with Alison Transynd. Both filters. No codes. Never had the "Alison default to just third gear". Last trip. set EFI on #1--did have shake happen. Never have the problem when driving truck empty. Usually use setting #3 when empty driving. Rarely use #5--maybe once in awhile for long drives, to get 20 MPH. Otherwise, very pleasant truck to drive. Is it possible the driveshaft carrier bearing is junk on the rubber mounting?

Thank you for your help. Jkat

Ron Nielson · Aug 16, 2022

Of course, it's possible. But easy to check. Roll under your truck and see if moves around more than 1/8 inch or so.

jmkat · Aug 16, 2022

I've got 3/8" to 1/2" movement. I'm thinking the rubber mounting is deteriorated. I'll replaced bearing tonight.
Thank you, jmkat.

Headless_Horseman · Sep 16, 2022

Do the one piece conversion. Had the same problem on my Chevy 3500HD DRW after upgrading the wheels and the shake only happened when it was loaded. Went through and had drive shafts balanced, trans rebuilt, carrier bearing replaced and all kept happening. Replaced with the 1 piece driveshaft and smooth as silk again.

2008 LMM shakes/floor rumble's climbing hills

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