Allison 1000 transmission

**2manymustangs** · 08-19-2014, 08:58 AM

I will give props to Chevy for the exclusive use of the Allison 1000 in their Duramax trucks / "lighter duty" trucks...

These are some bad mofos...

Here are some pics from a one ton 200k mile utility 4x4 work truck... The trans was still working well but the owner was noticing hard UP and DOWN shifts...

There was a needle/roller thrust betwen the low/reverse gear shaft and the output shaft that failed (common failure point)... The frictions/steels looked like new... I suspect that the metal in the system caused the pump housing to start to fail/wear prematurely and start to loose pressure causing the shift condition...

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**2manymustangs** · 08-19-2014, 09:02 AM

Worn pump housing and failed needle/shaft face (where they idle together / overrun each other):

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The face of this shaft should be flat smooth/ground surface. The face of the gear should have a the needle bearing that failed, and should lift right out (but its gone)...
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**2manymustangs** · 08-19-2014, 09:27 AM

Bad part:

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New thrust:

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**The Doctor** · 08-19-2014, 09:32 AM

The real trick to these units is to use Castrol "Transynd" fluid from your first change on. I've had a number of them (Bruce, you've ridden in them) and I've never met a person with an Allison failure who used the Transynd fluid in them.

**Stainless** · 08-19-2014, 09:55 AM

Great Trannys, had one in an '02 Dually, and presently have one in 2500HD and Motorhome. The 8.1 engine and Allison trans were why I bought the MoHo vs the V-10 Ford setup.

**2manymustangs** · 08-19-2014, 10:17 AM

My buddies at the shop here do SWEAR by the synthetic for these big slipNgrips... THey say that there is no doubt about the increase in hard parts life with the full synthetic on high high mileage transmissions...

Most of their work is on trash trucks with a BAZILLION miles on them... THese little 1000s are about 1/3 the diameter for the frictions/steels/torque converters...

**Paul65K** · 08-19-2014, 11:07 AM

Hey 2MM.......all I can say is "You know your shit".....very cool!!

**2manymustangs** · 08-19-2014, 11:08 AM

Originally Posted by Paul65K

Hey 2MM.......all I can say is "You know your shit".....very cool!!

I had a good teacher on these autos...

my favorite brain teaser is the AOD fully hydraulic OVERDRIVE valve body...

One clarification on this Allison failure, this transmission is from a 4x4 and the needle thrust that failed is smaller in the earlier version of the 1000 that has a transfer case hanging on the back end. The 2wd versions and the upgraded 4x4s have the larger thrust bearing in that cluster for the output shaft to ride against...