6 speed Allison won't lockup

[Yellow Jacket]

I have a friend who purchased a 2009 LMM with a suncoast gmax kit and Precision converter, supposedly... After a few weeks of owning now it is throwing converter slip codes and not locking up consistently. 9 out of 10 times it feels a little like it's locking, and very rarely anymore it will lock up pretty harshly, but then next time it won't lock up. Edge CTS is showing lockup command, it just isn't. Fluid has pretty good color but looks metallically, but not bad IMO... He has no clue who installed the kit and converter, any ideas on causes? I burned up a converter clutch back in 2009 pulling, but I was forcing lockup with a switch on a loose converter that was seeing too much slip, even at 4500-4800 rpm...and my fluid wasn't pretty...

 

[Mike L.]

How much power is he putting out? Does it lock at low throttle and not at full throttle?

 

[Yellow Jacket]

How much power is he putting out? Does it lock at low throttle and not at full throttle?

It has a lockup box, when we use that it sees a 100-150 rpm drop, but I can feel that there is slip yet... He said 3-4 weeks ago it shifted and locked up fine. Would the oil be nasty with material if it was converter slipping?

 

[Evan@InglewoodTrans]

It has a lockup box, when we use that it sees a 100-150 rpm drop, but I can feel that there is slip yet... He said 3-4 weeks ago it shifted and locked up fine. Would the oil be nasty with material if it was converter slipping?

Have you logged converter slip while it's supposedly locked up? When converters go the fluid usually smells horrible.

 

[Mike L.]

It has a lockup box, when we use that it sees a 100-150 rpm drop, but I can feel that there is slip yet... He said 3-4 weeks ago it shifted and locked up fine. Would the oil be nasty with material if it was converter slipping?

The fluid would not necessarily be burnt. Best way to find out is with a scanner and watch the rpm slip after lock up. GM says 20-50 rpm slip is acceptable. I disagree. I want to see ) 0 slip.

 

[Yellow Jacket]

Just a heads up for anyone who might care or run into similar issue...

Pulled the trans and Dave Goerend cut converter open and the prior owner/installer used factory converter bolts, they ran them in and bottemed them out dimpling the billet cover and tore up the front clutch friction material. Ordered a Goerend X converter for the guy. The Precision converter had a gas cast stator in it.......

 

[Evan@InglewoodTrans]

Just a heads up for anyone who might care or run into similar issue...

Pulled the trans and Dave Goerend cut converter open and the prior owner/installer used factory converter bolts, they ran them in and bottemed them out dimpling the billet cover and tore up the front clutch friction material. Ordered a Goerend X converter for the guy. The Precision converter had a gas cast stator in it.......

Happens all the time. People don't take the time to think about why the supplied bolts are shorter or they never knew they needed them in the first place.

 

[ALLY Fox]

That's one reason I don't mess with transmissions, I leave it to someone who knows what they're doing.