Allison 5spd no forward and no reverse

Rerywilson277

2002 LB7
Nov 7, 2013
25
0
0
Havre de Grace, Maryland
I got a used trans off a guy that had 50 miles on a ats build, he blew the main seals in the engine and that's why he was parting out the truck. So I got the transmission installed and it ran great for a half hour during the trans relearn. i get back to my driveway and when I stopped to put my truck in reverse I heard a very faint odd clunk when shifting from drive to neutral, and then had no reverse. Put it in forward and the same thing, nothing. So I put it back in reverse and give it some throttle and the truck started to move slowly so I revved it up enough to back it into my driveway. I got off the phone with mike L and he was helpful in telling me to pull the internal filter and if it was clogged up then the trans is toast. It has a few pieces of debri inside the filter but doesn't seem in any way to be clogging it up. Now I'm wondering what you all think? How could it wipe out forward and reverse at the same time? Could it be the pump being bad and not giving any pressure to the tc unless there is a lot of rpm? I just had head gaskets done on the truck and I'm drained of money. Any help is appreciated. Thanks
 

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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,661
5,808
113
Phoenix Az
the amount of crap in that filter tells us you have bad things going on in that trans.

you made two mistakes unfortunately...

1. you bought a used trans that was probably raped on but you wont know that without tearing it down

2. its a used ATS trans which is not know to be very reliable at all.

if you still have your stock trans, i would be swapping it back in till you can afford to build this one with parts OTHER than ATS
 

BlkMax

Member
Sep 1, 2008
743
4
18
Wasilla, AK
Un-ATSing an Allison is a bit of a pain, ask me how I know.:mad::mad: I would recommend running your stock one (again if you still have it), then having the stocker rebuilt.
 

Rerywilson277

2002 LB7
Nov 7, 2013
25
0
0
Havre de Grace, Maryland
I don't know if this makes any difference but it's not an ats trans in itself but a stock trans built with ats stage 6 clutches, a transgo shift kit, and tripleloc torque converter. I wish it was as much as just replacing the pump. Maybe the tc wasn't seated correctly when tightening up the bell housing or something
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,661
5,808
113
Phoenix Az
I don't know if this makes any difference but it's not an ats trans in itself but a stock trans built with ats stage 6 clutches, a transgo shift kit, and tripleloc torque converter. I wish it was as much as just replacing the pump. Maybe the tc wasn't seated correctly when tightening up the bell housing or something


What Mike told you is no joke. This won't be a simple fix. The internal filter with that crap in it agrees