Trans Advice on LQ9 Swap
Thread Starter
Registered User
Joined: Apr 2015
Posts: 3
Likes: 0
Trans Advice on LQ9 Swap Hi all,
I have an 51 Mercury M5 cabover and I have a deal pending on an 2003 LQ9 with low miles I would like to swap in. My problem is the transmission. I would like a 6 speed over a 4 speed as I intend to use this truck to haul a vintage trailer. As I understand, the 6L90 will not work with this older engine and I might be limited to either a 2006 or later Allison 1000 or using a 4l80E with an over/underdrive from gearvendors or something.
Does anyone know if an Allison can be made to work with this engine? I would like to avoid the additional cost of an over/underdrive if I can but I haven't been able to find an answer either way using the google.
I have an 51 Mercury M5 cabover and I have a deal pending on an 2003 LQ9 with low miles I would like to swap in. My problem is the transmission. I would like a 6 speed over a 4 speed as I intend to use this truck to haul a vintage trailer. As I understand, the 6L90 will not work with this older engine and I might be limited to either a 2006 or later Allison 1000 or using a 4l80E with an over/underdrive from gearvendors or something.
Does anyone know if an Allison can be made to work with this engine? I would like to avoid the additional cost of an over/underdrive if I can but I haven't been able to find an answer either way using the google.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
The 4L80E has an overdrive 4th gear; you would need need a gearvendors unit. A 6L90E has a wider gear ratio range. It will bolt up to any LSx engine, but you need an expensive aftermarket trans controller from PCS to run it.
Thread Starter
Registered User
Joined: Apr 2015
Posts: 3
Likes: 0
Thanks so much for the info! I am sure the cost of this controller will be less than a custom built 6 speed 4L80E or the gearvendors option. Looks like it will work with the Allison 1000 also but I have requested some more info regarding my build.
Thread Starter
Registered User
Joined: Apr 2015
Posts: 3
Likes: 0
Well, that's a bust.
"Thank you for your interest in PCS products. We don't support the GM 6L transmissions or Allison transmissions with harness or caibrations. Our TCM-2650 is a controller available to vehicle manufactures and OEM customers only. Sorry"
"Thank you for your interest in PCS products. We don't support the GM 6L transmissions or Allison transmissions with harness or caibrations. Our TCM-2650 is a controller available to vehicle manufactures and OEM customers only. Sorry"
