borg warner conversion for xjs
Guest
Posts: n/a
gm400 to th400 upgradw
Does anybody know what I have to do to convert my 89 to the later model th400 trans. Iv'e had seven xjs and in every case the GM 400 failed, and the th400 kept on going.
Last edited by jagcollector; Nov 1, 2009 at 12:23 PM. Reason: clarification of desired transmission
Veteran Member
Joined: Mar 2008
Posts: 25,495
Likes: 11,695
From: Pacific Northwest USA
The GM 400 trans was used from mid-1977 right up until the introduction of the 6.0 V12, which was 1994 model year as I recall. It was then replaced by the GM 4L80E which is essentially a 400 with a 4th gear added. As bolt patterns were different you'll need an adapter kit from Johns Cars or a similar vendor....which in turn requires the use of a trans from a GM model, not Jaguar.
A better bet is changing to the GM 700 trans, later designated 4L60 but you'll still need a conversion kit
Cheers
DD
Veteran Member
Joined: Mar 2008
Posts: 25,495
Likes: 11,695
From: Pacific Northwest USA
Actually, no, it would be difficult. The 4L80E is electronically controlled (thus the "E") so, besides adapting the transmission itself, you'd have to add in the entire electronic control system.
The 4L60 is a better, easier choice
Cheers
DD
Thread
Thread Starter
Forum
Replies
Last Post
scooternva
XJ XJ6 / XJ8 / XJR ( X350 & X358 )
29
Mar 25, 2025 12:45 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)