Home 
> Jensen Healey & Jensen GT Tech > Engine & Transmission > 4spd Gearbox and Overdrive Options

 Moderated by: Greg Fletcher  
AuthorPost
NJ_Brit
Member


Joined: 06-16-2016
Location: Martinsville, New Jersey USA
Posts: 16
Status: 
Offline
Apologies if this is a repeat question, but I've read up and am confused about Gearbox + Overdrive options. I'm not that interested in the Toyota 5spd conversion.

I understand that the Rootes H120 gearbox (that had overdrive) can be fitted to the JH, but is it the entire gearbox, or just the overdrive box? I am running a stock 4spd with ~90k miles on it, and it's weeping oil from the seals, so is due a rebuild (it's completely smooth otherwise).

I figure that if it's an easy swap (and I can find the parts) I may as well fit the O/D whilst the gearbox is being overhauled.

My other question is whether the Rootes O/D is the only option, or whether one from an MGB/Spitfire could be used as they are more plentiful...). They both seem to be Laycock type units. Apologies if that is a really dumb question...

For reference, my JH is unrestored, aside from maintenance, and a couple of engine rebuilds (years ago) and a conversion to Dellorto's, so she's pretty much as she came from the factory in '74.

NJ_Brit
Member


Joined: 06-16-2016
Location: Martinsville, New Jersey USA
Posts: 16
Status: 
Offline
Refining the question a little. The O/D unit used was either the D-type or the later J-type Laycock De Normanville overdrive.

Given the J-Type was used from '72 onwards, and the JH basically uses the stock Rootes gearbox, I am guessing a J-Type could be used. Correct?

Jensen Healey
Super Moderator


Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 983
Status: 
Offline
A little bit of info here:
http://www.jensenhealey.com/forums/view_topic.php?id=1892&forum_id=2&highlight=D+overdrive+



UltraBB 1.172 Copyright © 2007-2011 Data 1 Systems