I’ve been offered a GKN Laycock O/D complete with 4sp transmission for a S3 E-type.
Does anyone know what the O/D ratio is please?
0,75 or very close depending what it came from originally.
I believe mine is 0.80. Based on the RPM drop of 20% when I engage the O/D.
Could be. In the old forum ‘Brochure’ section it listed gear ratios in the tech specs at the back of each brochure. I think it has them in the XJ6, S-Type & MkX/420G brochures (i.e. models that used the Compact Type A overdrive). What’s five hundredths between friends 
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Philip, so did you go with the OD/transmission offer? I think it’s a great choice for any LWB E-type. I know alot of drivers with manual OD’s (particularly Healeys and Triumphs), and I’ve never heard any of them wish they had a 5-speed gearbox instead of the overdrive. The OD is quicker (and smoother) to shift in and out of 5th, which isn’t a big deal for interstate cruising, but really nice to have on the backroads. Plus, they’re a nearly forgotten bit of motoring heritage that work great for their limited purpose, and just make the car more authentic for the period. So I’m thinking, who wouldn’t want one if it’s a relatively easy conversion for longer wheelbase E-types?
Tim
'67 OTS
My car is an auto, so I would have to covert to manual. This means I also need the flywheel, manual starter (which I believe is different from the auto?), clutch pedal, pedal box & M/C, plumbing etc.
I have fitted a 2.88 diff quite recently which has improved cruising substantially over the 3.31 I had before.
Motivation to convert rather low now.
Hi,
Yes, the 3.31 is nice with the O/D, 2.88 plus O/D is a bit of an overkill, IMHO. I had the 3.31 and autp to MOD conversion in my ex S1 2+2 from 1966 for 16 years and loved it. And IMO it is also very good in the XJ6C I have with a factory 4sp + O/D and a 3.31 final drive, even a 3.54 would be ok with an O/D. In my case, both compact A type Laycock de Normanville overdrives drop revs by 20%. At 100km/h from 2500rpm to 2000rpm.
FWIW the starter is the same as long as you have the same kind of flywheel and amount of teeth on it. Pedal box is also the same, you just shorted the nylon bush inside it to fit a third pedal. But the gearbox top cover and pivot for the stick is different on an E-type than an XJ6 or 420G, so those parts need to be sourced. (I got mine from RM & J Smith in the UK back in 1996)
Cheers!
I had a highly-modded TR4, with the OD on 2nd/3rd/4th, and it was a ball!
The LdN OD us much more fun and yes, faster to shift, than a 5th cog.