J Type Overdrive ----- Convert to Operate on 2nd Gear.

[astontr6]

Has anyone done this conversion?

 

If so, how well does it work? As the J Type works different to the A Type.

 

Thanks,

 

Bruce.

[peejay4A]

I've done it. It works fine but I never, ever use it. No need on the 4A.

[TR NIALL]

I've also done it on a 6 but disconnected it as it's very Brutal if used in anger.

[Guest ntc]

+1 the J type is not up to it.

[astontr6]

Thanks for all your responses,

 

Bruce.

[Nigel A]

Colin at CTM did it for me (at my request) when he supplied the gearbox

 

Hardly ever use it except very occasionally when in traffic.

 

If I knew what I know now I wouldn't have bothered

 

Cheers

 

Nigel

[Austin Branson]

I did this about 8 years ago. The overdrive is still as original, and I use it all the time. I am aware that it is considered unsuitable, so only rarely engage while under heavy acceleration. My engine produces circa 180bhp. The only overdrive issues I have had are those bloody awful aftermarket micro-switches, with terminals made of re-cycled dog poo! They snap off if you look at them sideways. Get secondhand Lucas versions from TRshop. Make sure the operating height is correct. Follow wiring as in CP. In my opinion, it's a good mod. Austin

[Andy Moltu]

The simplest way is to use the top cover from a gearbox intended for an a type. Or drill and tap it to take the the extra switch.

[harlequin]

I did mine about 20 years ago with no issues so far, its very useful around town and in traffic but I rarely use it when driving hard

[rcreweread]

I have a Stag gearbox with a 28% J type OD, built for me by Pete Cox, who also modified it to work in 2nd gear ( as already stated, it's as simple as using an A type top cover with the extra switch ) and I have to say it's really made a difference ( it's in a TR4 ) - fitting was a bit of a pain but perfectly do-able.

 

I don't thrash it if I'm using 2nd OD but as suggested by several others, it makes driving in towns or slow speed areas more pleasureable, with far fewer gearchanges if you don't want to - cruising is also far more relaxed.

 

As my speedo seems to go on strike when it gets to 60, I'm not exactly sure what revs 70mph has been representing - I keep meaning to take my sat nav with me to check but always forget - 3000 rpm in OD top is a dodle which according to the minty lamb site ( thanks for the link ) is 78.5 mph - however the site doesn't list a 28% J type OD so these figures are based on a 28% A type OD - would there any speed difference between the two?

 

I was previously working on the mistaken assumption that 28% equated to 28mph/1000 rpm in top, 25% to 25mph etc so glad to have got that error sorted.

 

Bruce - back to the original question - go for it, but don't be too harsh in 2nd - I'n sure you won't look back

 

Cheers

Rich