Overdrive

[BarD]

Morning all,

I have a query on my overdrive.

When I bought the car it had an intermittent overdrive, sometimes worked, sometimes didnt.

Ive got it all working now, but its a bit aggresive when switched on/in & very aggresive when switched off/out.
This is in both 3rd & 4th.

Any ideas where to start would be most welcome.

Thanks,

Paul..

[DJT]

A-type or J-type?

[jleyton]

Not too sure but virtually everything you could ever want to know about both A type and J type overdrives is here: http://www.buckeyetriumphs.org/technical/technical.htm

It's a brilliant site and although it is specifically about TRs, quite a few parts (such as overdrive) were common to the Stag in the States (Eg TR6 was the TR250 in the States and had Strombergs)

I remember, back in the day, some advocated dipping the clutch when selecting overdrive, however I've never done it and my overdrive engagement is pretty smooth.

Cheers

Julian

[BarD]

Hi,

Not sure what type, will have a look tonight.
It has a big brass drain plug/bolt underneath, cant remember if it has fins.
Reading back through older posts here, it sounds like a J ??

Will double check tonight.
Will also be reading through that Buckeye site as well

Paul..

[DJT]

If it has a large brass plug underneath like this: image.jpg
then it is an A-type. There are a couple of valves which can clog up and give rise to poor actuation of the OD. One is accessible beneath the large rubber bung in the tunnel below the coin tray in front of the gear lever. The ROM describes how to remove, clean and replace it. The other one is behind the solenoid and is not so easy to get to.

[Hettiherald]

Hi paul. Always start at the begining, is there enough oil in the box? Low oil will give various problems.
Dave

[BarD]

Dave,

Yep, done a full engine/gearbox change.

Thanks,

Paul..

[Arbman Al]

What oil is in the gearbox? If it's a dexron type I believe it will stop the overdrive working properly?

[LAMBRETTLAD]

if you dip the clutch coming out of overdrive ,it puts less of a wear on the cones, a good understanding of overdrives ,but it a different car can be found on utube under mgb overdrives

[pollystag]

+1 on using the clutch when operating the o/d switch.

[PJM Stag]

When was the gearbox oil changed, it can take a while to replensih into the overdrive. Mine took a couple of days to work its way through.

[flying farmer]

I have a rebuilt A type on my Stag engine estate. It comes in with a hell of a whack compared to the J types fitted to everything else I own. A lot of this is probably due to the A type having a pressure accumulator, so it doesn't have to build up pressure from zero like the J type.

One problem I have noticed with the A type is its tendency to rip the brake ring out of the annulus with hard use, it has happened on both A types I have had, but I have never had it happen on a J type. Again, it is probably due to the more violent engagement of the A type, so the idea of using the clutch possibly has some merit.
I tend to avoid regular full throttle engagement in third gear on my more powerful engines as the overdrive struggles to keep up, though to be fair, the one on the TR is actually off a Dolomite Sprint which uses a lower operating pressure than the Stag unit so wasn't really designed to cope with 200lbft of torque. It has however covered at least 150,000 miles without a rebuild, so not abusing it obviously helps!
Neil

[BarD]

Hi,

Update:

Overdrive seems to be a bit smoother now.
"Out" is still jumpy, but "In" is much smoother.

Have started dipping clutch for dropping out as well now (even smoother)

Thanks for all info,

Paul..