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Mating new gearbox to used overdrive


Nick B.

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Hi

 

After the 10CR, I decided my 3-reail D-type ODgearbox needed some service. The syncro on 3rd gear are worn, and the change is not smooth, but requires a bit of fettling - or brutality.

I have a complete rubuild OD-gearbox I bought from GT a few years ago, and now want to put the thing into service.

Question is - is it straight forward to remove OD-unit from the old gearbox and put it onto the new box? Any traps to look out for?

 

 

Cheers

Nick

 

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Should be pretty straight forward.  Make sure the pump drive cam and it's retaining wire clip are there on the new box - and swap them across if not.  Resist the urge to twiddle the output flange while the OD is off.  There are two sets of splines inside the OD and they have to line up exactly for the OD to go fully home.  They come out of line MUCH easier than they go back into line.

Obviously it's worth dropping the sump on the OD and cleaning the magnets and filter.

Nick

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On 9/11/2017 at 9:37 PM, Nick Jones said:

Should be pretty straight forward.  Make sure the pump drive cam and it's retaining wire clip are there on the new box - and swap them across if not.  Resist the urge to twiddle the output flange while the OD is off.  There are two sets of splines inside the OD and they have to line up exactly for the OD to go fully home.  They come out of line MUCH easier than they go back into line.

Obviously it's worth dropping the sump on the OD and cleaning the magnets and filter.

Nick

Hi Nick

 

Thank you. It is assuring to know that things does not explode on the workbench when I take them apart. I really must resist the urge to twiddle the flange. I most certainly would have done it if I had not been warned. The Mad Welder kan confirm I am quite a fiddler who never leaves stuff untouched.

 

The new gearbox is one I bought from GT a few years ago, and I judge it is a good time to put it into service. Hopefully it will last better than the old one, where the new china-made syncros on third gear really is not up to the job.

And most definitely the magnets and filters will be cleaned. As you perhaps remember from 10CR my OD decided to retire itself from service about 5 hours after start. I suggest an electrical error though. It has always been a nice shifter without hesitation. Less than 1.5 seconds to engage, and instant disengagement.

 

Cheers

Nick

 

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  • 7 months later...

Oh, dear. I am slow :ermm:

Yesterday I actually managed to start pulling the box apart. I managed to remove the bellhousing and the shifter mech. 

 

Then I realised that I did not have enough silikone for the gaskets to complete the job. Besides, that I was missing the top selector gasket (slow delivery...)

I decided to leave it all on the floor, also because I could not remember what Nick Jones had told me NOT to fiddle with. In short, I was to tired to do anything, and I abandoned ship. 

Next tuesday I have an agreement with the box that it will be put back together and mated to the engine. And hopefully engine goes back into car.

Cheers

Nick

 

 

 

 

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Aligning the splines and ensuring the stay aligned (and line up with the splines on the GB output shaft) is probably the only tricky bit. IIRC turning the gearbox didn't help either as there was enough friction between the 2 splined sections in the OD for the first to drag the second around.... so they wouldn't line up.

Much flicking with a big screwdriver and peering into the OD with a torch.... and then when it finally slides together a big sigh of relief.

 

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Hopefully the proces will be easy as I take the old gearbox of, and then put the new gearbox in just minutes after. Lets hope.... And then hopefully the box is good. I trust Gareth has put a nice box together for me, and I can engage third gear without resorting to violence.

The syncro rings looked somewhat miscoloured on the old one, and there were quite a lot of yellow metal debris in the OD filter, very fine metal grit from the syncro rings. 

Cheers

Nick

 

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