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MG TD TF 1500 - Gearbox help needed

I bought new sliding hubs form Moss for my TD gearbox rebuild. Unlike my original part the 3rd and 4th sliding hub has one of the holes for the retaining balls drilled all the way through the hub. The purpose of the through hole is for the a ball at the bottom of the hole to locate into a detent in the mainshaft. My understanding is that it was added later in production to aid in locating the sliding hub. My problem is that I have an earlier gearbox that doesn't have the detent in the main shaft but the Moss sliding hub has the through hole. Has anyone come across this situation before? I guess my obvious solutions are to get another mainshaft or drill a detent into the current mainshaft. The problem with those solutions are one , the expense and two, I don't know exactly where the detent should go. Any advice would be greatly appreciated. The pictures show the bottom ball and the detent. (pictures from Barrie Jones' gearbox rebuild video

Tim


Timothy Burchfield

Tim,
My mate is currently refurbishing a few TD gearboxes and I have asked him to take some detailed photos of the detent. I will post them on here this afternoon.
You will not be able to drill it. Best done with a spark eroding machine. Here's a photo of how my other mate eroded the key slot for the speedo drive.
Regards
Declan

Declan Burns

Tim,
Here are the photos
No.1 Old gear
Regards
Declan

Declan Burns

No. 2 Newer gear with ball

Declan Burns

No 3 Detent position-it doesen't matter which spline is chosen. Depth 1.51mm. Diameter= diameter of ball.

Declan Burns

Declan, thanks very much. Hopefully I can figure out the location of the detent. I was wondering if drilling a detent would weaken the hardness of the shaft. Since my gearbox did not have the upgraded sliding hub I could do without the ball and detent . But if I don't have a ball in the bottom of the hole the spring would have to be longer and would rub on the shaft. Now I just have to remember where I put that spark eroding machine. :-)

Regards

Tim
Timothy Burchfield

Exact location of the detent. 16.32mm from the shoulder. If you need anything else let me know while these gearboxes are apart as it will not be for long.
Regards
Declan

Declan Burns

Declan, very much appreciated. Thank you for taking the time to help. Off to the machine shop today.

Regards

Tim
Timothy Burchfield

Tim,
The 16.32mm measurement is to the centre of the detent.
Regards
Declan
Declan Burns

Perfect. Thanks

Tim
Timothy Burchfield

This thread was discussed on 01/03/2019

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