MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - New threads in gearbox case

A few months ago I had to drill out a layshaft locator bolt that was broken off in a gearbox case. I pulverized the bolt by drilling it with a bit the same size as the bolt. A 6X1 tap threaded into the hole, so I thought that I had not damaged the threads in the hole. However, a 6X1 locator bolt falls in without touching the threads in the hole. The case is now a spare

Is this the best way to rehab the hole?

> Drill and tap for a larger metric bolt. Then mill the tip of the bolt to lock the layshaft. Any "gotchas" to look out for?

> is there a better solution?

Thanks,

Lonnie
TF7211
LM Cook

Lonnie could you not have it welded up & then redrill & tap the hole with the correct thread? Cheers
Peter TD 5801
P Hehir

Helicoil or Re-coil is your friend. I know that Re-coil has the 6 X 1mm size as I have a kit for that, not sure about Helicoil. Check with British Tools and Fasteners at: http://www.britishfasteners.com/ If that doesn't get you a kit, e-mail me at SUfuelpumps@donobi.net Cheers - Dave
DW DuBois


Use a 6 X 1mm Thread repair insert tool set. Their available through EBAY and work great. Example: EBAY # 311234906426
Just check to make sure you don't screw the insert in too far and interfere with the lay shaft fit. If the insert is too long, excess can be easily cut off with a Dremel cut off wheel.
Richard Cameron

Thanks guys. I'm a dufus about doing this. Don't mind learning, but don't want to possibly screw up the case.

Is it a pretty straight forward job with a good drill press? Or, for a one-time job, would I be better and cheaper going to a machine shop?

I really appreciate the knowledge that you and other members share on this site. You are gradually turning me into a semi-confident MG wrench turner!!

Lonnie
TF7211
LM Cook

Lonnie, Heli-Coils come with the proper drill bit and tap for the size coil you need. It's a straight forward job. I would use a drill press to keep the hole perfectly aligned. after the hole is drilled or reamed to size, remove the drill bit and put the tap in the drill chuck, which will keep the tap also perfectly aligned. turn the chuck by hand or what ever you have to grip it and start the tap in the hole as far as you can with it in the chuck,(make sure the power to the drill is shut off)!Loosen the chuck leaving the tap in the hole and finish with a tap wrench/T bar. That's how I do it and it works. It's easy to get the tap started on a slight angle if starting by hand, especially in a soft metal. PJ
Paul161

Will gear oil leak past the heli-coil?

Lonnie
TF7211
LM Cook

No, the head of the bolt will cover it , just like the old one. A little Aviation sealant will add insurance.
Richard Cameron

This thread was discussed on 18/10/2015

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now