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MG MGA - Removing nut on input shaft

Has anyone got a tip for removing the large nut on the gearbox input shaft - I know that the thread is the reverse to usual, but am having trouble getting it to move

I have dealt with the lock tab, and have used the right sized spanner, but no joy....

Don't think the box has ever been rebuilt, and I want to replace the input shaft bearing.

Thanks
dominic clancy

BIG piece of angle iron bolted to the flange, BIG wrench or socket on the nut. Have one person hold the angle iron, the other hold the wrench and put torque on it............while holding the torque, pour a kettle of boiling water on the nut. Its a bit gentler than using a "rattle gun" that is going to shock the rest of the gearbox.
If it does not work, you can use the rest of the water to make a cup of tea and think about your next step........


good luck,

Mitch
Mitch Smith

The box is dismantled for rebuild. I have the input shaft alone on the workbench
dominic clancy

Plan 1: If you have a bench-mounted vise, put a couple of pieces of 4 - 6 mm brass in the jaws and hold the input shaft while you have at the nut with a large box end wrench. I would not recommend an open-end or adjustable wrench for this job.

Plan 2: See plan 1, but substitute a stilson (pipe wrench and, if you are lucky, the jaws will not mar the nut too bad for re-use.

Plan 3: Since you plan to replace the bearing anyway, use a propane torch to heat up the nut and use plan 1 or plan 2, as appropriate.

Plan 4: If you don't have the right tools, including a bench-mounted vise, take the assembly to a machine shop. It's worth the money to reduce the aggrevation for a simple, but awkward job.

Steve
Steve Brandt

Step zero. Apply liberal quantities of freeing oil - diesel is pretty good.
Apply daily until you next plan to tackle it.
Dan Smithers

I waited untill I was back at work to verify and get a picture Dominic.
With the large nut in a bench vice you can slip the driveshaft slip yoke onto the input shaft splines. You can then put a long bar through the yoke and loosen the nut. Remember to turn it backwards.
I used to keep an input yoke from both sizes of Datsun transmissions in the toolbox. I used them to both plug the rear seal when removing a trans and to hold both the input and output shafts while dissasembling a trans.


R J Brown

RJ, - 1500/1600 gearbox input shaft is 1-inch 10-spline. Early 1500 gearbox output shaft is 1-inch 10-spline. Mid 1500 output shaft is 1-1/16-inch 10-spline. The propshaft coupling you show in the picture is mid 15000 type. The early 1500 coupling has a straight dust cup welded up the side. You have shown the 1-1/16" coupling pushed onto the 1" splined shaft. That might work well enough for a wrench, but a lot of torque may damage the mismatched splines.
Barney Gaylord

RJ -That's exactly the type of insider tip I was hoping for, I'll give it a try tomorrow and let you know the result. Thanks to all for the help.
dominic clancy

Dominic,
For securing and leverage, consider bolting a spent clutch disc to a long 4x4 piece of lumber with the center hole of the disc just off the edge of the board, and inserting the input shaft. Seek out a friend that works in an industrial facility that would have the correct, or nearly correct, size open end wrench to fit the nut. (I located one at a brewery. It was quite a large wrench.) That same friend can help hold the board as you leverage the wrench. I forget now how much the springs in the clutch disc were wound up before the nut yielded, but it worked well. No damage to the splines, nut, or the mechanics. (As always, wear eye protection just in case something breaks.)
Steve
Steve K

Heat! I used a torch (not porpane) to heat the nut to red and then using the correct socket, and a long extension bar, backed it off with no problem. Let the nut cool slowly so as not to distort it.
Robert Maupin

RJ's tip did the job perfectly - like a knife through hot butter. It also works great in reverse to tighten the nut once the new bearing is in place. Extending the great idea, it also works to tighten the nut behind the speedo drive - here I slipped the propshaft on the output slines and gripped the yoke ear in the vice, being then able to use a large wrench on the nut while the mainshaft was effectively held solid. The only trick bit was balancing the gbx on the edge of the bench and not having end up on my feet....
dominic clancy

You are Welcome, Glad I could help.
R J Brown

This thread was discussed between 01/12/2007 and 07/12/2007

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