Lotus Elan

Replacing bearings in 4 speed gear box

PostPost by: Certified Lotus » Sat Jun 13, 2015 4:04 am

I found the input shaft on my gearbox to have a fair amount of movement so I'm going to replace the large input shaft front bearing and the rear needle bearing.

Has anyone done this and what recommendations do you have?
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PostPost by: Panda » Sat Jun 13, 2015 8:16 am

Hi Certified,
It might look pretty simple, but you do have to take out the layshaft to allow the gear cluster to drop into the gearbox sufficiently enough to give clearance to pull out the input shaft. You are really talking about a complete overhaul. Not difficult, but a press or puller is required to do the task, along with a dummy short layshaft etc. Keep in mind that the input shaft is supported at the front by the spigot bearing, so a certain amount of play is inevitable. If the gearbox isn't noisy or leaking oil and the synchro's are ok..............
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PostPost by: Certified Lotus » Sat Jun 13, 2015 11:23 am

Alan, the gear box wasn't very noisy (what I do I know, this is my first Elan) but the amount of play on the input shaft was surprising. I realize I could change all the bearings and find out the same amount of play exists. But if I don't do it I'll always be thinking about it.

In reviewing the shop manual I realized the entire gearbox is coming apart to remove the input shaft to replace the bearings. I have a press, but tell me why I need a dummy short layshaft?

Glen
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PostPost by: rgh0 » Sat Jun 13, 2015 11:28 am

You need the short dummy layshaft shaft to lower the layshaft gear set into place with some string while holdng the layshaft needle rollers in place. You then drive the full length layshaft into the gear case displacing the dummy shaft that was holding the needle rollers in place

cheers
Rohan
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PostPost by: Certified Lotus » Sat Jun 13, 2015 12:04 pm

Thanks Rohan. Can the dummy shaft just be a piece of alum pipe cut to length or do I need a shaft of same dimensions to hold the bearings?
Glen
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PostPost by: Chancer » Sat Jun 13, 2015 2:41 pm

You will always find what looks to be an excessive amount of play but all is probably in good order.

When the gearbox is installed the front of the shaft is supported by the clutch spigot bearing, without this support the input shaft can pivot around the large front bearing.

I would leave well alone unless there was bearing noise or I could feel some roughness, at best any new parts you fit might just be up to the quality of those you are replacing but it very often is not the case.

40 years of manufacturing development should be giving us parts of far higher quality, new car parts are but without the manufacturers Q.A. being enforced its a minefield out there.

To answer a previous question the dummy layshaft needs to be just slightly down on diameter to the original to be able to slide out when you drift in the original one, its length needs to be the same length as the laygear cluster minus a tad to drop down into the box, I use a cut down and ground down old layshaft.

I rebuilt hundreds of Ford gearboxes more years ago than I care to admit but never once did I have need of a press, some pin punches, drifts and cold chisels were all I ever used.
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