Lotus Elan

Gearbox leak - Planning for a gearbox and engine pull

PostPost by: SENC » Tue Apr 30, 2019 3:07 am

As I've been wiping and cleaning things down, I've been planning the various seal replacements. When I replace the sump, there isn't any good reason not to just rotate the engine on its stand and do that replacement upside down, is there?
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PostPost by: mbell » Tue Apr 30, 2019 5:26 pm

It's what I did.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: SENC » Sun May 05, 2019 12:41 am

prezoom wrote:Did you find your leak?


Haven't finished cleaning the gearbox or pulled the seal, yet, but peering in it the seal housing is definitely damaged - and I pulled the propshaft and the yoke is clearly grooved, so little doubt the box was leaking from the rear. The forward propshaft u-joint movement is noticeably jerky in one axis, and the rear u-joint stiff in one axis - wouldn't be surprised if they haven't been greased in 50 years. Given the cost of a new yoke and 2 u-joints, I decided to order a replacement propshaft with all the bits from Kelvedon.

20190504_105842.jpg and
grooved propshaft yoke
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PostPost by: 2cams70 » Sun May 05, 2019 3:21 am

That grooving on the yoke surface is severe and abnormal. You will almost certainly need to replace the bush in the gearbox extension housing too.
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PostPost by: SENC » Mon May 06, 2019 2:16 am

2cams70 wrote:That grooving on the yoke surface is severe and abnormal. You will almost certainly need to replace the bush in the gearbox extension housing too.


I'd say you're right. Took tailshaft off and bearing damage is also obvious. Looks to me like some debris (maybe part of the dryrotted seal) got in between the bush and the yoke.

20190505_152743.jpg and
gearbox tailshaft bearing
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PostPost by: 2cams70 » Mon May 06, 2019 7:01 am

I'm quite surprised too by the length of the contact pattern on the yoke. I would have expected the Elan with its supposedly rigidly attached final drive unit would have a fairly short contact pattern compared to something with a suspended live rear axle. Maybe check your mountings too? - engine / transmission / final drive.
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2015 Honda City 5spd.
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PostPost by: SENC » Mon May 06, 2019 11:38 pm

The transmission mount was pretty bad, and I previously replaced a failed motor mount and not great differential mounts, so could very well have been some movement.

My bigger issue, on further inspection, is that the end of the gearbox extension is cracked, whether a previous problem, damage from pulling it, or damage from my trying to press out the bearing, I do not know. Regardless, I'll need another. I see that TTR/Kelvedon offers some reproductions, but before going to great expense does anyone have a spare? If not, what material would you choose preferentially?
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PostPost by: SENC » Fri May 10, 2019 2:36 am

Given findings so far, I've decided the wisest course is a full strip down of the gearbox to id and resolve any other issues. I see a number of resources suggest a special tool for extracting the reverse idler, is that really necessary? Alternate solutions? Any other special needs, tips, or tricks?
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PostPost by: SENC » Mon Jun 03, 2019 9:25 pm

Have been pulled away from this project for a bit, but had a few hours yesterday and disassembled my gearbox. In prepping I found some youtube videos someone had posted on putting one together but none on disassembly and several comments that such would be helpful, so while I took some video to share. Not great lighting and awful commentary, but may be useful for someone planning the same in the future or as a cure for insomnia.

Overall, I was pleased with the condition of the shafts, gears, and rings - I was a little worried after my tailshaft bushing findings, but the box and parts were pretty clean so selector forks are the only internals I plan to replace.

As always, open to observations and suggestions.

https://www.youtube.com/watch?v=BHcXB_9y464

https://www.youtube.com/watch?v=DC3WL2GGVK8

https://www.youtube.com/watch?v=Hcgo3ufR4as

https://www.youtube.com/watch?v=Up7KMHMarZU
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PostPost by: SENC » Sun Jun 30, 2019 2:59 pm

Main and lay shafts reassembled and reinstalled in the box. If I can carve out some time this afternoon I hope to get the extension on and selector rods and forks reinstalled.

A couple reassembly videos in hopes of helping someone downstream:

https://www.youtube.com/watch?v=0hUcB-4b9C0

https://www.youtube.com/watch?v=rlYP4NCYgys
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PostPost by: SENC » Sat Jul 06, 2019 12:17 am

Installing new sump pan and crankshaft pulley tomorrow - any tips, tricks or advice?
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PostPost by: 2cams70 » Sat Jul 06, 2019 5:40 am

Be careful where you source the crankshaft pulley. The offset is very slightly different on the Twin Cam compared to the regular crossflow pulley and some suppliers aren't aware of it. Can be corrected for though. Refer my posting about Burton cartridge water pump fitment issues. I take it you will be installing a new pulley seal whilst at it too.
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
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2015 Honda City 5spd.
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PostPost by: SENC » Sat Jul 06, 2019 5:12 pm

2cams70 wrote:Be careful where you source the crankshaft pulley. The offset is very slightly different on the Twin Cam compared to the regular crossflow pulley and some suppliers aren't aware of it. Can be corrected for though. Refer my posting about Burton cartridge water pump fitment issues. I take it you will be installing a new pulley seal whilst at it too.


Good call on the pulley, I believe I have the xflow rather than the tc pulley - any definite sources for the right one? In the meantime, I'll review the burton thread.
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PostPost by: 2cams70 » Sun Jul 07, 2019 12:54 am

The QED ones have the correct offset.
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2015 Honda City 5spd.
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PostPost by: SENC » Sun Jul 07, 2019 1:30 am

Thanks. New problem.

Got my gearbox put back together, all good until I tried to test fit the new yoke into the tail shaft. Starts fine on the splines, but a super tight fit into the bearing (tight enough it would require pressing in). I seem to recall a recent post with a similar problem and the poster concluding the new bearing was undersized, but can't find that post.

Looks like I'll need to pull the tailshaft extension and replace again - has anyone else done this recently that can confirm a source of a properly sized bearing?
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