Lotus Elan

Gearbox Selector Fork Rebuilding.

PostPost by: ceejay » Fri Apr 13, 2012 11:58 am

Further to gear box overhaul and rebuild work, pictures
below show 3rd & 4th gear selector, note the amount of wear
on the face.

Re building was done with Oxy and wear resistant
silver braze rod, this is a low melting point braze material
which means the metal deposit can be applied below the
heat point at which bronze will begin to sag.

Gear selector forks are often die cast in Aluminium bronze
which can be tricky to repair with nickel bronze.

With the correct metal preparation & technique the repair
can be done quite easily, the hard part is the careful hand
filing required. These reconditioned selector forks should
last for many more years.

I would not be at all surprised if many elan gearboxes
have badly worn selector forks considering the age
of them now.

Col.
Attachments
1A-selector-wear-illust.jpg and
2A-selector-re-build-illust.jpg and
3A-selector-finished-illust-0008.jpg and
ceejay
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PostPost by: Chancer » Fri Apr 13, 2012 12:38 pm

Yes I have done exactly that in the past on 2000E and Rocket boxes, I used normal brazing rods but it was a bit too close to the slump temperature for comfort, I presume the other rods are what I used to call silver solder rods.
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PostPost by: ceejay » Fri Apr 13, 2012 9:24 pm

Yes chancer that is correct, the silver braze melt point is well below
the slump or liquidas temp of the aluminium bronze . The anti wear
quality is also excellent.
Col
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PostPost by: Elan45 » Sat Apr 14, 2012 1:39 pm

Col,

I too have done this repair back in the early 90's when replacement 3-4 forks weren't available. I believe I used EasyFlo 3 silver solder. It is very tough. But rather than hand filing, I made a short stub spindle the same diameter as the shift rail that I could chuck in my lathe and later in the vise of my bench mill. Its a pretty small vertical mill, but easily does that job. the spindle makes sure that the cut surface is perpendicular to the rail which is exactly what is needed. I simply cut down to the original surface that was not touched by wear with the hub. I have a small pile of forks on the shelf waiting their turn under the torch.

Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
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PostPost by: ceejay » Sat Apr 14, 2012 10:10 pm

Roger.
The mill drill & lather would have done a perfect job, I only had
the one fork to do so opted to hand file, tedious, but it did the job.
Hand filing if carefully done is OK. Any high spots will soon bed in.
Col
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