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5 speed Gearbox selector shaft leak

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tr7dan
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5 speed Gearbox selector shaft leak

Postby tr7dan » 07 Oct 2022 19:11

Does anyone know the dimensions of the selector shaft O ring ..... or the diameter of the shaft itself ?

Got a leak unfortunately, only slight but it needs attention....

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dursleyman
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Re: 5 speed Gearbox selector shaft leak

Postby dursleyman » 12 Oct 2022 11:31

Darryl Walker ( TWOA ? ) did a mod to fit a new lip seal, hope these pictures have enough detail.

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Russ

1981 TR7 Sprint DHC & 1977 TR7 Sprint FHC
Dursley
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http://tr7russ.blogspot.co.uk/

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saabfast
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Re: 5 speed Gearbox selector shaft leak

Postby saabfast » 12 Oct 2022 22:13

Have you tried Robsport or Rimmers for a new one? Rimmers are showing them as 'in stock'':
https://rimmerbros.com/Item--i-UKC7
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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tr7dan
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Re: 5 speed Gearbox selector shaft leak

Postby tr7dan » 13 Oct 2022 00:14

Ok, thanks for the replies.

I couldn't get my caliper in to measure the the size of the selector shaft at first but a 5/8" spanner is almost a snug fit so it looks like 5/8" is the size, which ties in with the size of the lipped oil seal above, and yep, both Robsport and Rimmers do them but at nearly 5 quid inc postage from Robsport and a whopping £6.55 inc post from Rimmers for a teeny rubber ring the size of my thumbnail.... I think I'll pass.

Seals'R'us on Ebay do 5/8 imperial nitrile O rings at just £1.80 for 5.... with free postage. I'll give them a whirl....

Beans
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Re: 5 speed Gearbox selector shaft leak

Postby Beans » 13 Oct 2022 20:48

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1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

Beans
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Re: 5 speed Gearbox selector shaft leak

Postby Beans » 13 Oct 2022 20:52

tr7dan wrote: the selector shaft ... looks like 5/8" is the size

The LT77 'box is metric :wink:
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1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

tr7dan
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Re: 5 speed Gearbox selector shaft leak

Postby tr7dan » 13 Oct 2022 23:01

[quote="Beans"][/quote]
The LT77 'box is metric :wink:

I wonder did they mix metric and imperial because the above pictured oil seal looks to be imperial 1" x 5/8" x 1/4" (1 x 0.625 x 0.25) ? :wink:

Cobber
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Re: 5 speed Gearbox selector shaft leak

Postby Cobber » 14 Oct 2022 08:35

Maybe it’s meant to be 25mm x 16mm x 6mm
"Keep calm, relax, take a deep breath, focus on the problem & PULL THE BLOODY TRIGGER"

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busheytrader
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Re: 5 speed Gearbox selector shaft leak

Postby busheytrader » 15 Oct 2022 11:24

According to a vernier gauge on my spare gearbox, it measured the shaft at 15.97mm diameter…

Interesting to see the lip seal as a successful option. I’m not an engineer and always thought these were designed for sealing rotary motion items not reciprocating.

(The spare gearbox was an eBay purchase when the noises from the existing one sounded terminal. Removing the new aftermarket rubber gearbox mount for a Volvo part solved it)

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Re: 5 speed Gearbox selector shaft leak

Postby Beans » 17 Oct 2022 19:58

tr7dan wrote: I wonder did they mix metric and imperial because the above pictured oil seal looks to be imperial 1" x 5/8" x 1/4" (1 x 0.625 x 0.25) ? :wink:

Well it's an after market US conversion, and they were never good at metric dimensions :mrgreen: :P
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1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

Beans
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Re: 5 speed Gearbox selector shaft leak

Postby Beans » 17 Oct 2022 20:07

busheytrader wrote: ... Interesting to see the lip seal as a successful option ...

Bear in mind it is an extra seal, supplementing the original O-ring seal.
And in my case I also fitted a sealed rear main shaft bearing.
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

busheytrader
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Re: 5 speed Gearbox selector shaft leak

Postby busheytrader » 18 Oct 2022 21:00

Beans wrote:
busheytrader wrote: ... Interesting to see the lip seal as a successful option ...

Bear in mind it is an extra seal, supplementing the original O-ring seal.
And in my case I also fitted a sealed rear main shaft bearing.


A “belt and braces” solution as we would say in the UK. :D

tr7dan
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Re: 5 speed Gearbox selector shaft leak

Postby tr7dan » 25 Oct 2022 23:48

So, after a bit of head scratching I decided to see if I could fit an external seal to the selector shaft to save the hassle having to delve into the alloy gearbox end case to get at that O ring.... but it was very tight for space!

There was only about 4-5mm of space between the knuckle of the selector mechanism and the alloy case with the gearchange in the fully forward position and also there was only about 2mm of smooth shaft protruding on which to get a nitrile seal to sit.

After looking at all the various seal options I decided the only one that would fit was a M16 bonded seal washer (Dowty washer). I used Adiseal sealant / adhesive to glue it in place and, as the metal part of the washer isn't very wide I fitted a larger dished washer over it to give it more support.

I know this is not how they are normally fitted but it was a perfect fit on the shaft and up to now it has worked. I measured the gap between the selector mechanism and the seal, once I had reassembled it, and there is about 2mm of clearance.

Will it be a long term solution ? I don't know but it's worth a try and as it's easily removed and completely non-destuctive, what's the worst that could happen ?....

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dursleyman
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Re: 5 speed Gearbox selector shaft leak

Postby dursleyman » 30 Oct 2022 14:10

This thread got me thinking, never had the problem yet but thinking it might be a worthwhile mod on the spare gearbox before it is actually needed.
Russ

1981 TR7 Sprint DHC & 1977 TR7 Sprint FHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

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