Synchro mechanism

Technical advice Q&A
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Norton
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Joined: Tue Oct 15, 2019 5:51 pm
Location: Norway
Norway

#1 Synchro mechanism

Post by Norton » Mon Nov 21, 2022 10:55 am

Hi.
Manual gearbox 1973 series 3.
Rebuilding gearbox, new bearings etc. Worn layshaft and reverse shaft also needs replacing. Gearbox were making rumbling noises.
And gear stick moved forward when accellerating and rearward when decellerating. Have some sugestion that it might be worn synchro hubs. The syncro hubs, synchro rings & operating sleeves are dismanteled, but how can I determine wether they are good / worn / worn out? What to look for?
The box was shifting just fine, no crunches, grinding.
The hubs looks good to me, same with sleeves. There are some wear on synchro rings «teeth». But enough to cause any symptoms? I think ring for first is showing most wear.

See pictures, hopefully good enough? Operating sleeve: Screwdriver pointing at one of the teeth having three detent grooves.

Thanks. Rgds Harald
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DWW
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#2 Re: Synchro mechanism

Post by DWW » Mon Nov 21, 2022 3:16 pm

Hi, if you go and watch on YouTube a channel called garage time, a guy there is doing a Porsche 356 gear box with a similar issue on a recent video and goes into details of how to check and fix it.

https://www.youtube.com/watch?v=AplAVLZ0qw0&t=44s
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR

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Norton
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#3 Re: Synchro mechanism

Post by Norton » Wed Nov 23, 2022 7:14 pm

Thank you. Chekced it out. It reminded me that I also have to look at the top lid, checking springs, balls, detents etc. Also found a video on what to look for on the synchro hubs. After wathing that one I think mine is fine - for now at least.
Harald

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DWW
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#4 Re: Synchro mechanism

Post by DWW » Wed Nov 23, 2022 10:37 pm

I am happy I was able to be of some help and hope things will go well with yours :bigrin:
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR

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Allrand
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#5 Re: Synchro mechanism

Post by Allrand » Thu Nov 24, 2022 5:52 am

Everything looks fine. On reassembly I think it would be beneficial if possible to rotate the outer sleeves to a different position so that the detent balls run on new unwarn teeth.
Randall Botha
'64 3.8 fhc & '51 Mk 7

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