Gearbox Crunch

Talk about the E-Type Series 3

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antseries3etype
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#1 Gearbox Crunch

Post by antseries3etype » Tue Jul 07, 2020 7:27 pm

My recently purchased series three manual has a bit of a crunch on the gearbox when I am changing down from 4th to 3rd gear. The problem is only prevalent when the engine is over 1500 revs. I have spoken to my excellent mechanic who is very familiar with E Types and he is of the opinion that this is common and that changing down at lower rev's or potentially double de-clutching will resolve the issue.

Does anyone have any thoughts on this as I did not expect problems with a syncro box.

Regards

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angelw
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#2 Re: Gearbox Crunch

Post by angelw » Tue Jul 07, 2020 9:31 pm

Hello antseries3etype,
I don't agree that your issue is typical for a gearbox and clutch in good condition. The condition and effectiveness of the Synchro Baulk Rings (also known as Blocker rings) and the Gearbox oil used are the main contributors of a notchy down shift. Oil that has too high an EP additive will inhibit the performance of the baulk rings by reducing the friction between the Baulk Ring and the conical surface of the Sunchro Hub. Before embarking on a Gearbox refurbishment, many have success by switching to Redline MT90 Oil, or other oil with similar properties.

Regards,

Bill

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abowie
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#3 Re: Gearbox Crunch

Post by abowie » Tue Jul 07, 2020 10:00 pm

I agree entirely with Bill. Sounds like your synchros may be worn.

Many on the forum have had found improvement with Redline MT90. I use it in all my own cars and it's what we use in customer cars.

Double declutching may help.

The good news is that at least you can get the gearbox out of a S3 car without also removing the engine. A complete gearbox rebuild should cost you in the order of £1000 with parts plus additional labour for R&R of the box. If you do this have a good look at your clutch as well. personally I'd just replace it with new.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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lowact
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#4 Re: Gearbox Crunch

Post by lowact » Tue Jul 07, 2020 11:35 pm

1st try topping up yr gearbox oil. My car had same problem when "recently purchased". Fixed the crunch but exposed the root cause, stuffed rear oil sesl.
Regards,
ColinL
'72 OTS manual V12

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Topic author
antseries3etype
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Location: London
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#5 Re: Gearbox Crunch

Post by antseries3etype » Wed Jul 08, 2020 4:42 am

Many thanks for the most useful guidance.

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