Gearbox question

Gearbox question

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Discussion

KKson

Original Poster:

3,395 posts

124 months

Monday 27th June 2016
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Hi all, quick question but I've noticed on a couple of occasions when changing down from 3rd to 2nd on the 390SE that I can feel a slight catching of gear teeth as I cross the gate. It's not a crunch but I can feel the gear teeth slowly catching. It's only happened a few times but wondering what it can be? Also when I select reverse again on occasions the box crunches. If I go from second to reverse all is sweet and if I clutch down and wait for 10 seconds then also all sweet.

I'm intending to give the box a full "Adam flush" and Mobil 1 and Molyslip treatment, however it did have new oil in it earlier in the year when the gearbox seals were replaced.

Anyone have any clues as to the reason? Cheers.

Wedg1e

26,760 posts

264 months

Monday 27th June 2016
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Yeah, it was never intended to be a sports car gearbox. If it's been used like one for thirty years, it's bound to feel a bit tired.

adam quantrill

11,535 posts

241 months

Monday 27th June 2016
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It's not the Adam flush (though I've done it) it's the Ramon flush ;^)

Anyhoo it's worth a try, mine has been less notchy since the flush.

mrzigazaga

18,534 posts

164 months

Monday 27th June 2016
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I find reverse does crunch a little but a little rev before engaging normally sorts it...Are you depressing the clutch fully?...

Wedg1e

26,760 posts

264 months

Monday 27th June 2016
quotequote all
3rd to 2nd you say... it's not tired extension housing bushes allowing the housing to droop a bit and be clipped by the propshaft flange, is it?

ElvisWedgely

2,714 posts

164 months

Monday 27th June 2016
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To me, your description of the symptoms sounds like preliminary signs of the clutch cover and plate springs starting to fail. Normally it starts with difficulty in engaging reverse and then crashing on the down change. If it is that, it will last a long time yet. If you have had a clutch fitted recently, it could still fail, especially if it was fitted with a poor quality clutch.

Tony. TCB.

RCK974X

2,521 posts

148 months

Tuesday 28th June 2016
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Yeah, if clutch isn't quite disengaging all the time, you'll get a slight crunch between gear changes. If reverse crunches from full standstill then it's probably a clutch 'drag' type problem (not disengaging or stiff/siezed spigot bush).

If it's not happening when stood still, it could also be a worn sychro ring, but this will happen going up and down gears.

I would check clutch mcyl (etc) is working properly first.

adam quantrill

11,535 posts

241 months

Tuesday 28th June 2016
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Give the hydraulics a bleed and if it improves straight away you may have an impending problem.

Convert

3,747 posts

217 months

Tuesday 28th June 2016
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Wedg1e said:
3rd to 2nd you say... it's not tired extension housing bushes allowing the housing to droop a bit and be clipped by the propshaft flange, is it?
I'm with Ian, mine did this. Changing the bushes for Poly fixed it.

KKson

Original Poster:

3,395 posts

124 months

Tuesday 28th June 2016
quotequote all
Convert said:
I'm with Ian, mine did this. Changing the bushes for Poly fixed it.
Thanks for the replies. Given the type of noise and "feel" of the vibration, rubbing on the prop might be it. I'll get it up on the ramps and have a good pull on the remote to see how saggy the bushes are. Cheers.

gmw9666

2,734 posts

199 months

Wednesday 29th June 2016
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KKson said:
Convert said:
I'm with Ian, mine did this. Changing the bushes for Poly fixed it.
Thanks for the replies. Given the type of noise and "feel" of the vibration, rubbing on the prop might be it. I'll get it up on the ramps and have a good pull on the remote to see how saggy the bushes are. Cheers.
In the process of doing my box and I had a bush question. Poly better than rubber I get but why don't we solid mount the remote? Would there be any issues to this?

Wedgefan

75 posts

102 months

Wednesday 29th June 2016
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gmw9666 said:
In the process of doing my box and I had a bush question. Poly better than rubber I get but why don't we solid mount the remote? Would there be any issues to this?
Probably just slightly more noise in the cabin via the gear stick. More positive shift though I would think.

Pete

jon haines

950 posts

245 months

Wednesday 29th June 2016
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I had something similar but also reverse crunched and sometimes would jump out or was a real struggle to engage. It turned out the remote bushes were goosed and since replacing them the gear change through out is better and reverse symptoms have gone.

adam quantrill

11,535 posts

241 months

Wednesday 29th June 2016
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I used a few bits of 15mm copper pipe instead of the bushes - worked a treat. The bushes are for SD1's where you don't want noises coupled into the cabin, we can't hear none of that in our wedges.