Downshift into 3rd grinding - just had recent oil change and worse than before

[auzzam]

Hi everyone,

My Rev3 tubby has been grinding for almost a year now (synchro issue I guess), although its been pretty quiet and under 30mph there was no grind when going back into 3rd.


I've recently had my cambelt replaced and the garage had to drop my gearbox oil. I've no idea what they filled it back up with but since then the 3rd gear downshift grind is a lot louder and no longer can I silently shift below 30mph.


My question is do you think the wrong oil could of been used, therefore the noise is now louder? is it worth me spending £100 of Redline MT90 to see if it masks the problem?


Looking for a short term fix to get me through this year before any more expensive work is required on the car.

Thanks in advance

Auzzam

[SonicSW20]

Possible they've used a sub par oil which won't help - if you didn't specify or provide a specific oil they probably just used what they had in the shop in bulk - what does your invoice say?

There is only so much oil can do to hide it though. Is it just 3rd gear that's the problem?

My NA has also developed a 3rd gear synchro issue on downshifts, so to get round it I'm just doing double clutch gear changes for 4th to 3rd.

[auzzam]

Hey Gazza,

It was my uncles garage so the gearbox oil was changed FOC - I dont have the heart to tell him its grinding more :O but i'm assuming he would of used suitable oil as he owns a rev2 himself.


Yep it only happens in third will try double clutching when the weather a bit better! its been snowing all day

Whats the process?

1) clutch in
2) shift from 4th neutral
3) clutch out
4) blip the throttle
5) clutch back in
6) shift to third


Im just worried about track days to be honest as in normal driving I can just miss third on the way down.

Do you think its worth dropping redline into it?

[SonicSW20]

You would hope so! Might be worth just checking it has enough oil in it as well.

1) clutch in
2) shift from 4th neutral
3) clutch out
4) blip the throttle
5) clutch back in
6) shift to third

Yeah, pretty much - but there is some overlap in between the steps. Best thing to do is to learn it without braking at the same time first, taking your time so you get the sequence down. It's one of those things where you just have to do it to learn it!
Once you've got it spot on every time do it while heel toe braking (or big toe little toe as I do!). I can do a double clutch change just about as quickly as a rev match change now, and to be honest you don't need to perform a downshift super quick anyway as you're slowing down anyway so you want to be as smooth as possible.

[phaeton]

I would mention it to him, let him get it on the ramps to ensure that the gear cables are exactly in the right place

[SonicSW20]

I would mention it to him, let him get it on the ramps to ensure that the gear cables are exactly in the right place

Can gear cables cause this issue with 3rd gear only? Will check mine if that's the case.

[C35Rob]

If it is grinding, and not down to the cables then it may be worth trying one of the redline shockproof gear oils, I've used the lightweight shockproof before on slightly crunchy boxes with success, it's sold as 'not for synchro boxes' but opie oils recommended it and it was totally fine

[auzzam]

Would this redline one do? Gl4 (not sure what that means)

http://www.opieoils.co.uk/pv-1257-red-l ... GwodcxoJAw

[C35Rob]

http://www.opieoils.co.uk/p-1022-red-li ... 5w-90.aspx

http://www.mr2oc.com/61-3sgte-turbo/408 ... ation.html

[auzzam]

Thanks rob, will give this a go and report back

[auzzam]

Changed this over the weekend. The grinding has become a lot quieter (pretty much how it was before, so that's good I guess)


Weirdly though I only used 3.5 bottles, (3.2 litres) before the oil started coming out of the filler cap.

I ordered 5 bottles as I was assuming 4.5 litres, and we did drain it completely till the old oil stopped dripping.

Any thoughts? Mines a rev3 turbo with lsd

[phaeton]

Actual amount it 3.8L I believe, so assuming you can't get all the oil out via the drain, 3.2 isn't bad, did you do it on a flat surface or car ramps as that would change the angle as well & therefore the filling level

[auzzam]

It was up on a garage ramp (2 post hydraulic) so the car was level.

Hmm if its 3.8 maybe its not too bad then.

[steven63]

The only cure for this problem is gearbox removal and repair at a specialist

[jimGTS]

maybe worth adjusting the clutch pedal?

[auzzam]

Thanks guys,