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Information and Technical Guides, Automotive problems etc..
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by Zaphod » Mon May 21, 2012 9:53 am
I'm looking for some advice.
A few weeks ago I started to notice that, when changing into 4th gear with revs above 4k, that the gearbox was graunching. I drove around this by holding off the gear change until the revs were lower, around 3k, or missing 4th and going straight to 5th at the top of the rev range.
However, on Saturday when missing 4th and going to 5th I noticed that going into 5th is graunching too.
Is it that the synchromesh for 4th and 5th are worn, or is it a problem with the clutch maybe?
Any help would be greatly appreciated.
Regards, Tony.
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Zaphod
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by man83g » Mon May 21, 2012 10:05 am
If its only jut started you MIGHT get away with changing the gearbox oil...
Now with added booooooost!!! 1.7bar peak holding 1.6 ish....
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by JayJay » Mon May 21, 2012 11:27 am
The gearboxes in the Prelude I own are notorious for the "5th gear crunch", changing from 4th > 5th. Mine started it, not badly but it had started. I switched the gearbox oil to Amsoil MTF as opposed to the Honda stuff and cured it instantly. Brilliant oil, highly recommend it (but it's expensive!). http://www.opieoils.co.uk/p-60092-amsoi ... -gl-4.aspxDepending on the gearbox you'll most likely need 2 -3 bottles.
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by Roadie » Tue May 22, 2012 8:38 pm
You could always try double declutching with rev-matching. If by doing this it stops it sounds like the synchromesh on the box may be going.
To be honest I would expect more crunching of the selector rings on to the dogs to happen when changing down, this is where the gear box has to spin up to speed to match the Engine Revs and with this the Synchro has to work a hell of a-lot harder than when changing up as the gear box spins down on it's own accord and usually closely matches the Engine Revs when engaging. By the way If you miss out a gear then the Syncro has to do even more work. (Sorry if you already know this).
If double declutching with rev-matching doesn't work then possibly the clutch is dragging.
I'd say changing the oil if worth a go as it's a darn site cheaper than dismantling a gearbox!
Good luck!
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by JayJay » Tue May 22, 2012 9:48 pm
Roadie wrote:By the way If you miss out a gear then the Syncro has to do even more work. (Sorry if you already know this).
Nice, I wasn't aware of this I do know that if you have a shortshifter fitted, if the link cable is moved from it's original position (i.e. change the cable travel, in this case shortening, true short shifters shorter the gearstick length and allow you to adjust the throw) by too much the synchros need to do more work causing undue wear on the box. Thought that was interesting. Personally I double clutch every time I gear down except when I gear down to slow down! After a while you can rev match perfectly and it makes driving that much smoother. Does help to have a very light flywheel though...
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by Zaphod » Wed May 23, 2012 11:24 am
Thanks for your help guys. I'm currently getting quotes for a recond box versus getting it removed and recond here. I'm not sure that oil changing will do it as the car is always serviced by the dealer on time and the oil level is OK.
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by Nitro » Wed May 23, 2012 7:27 pm
Zaphod wrote:Thanks for your help guys. I'm currently getting quotes for a recond box versus getting it removed and recond here. I'm not sure that oil changing will do it as the car is always serviced by the dealer on time and the oil level is OK.
Have they definitely changed the gearbox oil?, most garages don't until you ask, most service books don't suggest a gearbox oil change until 75,000+ miles, sometimes they're classed as "life long" and never get changed!
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by man83g » Wed May 23, 2012 7:51 pm
Zaphod wrote:Thanks for your help guys. I'm currently getting quotes for a recond box versus getting it removed and recond here. I'm not sure that oil changing will do it as the car is always serviced by the dealer on time and the oil level is OK.
Changing the oil is going to cost a max of £50. Including the oil and labour. I would deffo be trying that first. And even if it doesn't completely fix the problem, it SHOULD increase the life of the gears while you do source a replacement. I would also suggest trying HCS transmissions in balthane. Heard he's pretty good....
Now with added booooooost!!! 1.7bar peak holding 1.6 ish....
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by Zaphod » Thu May 24, 2012 9:11 am
man83g wrote:Zaphod wrote:Thanks for your help guys. I'm currently getting quotes for a recond box versus getting it removed and recond here. I'm not sure that oil changing will do it as the car is always serviced by the dealer on time and the oil level is OK.
Changing the oil is going to cost a max of £50. Including the oil and labour. I would deffo be trying that first. And even if it doesn't completely fix the problem, it SHOULD increase the life of the gears while you do source a replacement. I would also suggest trying HCS transmissions in balthane. Heard he's pretty good....
Spoke with http://www.apiimpreza.com yesterday and was quoted for a fully recond unit that comes with a 1 year guarantee for 850 + VAT. I'll try HCS Transmissions - thanks for the heads-up.
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