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Breva 750 gearbox whine

Printed From: guzziriders.org - moto guzzi forum
Category: Technical
Forum Name: Small Blocks
Forum Description: V35 up to V750 including Breva750, V7, V9 and new V85.
URL: http://www.guzziriders.org/forum_posts.asp?TID=9065
Printed Date: 28 Mar 2024 at 15:57
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: Breva 750 gearbox whine
Posted By: Christy
Subject: Breva 750 gearbox whine
Date Posted: 28 Jul 2018 at 13:53
My recently purchased 2003 Breva has a gearbox whine that is rather annoying. This happens under load in all gears and stops on overrun. I have changed the clutch plate an pressure plate to no avail. I changed the gearbox oil and it was clean. The noise subsided slightly with new oil, but it is still noisy and I get some vibration through the foot rests. I have run it in gear on the stadium and the noise seems to be from the gearbox not the bevel box. The UJ looks fine too. I have heard that some early Brevas had a problem with gears pitting. I am now trying to decide what to do. My first thought is to take the gearbox to Nigel at NBS for a look. I am worried about the cost of this against buying a used box. Nigel might get in there and tell me it had it and I have to buy one anyway. Has anyone encountered this problem or had a gear box rebuild if so how much?





Replies:
Posted By: nab301
Date Posted: 28 Jul 2018 at 14:55
My '04 750 Breva does whine in 4th and  5th but as I'm a Guzzi newbie  I've never got around to asking the question on here but I've been hoping the answer will be  "they all do that it's called character"  Wink  It doesn't vibe though  (well not annoyingly).

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Nigel
Keep smiling , it makes people wonder what you've been up to!
'19 CB125F,

'18 DL250 SUZUKI V STROM,'99 Bmw R1100S, '03Bullet 65 500, '93 MZ301 Saxon fun (offroad)


Posted By: Andyb
Date Posted: 28 Jul 2018 at 15:14
I have had BMW airhead gearboxes whine for many many miles....generally in 4th gear .....but if the problem is a bearing then it needs sorting out as that can get worse suddenly.   A whine from the gears is less serious IMHO.   How you tell what is making the noise I don’t know, but if the noise is there in all gears then it suggests a bearing.  If it was gear teeth it would only happen when those teeth are in use, ie in certain gears.
Andyb


Posted By: Christy
Date Posted: 28 Jul 2018 at 16:51
That makes sense.  I think I will have to bite the bullet and pull it apart again. Thanks for the advice.


Posted By: Christy
Date Posted: 07 Aug 2018 at 10:02
Gearbox removed in  2 and a quarter hours. ( getting good at this now Smile) and dropped off at Nige's for investigation. I hoping it is not pitted gears or I may be looking for a gearbox.Cry


Posted By: iansoady
Date Posted: 07 Aug 2018 at 11:54
My V50 sounds as if I have a corporation tram following me. It's associated with engine speed rather than gearbox speed.

It may be a bearing but in my experience (with other makes of course) bearings don't make that sort of whine but it's more likely to be the input gears. But I'm probably being overoptimistic.....


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Ian
1952 Norton ES2
1986 Honda XBR500
1958-ish Greeves/Triumph in progress


Posted By: Dave P.
Date Posted: 07 Aug 2018 at 12:32
The four-speed box of my V7 Special whines and used to worry me.I've since found out that "They all do that sir" albeit to varying degrees.The five-speed of my 850GT whines a little but I don't worry about it.None of this is of any help to you, of course, sorry, I'm just rambling, NURSE !!!


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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.


Posted By: Christy
Date Posted: 07 Aug 2018 at 13:01
mine was whining in all beats and vibrating through the the pegs. So it needed investigation.


Posted By: rapheal
Date Posted: 07 Aug 2018 at 13:29
Mine has been whining for 15 years
it still works ok so I put up with it


Posted By: red leader one
Date Posted: 07 Aug 2018 at 14:09
I thought we'd agreed not to talk about the wife.


Posted By: Christy
Date Posted: 10 Aug 2018 at 09:14
I have just heard back from NBS. My gearbox is scrap, 3 of the gears are severely pitted. One of them is £400 on its own! Cry
I'm on the hunt for another box now


Posted By: Mr Grumpy
Date Posted: 10 Aug 2018 at 10:11
My sympathies....


Posted By: Roadrunner
Date Posted: 10 Aug 2018 at 15:02
Blooming Eck👎   

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Malc


Posted By: Christy
Date Posted: 10 Aug 2018 at 17:12
Nige has tracked down a good box for me. It will be available later in the month when the bike is broken. It will give me chance to do some renovation work whilst the bike is in bits.


Posted By: Mike H
Date Posted: 10 Aug 2018 at 17:13
Thumbs Up




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"Chicken nuggets don't dance on a Tuesday."



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