GSXR750M Final Drive Bearing

[GIXERD]

Hi Guys

First post but hoping for some guru guidance....I have a 750M which I have had for several years (all sorts of reasons why it doesnt do many miles, largely summed up as 'life').  Having fitted new disks/pads to it at the weekend (despite the minimal run out on the originals it got scary when you went straight from throttle to brake...) I took it out for a run which, about 40 miles in as I exited one of the picturesque villages we thrive on round here it felt wrong....Immediately lifted the clutch, coasted into a farmers track and went round it thinking 'what did I fail to torque up...' Couldn't see a problem so pulled away but have noises from the underside that say otherwise - going from first to second  this developed into a significant whine.  Pull up again and notice that I now have much more chain slack than before...

Hands up - I know the most likely cause of a final drive bearing is an overtightened chain - it got picked up that it was too loose as an advisory on its last MOT when it was last done (2 years ago....)  so this time I double checked - I checked the chain in umpteen places and seemed to have sufficient slack - in retrospect, I think it was too tight (I don't generally use the clutch on an upchange and it just felt a little 'tight') and yes, I should have known better but even rapidly approaching 50 the ignorance of my youth fails to desert me......

So, I am pretty sure its munched the final drive bearing - from what I can see, at some point during the waterjackets life they changed it so that you could remove a plate and pull the bearing.  The M however is going to require the motor out and the cases split to replace it.  I will roll into the stupid questions now:

- I am assuming that  I can drop the motor, remove the sump and split the cases, change the bearing (and in the immortal words of those workshop manuals...) 'Assembly is generally the reverse of disassembly' 

- What else needs to come off the motor for me to split the cases?

- As far as I can tell there is no gasket between the two halves of the cases - basically uses what used to be called instant gasket and now seems to be called a variety of things - Is this right?

- Which other gaskets will I require - exhaust gaskets are obvious, same for the clutch, as is the other side gasket (ignition pick ups under there?) but are there any others?

- Any bolts that I am removing that need to be replaced?

-  I haven't stripped an engine in a number of years - my first engine was with my late father, stripped and rebuilt a 250 superdream (from the best bits of 2 engines and 30K later it was still going) a GS550EZ (with the 650 wiseco kit) and a Z650 but all of these were complete strips and rebuilds so you need everything (which is more straightforward but when I do rebuild the M - or have it rebuilt - I would prefer to go silly and have everything done - the situation with the M is that whilst in the next couple of years I may want to refresh it (this is a bike I want to keep) at the moment I just want to know what I can get away with.  The problem with the Haynes manual is that it assumes that to access the bottom end you are pulling down the whole engine - whilst I am prepared to do that, I would prefer to understand if I can get away with splitting the cases from below and dropping the drive shaft, the pulling some favours with the bearing replacement (I assume a bearing puller will get the old one off no problem, what about refitting?)

I have looked and whilst I can see references elsewhere to this bearing failing, I cant find much regarding the remedial - happy to take some pics and share them on here for anyone else who finds themselves in the situation but am figuring with the level of experience evident in these forums I am far from the first person to be looking at this.....

I hope someone with experience on the slingshot engines can help....

Cheers.

D.

[Swiss Toni]

Fuck me! Monumental! You can strip the bottom end of the motor, leaving the top end intact. Gaskets you'll need to replace are the o rings  you'll come across when doing it. Also the sump. You will also need to remove the clutch, the oil pump gears behind it, and the plates that span the crankcase halves. They're tight!  You'll need an impact! Take ALL the case bolts out, top and bottom, and before you try parting the cases, check again they're ALL out! DO NOT use that instant gasket shit on re-assembly! Use Hylomar or preferably Wellseal on the case halves. Lastly. Bit of advice. Try introducing yourself first instead of jumping straight in with your size nines 

Edited August 7, 2017 by Swiss Toni

[Portaz13]

Sounds like a decent job,  any pics of the old girl? 

[GIXERD]

Cheers Toni - At least I now know that I can get to it from the bottom end of the motor...... Apologies for the lack of an introduction (etiquette failures a speciality...) tbh I was so pre-occupied with the issue in hand it never even crossed my mind....At work at the moment but will try and provide a slightly more appropriate introduction....... 

[no class]

Sounds expensive ..... especially when using new Suzy parts. Chances are that output shaft is shagged and depending on how bad the bearing was , if that shaft was out of allignment due to that bad bearing ... and spun for any amount of time... it probably aided in a few chipped tranny teeth ....

[Rene EFE]

8 hours ago, GIXERD said:

(etiquette failures a speciality...)

You'll fit right in 

[GIXERD]

 

OK – I’ll start with an apology, gotta be honest, once my mind focuses on one thing (in this case a munched final drive bearing) it struggles to cope with much else.  Consequently I leapt into a forum where I’d never communicated with anyone (although I have viewed various posts over the past few years) only interested in MY PROBLEM!

Life history would be dull (so I will give it to you anyway….) the M is much more interesting  Actually I won’t, but if anyone is that interested than I am sure that at some point we can cross paths and if they serve Guinness I will tell you more than you could ever be interested in.

Short version – licence for 30 years, despatched in central London for the first 4/5 years (or according to my now wife partying, sleeping and occasionally rolling in for a job…).  Used various bikes for commuting to various other roles (initially London, then Sittingbourne – I grew up in Kent…well. I say grew up…) then career progression, employer expectation etc meant that I didn’t do as much commuting.  Got into some race school/track based stuff and figured this was the way forward so swore off road bikes (I am not the most disciplined of individuals) – then had a sprog, moved to North Oxfordshire for a job, more money for me, bigger mortgage but wife no longer working in London.  Managed a couple of years before the lack of bike time had me clucking like a crazy person.  Didn’t want the latest missile (love them on the track but previously mentioned lack of discipline makes them a liability on the road) and had a thing for a 750J that I used to ride past every day, probably around 93/94.  Started out looking for one of those and then the M came up. 

I’ve only used it sporadically – work means I am out the country for 8 weeks plus per year and all those grown up responsibility things kept getting in the way (I realise most will see this as no excuse…).  I have to say it is everything I want it to be – still dangerously quick from a licence perspective (and losing mine would be ‘career limiting’) but you have to focus on what its doing 100% of the time – its not an easy bike to ride fast but when you do and it strings together, for me it is soooo much more satisfying than a waterjacketed rocket ship. For sure the pain in the wrists, the numbness from the vibration – some people wouldn’t like that but I do….

For No Class – yeah, it could be expensive but that’s the joy of motor vehicles.  When I called recovery on Sunday I was clear it needed recovering and at the good end it had munched the final drive bearing, at the slightly worse end (!) it had destroyed the box.  One of the advantages of getting older I find is I do look at it now and think it is what it is. If I have trashed the box (or the cases if the bearing spun) then I have a different job in front of me.  I will get it apart and see how bad the situation is. I cant stress enough – this M will never be for sale. Its MINE.

 

Guessing that was a much longer introductory post than required but you should meet me IRL (hind legs and donkeys are appropriate references)…..Hope that explains my position. Pics with a couple of comments to follow....

[Fazz711]

Hi bud. Welcome to OSS 

[GIXERD]

OK, couple of recent pics - far from concourse but that isn't the point. First one after she got her new boots a fortnight ago. Second one is Sunday around the time she decided to go to lunch on a bearing.....Age related stuff, few scuffs (but no real dinks) lacquer on the tank decals has gone nasty (common I understand) and  the current pipe (original) has had a little mod to keep the baffle in place...).  Needs some tlc for some of the cosmetic stuff but still goes like stink....(ignoring the immediate issue.....dont want to use past tense...)

[Antman]

Hi and welcome from Oz

Tidy looking bike mate, shame about the bearing best of luck with the repair.

Ant

[canamant]

You got off light with that bust gearbox bearing.  Mine went at the top of Bray Hill during qualification fo rthe 2016 Manx GP/Classic TT just after I'd pulled out of the pitlane.  It's a cheap fix really - just a second hand gearbox.  My box was OK but seeing as the beating would have been awkwrd to get off the shaft and I had a spare one available I just replaced the complete shaft.  Your sump gasket should be about a tenner, Clutch gasket similar, and ign cover about a fiver.  I make my own so it was cost free for me.  One tip.  When replacing the alternator, make sure the gear engages cleanly with the drive gear on the bak of the clutch basket otherwise it will break and there will be tears 

When you split the cases there are 2 hidden fastenersone on each side of the gearbox area.  They are M6 10mm nuts,  There are also 2 sneaky allen head bolts hidden by the oul filter.  To get one of the outer main studs out you will also need to remobe the main oil gallery blanking plug (allen driver).  Good luck.

 

[GIXERD]

Cheers canamant.  Been away for the last 10 days so hadnt had a chance to update.  Thanks for the heads up on the hidden fasteners.  Top of Bray isnt somewhere you want anything to break, least of all any bearings related to drive!! I have made a start...front sprocket nut was a little on the tight side so (after much cursing and swearing with a large breaker bar) I treated myself to a Clarke impact wrench, a mains one as I havent got any space for a compressor and although one of the top end cordless may have been able to hack it, as I have access to power this seemed like the most cost effective solution - took all of about 4 seconds to shake it loose.  Oil drained,  cooler off, carbs out, all the electrics disconnected,  clutch is out and its about ready to drop the motor but I have hit a bit of a problem.  Knew the pipes hadnt been off in a long while and the headers are quite corroded (I have a spare system so this isnt an issue).  Expected the header bolts to potentially be a problem but they had all been copper slipped so it was relatively straightforward.  The headers for 1 & 4 were relatively easy to get some movement on and get the collets out but 2 & 3 wont move at all.  Tried to clean as much of the surface rust around the collet/header as possible and have given it a number of blasts with penetrating oil and tried to give it some gentle persuasion with a rubber mallet - so far no joy. Unfortunately not going to have a chance to do anything with it this weekend so I'll give it another blast with the penetrating oil this evening and see if I can give them a bit of a worry and free up any movement.  If anyone has encountered anything similar I'd be happy to hear your solutions....

[Damienga15de]

Usually the use of a larger hammer does the trick. If that fails keep increasing hammer size. If that fails you have a problem. 

[fatblokeonbandit]

Make sure you get the "hidden" crankcase blots, and use the jacking points provided by Mr Suzuki to split the cases not a hammer and chisel