Transmission slipping out of 6th

[rhill]

Transmission on the 750 started slipping out of 6th the last two sessions at Summit.

Rode the rest of the 7th session only hitting 5th gear to avoid the issue.

About to start tearing into the thing and figured I'd throw this up to see if anyone has any tips or recomendations. Never dove this far into an engine/transmission before.

 

[wmhjr]

http://forums.13x.com/index.php?threads/2008-suzuki-gsxr-750-race-ready.333074/

 

[borislav]

Get yourself a service manual, make sure to pay attention if the certain bolt is different than others, where does it go...
Put bolts from one are ( for example oil pan) in to the ziplock bag and mark the bag, you WILL need good ACCURATE torque wrench, cases are aluminium and you don't want to strip or crack something.
Take your time!!!
I have 06 750 servuce manual on disc and since I don't have my 06 750 anymore you can have the disc fo $29.99 BUT WAIT THERE IS MORE...


















kidding you pay for shipping and it's yours, or go with the above post!

 

[rhill]

http://forums.13x.com/index.php?threads/2008-suzuki-gsxr-750-race-ready.333074/

I'm contemplating getting rid of the 600/some spares and looking for something newer over the winter, but I'm keeping this 750 as my track day bike. If I do get a newer bike, it would be either a 600 or 1k to have more racing options.

Get yourself a service manual, make sure to pay attention if the certain bolt is different than others, where does it go...
Put bolts from one are ( for example oil pan) in to the ziplock bag and mark the bag, you WILL need good ACCURATE torque wrench, cases are aluminium and you don't want to strip or crack something.
Take your time!!!
I have 06 750 servuce manual on disc and since I don't have my 06 750 anymore you can have the disc fo $29.99 BUT WAIT THERE IS MORE...




kidding you pay for shipping and it's yours, or go with the above post!

Just printed a bunch of stuff from the service manual last night while trying to determine the potential causes.....thanks for the offer! Agree that staying organized with the teardown is key to a smooth rebuild.

After a little research,(without laying a hand on the bike yet) I'm thinking I'll find a worn/damaged No. 3 shift fork, which didn't fully engage the shift dogs between 6th and the 3rd/4th combo gear.....causing them to wear till they can no longer hold under load. The shift drum could be worn as well, or damaged from popping out of gear. Same goes with the fork.

The thing that concerns me; I've never inspected any transmission components before. So, unless it is pretty obvious, I won't have a clue if a shift fork is tweaked or the drum is worn. I've found a few complete 600 transmissions for pretty cheap....90% cross over, so I've been thinking of picking one up for comparison purposes and maybe use a fork or the drum. Unfortunately the gears/dogs I'll need don't match up 600-750.

Ron Ayers is the bomb...
http://www.ronayers.com/oemparts/a/suz/50d3c74ff870021958f27ae1/gear-shifting
http://www.ronayers.com/oemparts/a/suz/50d3c74ff870021958f27ae0/transmission

 

[Dave561]

Use smaller rear sprocket and only 5 gears. Cheaper

 

[rhill]

Use smaller rear sprocket and only 5 gears. Cheaper

Crossed my mind....ran my personal best at Main in the 7th session with only 5 gears. The 750 could be a Shenny/NYST bike and nothing would have to change

 

[Mike:p]

I have an o6 750 that I'm thinking about parting out. Let me know if you are interested. It might be easier replace the transmission then to repair it.

 

[rhill]

I have an o6 750 that I'm thinking about parting out. Let me know if you are interested. It might be easier replace the transmission then to repair it.

Thanks, but the 06+ had a significant change to the transmission, doubt much carries over. Why are you considering parting it out?



I was considering taking photos as the thing comes apart to help anyone going through the same trouble, but have found some pretty good walkthroughs/photos. Might still snap a few to help when reassembling. Here are a couple of the better posts that I saw:
http://www.pistonheads.com/gassing/topic.asp?h=0&f=74&t=704477&i=100
http://929and954.blogspot.com/2015/08/how-to-rebuild-motorcycle-transmission.html

 

[dave675]

Sounds like it's time to get an SV

 

[rhill]

Sounds like it's time to get an SV

Funny you mention that, was consider trading my 600 for an SV if I ever get the thing back together.



More fun with the current project, damn case bolt stripped, so the engine is loaded up to get a nut welded on to get the bolt out and this thing apart.

Everything visible with the oil pan and clutch removed (shift star, linkage, most of the shift drum) look like new with minimal wear paths.

Doubt I'll be ready for NYST next weekend unless I slum it on the 600.

 

[rhill]

Bolt is out and parts are scheduled to arrive tomorrow. Could make NYST this weekend if I pushed it, but I'm going to hold off and use the weekend to take my time and get some other stuff done with the bike.

 

[rhill]

Ugly....but I ordered the right parts before splitting the case. Shift fork for the 3/4 gear and the 3/4 & 6th gears on the output shaft are garbage. Spinning the gears by hand, unless the 3/4 & 6 dogs were completely meshed, they would force themselves apart.....since the fork was chewed up, it wasn't moving the gear completely over.

shift dog for 3/4 gear on output shaft

3/4 gear on top, 6th gear on the bottom....photos didn't turn out great, but you can still make out the wear on the dogs.

 

[rhill]

Ugly....but I ordered the right parts before splitting the case. Shift fork for the 3/4 gear and the 3/4 & 6th gears on the output shaft are garbage. Spinning the gears by hand, unless the 3/4 & 6 dogs were completely meshed, they would force themselves apart.....since the fork was chewed up, it wasn't moving the gear completely over.

shift dog for 3/4 gear on output shaft

3/4 gear on top, 6th gear on the bottom....photos didn't turn out great, but you can still make out the wear on the dogs.

broken links originally, corrected in the reply

 

[rhill]

Question...should the oil hole in the shaft line up with the hole through the gear to lubricate the shift fork?

Photo shows as it was disassembled....the shift fork and gear both show heavy wear in this area, but I don't know if that is a result of the hole misalignment.

There was no mention of the hole alignment in the manual, only talking about aligning the bushing oil holes.

The thing that makes me think it shouldn't be aligned, there are two holes in the gear. There is only one hole in the bushings(which should be aligned) and they are smaller than the holes in the gear/fork interface.


no

 

[rhill]

highlighted the holes to make it a little easier to understand

the 3/4 gear has 2 holes, 180 degrees from each other....shaft only has the one hole visible in the photo

Find it weird that it was 2 splines over when disassembled, seems like it should be at a 90 or aligned.

 

[rhill]

After checking the other shift fork paths, the gear holes are all a couple splines off the shaft oil ports...although they are not all equally spaced. So it is going back together the way it came apart.

 

[rhill]

Guess I should add some closure.....she is back together and 5 issue free track days in since the repair.

 

[vinny337]

Nice!!