Masher's Transmission

[Mashermoto]

I think most of you know the project bike, but just in case, It's a 1978 XS1100E Standard. I ran into transmission trouble today during my first ride since the rebuild. I'll explain the symptoms in detail later.



All the transmission parts looked clean and nothing showing excessive wear during the engine rebuild.



The only transmission modifications I've made are to back cut the gear dogs and slots, and move the transmission spacer per Bob Jones technical fix.

WHAT HAPPENED
I got the engine to start for the first time today. I drove it around the neighborhood for about five miles and everything seemed to perform well. No odd noises, and the transmission shifted smoothly.

Later the same day I took it on a 50 mile drive. About half was city and rural roads at speeds not exceeding 55 mph. The last half of the trip was on I-40 at speeds not exceeding 65 mph. At this point, still no problems. Shifting was precise and no unusual noises.

When I got on the interstate exit ramp I noticed a whining noise during deceleration that sounded like it was from the mid transfer case. It wasn't loud enough to bother me that much.

My final stop was about a half mile away through city streets and residential streets. It seemed to get louder and still only made noise during deceleration. When I got to my destination I shut the engine off for about a half hour.

On my final drive home things got worse. About one block away and in a residential street, I rolled off the throttle for a left hand turn and the whining was now loud. Acceleration would make it quit. I was in second gear and shifted into third. It felt like it shifted in place ok, but I got what felt like some gear jumping. I shifted into fourth and it cleared up, but the whining continued antime I decelerated. A couple of blocks later second gear showed signs of what third gear was doing. I rode the bike home very slowly and avoided deceleration. It's now parked in the garage.

Later on I'll start pulling off the shifter case, oil pan and clutch case to see if I can detect anything. In the mean time, does this sound like anyone elses experience

Any suggestions where to look first

I do have a spare engine on the ground, so at least I should have a replacement if needed

[TopCatGr58]

Hey Masher,

It sure sounds more like the middle drive, not the tranny!! You did a good job of undercutting those 5 gear dogs, and they will not cause a whining noise! So...before getting into the engine, check your middle drive for oil, you may have a small leak that you were not aware of , and ran low or out of oil!! Folks have found this, and were able to put oil back in it and did not suffer any real damage to the middle gear. Others have ridden to the point of locking up the middle drive!
T.C.

[Mashermoto]

TopCat,

OK, I'll start there. I also have a spare middle gear if needed.

Thanks.

[Larrym]

10w-40????

Masher,

I'm onboard with TC's "suspect the middle drive".

In particular I would suggest that just examining the oil level might not be enough. The middle gear drive requires Hypoid Gear Lube of the right level and viscosity. (Your Temperature determines the specific weight of the lube..) Unless you personally were the one that measured and added the right lube then you're trusting the person that did.

If you do decide to drain/refill the middle drive then I'd suggest using a very clean catch pan for the oil. Given your description of "gear jumping" it would be prudent to examine the drained "fluid" for metal flakes, bits, or powder. Couldn't hurt to flush the system further by adding fresh lube while the drain is open to wash anything stubborn out the hole. Anything other than fluid in the drain pan is not a good sign...

Hope the post-check/service run goes well.

[byynow]

Don't overlook the final drive. I had very similar symtoms on a Vmax and it was a broken pinion shaft. It had snapped at the base of the threads for the pinion nut but the drive shaft coupler held it together and I made it home. It snapped on a down shift.

Ken

[Mashermoto]

I should know more tomorrow. I hope it is the middle transfer, because that will be much less evasive than a transmission diagnosis.

Larry,

When I rebuilt the engine I filled the middle transfer with oil. First check however will be to see if it is still there. I have read about someone who had a bad seal on the drive pinion shaft and oil leaked into the engine oil. I installed a new seal, but that doesn’t mean it was good.

I also read the middle transfer tech post and downloaded Catatonic Bug's Yamaha Shaft Drive Service Manual. Between the two references I should be able to spot any trouble.

Byynow,

If it's not the middle transfer, then I would suspect the transmission next. The sound was right around my left foot peg. However, the shaft drive service manual does cover the final drive if needed.

[red bandit]

Don't know if you did the 750 final drive mod. If the nut on the pinion shaft comes loose it will make noise/whin on deceleration and clear up on exceleration, light/mild or heavy. This doesn't explain the gear jumping unless something is broken inside it.

[trbig]

Pull off the clutch cover and see if the bolt that holds the gear shaft has backed out against the clutch basket.


Tod

[Mashermoto]

TopCat gets the winner winner chicken dinner this time The Middle transfer drive was the problem.

I got lucky twice with this trouble issue. The first is that I didn't lock the middle drive up yesterday and the second that it only required installing three bolts for the fix

What happened is that of the two middle drives I had to choose from, I apparently used the one that the PO had removed the three large allen head bolts that hold the driven shaft in place and I hadn't noticed they were missing. The driven shaft mounting plate had backed out about 3/8th inch

I drained the gear oil and didn't see anything offensive, so I located the bolts in my parts bike pile and reinstalled them. It was tight manuvering around the rubber boot, but I got them in without having to remove the middle drive case.

So I took a test drive around the neighborhood and all was well. The middle case was quiet and the transmission shifted smoothly. After fixing a brake light problem and a left turn signal problem, I took a 40 mile drive and everything is still good to go.

Thanks once again for the help

[joceiphus]

Good for you! I'm glad you got it going.

[clcorbin]

You are a lucky man! I'm glad your fix was so simple! Now you can really start to enjoy that beast. It's all the more sweat because of all the work YOU put into it.