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1100 RT transmission noise when under slight load


SmokinRZ

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Hello and first post.

 

I just purchased a 99 r1100GS with a 99 RT transmission. The PO replaced the original at 60K miles and now the bike has 80K. The transmission has a rattle or clatter sound at slight loads. Under load of full off the transmission is quiet. It reminds me of my old dirt bike days when the chain would slap the chain slider going down the road with partial throttle.

 

I changed the transmission oil and final drive oil and they were both dirty with lots of fuzz on the drain plug but no chunks of metalic particles in the oil. The oil was royal purple with almost 20K. Replaced with Valvoline 75w80 with no change.

 

The clutch was replaced with the transmission seibenrock) and the PO stated it did this from day one after the change and has never gotten any worse. I rode a 98 for comparison and it shifted a lot clunkier but no driveline lash or noise to speak of. It makes a lighter clatter with the clutch is disengaged. I'm thinking input shaft bearing but I'm relatively new to BMW's. I know diagnosing noises over the internet is hard but maybe someone has has this issue. Suggestions?

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Have you completed a valve adjustment check and throttle body sync? Noise at idle or slight load could be throttle body rattle due to worn shaft or poor sync. Do a good sync then check the noise.

 

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Evening SmokinRZ

 

That is going to be difficult diagnosis without having the bike to evaluate. Even then internal transmission noises are very difficult to find & root cause without disassembly.

 

Can you give us more information on the rattle? Such as does it only happen on a hot bike or after ridden for while or do you also get it on a cold bike?

 

BMW boxer transmission rattle at idle (in neutral) is pretty normal but that rattle usually goes away under load.

 

Is the engine running smoothly at low-load low-speed? An engine running raggedly at low speeds can cause a trans rattle.

 

Otherwise you are in a bad spot as you don't have a history on the noise yourself. If you had the bike from new & the noise keeps getting worse then you definitely have something to worry about.

 

On the other hand if it has been making the same rattle for many miles & isn't getting worse then probably not a big deal.

 

 

 

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Yes, I know internet diagnoses is not easy. The noise happens when hot or cold, makes no difference. The oil change might have helped some. The bike runs and idles great. I can feel it in the footpegs and the driveline lash feels excessive compared to the 98 I rode. It is definitely not normal. I have the original transmission so I might open it up and familiarize myself with it before I dive into the one on the bike. Thanks for the replies.

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Yes, I know internet diagnoses is not easy. The noise happens when hot or cold, makes no difference. The oil change might have helped some. The bike runs and idles great. I can feel it in the footpegs and the driveline lash feels excessive compared to the 98 I rode. It is definitely not normal. I have the original transmission so I might open it up and familiarize myself with it before I dive into the one on the bike.

 

Morning SmokinRZ

 

 

When it comes to motorcycle transmission noises you really want to do your best to identify the noise location & if possible ALL the conditions that relate to it before removing & tearing into the transmission.

 

Nothing worse that tearing into a transmission only to find some small problems but no smoking gun. Those are the ones that get removed 3 times & the problem still isn't identified.

 

One approach is to just ride it until the noise gets worse (or bad enough to be sure that it has issues) then use that extra time to find a good used trans to have on hand to swap in in a day or two turnaround. Then you have all the time that you need to dissect the old gear box & find it's problems.

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Yes, I can feel it in the footpegs and the driveline lash feels excessive compared to the 98 I rode. It is definitely not normal.

 

If when on the centerstand you rotate the rear tire in 1st gear to check the backlash in the drive train and you find that you have excessive play, and by that I mean the tire rotates a few inches before stopping or meeting resistance, then I suspect you have a failing drive shaft u- joint. Most likely the one at the tranny output shaft

In fact,if you can start your bike while on the centerstand and put the bike in gear and let it run at idle speed, you may be able to hear the worn u-joint rattling in the swingarm. Ask me how I know this.....

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Also, if you only remove the rear drive, you have acess to the drive shaft.....if it's shot then you will know when you grab the end of it and attempt to turn it, you'll feel the play in it. If it turns out to be OK then you gave yourself a great excuse to lube the splines on the driveshaft and grease the swing arm bearings.

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Yes, I can feel it in the footpegs and the driveline lash feels excessive compared to the 98 I rode. It is definitely not normal.

 

If when on the centerstand you rotate the rear tire in 1st gear to check the backlash in the drive train and you find that you have excessive play, and by that I mean the tire rotates a few inches before stopping or meeting resistance, then I suspect you have a failing drive shaft u- joint. Most likely the one at the tranny output shaft

In fact,if you can start your bike while on the centerstand and put the bike in gear and let it run at idle speed, you may be able to hear the worn u-joint rattling in the swingarm. Ask me how I know this.....

 

Hi snookers,

I Don't want to be argumentative, but your suggestions aren't ideal.

You will always find a lot of backlash in the drive, It is normal to have backlash there. The only useful way would be to pop the FD off and using a torch (flashlight), inspect them visually.

Running a bike in gear on the centre stand will always display horrible noises due to the fact that there is no load for the engine to work against. All of us would be in trouble if that were the case.

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dirtrider. .... No arguments needed. All I am saying is that if your u joint off the tranny is pooched then depending on what stage of disentigration is is at, you should be able to hear it through the swing arm . An inspection with the final drive removed is obviously the best way to be sure.

Hope you find the problem.

Edited by snookers
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Yes, I know internet diagnoses is not easy. The noise happens when hot or cold, makes no difference. The oil change might have helped some. The bike runs and idles great. I can feel it in the footpegs and the driveline lash feels excessive compared to the 98 I rode. It is definitely not normal. I have the original transmission so I might open it up and familiarize myself with it before I dive into the one on the bike. Thanks for the replies.

 

I'm thinking input shaft bearing but I'm relatively new to BMW's. I know diagnosing noises over the internet is hard but maybe someone has this issue.

 

Afternoon SmokinRZ

 

Do a little more evaluation on your noise-- does it change with engine RPM's (that would probably mean input side like input shaft bearings etc)

 

Or does it change with road speed ( that would more point to output side like output shaft, drive shaft, etc.

 

If you get a frequency or intensity change at the same road speed but different gears then that is more towards intermediate shaft or in the gear sets as long as you can eliminate the engine/input from this)

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Good call Snookers on the driveshaft. I will try that this weekend to see if there is excessive lash, I have access to the 98 to compare it to. It would be an easy fix. However, I believe the PO stated that the noise started after the transmission change but I might try to contact him to confirm. I thought about the U joint earlier but I wouldn't think a U joint would last 20K miles. I'm not sure how much credibility to give a guy that was trying to sell a motorcycle with a noisy transmission

 

Dirtrider, the noise occurs only when there is no load on the transmission. I know my heading says "slight load" but now that I think about it, It occurs in that slight window between on and off throttle. I believe it does it in every gear but most noticeable the higher the gears (4th and 5th). If I was just on or off the throttle I would never notice it, but my OCD knows it's there :)

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Hey, SmokinRZ, CONGRATS on the RT!!

 

You will quickly learn that Mr. DirtRider is one of the most prolific, knowledgeable, and helpful members on here.

 

One tiny suggestion to add to this: you might try a stethoscope (or a wood dowel, long screwdriver, even a broomstick, etc.) to listen to most anything mechanical to isolate a noise. I've use all the above to find which lifter on a car is clicking, which end of an alternator has the bad bearing, bad water pumps, bad idler pulley bearings, etc. Unaided listening can be very deceptive with all the other parts reflecting, amplifying and creating noises, but its amazing how well this works.

 

Press one end of the dowel/screwdriver handle firmly on the little flap of skin just in front of your ear canal and put the other end as close to the suspect bearing as you can get. Of course, it has to be running and making the noise while you do this.

 

What if you put the bike on the centerstand, running and in gear, then apply the rear brake to provide a "light load" and create this noise while you listen all around with a long dowel for the offending parts??

 

A 36" long x 1/2" or 3/8" dia wood dowel works well, just round off one end to make it comfortable for your ear. An 18" or 24" screwdriver with a rounded handle works really well. Only thing it doesn't work on is a spinning u-joint, but you can definitely tell which end of the drive shaft has the bad u-joint. Put it on your valve cover and listen to the lifters/rockers.

 

Good Luck!!

 

 

 

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Thanks for the tip Lowndes, I have a stethoscope from when I was diagnosing a bad fuel injector on my truck. And nice looking S! Reminds me of my riding buddy's black S that I rode out west with a few times. Never seen a bike garner so much attention from the general public. Of course the two bros pipes needed repacking badly :)

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Well I rode it again today and made a big discovery. The noise occurs when I pull in the clutch and increases rhythm with speed which explains why I could only detect it in 4th and 5th. I compared the backlash of the back wheel on the stand with the 98 and they there was no measurable difference. I believe my issue is with the driveshaft. I was under the impression that these failed suddenly. I'm hopping it is the driveshaft - time to order a 30MM hex socket and tear into it.

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Well I rode it again today and made a big discovery. The noise occurs when I pull in the clutch and increases rhythm with speed which explains why I could only detect it in 4th and 5th. I compared the backlash of the back wheel on the stand with the 98 and they there was no measurable difference. I believe my issue is with the driveshaft. I was under the impression that these failed suddenly. I'm hopping it is the driveshaft - time to order a 30MM hex socket and tear into it.

 

What brand of tyres do have fitted?

I once had the final drive stripped and checked (under warranty) by a dealer who found nothing wrong, but there was a road-speed related vibration and noise. Turned out to be a worn, slightly cupped, rear tyre...

 

Andy

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Metzler Tourance - it is a metallic thrashing sound.

 

Check for cupping - mine sounded like a shot bearing

 

Andy

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  • 7 months later...

Ok, I have my transmission out to tackle this light load transmission rattle. The input shaft is smooth as silk, so is the tail shaft. The PO said it made this noise after he replaced the transmission 20K miles ago and not to worry. I have a low mileage transmission located from a owner with a front end collision RT, so that was my plan but now I'm confused that the input shaft is so smooth. Rattle come on between on and off throttle and most noticeable in the upper gears, like a rod knock except it goes away with the clutch in. Going back out to take off the throwout bearing. Drive shaft U joint also smooth as can be. PO put in Seibenrock clutch and Sachs pressure plates from Beemer Boneyard.

 

I'm sure it is the transmission, maybe intermediate shaft.

 

Edited by SmokinRZ
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Afternoon SmokinRZ

 

Now that you have it out & apart you are committed, so you either need to identify SOMETHING major or you will have that trans out again in the future.

 

Your smooth running shafts don't surprise me as your rattle didn't sound bearing related but more gear slop related, or shaft end play related, or clutch pack related, or possible drive shaft related.

 

So how is the end play on all 3 trans shafts???

 

Also don't rule out that non-OEM clutch disk or plate as being part of or all of the rattle.

 

How do the trans input splines look?

 

How much radial play in the clutch disk to the trans input shaft splines?

 

If it were me & I removed the trans before fully identifying the noise source I would have the entire clutch out & be measuring comparing all the parts, be looking at the tightness of the clutch spring, be checking the trans shaft end play, be checking the engine rear main bearing for excess movement, be looking at the clutch release bearing (closely), be looking for a bent clutch push rod, be looking at ANYTHING that could rattle under engine firing pulses.

 

Look closely at the clutch pack parts for signs of rubbing/contacting producing that rattle.

 

Something is moving or rotating producing that rattle so start with the engine rear main bearing & work your way to the rear measuring & meshing EVERY part until you find the area or parts that are out of spec producing that rattle.

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The end play on the output shaft is nil, the input shaft makes a little thud if pull hard but I don't think it is excessive.

 

The splines look great and the clutch hub looks great. I pulled and tugged on the clutch pack and rotated the motor with it by hand. No leaks I can see on the main seal.

 

The drive shaft is nice and smooth. Didn't make noise in neutral coasting. Only when in gear during the transition between load (accelerating) and reverse load (engine braking). In all gears but more noticeable in the higher gears.

 

Push rod is fine but I didn't get a chance to look at the release bearing.

 

I pulled the trigger on the used transmission. I just put a OEM clutch in my 98 GS, so I started this project while all the tools were out and the process fresh in my mind. Worse case I'm back in there again. At least everything will be clean which eats up most of my time working on things.

 

Thanks for your time DR, I visit the oil head section every day since getting my first BMW 18 months ago. Been wrenching and riding Japanese bikes for over 40 years, but the BMW is a different experience.

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Morning SmokinRZ

 

The end play on the output shaft is nil, the input shaft makes a little thud if pull hard but I don't think it is excessive.-- You can't tell much about the intermediate shaft without opening up the trans so that shaft is still suspect. Also remember that input shaft has a spring loaded coupling drive gear that could be loose on the shaft.

 

The splines look great and the clutch hub looks great. I pulled and tugged on the clutch pack and rotated the motor with it by hand. No leaks I can see on the main seal. -- You can't always tell by looking. Remember that BMW offered a (special) tighter fit clutch disk & new input shaft due to knocking noise complaints on the R 1100 bikes (all looked good to the eye, just too much play between disk hub & input shaft splines). The knocking complaints were mostly at hot idle but they could also knock as the loading changed during float to over-run. It's not the rear main SEAL that causes the problems it is the rear main bearing that wears in the lateral direction causing the crankshaft to move back & forth during opposite piston firing.

 

I pulled the trigger on the used transmission. I just put a OEM clutch in my 98 GS, so I started this project while all the tools were out and the process fresh in my mind. Worse case I'm back in there again. At least everything will be clean which eats up most of my time working on things.--Just make sure that the knocking isn't coming from the clutch parts. You really can't tell much by pulling or shaking on the clutch parts as the DIAPHRAGM SPRING keeps everything loaded & tight.

 

You might want to be sure that the DIAPHRAGM SPRING isn't rattling (I have seen that happen), or that the PRESSURE PLATE isn't rattling (now is the time as you already have the trans removed)-- you really can't do that effectively with the spring load on the clutch parts.

 

Is the new clutch disk the correct thickness as that can effect the diaphragm spring contacting & rattling under certain circumstances.

 

 

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  • 2 months later...

I wanted to report back since I hate reading threads without an ending. I got the new/used 99 RT transmission installed and and everything is working great. The new transmission shifts great with no more rattle noise. At some point I will crack the old transmission open and figure out which bearing is bad. It shifted great also so it's worth fixing.

 

 

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