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Sudden new rear end noise on decel


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On the way home a new noise cropped up on my 88 after getting off the highway. Fairly loud gear whine when decel or coasting. Sounds as it is coming from rear end. Slightest bit of throttle quiets it right down. Checked pumpkin and engine oil, fine.

 

Prior to this the bike made pretty much the same mechanical sounds as a brand new 2010 I took for a test drive. Some noise at coasting and decel but it definitely just got louder all of a sudden.

 

This bike is new to me (64K mi now) so don't know what maintenance has been done to the splines drive pins etc. I'll pull it apart this weekend and have a look and slop some moly 60 in there. Is this a common noise (decel only) for dry splines and pins or am I looking at a bad rear pumpkin?

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Well my 89 has always whined on deceleration, noticiable at lower speeds.

Its the same now,as when bike was new, ( 81K )

However best to remove pumpkin, and drive shaft, give it all a good greese job.

On re-assemble, re-torque the 4 nuts holding pumpkin to drive shaft houseing and the Axel nut in steps. Tap Tap on everything to relieve STRESS, as your re-torque all the nuts.

I never worried about the whine, just seems to be what the beast does.

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Mine has always whined as well. Like wives I think they all do:confused24:.

 

But it SUDDENLY got MUCH worse. Randy's explanation seems consistent with the behavior. Guess I'll know this weekend.

 

Does anybody know which years of VMAX rear ends fit in case major surgery is required. I know from Skydoc's explanation his shim is needed.

 

Thanks

Wally

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I think know why I broke it. I was hot dogging a lot in the last week or so which included taking it to red line in 1st & 2nd then dropping the throttle - a number of times.

 

1100 Lbs of bike, rider, fuel etc

Plus

7500RPM

Plus

65MPH

Plus

10.5:1 compression

Plus

Sudden full engine braking

Rinse Lather Repeat

 

Equals sign%20busted.gif Pinion Nut. Accelerating, the pinion thrust is one way due to the cut of the gears and good engineering practice for a powerful bike would have the pinion shaft in compression, not stressing the thread/nut. On Decel the thrust is exact opposite and most likely putting the pinion shaft/nut in tension. I was NOT gentle with it so BANG the pinion/nut suddenly took a lot of tension load.

 

 

Was it fun? - hell ya!:rotf:

Will I do it again? - you bet! (But this time with a little gentler roll off on the happy handle:no-no-no:)

 

My Vmax final drive is on it's way:mo money:

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Wouldn't the broken pinion nut be making a racket all the time...?Grisolm, did you actually find the nut broken??? After looking in the service manual. Randya, I think what you mean by "broken nut" is the pinion end with the nut has broken OFF! THus you would need a pinion. With all the hard miles on mine. I think a bad noise would have been noticed when I ran mine on the dyno last week...for over an hour. But I could have a broken pinion end too. As the last rear oil change had a bit more metal than usual on the magnet.

Edited by jasonm.
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That noise is from excessive gear lash in the final drive.

 

On mine the pinion had snapped right below the nut. Without the compression on the bearing it's halves separate and let the pinion float in and out. As stated before, acceleration pulls the pinion into the ring and takes up the lash; deceleration pushes it out and the noise comes.

 

The nut doesn't rattle around because there is a spring that keeps it against the coupler.

 

I don't think you broke it from getting on it hard. IMHO it's a design or manufacturing defect. It's too common an occurrence to be anything else.

 

Yamaha doesn't sell the pinion without a complete final drive. They were North of $800 when mine failed. I got a final off a 2nd gen that had been triked to replace it

Edited by MiCarl
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I haven't pulled it apart yet. I plan on doing this when the Vmax rear arrives and I'll report what I find. The noise is too consistent with a floating pinion gear to be anything else, or to be safe to ride. So buying the Vmax rear was a small leap of faith to my diagnostic skills.

 

It could well be a design or manufacturing defect but I'm sure I helped it along with the repeated sudden engine braking from redline in 2nd gear. Drive it more sanely and I'm sure my pinion would be going strong for many years.

 

Anybody used Redline Shockproof gear oil in these pumpkins? It worked well in quieting down my Road King tranny and I run it with good results in my Guzzi's tranny and rear end. It's really thick but is rated at a lower viscosity. It likely wouldn't have prevented this pinion breakage but might take some of the rear whine out of the ventures.

 

specs below from Redline website

 

Heavy Shockproof A unique lubricant containing a suspension of solid microscopic particles as an extreme pressure agent--unique solid dispersion which cushions gear teeth to help prevent tooth breakage and allows the use of lower viscosities.

Recommended for heavily-loaded racing differentials and transmissions, Off Road racing and problem gearboxes. The viscosity characteristics allow the lubricant to resist throwoff and provide a film thickness similar to a 75W250 grade, while providing the same low fluid friction as an SAE 75W90.

The Red Line Heavy can be rated as a 75W250 Gear Oil, but has the lower internal fluid friction of an SAE 75W90. The LightWeight can be rated as a 75W140 Gear Oil, but has the lower internal fluid friction of an SAE 30 motor oil.

 

  • Greatest extreme-pressure protection
  • Lowest coefficient of friction available
  • Reduces temperatures dramatically
  • Provides thicker oil films between gear teeth
  • Completely resists throw-off
  • Reduces metal-to-metal contact
  • Compatible with petroleums and synthetics
  • Low fluid friction to improve power transfer
  • Provides gear teeth shock loading protection
  • Reduces gear noise and has little odor

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It's not a Design Flaw. It's abuse on already used mechanicl Parts. We have this happen on the 1Gen Maxxes once in a while, maybe one per thousand Bikes per Year. It's repairable, but a the Price of used Pumpkin in US, i wouldn't bother with it.

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It's official - snapped pinion shaft. Broke at the base of the nut like others on the site have reported theirs did.

 

Guess I'm one in a thousand.

Looking into the manual. I see if that nut assy.breaks. The "splined" area that holds the shaft will or could wobble. Did you find or notice this? I gather this would be the source of some noise also.

Edited by jasonm.
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It's official - snapped pinion shaft. Broke at the base of the nut like others on the site have reported theirs did.

 

Guess I'm one in a thousand.

Hey I'm from Missouri, "show me state". Can you post pictures of the problem area? Thanx, I too am experiencing noise, I thought that the nut on the pinion shaft wasn't torqued correctly, As it was loose, I forgot to use locktite had to go back and do over. The whine has worsened, it is prevalent on acceleration, not as noticeable on the deceleration, whats that about?

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I have my wheel off...waiting for a tire. I pulled the shaft drive assy. out on my '87VR. I am debating on yanking the shaft from the drive. Thus waisting the damn $15 seal, just to check the nut on mine. Was noise the only reason you checked for the nut.?AND could you wiggle the "splined coupler"? Note: my coupler seems fine.

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Pics are a problem for me today. I'll try to post later, but it's easy to see if you have the problem.

 

 

If your drive shaft pulls off the pumpkin in one piece (i.e. you can see splines on both ends) you are OK.

 

My driveshaft had the spline socket from the pumpkin with it. When I pulled these two pieces apart on the bench, the nut, spring and broken piece of pinion shaft fell out.

 

My pumpkin is sitting there without the spline socket. I can push on the broken shaft that remains and feel play.

 

This only made noise on decel. During accel it was quiet as a kitten.

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  • 2 weeks later...
Pics are a problem for me today. I'll try to post later, but it's easy to see if you have the problem.

 

 

If your drive shaft pulls off the pumpkin in one piece (i.e. you can see splines on both ends) you are OK.

 

My driveshaft had the spline socket from the pumpkin with it. When I pulled these two pieces apart on the bench, the nut, spring and broken piece of pinion shaft fell out.

 

My pumpkin is sitting there without the spline socket. I can push on the broken shaft that remains and feel play.

 

This only made noise on decel. During accel it was quiet as a kitten.

 

Any pics yet?

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Here's the thing, it's not the metal grind of pad rivet to rotor... more like the sound when your bracket fails and you drag a muffler...

 

My friend's 84 has had a "griding" sound when medium to hard brake is applied. Not constant but seems to come and go. We changed the rear pads (for giggles I guess) and the old ones showed lots of life but we still put new ones on. Added the supplied lub to the back of the pad, cleaned all the parts and assembled. He was tickled for about a week and then called again...

Edited by mbrood
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Sorry I can't get any pics up. 14 hour days give me little time to do anything lately. Then the wife whines louder than my rear end did.

 

Suffice to say it's REAL obvious if you pull your pumpkin off. All you will see in the pumpkin end is splines on the pinion shaft itself and the stub of the broken threaded end. The drive shaft will have the receiver cup/hub/spline thingy attached. When you pull the receiver thingy off the driveshaft the broken nut/piece of pinion shaft falls out with the spring.

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  • 2 years later...

i just acquired a 3rd hand 91 venture, awfull noisy rear end noise on deceleration. Opened her up and tadah! i found the culprit loose sheared pinion nut. the guy I bought it from said he didn't know what the noise was and that he had been riding it this way since he bought it 4 years ago. hmmmmmm. Any how I found a 87 pumpkin on ebay just waiting for the shipping cost. Funny thing though the pinion gears were very polished further examination showed there was no backlash between the 2 gears and their operation was somewhat binding. Could this have directly induced the fractured shaft??? BTW the bike has 72,000km

Edited by yamihami
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I have my wheel off...waiting for a tire. I pulled the shaft drive assy. out on my '87VR. I am debating on yanking the shaft from the drive. Thus waisting the damn $15 seal, just to check the nut on mine. Was noise the only reason you checked for the nut.?AND could you wiggle the "splined coupler"? Note: my coupler seems fine.

 

If the nut broke off you can pull it apart without breaking the seal. The coupler the shaft goes into is held into the final by that nut. You can pull on the coupler to see if it's loose. On mine the shaft stayed in the swing arm when I removed the final drive.

 

The reason the motorcycle will still move with a broken nut is that there isn't enough room for things to come apart (until you pull the final off the housing).

 

The bearing on the pinion shaft has a split race, the load from the nut holds the two halves together. When the nut breaks off, the races separate a bit letting the pinion shaft move out of alignment. The misaligned gears make the growl or moan.

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Over the years Ive had 5 mkII's all but one had bad final drives, from ebay I got a 2nd gen rear to replace one of my bad mkII's rear it to was bad, and when I say bad I could move the cup that holds the drive shaft with my hand. Have had 4 MKIs all high miles all with good final drives.

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  • 2 weeks later...
  • 1 month later...

I had the same problem on the 91 venture I acquired in August at first I was puzzled the PO said he bought the bike second hand with that problem and he beleived it was NORMAL. :whistling:Any how I swapped it out with a used one I found on ebay. I kept the broken pieces I think they make an excellent conversation opener. I will post pics. Hmmm would be interesting to have a pole to see how many broken pinions gear shaft nuts have broken. I had a friend who had a Seca 750 which in 84 was also my first machine. Anyway he also broke the shaft nut trying to do a wheely. I guess these Yamaha parts are not over engineered. My second bike is a BMW K100RS and I did manage to do a 6 inch off the ground wheely many many years ago when I was slightly younger and nothing ever broke and I have had the rearend off for lubing the splines and there was no visible damage. Me thinks German over engineering. PS I have always done my maintenance as requested. People seem to think shaft drive meens no maintnance but cleaning and lubing the splines as required is a must. BTW I was surprised to find out that on the Mk II's the oil in the final drive splashes up past the bearings and the pinion gear to lube the splines so there is no requirement for greasing them.

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The 1300s are very good. My '87 has seen it fair share or front wheel in the air time. But this was within the first 40k on the bike and 20 years ago. I have had this bike since '89, starting with less than 5k on it. My frequency of such "fun things" is far less now. But I did do a power shift just a few months ago. And the front wheel enjoyed some significant air time. No worse for it. As I bet failures are from a lot more miles, lack of rear end oil changes and abuse. Or any combination. These are well made drive units. Be happy you do not have a newer BMW having the "large bearing" failures. That happen at well under 40k. FYI, I have always used synthetic gear oils, Mobil1 , Spectro SPL, etc. Will mine last forever? I have a spare knowing, forever does not exist unless you are and astronomer. For the play you speak of on the '87. The play is measured in a few thousandths using an extender to measure this minute play. So that, according to specs, likely would be a good one. As for the 1200s, the wear is the spline area needing grease. And the fitting is useless. I have never seen a 1200 rear w/high miles....I think you guys are saying MK1 is 1200s and MKII 1300s...? I thnk mmaleney is saying the 1200s are better ...news to me.

Edited by jasonm.
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