Rear wheel nut won’t stay tight
Post Reply    Forum -> MP3 Discussion
Author Message
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Sat Sep 12, 2020 3:49 pm quote
After the latest rear tire change, there was a constant rattle coming from the rear wheel. We made sure the main nut was tightened to spec, and the noise went away. After a few hours of riding the noise came back. Checked the wheel, there was some side to side play in the wheel. Checked the nut, it was loose (or at least not within spec). Retightened, noise went away. Next ride of a few hours, the rattle is back.

Why won’t the nut stay tight?

Thank you.
Enthusiast
Piaggio MP3 ie 400
Joined: 01 Jul 2017
Posts: 86
Location: Sydney
Sat Sep 12, 2020 4:51 pm quote
Re: Rear wheel nut won’t stay tight
Carolan wrote:
After the latest rear tire change, there was a constant rattle coming from the rear wheel. We made sure the main nut was tightened to spec, and the noise went away. After a few hours of riding the noise came back. Checked the wheel, there was some side to side play in the wheel. Checked the nut, it was loose (or at least not within spec). Retightened, noise went away. Next ride of a few hours, the rattle is back.

Why won’t the nut stay tight?

Thank you.
I had the same thing happen to me the last tire change, and my tire used to wobble too, it could be that who did change it, did not tighten things inside well, like the bearings, and also, there is a pin that goes in the middle of the nut, they may have forgot to put it in. Sorry my mechanical terminology is limited, if you looking straight at the wheel ( bike standing up right and your view is 90 degrees at the nut) the pin will go through the nut from side to side, the pin looks like capital "A" without the "-" in the middle, and it is like a spring, once you try to put the far sides together it would open up by itself. I hope I made it clear,
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 38955
Location: Pleasant Hill, CA
Sat Sep 12, 2020 4:54 pm quote
Re-assembly after the tyre change wasn't done correctly - if it had been, the nut would stay tight. Some washer or whatever has been misplaced/mis-aligned.
Hooked
50cc Beo, BigBeo
Joined: 30 May 2015
Posts: 265
Location: Chelyabinsk, Russia
Sat Sep 12, 2020 7:14 pm quote
There's a not so obvious reason for that. Here you are:

Assembling the rear wheel, you should first draw the brakepads to their basic positions. Else nut tightness is provided not by tight assembly of all spacers and bearings, but by brake disk that abuts to a brake pad and cylinder. Sorry for non-native-speaker-explaination.

BTW if brake pads and cylinders aren't easily going back to their positions, you should rebuild (clean, primarily) your caliper and use brake grease like ATE or TRW to re-assemble it. And never lubricate brake cylinders by brake fluid.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8635
Location: Ashburn, Va. Home to the Internet
Mon Sep 14, 2020 4:06 pm quote
Make sure the cotter pin you are using is big enough too. Mine came loose due to that one time, was 1 size to small and the castle nut could still loosen.
Hooked
50cc Beo, BigBeo
Joined: 30 May 2015
Posts: 265
Location: Chelyabinsk, Russia
Mon Sep 14, 2020 7:34 pm quote
That's nothing about cotter pin. It just prevents nut from totally being lost if it becomes loose. For example, my Big Beo does not have it at all (meanwhile the wheel shaft has a hole for it)

2020-09-15_08-32-50.png

Hooked
2010 S50 Modified "Punkin"; 2003 ET4 150 "ISO"
Joined: 18 Feb 2017
Posts: 463
Location: Deepinnaharta, Texas
Tue Sep 15, 2020 7:58 am quote
Greetings:

If that rear wheel went catty-wompus not once but twice, I would be very concerned about the condition of the splines on the output shaft and inside the wheel. With the wheel installed on the shaft and the rear brake locked, with the nut snugged but not Tight, there should be NO ability to roll the wheel fore and aft. If it moves even a mm or two, close inspection is warranted.
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Thu Sep 17, 2020 3:32 pm quote
Thank you everyone for their input. I'm going to post a few videos detailing the symptoms. Hubby is poised to tear the whole back end apart to look for the culprit, but ideas would be appreciated. Are we going to have to haul it to a dealer to get it fixed, or is this something we can DIY?

My apologies, I couldn't get the videos to work. There's a space in the link - copy the line, paste in browser, and remove the space.

Vid 1
http s://youtu.be/upamnC1hivw


Vid 2
http s://youtu.be/VKt3TQYXwQU


Vid 3
http s://youtu.be/VNEgN6bIHCs


Vid 4
http s://youtu.be/6a3VDecyPm0
Hooked
Piaggio MP3 500
Joined: 21 Nov 2017
Posts: 282
Location: Austin, TX
Fri Sep 18, 2020 7:37 am quote
OOo, that's nasty. Don't ride it like that.

My guess is that the splines are shot. The reason I believe that is that the nut won't stay on- if the wheel can wobble on the splines, the nut will come off pretty quickly from precession.

And possibly the bearings are toast. I would definitely take it apart, and see where it wobbles- I'd definitely replace the bearings anyway, since everything is apart.
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Fri Sep 18, 2020 7:42 am quote
Thank you. That's what I'm afraid of. *sigh*
Squeazel wrote:
OOo, that's nasty. Don't ride it like that.

My guess is that the splines are shot. The reason I believe that is that the nut won't stay on- if the wheel can wobble on the splines, the nut will come off pretty quickly from precession.

And possibly the bearings are toast. I would definitely take it apart, and see where it wobbles- I'd definitely replace the bearings anyway, since everything is apart.
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Fri Sep 18, 2020 7:54 am quote
Squeazel wrote:
since everything is apart.
Could you give me an idea which schematic I need to look at to find the correct part(s) to replace? Sorry I'm so clueless. Trying to save my husband some work.

https://www.parts-piaggio.com/piaggio-scooters/400-PIAGGIO-SCOOTER/MP3/2009/MP3-ie-MIC/Engine/43019052/1672
Ossessionato
Gilera Fuoco 500ie
Joined: 11 Oct 2009
Posts: 4206
Location: Netherlands Olst
Fri Sep 18, 2020 10:39 am quote
bearings of the transmission gears
Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2012 Honda NC700 DCT
Joined: 02 Mar 2013
Posts: 6148
Location: Madison, Wisconsin
Fri Sep 18, 2020 12:15 pm quote


To my eyes that's a complete teardown of the final drive.
It's not just the rear wheel slipping on splines; the whole axle shaft is moving.
I think I'm with Maksor on this one....
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Fri Sep 18, 2020 12:19 pm quote
Thanks, everyone.

Jeez, how did this thing fall apart so fast??

The front needs steering bearings, now the transmission is having issues. *face palm*


Do we need any special tools to work on the drive?
Hooked
Piaggio MP3 500
Joined: 21 Nov 2017
Posts: 282
Location: Austin, TX
Fri Sep 18, 2020 12:59 pm quote
#3 and #2 on the reduction unit, probably. That's the bearing and seal. I don't know if any of the internal bearings are shot, but it's probably best to open the reduction unit up and check. need a new gasket as well. Has the final drive oil been changed lately? Also there's another bearing on the arm that holds the muffler shown in an earlier post that probably should be replaced. And if the splines are shot, you'll need a new rear wheel. But the best way to tell is to open everything up and check, then order the parts that are broken. The gears might be bad as well. Ouch. It's not terrifically hard to do, just a bit oily and you don't know how much is broken, so it may be a mess. You'll need to remove the clutch assembly as well.
Addicted
MP3 400 "Merlin"
Joined: 01 Jul 2012
Posts: 915
Location: Northwest Ohio
Fri Sep 18, 2020 1:02 pm quote
Got it. Thank you!

I've checked the gear oil every time I do a regular oil change. But I've never changed it. Might as well do that while it's all apart anyway.
Squeazel wrote:
#3 and #2 on the reduction unit, probably. That's the bearing and seal. I don't know if any of the internal bearings are shot, but it's probably best to open the reduction unit up and check. need a new gasket as well. Has the final drive oil been changed lately? Also there's another bearing on the arm that holds the muffler shown in an earlier post that probably should be replaced. And if the splines are shot, you'll need a new rear wheel. But the best way to tell is to open everything up and check, then order the parts that are broken. The gears might be bad as well. Ouch. It's not terrifically hard to do, just a bit oily and you don't know how much is broken, so it may be a mess. You'll need to remove the clutch assembly as well.
Hooked
Piaggio MP3 500
Joined: 21 Nov 2017
Posts: 282
Location: Austin, TX
Mon Sep 21, 2020 6:37 am quote
Yeah, if you take apart the final drive, the oil will get changed, whether you want it to or not. Anyway, check for metal flakes and crumbs in the oil as you drain it- that would be a bad sign, indicating gear and bearing damage. Let's hope it's clear, then it's probably just the outer bearings and the wheel casting. A full rebuild may be necessary, in which case there are a couple more bearings in the drive that will need replacing.
Land of 10,000 Scoots Rally   vespa scooterwest scooter west Motorsport Scooters   Cool Ass scooter seat cover
Post Reply    Forum -> MP3 Discussion
[ Time: 0.3091s ][ Queries: 27 (0.0437s) ][ Debug on ]