U-Joint or Something else

[Psycheonabike]

Hi,

Sorry to bang on about this bumpy ride I have, but I have noticed a few things that might help diagnose properly!

Its DEFINITELY worse when in gear riding up a small hill - THAT is when its most obvious. Feels like the rear wheel is hexagonal!!! Its still there on the flat but nothing like as noticeable!

I have a replacement U-Joint that I could put in over the weekend as despite having had the shaft drive out last week and it and the U-Joint 'looked' ok i am wondering if it could be a warped or bent U-Joint given the riding up hill thing?

Also, do I need to remove the whole swing-arm to get the new U-Joint in or can I just drop the right side?

Or am I barking up the wrong tree???

[Rednaxs60]

Just drop the right side.

[Psycheonabike]

So, what would you look at first re this bumpyness.

U-Joint (do they really bend?) I'd have thought they just go pop rather than weaken?

Or shocks?

Both PITA jobs so guess I have to choose!

[ekvh]

Pull the boot back and hold it with a bungee cord. You can view the ujoint from there. Rub a magnet inside the lower portion of the boot. If it yields metallic pieces it’s going . From your description, you would likely be able to see the wear marks on the yokes and it would be close to disintegrating.

[Psycheonabike]

...its not the U-Joint then.....

[Maz]

Have you checked the final drive unit on the rear wheel?

Maz

[Psycheonabike]

Have you checked the final drive unit on the rear wheel?

Maz

I have...twice

All seems in order. Put back and Moly added. I am completely confused to be frank!!

[geraldm]

You have done everything else have you checked to make sure your front yolk neck bearing is not loose.

[Psycheonabike]

Thanks but I am 99% sure its coming from the Drive Line somewhere...

[Maz]

So, what would you look at first re this bumpyness.

U-Joint (do they really bend?) I'd have thought they just go pop rather than weaken?

Or shocks?

Both PITA jobs so guess I have to choose!

U joints don't bend, but they do get stiff. When you examined yours could you move it smoothly (without being loose) in both directions? Did you check that the actual drive shaft is perfectly straight?
I really can't think of anything else.
Maz

[Psycheonabike]

That's exactly what I did mate...felt good in all respects. Defo not Joint.

I'm at a loss too...

[Maz]

Just out of interest, what does the oil in the final drive look like? Any 'bits' in it? Maybe poke around through the filler hole with a magnetic screwdriver or similar to see if there are any bits of worn or broken teeth from the bevel gears in there.

Maz

[Psycheonabike]

Hi and thanks....thats one of the very first things I checked. It might even be a 'new'(ish) U-Joint as even looking past the rubber boot it looks in as good condition as the one I bought as a replacement - hence not fitting it!

[Maz]

The last suggestion I have is to strip the FD and examine/replace all of the parts in the diagram:

Maz

[julimike54]

Haven't noticed anyone mention the swingarm bearings, they could be worn and causing a 'notchiness' (my word) cause the swingarm to not smoothly transition from full compression to full extension. That's my guess

[Psycheonabike]

So if you guys had to ask a mechanic to look at this what would you be asking them to concentrate on? Currently general consensus seems to be the following:

1. U-Joint- (but why?)
2. Rim (bent?)
3. Tyre (bad fit)?
4. Swingarm Bearings (would that really make it feel like I am riding over cobbles?)
5. Rear Shocks (but they both seem to function well)
6. Final Drive Flanges (Again, not sure why?)
7. Forks (would that affect the bouncing under the seat as that's where it feels it is most?)
8. Wheel Bearings (Ill nit be happy if thats all it is as mechanic said he'd checked)

Is there anything else you think I should look out for?

Thanks....

[Rednaxs60]

Have you had a good look at the cush dampers in the rear wheel. Check to see if the holes are elongated. Could prove to be an issue. Here is a picture of the cush dampers: