My baby is crippled!

[Hymes Inc.]

I think the front U-joint gave out on me today. Just tooling down the road and she started shaking real fast followed by a very loud bang. In neutral the rear wheel would intermittently lock up then let go. Clucking noise was coming from that area. Only 50 miles since ending a 900+ mile trip last weekend. Could have been worse.

[Arizona Wayne]

How many miles before the U-joint  gave it up?

[Hymes Inc.]

Well... The bike had 15,000 miles before sitting in a cruddy shed for 15 years. Not sure how many I have put on it since then, no odometer anymore.

[Hymes Inc.]

I think the front U-joint gave out on me today. Just tooling down the road and she started shaking real fast followed by a very loud bang. In neutral the rear wheel would intermittently lock up then let go. Clucking noise was coming from that area. Only 50 miles since ending a 900+ mile trip last weekend. Could have been worse.

So I said "front" U-joint. Do I understand this correctly that there is only one?

[pete roper]

Yes, the small blocks, (Up to the V9.) only use a single Hookes coupling at the front of the shaft. Check around the back of the gearbox. It may of taken out the rear encase when it let go.

Pete

[wymple]

1st world problem. We'll fix it.

[sib]

Only slightly off topic, from Wikipedia:

In Europe the universal joint is often called the Cardano joint or Cardan shaft, after the Italian mathematician Gerolamo Cardano; however, in his writings, he mentioned only gimbal mountings, not universal joints.

And, something I didn't know:

The Cardan joint suffers from one major problem: even when the input drive shaft axle rotates at a constant speed, the output drive shaft axle rotates at a variable speed, thus causing vibration and wear.

[pete roper]

That's why they are usually paired and why the smallblocks with only one trunnion have such soft Cush blocks.

Pete

[charlie b]

Also why, even when paired, as on a car driveshaft, they must be aligned to one another or you still get that jerky motion from them.

[sib]

Also why, even when paired, as on a car driveshaft, they must be aligned to one another or you still get that jerky motion from them.

I guess that means that for a shaft drive, even with paired U-joints, the output becomes increasingly jerky at the ends of the swing arm travel, where there's an increasing angular difference between the axes of the input and output shafts.

Has anyone ever used a true constant velocity joint on a shaft-drive motorcycle?

[Wayne Orwig]

And, something I didn't know:

The Cardan joint suffers from one major problem: even when the input drive shaft axle rotates at a constant speed, the output drive shaft axle rotates at a variable speed, thus causing vibration and wear.

That is why you always want them in pairs.

https://www.youtube.com/embed/NNcIlgRuHTc

[omega1987]

That is why you always want them in pairs.

https://www.youtube.com/embed/NNcIlgRuHTc

So would you say the twin U-joint V9 is superior in design to the earlier single U-joint small blocks?

I'm guessing the older design is still quite robust as they're are a number of high mileage small blocks out there still on original drive shafts.

[Muzz]

Has anyone ever used a true constant velocity joint on a shaft-drive motorcycle?

Someone has just recently, can't remember the thread sorry.

I do remember him saying that he used one off a car but if he ever did it again he would use one off a quad bike.

[Hymes Inc.]

Finally got to taking the swing arm off. U-joint is trashed, everything else looks good. So how does the yoke from the output shaft come off?

[Hymes Inc.]

[Hymes Inc.]

I got it off, needed some convincing though. Now to see what we can fit on there.

[Hymes Inc.]

http://www.ebay.com/itm/09-Moto-Guzzi-V7-Classic-Drive-Shaft-26F-/131571064723?hash=item1ea23f1f93:g:mmIAAOSwjVVVraVq&vxp=mtr

Is there anywhere/anyone that can tell me if this is the same? Looks the same. Not finding anywhere that gives me specs on mine or this one.

[chuck peterson]

Just finished a 900 miler? And then it breaks after getting you home...that there is the Popes blessing in effect. Happens all the time. Can't tell what bike you own to see if that one fits

[Hymes Inc.]

Just finished a 900 miler? And then it breaks after getting you home...that there is the Popes blessing in effect. Happens all the time. Can't tell what bike you own to see if that one fits

I have a 1984 V65c. I have messaged the seller to see if he will get me some measurements. The drive shaft end has the same spline count as mine, hard to tell about the yoke.
 

[rodekyll]

Sib -- I am using true cv joints on the drive shaft of my trike -- VW type-1.

[SmithSwede]

wow.  That looks dry, crusty, rusty nasty.  And broken. 

But it got you home after the 900 miler!

[Antietam Classic Cycle]

I have a 1984 V65c. I have messaged the seller to see if he will get me some measurements. The drive shaft end has the same spline count as mine, hard to tell about the yoke.

It's the same part number and MG Cycle lists the V65C and the V7 Classic both as using it.
http://www.mgcycle.com/index.php?main_page=product_info&cPath=35&products_id=936

[Hymes Inc.]

That is what I needed to hear. Bought it. Thank you for your help. The old one was a bit rusty, sat in a crummy shed for 15 years. Really didn't surprise me when it went, don't remember if we checked it or not when we were resurrecting the bike.

[wymple]

59 bucks. Cheap skate

[rboe]

I see why chain drive is so popular..... 

[Hymes Inc.]

Drive shaft came in today. Took apart the cross, greased, and reassembled. Smooth. Getting the bike back together was a bit of a trick but I got it done in 30 mins. Will be riding her to Elkader. See you there.