Leak at u joint boot?

[weasel01]

I am slowly going throught this old machine trying to get it back in shape.
I plan to do the spline lube next but noticed a leak coming from the boot area?
Is this just a boot replacement or is there another seal I need to change?
I should say I went with a synthetic gear lube for the first time,,,I've heard it sometimes leakes and then a change back to real lube stops the leak ....for a while?
Any experience here?

[Justin B.]

The boot deteriorates (just like any rubber part) over time and develops cracks.  Also, the clamps might be a bit flaky so I would suggest you get a new pair of clamps along with the boot.  I saved quite a bit on the "Junkyard Dawg" by ordering these items from Moto-Bins.

Synthetic doesn't actually make things leak but it is more likely to illuminate marginal gaskets and seals by being slipperier and a better cleaner than dino oil.  I have read (long, long ago) that crud and varnish can build up on shafts using dino oil and actually form a "dam" at the seal/shaft interface thus helping a marginal seal do it's job.  After changing to synthetic this "crud dam" can be dissolved resulting in the marginal seal not being up to the task.  Usually switching back to dino will "fix" the leak, as long as it wasn't much more than a "seep", due to the dino stuff not being as slippery...

[weasel01]

So Justin you think its just the boot?
I think that requires a special tool and replacing the bolts with the short ones?

[montmil]

Requires a 12-point box wrench to fit the four bolts and a 27mm modified socket to pull the swing arm pivot lock nuts. It's a great opportunity to do a spline lube, too.

Monte

[Justin B.]

You haven't listed what year bike so I have no idea about your bolts and the rest is what the "old cheap one" said...

[weasel01]

it's a regular ol' 1983 R65

[Bob_Roller]

Check the clamps that hold the boot on, there is a channel shaped piece of metal that bridges the gap between the two 'ears' that the small screw goes through .

It's spot welded to one side, but it comes loose pretty easily .

It's easily lost, best to check your drain pan for extra parts, before discarding the used oil .

[Justin B.]

The '83 will probably have the updated bolts and no split lock washers.  Technically the flange bolts are to be replaced but I (along with many other BMW owners) have started reusing them with blue thread locker.  But, if you run into the ones with washers they need to be "upgraded" to the new ones and toss what's left of the washers.

[Semper Gumby]

I replace the boot everytime I do the spline lube AND the throwout bearing service.  (Please remember to do the throwout bearing service when you do the spline lube!)  This happens every 15,000 miles for me.  As I have plans to head into the wilderness at some time this is just prevenative maintenance for me.  Ozone chews up exposed rubber parts quite quickly.

This crappy advise worth 2 cents.

[Justin B.]

Well, Bill, the boots will usually last (in TX) 7-8 years...

[montmil]

...the "old cheap one" said...

Frugal. That's frugal...  [smiley=cowsleep.gif]

I did drive to Austin this past weekend to visit grandkids and fix my son's bathtub drain plumbing issues.

Bought new "short" bolts for the 81's boot replacement chore and love the parts guys at Lone Star BMW n Austin. They "reminded" me that washers are no longer used with the U-joint bolts. Also told me they maintain a large inventory of airhead parts.

Senor El Cheapo Grande averaged 28.6 MPG over 600+ miles from the 315 HP Northstar V8 in wife's new Cadillac Deville Touring Sedan. Regular gas. 70 MPH cruise and was indicating 1900 RPM on the digital tach! I love our big economy car!

Monte

[flongr65]

I noticed my new boot leaking slightly some time after I did the spline lube. I simply needed to align the rear clamp better and tighten it. By the way my original boot was still in great shape, but changed to a new one regardless. I spray the boots with silicone every once in a while. Seems to keep em soft.

[Justin B.]

Did I really say that?  

[steve hawkins]

Be aware that the boots also have to be orientated properly.

There is an indent on the boot for the tab on the swinging arm.  If you do not orientate it correctly it will leak.  The boot is also designed to deflected in a particular plane -i.e. up and down.  Thats why it is shaped the way it is and the indent is there to get us to put them on properly.

Don't ask me how I know

Its a pig of a job to get the boot back on, but persevere and you will be rewarded...(it might take a little time though )

[weasel01]

I've read that it's a tough job...what's the trick ?

Is it real tight? the micro fiche says it can be installed with an o-ring removal too...l