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Thread: Drive Shaft Band Clamps

  1. #1
    Registered User lmo1131's Avatar
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    Drive Shaft Band Clamps

    I've been fighting a dripping drive shaft boot for a year now. The increasingly frequent drip is on the "drive shaft side" of the boot. The transmission side is tight and dry as a bone; there is about a 5-6mm [0.197- 0.236"] gap between the ends of the clamp. It has been suggested that that drip is actually being caused by the rear transmission seal leaking and over-filling the swing arm tube. When I drained my swing arm this afternoon it had 115cc of oil in it; less than spec'd amount. Overfilling is not the problem.

    What I discovered, while crawling around on the floor, (yeah I know... grow up, buy a lift) is that the band clamp (on the drive shaft side) is bottomed-out and can exert no further constriction on the boot. I replaced the boot and the two clamps last spring (MAXBMW); the leak began immediately. I still have the old clamps; they are stamped with the number "82" on them near the fitting on the threaded end of the clamp. The new clamps have the number "83" stamped onto them. I do not know if these number correlate to "length", but I suspect that they do. I ran out of time and have not removed the new clamp to compare it to the old.

    The only other cause of this leak that I can think of is that the thickness of the rubber on the new boot is less than on the old boot (wouldn't surprise me to discover this) and that as a result the clamp has to be tightened further than before.

    If anyone has the time and/or inclination I'd appreciate learning if there is a significant gap (2mm [0.078"] or greater) on the drive shaft side of the back clamp.

    Ref. image (not my bike)
    Showing "transmission side" band clamp with gap between ends of the clamp.




    Vielen Dank!
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  2. #2
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    should be a gap or you have no way of knowing if reasonable compression is applied to rubber
    my still original clamp 72 R75/5 looks maybe narrower than newer style clamp in your pic

    Try temporary test by wrap of inner tube rubber between your clamp and drive boot to see if seal is accomplished
    if so then buy shorter clamp

  3. #3
    Registered User lmo1131's Avatar
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    Try temporary test by wrap of inner tube rubber between your clamp and drive boot ...
    Good idea in theory, but you have obviously never installed a drive shaft boot....
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    Administrator 20774's Avatar
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    Lew -

    On my clutch change a couple of years ago, I replaced the rubber boot as a matter of course and reused the clamps. I don't recall the numbers stamped on them...the fiche shows the same clamp used front and rear up to at least 1980. I checked the fiche for a 1982 R100RS and the clamp was shown to have the dimension of 83mm, so that number does appear to be the diameter. If you have 83s, then likely you have the wrong part.

    I did have a leak at the rear of the boot after my first ride. After cleaning the boot up, I could see that I didn't have the boot fully on the flats of the driveshaft boss. Once I repositioned the boot, all has been fine since then.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    Hacker
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    I have reused those clamps over the years. They have very few problems. Replaced one a couple of years ago because the screw was worn and it wouldn't tighten properly. Only clamp I've had to replace in 14 years with same R90/6. If you have no gap in the ends of the clamp it is the wrong clamp.

    Just realized I never introduced myself here. I'm disston or called by my name Charlie. I own a 1975 R90/6 with several hundred thousand miles on her. Runs pretty strong I think. Stronger than I can run most of the time.

  6. #6
    Registered User lmo1131's Avatar
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    Hi Disston, thanks for the information.

    Kurt thanks for the specific 83mm info. As I mentioned, my old clamps are 82s. I replaced them because they were nasty looking, no other reason. I'll pull the 83 off of the drive shaft this morning and re-install the 82. Hard to believe 1mm would make a difference. BTW, both of the old clamps are 82.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  7. #7
    Administrator 20774's Avatar
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    Using 83 and 82 as diameters, the circumference for the 83mm bands would be 260.75mm while for 82mm it would be 257.61mm. So, it might be that you'll end up with 3mm of "gap" to use for snugging up. That might be all the difference you need.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  8. #8
    Registered User lmo1131's Avatar
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    The "82" made a big difference; I now have about 3-4mm gap between the ends of the clamp. Now we'll see if it stops dripping.

    Thanks guys.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    "Try temporary test by wrap of inner tube rubber between your clamp and drive boot ...
    Good idea in theory, but you have obviously never installed a drive shaft boot.... "

    Not theory at all - have installed many many drive shaft boots and made temporary repair on tour of
    split boots by wrapping entire boot with slab of inner tube rubber cut from usually
    ATV or trailer size tubes and leaving the overlap of a couple of inches on the top - the clamps are
    long enough to trap the inner tube material between the clamp and the boot. Usually carry a slab
    of inner tube rubber with me when I tour a questionable old junker just in case.

    All I was suggesting is that if you think your clamp may be too big - you can just wrap inner tube
    rubber around the outside of the boot under the clamp and gain some gap to prove if the leaking
    is due to lack of clamp pressure before you buy different clamp. The original style clamps
    completely unscrew so you can wrap them around whatever and then tighten them up.

  10. #10
    Registered User lmo1131's Avatar
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    Thanks 44. My comment, on second reading, did sound a bit snarky, and more than a little condescending. My apologies sir.

    As I reported, I swapped out my old 82mm ?ΓΏ clamp this morning and it made a big difference in "gap". An eighty+ mile ride this afternoon got everything good and hot with no drips after being parked an hour. We'll see what morning brings. I've been riding this bike forever ... I guess my pack-rat obsession paid off by not pitching the old clamps.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  11. #11
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    Just for fun, Lew, checked my boot clamps, original 82s, new ones 82s, gap at the front clamp, 11mm, at the backend, 8mm. both are are tight from two years back, the boots possibly might come out of their various moulds with slightly differing thicknesses. '74 900.

  12. #12
    Registered User lmo1131's Avatar
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    ... the boots possibly might come out of their various moulds with slightly differing thicknesses. '74 900.
    這是我想太多(... that's what I think too) and who knows where the parts are molded.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    Here's another fix that has solved my drive shaft boot aft-end drips, on my three Airheads !

    While I had the swing arm, with boot, out of the frame for other maintenance forward of there, I cleaned the front of the drive shaft tunnel where the boot mounts with aerosol brake parts cleaner. Then, using paint stripper, stripped to bare steel that same half inch, following with another wipe of brake parts cleaner.

    I prepped the new boot at the aft end with a wipe of brake parts cleaner. Using 3M Weatherstrip Adhesive (black) as per their instruction, I lightly coated the mating surfaces of both the tunnel and boot, let flash dry. Applied another light coat to the tunnel, slipped the boot over it and quickly clamped it down with an "82" clamp with the screw/nut at the bottom, leaving about 3 - 5mm gap between the clamp ends.

    Agreed, it does take some care to install the assembly back in the frame, rolling the swing arm clockwise about the drive shaft axis helps, to finesse the boot between the frame cross-tubes. As we all have probably come to realize, there is a certain amount of "lost religion" involved anyhow with positioning the forward end of the boot over/around the universal joint and onto the transmission: barley therapy beforehand does help.

    My observation has been that the elongated oval of the tunnel does not allow for complete/equal clamping pressure by the band-clamp. Using the "glue" compensates for that and I've had zero seeps in thousands of miles.

    Come boot replacement time, I just cut them off, use MEK or lacquer thinner to remove the old adhesive and repeat as required.

    FWIW... don

  14. #14
    look out!!! Visian's Avatar
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    One time... in band clamp.... whoops, wrong movie!

  15. #15
    ONE LESS HARLEY 04r1150rs's Avatar
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    be careful and don't over tighten the boot clamp. If so the boots might wrinkle at the ends of the clamp and cause a drip..
    Richard
    2004 R1150RS
    1984 R80 G/S
    2003 Suzuki DRZ 400S

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