Between the hours of 7pm and 9pm on most evenings, in our house its a cycle of Emmerdale, Corry, and sometimes Emmerdale/Corry again. Hence a good time to retire to the garage and fiddle.
Fiddling with the back end of the BMW GS showed a little bit of play at the rear wheel. On the GS this can be either the bevel output bearing or simply play in the paralever pivot bearings. You check which it is by putting the rear brake on, and then feeling for play with the brake applied - if it still moves, it's the paralever bearings - if no play, it'll be the bevel bearing.
This time its the paralever pivot bearings, which can be adjusted simply enough.
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| Off with the back wheel - you adjust the inner pivot. Its mate on the outside is a fixed pivot and not adjustable. |
This is the first time I've tweaked these, so they'll probably still have the original Loctite on them meaning you're best applying a bit of heat to soften the Loctite before attempting to loosen the locknut and the adjusting pin. You need a 30mm socket to slacken the locknut and a good quality 12mm allen key for the pin. I bought a cut out socket and allen driver some time ago to do this job, more pertinent for tightening up to ensure the pin doesn't move when torqueing the lock nut back up.
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| Not strictly necessary but only about £10 - Laser Tools 4740. |
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Paint stripper Hot air gun to heat up locknut & pin. Move the rubber boot out of the way just in case. Direct heat at the pin not the casing. |
This is the locknut and adjustable pinion. The other side is non-adjustable and has no locknut. Its fastened to a high torque and uses high strength loctite. The nut needs to be heated to around 120c in order to soften the loctite. I got it up to about 95c, tried it and it loosened off fine.
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| Flash git has got a non contact surface thermometer. (seen them in Maplins for about £18 some time ago. Used mine for trying to balance central heating radiators) |
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| Breaker bar and 30mm socket to undo the locknut |
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| Pivot pin, no marks - cleaned off all the old loctite before putting back |
Off comes the locknut and out comes the pin. The pin was a little stiff coming out due to the loctite, but another blast for a minute or two with the hot air gun to soften a bit more. (its a hot air paint stripper in its day job). All the old Loctite got cleaned off on the pin thread and the internal thread with a little scraper pick and a bit of acetone. You can get general purpose acetone from high street chemists in little 50ml bottles for about £1.50 or off ebay in larger volumes if the missus objects to you nicking her nail varnish remover.
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| Pivot pin wound back in by hand as far as you can then torque it up. |
Pivot pin back in and wound in by hand until you feel the preload point as it just bottoms out. By then its getting too tight to turn without a lot of effort. On with the torque wrench and I've tightened to 12Nm. I'm not bothering with loctite again as it'll be easier in future to adjust without the palaver of heating up and winding the pin out to clean it etc etc. - its got a f*****g tight locknut on it after all. You can also then do the adjustment without taking the rear wheel off by working through the spokes with an extension bar. Also, no more Loctite means no more application of heat to soften it, which also means no more risk of the grease in the needle bearings heating up and dropping out.
Locknut next, and this is tightened up to 160Nm - important that the pivot pin doesn't move and tighten further when you do this, hence the special socket to hold the pin with the 12mm allen key whilst you tighten the locknut. Easier with a third pair of hands for this bit. I had to wait for the advert break during the second episode of Corry at 8:45ish for my third hand. I also put a witness mark on the pin at 12 o'clock position to double check it didn't move.
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| 30mm socket with cutaway and 12mm allen key held by 10mm spanner to stop pin moving as the locknut is tightened. |
Refit the rubber boot, back on with the backwheel and jobs done.
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| Something I've always done is put a mark on the part of each rear wheel nut facing the centre as a quick check that they're not loosening off - never had one loosen but still do it anyway! |
