Front fork and gaiters

[DiecastDick]

Just installed gaiters on my bike's fork and was was happy at how it looked. Until we put it off the center stand.  

The gaiters in the pic measured 7 1/2" and compressed to about 6 1/2" when off the center stand (no rider). Do you think the fork needs some adjustment? Now that I recall things I do get the opinion that they are probably bottoming out because I think when I run over some potholes I get the feeling it always sounded "violent" for comfort. Not sure but maybe you guys can tell with just the numbers I gave. TIA  

[Barry]

The gaiters in the pic measured 7 1/2" and compressed to about 6 1/2" when off the center stand (no rider). Do you think the fork needs some adjustment? Now that I recall things I do get the opinion that they are probably bottoming out because I think when I run over some potholes I get the feeling it always sounded "violent" for comfort. Not sure but maybe you guys can tell with just the numbers I gave. TIASmiley

If the forks compressed 1" when taken off the stand that is fine. It means you have 1" of unladen sag. Mine is 30mm which is near enough certainly you don't have too much unladen sag and so that is not the issue with the gaiters.

The noise you get over pot holes may be the opposite of what you are thinking in that the noise occurs when the forks are at full extension. That's the first thing that happens when you ride into a pot hole, the fork extend fully as the wheel drops into the hole. Same happens when you ride off a kerb if that helps with the diagnosis. Clonks at full extension are not an uncommon problem.

The forks will compress going out the other side of the pot hole but it has to be a very severe impact to achieve full compression and there is a hydraulic bump stop so it shouldn't clonk.  Clonking at full extension is much more common even though it's not our natural instinct to realize that is what is happening to the forks. A cure is possible by increasing rebound damping but I would first check the diagnosis.

[montmil]

The gaiters shown are not the correct bits for the R65, hence the 'bunched up' look. R65s do well with a 12-13 rib boot. I believe the BMW part is #31 42 2 002 115.

There is a rubber bump stop within each fork assembly that disintegrates over time. Not a difficult replacement but will do a lot to eliminate the thunk with sharp bumps. Check fork oil levels and fluid weight. The fork oil is a way to alter the damping and rebound responses... just a little.

[nhmaf]

Actually, there are 11-rib BMW gaiters that I think work best for the shorter travel R65 forks.  The longer travel /6 /7, etc forks have a 13-rib gaiter.   A BMW dealer or someone who sells BMW parts will have them.

[montmil]

Actually, there are 11-rib BMW gaiters that I think work best for the shorter travel R65 forks.  The longer travel /6 /7, etc forks have a 13-rib gaiter.   A BMW dealer or someone who sells BMW parts will have them.

Point taken, Mike. I was surfing Hucky's when I tripped across the photo. Either would be better than 20+ ribs.

[DiecastDick]

Thanks for explaining that thing about the sound coming from extension rather than the compression.

I meant to write 7 3/4" while on center stand but just the same 1 1/4" of unladen sag shouldn't be the issue.
I got those gaiters on ebay and relied on the stated measurement range. Now I have the wrong kind. Oh well gotta look again.

Thanks for the part number Monte, Mike. We were planning on checking the oil level as well.

[Dustybin]

Nice chunky looking tyres there, who makes them?

[DiecastDick]

Those are Shinko 705's Tony

Nice chunky looking tyres there, who makes them?

[marcmax]

What size Shinko's are you running. I can't find anything but 19 and 21 inch front tires in the 705 in the States?

[Barry]

I meant to write 7 3/4" while on center stand but just the same 1 1/4" of unladen sag shouldn't be the issue.  

1 1/4" of unladen sag is spot on what it should be.

[DiecastDick]

Monte, the part number you gave lists the following model compatibilities (2wheelpros.com):

1967-1969 BMW R50US (T50)
1967-1969 BMW R60US (T60)
1967-1969 BMW R69US (T69)
1969-1973 BMW R50/5 (2476)
1969-1973 BMW R60/5 (2476)
1969-1980 BMW R75/5 (2476)
1974-1976 BMW R60/6 (2476)
1974-1976 BMW R75/6 (2476)
1974-1976 BMW R90/6 (2476)

Would you know which is closest to my bike? Mine is a 1979 model.

The gaiters shown are not the correct bits for the R65, hence the 'bunched up' look. R65s do well with a 12-13 rib boot. I believe the BMW part is #31 42 2 002 115.

There is a rubber bump stop within each fork assembly that disintegrates over time. Not a difficult replacement but will do a lot to eliminate the thunk with sharp bumps. Check fork oil levels and fluid weight. The fork oil is a way to alter the damping and rebound responses... just a little.

[AlfromNH]

I have a pair of stock R65 gaiters, I went with boots instead. They're used, and one has a small split, but let me know if your interested.

[disco51]

Another option is to go with the Rancho shock boots.  Snowbum mentions these as a good alternative in his fork article.  They are cheap and easily accessible at your local FLAPS.
I've also found that the boots may need a small air hole at the bottom to prevent the bunching up.  Not sure if that's already on that particular set, but I had to add one to the Rancho boots to prevent that bunched up look on full compression.

[marcmax]

I put a set of the 11 rib gaiters on mine and they work perfectly. I did have a problem with them collapsing due to no air flow during compression/ expansion cycle.

My mentor in all things Airhead told me to check the top of the gaiter. There is a hole through the rubber at the top. He said to drill a small hole through the bottom of the triple tree and insert a roll pin through the triple tree and into the hole in the top of the gaiter. It allows air to pass in/out of the gaiter and locates it so it doesn't shift around on the fork stanchion.

Haven't had a problem since.

[montmil]

As I mentioned in my earlier post, I snagged that photo and part number off Hucky's site just to show what the boots with fewer ribs look like. To determine which boot would be 'correct' for your R65, suggest calling with upper and lower diameters of the stanchion and lower slider. As there were no "R65 specific" boots, you'll need to confirm with the seller.

Bob's BMW also has some excellent parts dept folks answering questions just like yours.