The Saga Begins: January 2000
Anyone who owns a 1998 and newer KTM has the PDS damping system, which is
pretty cool because there's no shock linkage to maintain. One slight problem,
though: the bearing in the lower shock mount is a teflon coated heim-type bearing
(sometimes referred to as spherical-type). The heim isn't the problem; actually it is
necessary to handle the slight side-to-side movement that would destroy a
conventional bearing in no time. The KTM engineers decided to use a bearing with
a "maintenance-free" teflon coated race. In theory, good choice. In reality, bad
choice. Because of the various movements of the swingarm, the seals can't keep
out all the dirt and water from contaminating the teflon coating (the seals actually
move around a bit). Normally you would smear a bunch of grease in the heim and
around the seals, but that's bad, because the grease breaks down the teflon
coating. So you're kinda darned if you do, darned if you don't grease the thing.
Without any servicing at all (as with mine the first year I owned my KTM), the teflon
breaks down after 60 or 70 hours of use and play develops in the swingarm. I
found this out by putting the bike on a stand and lifting up and down on the
swingarm. The end of the swingarm had about 1/4 inch of movement before
engaging the suspension.
What's the solution?
Prolonging the life is about all you can hope for. And since they can cost $40 or
more, you don't want to replace these too often. In January 2000 I replaced the
heim bearing and began wrapping the lower shock mount with an old inner tube.
The goal was to keep as much water, dirt, and mud from contaminating the teflon
coating. Also, I've been regularly pulling out the seals and smearing a light layer of
waterproof grease around the edges. The second heim lasted about 100 hours,
so these precautions added 30-40 hours to its useful life.
Another thing I would recommend is buying a heim bearing tool from eRider (look
under "Cool Tools"). When I replaced the bearing, I used the 'ol hammer and
socket method of driving out the old bearing and put a groove in the soft aluminum
housing. My Dremel tool smoothed it out, but the bearing tool is a better alternative.
While I'm plugging eRider, I'll also mention that they have lots of cool stuff
especially for KTM's that can't be found anywhere else.
Update: February 2001
Several individuals on various internet discussion groups have researched this
issue and discovered a greaseable, non-teflon heim bearing. Apparently INA and
ELGES make both a teflon-coated and a geaseable equivalent. Here's what the
part numbers were listed as:
GE16PW = (Teflon)
GE16PB = (Grease)
Hirschmann Engineering in the Chicago area sells the INA manufactured
replacement heim. The greaseable, bronze-lined bearing price is approximately
$19 (part number SC-16). Hirschmann can be reached at 847-468-9700. The
greaseable version can be used with a grease nipple if you're handy with a drill.
Use your best judgement. However, by the time you buy new bushings and seals,
the price may not be that much less than the price for the whole set from discount
KTM parts dealers like Cycle Hutt or Cycle Zone KTM.
Update: May 2001
Okay, I finally had to replace the damned thing. Total life on heim #2 was about 18
months, compared to 11 months on the first one. But the second time was much
easier than the first, with help from the eRider heim bearing tool. Even though it is
basically a 6-inch piece of round steel, it is the perfect size for the job and is milled
so that the pressure is only on the race, and not the ball of the heim. A few sharp
hits with a small sledgehammer was all it took to drive out the bad bearing (no heat
necessary). Installation of the new bearing wasn't too bad, either. I didn't have to
stick the bearing in the freezer or use heat of any kind. I have taken the same
precautions on heim #3 and hope to get another 18 months of use.
O.K., you say...this is all fine and good, but how the hell do I replace the *%?$#
thing?
Heim Removal & Installation
1. Remove the swingarm. Not completely necessary, but you need to grease the
swingarm bearings anyway. Don't forget - gotta take off the chain guide, too.
2. Pop out the bushings using a drift or other long metal object. Work at them from
within, attacking them from the opposite sides. After a year of corrosion, they may
need some persuasion.
3. Pop out the seals around the heim bearing using a flat blade screwdriver.
4. Use a socket or eRider's heim bearing tool to drive out the bad heim. Pound on
it like hell, and use some heat around the housing if it won't budge. Be careful not
to get the bearing mis-aligned on the way out or it will dig into the soft aluminum
housing. If this happens, a Dremel tool or file can be used to smooth off any rough
spots. The heim can be removed from either side.
5. Line up the new bearing and start tapping it gently until you know it's going in
straight. A night in the freezer (the bearing, not you) helps with installation. If you're
using a socket as a driver, make sure it is only contacting the outer race and not the
round thingie that swivels inside (you DON'T want to ruin your new $40 bearing,
trust me). Then pound like hell until it's centered in the housing.
6. Tap in the new seals (don't even think about trying to re-use the old ones). A little
dab of grease around the seal lips is a good idea.
7. Put in the new bushings.
8. Re-assemble the swingarm and shock. Take my advice...wrap the lower shock
mount with something, anything to keep some of the crap from ruining your bearing.
Anyone who owns a 1998 and newer KTM has the PDS damping system, which is
pretty cool because there's no shock linkage to maintain. One slight problem,
though: the bearing in the lower shock mount is a teflon coated heim-type bearing
(sometimes referred to as spherical-type). The heim isn't the problem; actually it is
necessary to handle the slight side-to-side movement that would destroy a
conventional bearing in no time. The KTM engineers decided to use a bearing with
a "maintenance-free" teflon coated race. In theory, good choice. In reality, bad
choice. Because of the various movements of the swingarm, the seals can't keep
out all the dirt and water from contaminating the teflon coating (the seals actually
move around a bit). Normally you would smear a bunch of grease in the heim and
around the seals, but that's bad, because the grease breaks down the teflon
coating. So you're kinda darned if you do, darned if you don't grease the thing.
Without any servicing at all (as with mine the first year I owned my KTM), the teflon
breaks down after 60 or 70 hours of use and play develops in the swingarm. I
found this out by putting the bike on a stand and lifting up and down on the
swingarm. The end of the swingarm had about 1/4 inch of movement before
engaging the suspension.
What's the solution?
Prolonging the life is about all you can hope for. And since they can cost $40 or
more, you don't want to replace these too often. In January 2000 I replaced the
heim bearing and began wrapping the lower shock mount with an old inner tube.
The goal was to keep as much water, dirt, and mud from contaminating the teflon
coating. Also, I've been regularly pulling out the seals and smearing a light layer of
waterproof grease around the edges. The second heim lasted about 100 hours,
so these precautions added 30-40 hours to its useful life.
Another thing I would recommend is buying a heim bearing tool from eRider (look
under "Cool Tools"). When I replaced the bearing, I used the 'ol hammer and
socket method of driving out the old bearing and put a groove in the soft aluminum
housing. My Dremel tool smoothed it out, but the bearing tool is a better alternative.
While I'm plugging eRider, I'll also mention that they have lots of cool stuff
especially for KTM's that can't be found anywhere else.
Update: February 2001
Several individuals on various internet discussion groups have researched this
issue and discovered a greaseable, non-teflon heim bearing. Apparently INA and
ELGES make both a teflon-coated and a geaseable equivalent. Here's what the
part numbers were listed as:
GE16PW = (Teflon)
GE16PB = (Grease)
Hirschmann Engineering in the Chicago area sells the INA manufactured
replacement heim. The greaseable, bronze-lined bearing price is approximately
$19 (part number SC-16). Hirschmann can be reached at 847-468-9700. The
greaseable version can be used with a grease nipple if you're handy with a drill.
Use your best judgement. However, by the time you buy new bushings and seals,
the price may not be that much less than the price for the whole set from discount
KTM parts dealers like Cycle Hutt or Cycle Zone KTM.
Update: May 2001
Okay, I finally had to replace the damned thing. Total life on heim #2 was about 18
months, compared to 11 months on the first one. But the second time was much
easier than the first, with help from the eRider heim bearing tool. Even though it is
basically a 6-inch piece of round steel, it is the perfect size for the job and is milled
so that the pressure is only on the race, and not the ball of the heim. A few sharp
hits with a small sledgehammer was all it took to drive out the bad bearing (no heat
necessary). Installation of the new bearing wasn't too bad, either. I didn't have to
stick the bearing in the freezer or use heat of any kind. I have taken the same
precautions on heim #3 and hope to get another 18 months of use.
O.K., you say...this is all fine and good, but how the hell do I replace the *%?$#
thing?
Heim Removal & Installation
1. Remove the swingarm. Not completely necessary, but you need to grease the
swingarm bearings anyway. Don't forget - gotta take off the chain guide, too.
2. Pop out the bushings using a drift or other long metal object. Work at them from
within, attacking them from the opposite sides. After a year of corrosion, they may
need some persuasion.
3. Pop out the seals around the heim bearing using a flat blade screwdriver.
4. Use a socket or eRider's heim bearing tool to drive out the bad heim. Pound on
it like hell, and use some heat around the housing if it won't budge. Be careful not
to get the bearing mis-aligned on the way out or it will dig into the soft aluminum
housing. If this happens, a Dremel tool or file can be used to smooth off any rough
spots. The heim can be removed from either side.
5. Line up the new bearing and start tapping it gently until you know it's going in
straight. A night in the freezer (the bearing, not you) helps with installation. If you're
using a socket as a driver, make sure it is only contacting the outer race and not the
round thingie that swivels inside (you DON'T want to ruin your new $40 bearing,
trust me). Then pound like hell until it's centered in the housing.
6. Tap in the new seals (don't even think about trying to re-use the old ones). A little
dab of grease around the seal lips is a good idea.
7. Put in the new bushings.
8. Re-assemble the swingarm and shock. Take my advice...wrap the lower shock
mount with something, anything to keep some of the crap from ruining your bearing.
| "Heim" In Trouble |
| The Infamous Heim Bearing |
| Not pretty, but effective |