Steering Head Bearings Problem

badgermilk · Mar 8, 2011

I need help please folks. I replaced my steering head bearings last year for some Koyo tapered rollers part number 32907 JR3 from Marksman Industrial. Ever since they haven’t been right (the steering was either too stiff or too slack). :confused

So I decided to remove them again and replace with new, again! On removal I noticed that the rubber around the lower bearing dust seal was pretty chewed up. This was due to the seal not sitting all the way in the frame, it was resting on the lower yoke between the bearing and yoke.

After I removed the Koyo bearing I measured them with a digital vernier to be 14.1 to 14.2mm deep. The original axial ball bearings are 14.5mm deep, I have contacted Marksman Industrial who confirmed that the Aprilia RSV steering head kit that they sell is roughly 14mm. I didn’t think the 0.5mm difference would matter but I’m now thinking that it might. So a few questions.

1. Has anyone else had success in installing tapered bearings and what type did you use?

2. Can someone take a look at their lower bearing seal to see if it sits all the way in the frame?

3. Is the lower dust seal supposed to stay still when the bars are rotated? I cant see how this can happen if the lower bearing is fully seated on the yoke.

I don’t know what to do next. Try another tapered head bearing from All Balls (around £30) or pay out for the OEM Aprilia ones around £100?

Sorry for the long message but wanted to get all the facts. Thanks for your help.

TTM · Mar 9, 2011

Hmm, I'm going to be watching this, I just bought the same kit from Marksman Industrial which I was hoping to fit next week! My bearings are JR2's though, not JR3, does one of us have the wrong part?

badgermilk · Mar 9, 2011

TTM did your bearings come with seals top and bottom?
Can you measure the depth of the bearings please?
I don't think there's much difference between the JR2's and 3's but could be wrong. Cheers

TTM · Mar 9, 2011

Yeah they came with seals. The seals are essentially a very thin large diameter washer with a sort of double grooved oring on the end.

On the Marksman website >here< they describe your JR3's as having an "o ring groove" and my JR2's as not. I wonder if they've just sent you an oring without the spacer which makes the inner race sit lower to the bottom yoke making the bottom of the headstock catch on the bottom yoke? This would make sense if your seal is chewed up.

I ordered Steering kit 22-1039, did you?

I'm at work at the moment, but I'll try and measure the bearings when I get home, but I don't have a vernier gauge, only a ruler

I'll take some pictures of the bearings and seals too.

My Dad works for Koyo, I've sent him a text asking him to see what the difference is between the JR3 and JR2.

badgermilk · Mar 9, 2011

Yes I ordered the same kit but it was back in 2009. It sounds like I have the same seal as you - metal washer with a rubber outer. Still not sure why it didn't sit all the way in the headstock frame.

Thanks for your help, hopefully your dad will shed some light. Legend.

I was hoping to have this sorted by Friday for Snetterton but it doesnt look like it will be. Gutted!!

TTM · Mar 9, 2011

The guy at the bottom of this page used the Koyo ones you have on his Futura and seems to be OK. He did use the old seals though.

lester · Mar 9, 2011

Just in the middle of changing to marksman tapered roller bearings on my 2000 mille.(didnt know there was a kit til after i'd bought the bearings alone) the problem i found was that the original bottom seal fouls on the bearing and effectively stops it from rotating freely.I only found this out after fitting the seal and bearing and as i wasnt going to remove a new bearing i got round it by gently peening the dust seal away from the bottom bearing until it rotated freely. the top one does the same, i decided to leave it out and use a smear of silicon on the outside lip to create a seal from the big black plastic seal cover. i know its a bit half arsed but i figure if i know what ive done, i can check it regularly and sort any probs if they arise. + i know better for the next time.
hope this helps

badgermilk · Mar 9, 2011

Lester do you remember the part number for the bearings you fitted?
Does the bottom seal sit inside the frame headstock and do you know if it stays still when you turn the bars? Cheers

lester · Mar 9, 2011

as far as i remember the bearings were 32907 with no oil seal groove which i think is jr2 (i think the jr2 are 14mm deep and jr3 are 15mm deep) anyway the dust seal is meant to sit inside the headstock on both top and bottom and it is pinched between the inner race and the bottom yoke. the upper being held between the inner race and the retaining nut. i suspect yours was mangled cos it was fouling on the bearings like mine and therefore locking the entire bearing instead of the outer race moving on the inner race. which may account for the steering being tight. hope that helps but bear in mind its only me guessing and it may well be a complete load of pony as i am a bit thick!

TTM · Mar 9, 2011

I think lester's right, I've got the bearings in front of me and with the seal on the inner race the seal protrudes too high and presses against the outer race too hard and makes it quite hard to turn. Uploading photos now

TTM · Mar 9, 2011

Packet

Seal on its own

Inner race

Inner race with seal, notice how high the seal comes up compared to the image without the seal

Seal attached to inner race correctly, it has a snug fit around the inner race

Outer race on inner race without seal

With seal. The seal is holding the outer race off the inner race

Compression needed to make outer race touch the rollers

Model numbers

The seals protrude outwards which would create a seal against the inside of the headstock, and upwards which creates a seal against the outer race but makes it all stick. As the outwards lip on the seal would be stopping crap coming through in between the headstock and inner race I reckon the lip that touches the outer race is not needed and you could cut this off with a Stanley blade.

badgermilk · Mar 9, 2011

A big thank you for the info guys and especially for the pics.:thumbup

I think I have figured out the problem.

Marksman sent me the JR3's :angry

The JR3's inner race has a recess on the very inner part. This has caused the upper nut to deform the dust seal. I'm not sure about the bottom seal cos I mangled it getting the bottom bearing off the steering stem. But this must have reduced the overall effective diameter of the bearing considerablly as the recess in the bearing is 2.6mm deep.

Also from your pictures the seal looks completely different. That may explain why it wouldn't sit inside the headstock.

I have measured up the OEM bearing to be 14.5mm and the Koyo to be 14.1mm however the OEM dust seal is thinner than the Koyo bearing. With the dust seals installed both bearings roughly measure 15.2mm.

I think if I get the JR2 bearings all should work fine. I might ring Marksman tomorrow and make a complaint.

Cant thank you enough its been pissing me off for over a year why it wouldn't fit properly. The zone members come through again :thumbup

TTM can you just confirm that the JR2 inner bearning doesn't have a recess like the JR3?

TTM · Mar 9, 2011

Yeah, no inner recess, my last picture (under "model numbers") has a picture of the bottom of the inner race on the right.

Excellent news you've figured it out at least, and that I know mine are right. I phoned Marksman last week so see if they'd send just a seal and they seemed alright to talk to, so hopefully they'll be OK with you

TTM · Mar 11, 2011

Badger, any luck with this?

badgermilk · Mar 11, 2011

Yes got a good result I contacted marksman industrial yesterday and explained the problem and they sent out some replacements straight away free of charge. I will fit them tomorrow and let you know how I get on. Happy with the service from matksman though

badgermilk · Mar 14, 2011

Received the new bearings and seals and fitted them over the weekend. I am now very happy, the new bearings and seals were a much better fitt than the old ones. I wish I had sorted this problem months ago, the bike handles completely differently steering is much smoother.

TTM if you need any help or advise fitting your bearings let me know I must have stripped the front end of my bike now half a dozen times lol

Only problem I now have is with my Ohlins steering damper that I removed to install the bearings. When I removed it I noticed that the bushes from the mounting bolt are missing. Probably never installled by the previous owner. I will contact Ohlins and see if they can send out replacements.

TTM · Mar 21, 2011

I missed your reply, glad it's all sorted now. I fitted mine a few days ago and it's a big improvement too

I cut that second lip off my seal as it felt to be slowing the steering movement a little when I first installed it - probably overkill now I look back but the bottom part of the seal is a good fit against the headstock.

To anyone who may come across this in the future, make sure you have JR2's and not JR3's.

Garvey20031 · Mar 22, 2011

right little confused, the bearings i have are the ones in the pics

, but Im a little stuck on which way around the bottom ones go? The old type the race is at the bottom then the bearings, but theses the race is not tight against the pole?

Sabre · Mar 23, 2011

Have you driven the race all the way on to the steerer tube (pole)?

Garvey20031 · Mar 23, 2011

its ok, I was just being stupid

all fitted now

finished 3am this morning, hope it passes the mot now

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