A significant saving over the OEM bearings
NTN 32907XU Taper Roller 35 mm ID Roller Bearing, 55 mm OD | RS
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Headrace bearings?
Yes headrace bearings and made in Japan
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since fitting non OEM taper bearings to my v85tt I have a steering wobble at high speeds.
unfortunately I have not narrowed down exactly what is causing it as I changed tyres at the same time and had a wheel bearing failure.
since then I’ve had new wheel bearings and hub spacer, didn’t fix it, new wheels c/w bearings and spacers, made a small improvement but didn’t fix it, and new rear tyre of the same type, also no change.
also had the torque checked on the headstock bearings twice, apparently they were slightly too tight. redone looser, didn’t fix the wobble.
if it’s tyres I will be surprised, as nobody else has reported any issue with them - michelin road 6.
You shouldn’t torque up taper roller bearings, they need a small clearance or they will bind. They should be run as loose as possible just enough so there’s no detectable play when checking with the fork legs. Sounds to me like they’re still too tight. Try backing them off.
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they were fitted at the dealer, then while I was in over in England checked by a guy who races aprillia (he’s got PADS etc for services but doesn’ sell bikes).
Then checked again at a different dealer in Ireland after I got back.
I had read on here that being too tight can cause issues which is why i got them checked, the aprillia guy said he isn’t a fan of the tapered bearings although he couldn’t say if that was definitely the source of the problem.
I’m thinking of getting the OEM bearings just to rule that out, even though the two part design isn’t as strong or cheap as the replacements.
Next tyre change I will go back to metzlers, again another thing to rule out, never had a wobble with them, really good in the wet, don’t last as long as michelin though at all.
Hi Sid.
I used these tyre’s on my V85tt and also most bikes I can get them for including my big old Stelvio 2008 model. I find them very pressure sensitive and I run them slightly higher than the standard pressure. I know all the tyre experts will tell me its dangerous but it works for me. They do tend to weave at high speed so maybe try lowering the front pressure slightly.
I am no expert but I this works well for me.
Cheers.
Michael.
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I was amazed that the OEM bearings were still ball not taper roller, I thought most manufacturers changed to taper rollers in the 90s other than on smaller cheaper models?
I think that in this application ball bearings are technically slightly superior due to less drag from grease and friction but they are more fragile.
This taper head race bearing installation guide from SRM is very good Taper head race fitting (SRM)
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my 1970 V7 special still runs on the original taper roller head bearings. I got the bike early 80’s. re-grease every few years or so. Has done silly mileage 180,000 ish KM
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Are the forks straight in the yokes and at the original height?
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forks have never been lowered/moved in yokes from new.
the only adjustment was a half click firmer on the preload, which didn’t solve the wobble.
Curious what pressures you run on your Michelins? Also who balanced them after fitting and are they right?
When you say the wobble is at high speeds I’d doubt if it’s anything to do with bearings. They’d have to be seriously loose not to be apparent at lower speeds.
Makes me also wonder about brake discs and associated bits. Just spitballing here. Are they semi floaters?
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the disks are the same floating disks from the bike was new, they were found to be loose at last service approx. 1-2k miles ago but the wobble is present since almost 2 years ago when the tyres, wheel bearings, and head stock bearings were changed. the disks passed MoT last year and were not loose until recently.
tyre pressures are always (unless rear has lost air, which it does over a few weeks) 2.8bar rear, 2.5bar front. same pressures have been fine on dunlop trailsmart max, dunlop meridian, metzler roadtec 01.
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@Philabeg51 Thanks for spotting that Sid said ‘high speed’ i had missed that.
Sid, is it possible that forks or frame are bent or the wrong suspension units are fitted etc and your steering wobble is the beginning of a tank slapper (what the more dramatic types across the Atlantic call a ‘death weave’)
If not a high speed wobble is much more likely to be caused by wheel balance: tyre or rim than steering bearings.
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it does feel like the start of a tank slapper but I’ve always eased off before it got that far.
I don’t see how the forks or frames would have got bent while at the dealer getting bearings replaced, it was not wobbling prior to tyre change and went into dealer about a week after the tyre change.
wheels were balanced each tyre changed and since I changed the wheels entirely to brand new wheels c/w bearings, unless he didnt balance the front wheel, I don’t think it’s that either. back tyre has been changed and balanced while i was at the tyre place. front was done in england while I was not present, removed from old wheel and fitted to new wheel.
one thing i suspect but hasn’t been mentioned is worn shock absorber, 36k on the bike and at least 50% of that with pillion and luggage, probably has put a fair amount of wear on it?
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In other words it ain’t the tyres manufacturer. Pressures, for me at least, sound a tad on the high side. especially if cold settings. If nothing else I’d try a couple of pounds less on both ends, see if you can notice any different. (I have never liked using the ‘bar’ scale. PSI and finer divisions tells me more accuracy and a quality aneroid gauge. Yeah, I’m a pedant! 
)
You say discs ‘found loose’? The discs themselves of the bobbins? I’d be more interested in the bobbins, giving them all a clean and twirl round with brake cleaner might eliminate one more variable at least.
My other thought is the mild possibility of something on the rear since sounds like you have been round the houses with just about everything at the front? It’s a puzzler for sure.
those are the recommended pressures for V85s, I use the finer scale kPa or whatever it is on the gauge which is equivalent to bar but in decimal steps so it’s more accurate. there was never any wobble at these pressures with other tyres, at any speed. I don’t run the tyres softer as luggage or pillion use is frequent.
it’s the play of the disk on the bobbins which is excessive, it’s a shame because plenty of metal left on the disk part but been checked and told it will fail MoT so they have to be changed.
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Hmm that could be at least a part of your problem? BTW having changed out discs recently get yerself a set of S/S or Titanium bolts. The cheese curd originals are prone to shearing on you.