Trap for young players

[Bass]

I have been doing a bit of work on the DR for no particular reason other than I felt it was time to have a look.
Back wheel out and stripped down the suspension linkages.
The linkages were all completely pristine and so a bit of fresh grease and back together they went - awesome. The wheel bearings were pretty tired however.
No sweat - common size bearings and common diameter seals or so I thought. The bearings were readily available but the seals were an odd width and so had to be sourced through Suzuki NZ but it was an overnight courier thing and so no drama as it turned out.

Then the fun started.
Now changing a set of wheel bearings should be a pretty uncomplicated task and the setup I was looking at, seemed pretty standard to me.
There was a single bearing and seal in the cushion drive - no sweat, a quick warm with the propane torch and straight in. There are 2 bearings in the wheel with the usual spacer in between.
Now the normal setup here is that the 2 bearings go up against shoulders in the hub and the distance between the 2 shoulders is about 2 thou less than the length of the spacer that holds the bearings apart. This arrangement allows the bearings to run freely with all the axle bolting pressure taken along the various spacers and bearing inner races, on the axle. It also locates the wheel accurately because it can only move a couple of thou from side to side.
That appeared to be exactly the arrangement I was looking at.

So, warm up the cush drive side of the hub and tap the bearing down to its shoulder. Then turn the wheel over, drop the axle spacer in and run the second bearing into the hub until the inner comes up against the spacer. All good so far.
Then I try and put the seal and outer spacer into place, but it's just not happening. The recess is not deep enough and so the seal will not go all the way home. It just keeps popping back out at me.
This is weird!
Check the seal against the one that it's replacing and it's identical.
What the hell is going on here?
Get the verniers out and check the recess depth. Sure enough, it's a bit over 2 mm too shallow for the seal to be retained.
Why?
Finally work out that the only possibility is that the first bearing I put into the wheel cannot go up against the shoulder - also that there must now be about 2 mm clearance between the second bearing and it's shoulder, in turn meaning that the assembly of 2 bearings and their spacer has to move over about 2 mm in the hub.
This proved to be exactly the case and of course all the gaps (or not) were hidden behind the bearings and so impossible to either see or measure. The thing that pissed me off most of all was that I had to move one of the bearings in the hub by driving against the inner race which is of course potential really bad for the bearing. However, I had no choice and so I warmed the hub up as much as I dared and in the event, didn't need much force to get the bearing to move. Big sighs of relief and the seal now goes in and retains, but only just.

So the bike is now back together and everything seems fine but this worries me.
It worries me because it means that the wheel is potentially free to move sideways on the axle by that 2 mm clearance that I have been harping on about and so to push the seal out again. Now, this must have always been the case and it has not happened so far. I therefore assume that the bearings are a tight enough fit in the hub to remain in place, but it still seems to me, to be piss poor engineering and so I am wondering if anyone else out there has encountered this one before.
Could it be that I simply have a wheel where someone has screwed up the internal machining?
However, the possibility exists that this is standard and is the reason that I mention it here.
If you have a DR 650, the major points are: -
1. Do not let the rear wheel bearings deteriorate to the point where they might turn in the hub because they can move sideways enough to displace the seal on the right hand side.
2. If you are replacing the rear wheel bearings, insert the RHS one first!
3. If the bearings are a tight enough fit so that the wheel is laterally located by friction alone, a bit of heat when removing or inserting bearings is probably a good idea. You do not want them picking up on the hub!

Lastly, all the bearings that came out had a rubber seal on one side only. All the bearings that went back in were 2RS. I suspect that the only reason Mr Suzuki fitted 1RS bearings was that he repacked them with some special grease (e.g. water resistant). Can anyone out there confirm this or correct me please?
In any case, because I did not have any particularly high performance lubricants available, as stated 2RS bearings went back in but I would like to know for future reference.

[ducatijim]

M8, wot a commotion!:yawn:

I did mine a while ago now and all I did was bang both the buggers out, cold, and bang the new ones in again, also cold.

Done.:beer:

[That looks like fun]

Cant help you much with the bearings. I havent pulled a Suzuki to bits for many years. What you have described sure dont sound right tho :oi-grr:
However, Grease, Mobil 1 lithium Based. Its blue and bloody good :woohoo:
Packed some TK Bedford front wheel bearings with it once. Standard practice where I worked was not to wash new bearings, just pack em and fit em.
Six months later they failed COF, much to the disgust of the owner :angry2: Jacked it up and spun the wheels. Sure enough rumbled like hell :crazy:
Stripped the bearings out and found that the micro thin protective coating that they put on wheel bearings to stop them rusting was still there. Washed it off (should have done that in the first place) and bearings were faultless.
The grease was to good and the protectant hadnt just dissapeared like it normally did.
Also being Lithium Based it is good in water. Thats why they use it to lube prop shafts on boats
:beer:

[Crisis management]

I don't recall having that sort of drama Neil and I had done the DRs bearings 2 or 3 times I think, the sealing is crap and they rust out badly with a few river and sea immersions.
I suspect the machining is incorrect in the hub or the spacer is too long between the bearings.....never happen in a KTM (said pompously).


I'm off to see if me water pump is leaking...its scheduled maintenance at 15,000 kms and only takes 2 days to do....where's the BIG hammer???:crazy:

[Taz]

I'm off to see if me water pump is leaking...its scheduled maintenance at 15,000 kms and only takes 2 days to do....where's the BIG hammer???:crazy:

Christ 2 days?? Mine took an hour. Didn't even have or remove anything to get at it either :)

[Crisis management]

Christ 2 days?? Mine took an hour. Didn't even have or remove anything to get at it either :)

Note to self....find a self deprecating humour emoticon

Seriously needed around here.

[Bass]

M8, wot a commotion!:yawn:

I did mine a while ago now and all I did was bang both the buggers out, cold, and bang the new ones in again, also cold.

Done.:beer:

Excellent!
In that case I'll get you to do mine next time.
Bear in mind though, that I prefer to do the job before they are trying to fall out of their own accord.

[Bass]

I don't recall having that sort of drama Neil and I had done the DRs bearings 2 or 3 times I think, the sealing is crap and they rust out badly with a few river and sea immersions.
I suspect the machining is incorrect in the hub or the spacer is too long between the bearings

These bearings have actually survived quite well and the seals were still in reasonable order. I do suspect that the hub machining is wrong though - it just makes no sense otherwise. I doubt the spacer is overlength because the wheel wouldn't go into the swingarm if it were.

[Bass]

However, Grease, Mobil 1 lithium Based. Its blue and bloody good :woohoo:

:beer:

You're right! It is!
It would need to be at the price.
Actually, I tend to think that Mobil make some very good specialist lubricants. I design refrigeration systems and we have got to the point where we specify only Mobil for the very low temperature stuff (-40 C)

[Taz]

Could you make or get made a spacer (shim?) to pack it out with?

[Bass]

Could you make or get made a spacer (shim?) to pack it out with?

Yes I could and that's a very sensible idea. Thanks

[Transalper]

Before messing with it have you read the manual?
For a start it says to install the right side bearing first (which you seem to have learnt from trial and error) and from the diagram it looks to me like you can expect a clearance inside the left one when you then do it.
I don't remember doing the bearings on any of our DRs myself but I have attached a screen shot of part of the manual page so you can look and make your own judgment.

[Crisis management]

What is this manual thing you talk of?
Is it a south island thing?
Am I missing out?
Will it improve my quality of life?
What has it to do with motorcycles?


:wacko:

[Transalper]

lol, it can improve the quality of your life on some occasions. I downloaded mine from somewhere long time ago. It does however lack some stuff about woman I'd like to know though, but then I suspect the info on that subject would turn out to be wrong anyway as they are likely to have changed the rules as soon as it was printed :wacko:.

[Bass]

For a start it says to install the right side bearing first (which you seem to have learnt from trial and error) and from the diagram it looks to me like you can expect a clearance inside the left one when you then do it.


Thanks for that and no, I didn't read the manual as the job appeared to be totally straightforward. Doh!
However, as I said, I expected some clearance. There needs to be at least a few thou (say about 75 microns if we go metric) to avoid axially loading the bearings: -
1. Under bolting (axle nut) loads or
2. Temperature changes - the alloy hub will expand a lot faster with temperature than the steel axles and spacers.

I didn't measure the total clearance accurately, but I can say with certainty that it was between 2 and 2.5 mm. Now I admit to being not particularly bright, but I can't see why the gap needs to be that big. As I discovered, if for any reason the wheel moves axially on the bearings, the gap is large enough to allow it to pop the seal out.
Mr Suzuki is a better engineer than I will ever be and I would like to know why he has done it this way - for curiosity's sake if nothing else.

Lastly, it has occurred to me over years of fiddling with all types of things mechanical, that some of these well written workshop manuals, from time to time, tell you to do things in a certain way so as to get around design eccentricities or even design flaws. I wonder if this is one of those times?
This particular manual assumes a well equipped workshop with loads of special tools.

[Bass]

For a start it says to install the right side bearing first (which you seem to have learnt from trial and error) and from the diagram it looks to me like you can expect a clearance inside the left one when you then do it.


Thanks for that and no, I didn't read the manual as the job appeared to be totally straightforward. Doh!
However, as I said, I expected some clearance. There needs to be at least a few thou (say about 75 microns if we go metric) to avoid axially loading the bearings: -
1. Under bolting (axle nut) loads or
2. Temperature changes - the alloy hub will expand a lot faster with temperature than the steel axles and spacers.

I didn't measure the total clearance accurately, but I can say with certainty that it was between 2 and 2.5 mm. Now I admit to being not particularly bright, but I can't see why the gap needs to be that big. As I discovered, if for any reason the wheel moves axially on the bearings, the gap is large enough to allow it to pop the seal out.
Mr Suzuki is a better engineer than I will ever be and I would like to know why he has done it this way - for curiosity's sake if nothing else.

Lastly, it has occurred to me over years of fiddling with all types of things mechanical, that some of these well written workshop manuals, from time to time, tell you to do things in a certain way so as to get around design eccentricities or even design flaws. I wonder if this is one of those times?

[Taz]

Manual pfft! When has any red blooded Kiwi male used a manual?? That's just as bad as asking for directions or being good in bed!! Over rated maybe?























I'm Australian by the way so always read my manual from cover to cover, Use a gps to find my way and am very very good in bed :lol:

[Bass]

What is this manual thing you talk of?
Is it a south island thing?
Am I missing out?
Will it improve my quality of life?
What has it to do with motorcycles?


:wacko:

Answers.
It is a book of words explaining various uses for your hand
Yes
Are you married?
Yes, if you are married.
It describes an activity typical of KTM owners.

:whistle:

[Taz]

It describes an activity typical of KTM owners.

:whistle:

Hey!!! Not fair!! :angry2:





Anyway I use both hands. And if I wasn't a wanker I wouldn't have three beautiful kids. Ah such is IVF :tugger: :)

[Bass]

Hey!!! Not fair!! :angry2:





Anyway I use both hands. And if I wasn't a wanker I wouldn't have three beautiful kids. Ah such is IVF :tugger: :)

Oh dear!!
How embarrassing Andy!
My profound apologies - I was talking about high levels of maintenance.
Oh well.... perhaps it's the same thing in the end.

:Oops:

[Taz]

I was talking about high levels of maintenance. :Oops:


:o Oh ummm yeah that's what I was talking about too :o Honest :lol:

[MXNUT]

I'm Australian by the way ....................................

That now explains soooo many things :weird: :spanking: :tugger: :finger: :moon:

[Transalper]

Um yea, back to the book, it's a pity it don't seem to give any actual indication of how big they think the clearance should be. At least at the glance I gave it I didn't see anything there and I can't go back for another look now as I've gone to work.
Have to agree Bass, everything you say about the gap being excessive sounds reasonable.

[Taz]

That now explains soooo many things :weird: :spanking: :tugger: :finger: :moon:

Struth mate now thats just mean :crybaby:

[Bass]

Um yea, back to the book, it's a pity it don't seem to give any actual indication of how big they think the clearance should be. At least at the glance I gave it I didn't see anything there and I can't go back for another look now as I've gone to work.
Have to agree Bass, everything you say about the gap being excessive sounds reasonable.

I have the manual on my work puter.
It doesn't give a value for the clearance but thanks for making the effort.

[warewolf]

Umm, not sure what all the angst is about. There's gonna be clearance between the bearing and shoulder on one side, or the other, innit? Bass just picked wrong first time? No drama. Or am I missing something?

On disassembly I usually check which side has the clearance, as that is the side installed second. On assembly the far side is driven home to the shoulder, insert spacer, install second bearing to the spacer. Wheel's not gonna go anywhere except round. Usually the clearance is several mm or at least visible fractions thereof. You wouldn't see 75 microns with the nekkid eye.

The DR-Z250 used to go through rear wheel bearing pretty fast, seem to replace them all too often. I'm sure the gap was around 2ish mm. Hey, it is just a cheap, crude japper after all. The KTM clearances are much closer though. :Pokey:

If you can remove the bearings cold then you should use something like Loctite 641 Retaining Compound - Super Bearing Mount to hold them in place. And if they rattle you can use another Loctite variant that holds in a bigger gap.

[Bass]

Umm, not sure what all the angst is about.

I'm sure the gap was around 2ish mm. Hey, it is just a cheap, crude japper after all. The KTM clearances are much closer though. :Pokey:

If you can remove the bearings cold then you should use something like Loctite 641 Retaining Compound - Super Bearing Mount to hold them in place. And if they rattle you can use another Loctite variant that holds in a bigger gap.

I think that you answered your own question there.
You're right - it is cheap and crude, but $8,000 is still good value.
What irks me is that, even so, I expected higher engineering standards - foolishly perhaps, but they are better in other areas of the machine. Consequently, it never occurred to me that I was dealing with a motor vehicle that required me to use loctite to keep the wheels located on the axles.
How can you be relaxed about that?
It just makes no sense given that it would be NO more expensive to do it properly. Even my old Morry Thou did it right and that was 50 years ago.

Having said all that, I guess the relative lack of end thrust on a bike's wheels bearings is a factor.

[Woodman]

A correctly used retaining compound with a transition (slip) fit bearing is superior to an interference fit in an aluminium housing.

[warewolf]

Consequently, it never occurred to me that I was dealing with a motor vehicle that required me to use loctite to keep the wheels located on the axles.
How can you be relaxed about that?
It just makes no sense given that it would be NO more expensive to do it properly.Ya gotta do what ya gotta do. Doesn't worry me in the slightest - as Woodman says, Loctite can be better than not. I'm far more worried about the dickhead behind the wheel of that car. And far more worried about tyres/chains failing than any other consumable on the bike. When they fail it is fairly rapidly catastrophic; bearings tend to give you quite a bit of warning.

It does cost more to get the tolerance closer - but you'd never get it to zero, so you're always going to have some gap. 0.01mm or 1.00mm probably makes nil difference to the strength or reliability of the assembly. Once the bearing starts to move, it'll flog out. Maybe Suzuki could reduce the tolerance, but I don't think how it is now detracts from the bike at all.

I must say it was very satisfying when changing the bearings to have to crack loose the retaining compound. You just knew the bearing hadn't moved.

[Bass]

A correctly used retaining compound with a transition (slip) fit bearing is superior to an interference fit in an aluminium housing.


Ya gotta do what ya gotta do. Doesn't worry me in the slightest - as Woodman says, Loctite can be better than not. I'm far more worried about the dickhead behind the wheel of that car. And far more worried about tyres/chains failing than any other consumable on the bike. When they fail it is fairly rapidly catastrophic; bearings tend to give you quite a bit of warning.

It does cost more to get the tolerance closer - but you'd never get it to zero, so you're always going to have some gap. 0.01mm or 1.00mm probably makes nil difference to the strength or reliability of the assembly. Once the bearing starts to move, it'll flog out. Maybe Suzuki could reduce the tolerance, but I don't think how it is now detracts from the bike at all.

I must say it was very satisfying when changing the bearings to have to crack loose the retaining compound. You just knew the bearing hadn't moved.

Sorry guys but you are both missing the point. It's not about the bearing fit. It's simply that if the internal spacer was about .003" (say 75 microns) longer than than the shoulder to shoulder distance in the hub, clearances and fit would be all but irrelevant. Just bang it together and everything is self locating (and you can throw the fkn Loctite away). In addition, it costs no more to manufacture than what they are doing now - maybe less, because the bearing fit becomes less critical.

[ducatijim]

A correctly used retaining compound with a transition (slip) fit bearing is superior to an interference fit in an aluminium housing.

Doh....I wonder wot that means?......No, hang on a moment.......:argh:

......I don't!:beer:

[clint640]

Doh....I wonder wot that means?......No, hang on a moment.......:argh:

......I don't!:beer:

It's engineer speak. Basically having a slightly looser fit of yer bearing in it's hole then gluing the fucker in there is better than having a real tight fit & having to whack the bastard in with a FBH.

Cheers
Clints Engineer-Farmer Translation Services Ltd

[Crisis management]

In addition, it costs no more to manufacture than what they are doing now - maybe less, because the bearing fit becomes less critical.

You need to buy a KTM.









Oooooh look, here's one I have for sale!


:whistle:

[warewolf]

Sorry guys but you are both missing the point. It's not about the bearing fit. It's simply that if the internal spacer was about .003" (say 75 microns) longer than than the shoulder to shoulder distance in the hub, clearances and fit would be all but irrelevant. Just bang it together and everything is self locating (and you can throw the fkn Loctite away). In addition, it costs no more to manufacture than what they are doing now - maybe less, because the bearing fit becomes less critical.Yep, you've lost me - I'm trying, but I just don't get it.

I don't see how bearing fit is any less critical when the gap to the shoulder on the second side approaches zero. You still need a tight fit to maintain the radial positioning of the wheel on the axle, irrespective of the gap to shoulder.

Even if the gap was only 75um, you'd still need a retaining compound as the hub aged and flogged out.

Radial positioning is far more important than lateral. To that end, I've seen plenty of hubs with radial wear causing problems; can't say I've seen any with much if anything in terms of lateral wear.

[Bass]

Yep, you've lost me - I'm trying, but I just don't get it.

I don't see how bearing fit is any less critical when the gap to the shoulder on the second side approaches zero. You still need a tight fit to maintain the radial positioning of the wheel on the axle, irrespective of the gap to shoulder.
Radial positioning is far more important than lateral. To that end, I've seen plenty of hubs with radial wear causing problems; can't say I've seen any with much if anything in terms of lateral wear.

Everything you said is correct except that the tight fit is necessary for radial positioning. That is just not true. The axle is an easy slip-in fit after all.
There are literally millions of machines out there where the bearings are little more than a drop-in fit and they perform just fine because the bearings are located against shoulders.
Where the bearings turn in the housings, the process is usually started by lateral loads, but once it starts, of course it generates radial wear.

For the case in point, the tight fit is required to locate the bearings laterally. With correct design, the bearing contact area with the housing is large enough so that, to initiate wear, rotation relative to the housing is required. For a bearing in good order, the fit does not need to be tight to prevent that relative rotation.

However, my point in all of this was that the lateral clearances provided are so large that if the hub does decide to move on the bearings, it can move so far that the RHS seal can be completely ejected.
I grant that, because this is a 2-wheel vehicle, the lateral loads relative to the radial loads, are quite low and so with reasonable precautions, lateral movement is unlikely.
Even so, it is just poor engineering practice and as I pointed out earlier, requires a particular assembly order to dodge the trap.
Further, as you have pointed out, the bearing fit is tight as a consequence and despite what others have said, requires heating of the hub for safe assembly/disassembly.
Neither of these measures would be necessary if it was set up as I suggested.
Having said that, Mr Suzuki is a far more talented automotive designer than I and so I am interested in why he has done it this way. There will be a good reason.
The rest of the discussion is largely irrelevant.