Re:What did you do to your jimny today?

Can't beat shiny balls, just finished shining one of mine, nice work.

I also have the answer to a question no one has ever asked or wants to know.

Q How much preload does the standard Jimny setup apply to the kingpin bearing before you start to add shims?
The answer is 20 thou or .5mm preload shared between the two. I have too much time on my hands.

That's quite a lot in the world of taper rollers, but then they aren't spinning as such in this application. No help and not wanted, but I've always wanted to know 

 

Pre-load is a measure of the pressure applied -in this instance- onto the inner bearing of a taper roller bearing to remove any unwanted clearance. On re-assembly the steering knuckle is fitted with a spring tension gauge pulling on the knuckle arm. The pull, measured in lbs/kgs is noted and that figure is compared to the figure that Suzuki give in their w/shop manual. Except they don't. In the Gen.4 manual they don't mention pre-load or shims at all! Know I know Martin sells a kit of shims but he does not mention the pre-load and the only other source of info. says 2.0 to 4.0 but fails to say whether that is lbs or kgs. As a matter of interest the 70 series Land-Cruiser is 5.5 - 9.9 lbs with the 80 series at 6.6 - 14.3 lbs. This may indicate the Jimny figures are in lbs. but hopefully someone has more information. The SJ used shims that fitted between the bearing cap and the steering knuckle main body With this set-up adding thicker shims reduced the pre-load. The shims Martin supplies fit between the bearing cap and the inner race of the bearing. Adding shims will increase pre-load in this case.

Roger

Yes, preload is the pressure applied, thou or mm compression is just another way of measuring it.
Its mainly used for none user adjustable assemblies such as the G3 kingpin, which I believe Suzuki never intended for user adjustment as they never offered shims, I could be wrong.
I was just interested in how much Suzuki squeeze these bearings in the hope of achieving the correct preload, measured as you indicate as moment of force on the complete assembly which is very hard to measure with any accuracy.
 Suzuki compound the problem as they don't tell you if this figure is set with the hub fully assembled, or striped of hub seal, grease and drive shaft, all will change the result. I assume fully assembled, which makes adjustment a real pain.
Its actually quite easy to measure the gap before you "squeeze" the bearings. It's a pity for me that they don't state this figure as I could simple add shims to get the gap correct, then bolt it all up knowing it's set correctly.

Suzuki presumably designed for a specific axial preload force and built in enough preload to achieve that force. Modern machining tolerances are pretty close. Say they can achieve an accuracy of +/-0.05mm, which is pretty sloppy by modern standards. That's only 10% of the preload. In that case there is no point adding the costly step of installing shims and checking the preload.

100% correct, Les, in production you would never assemble something, measure and then take apart and add shims, it would take far too long and needs a few bins of shims of different sizes, that might run out at any time. If it needed factory adjustment, they would make an easier method of doing it.

If they don't do it in production then they are unlikely to do it on a service, they would just say the hub or bearings are out of tolerance and say you need a new one.

Robin

wrote:

Suzuki presumably designed for a specific axial preload force and built in enough preload to achieve that force. Modern machining tolerances are pretty close. Say they can achieve an accuracy of +/-0.05mm, which is pretty sloppy by modern standards. That's only 10% of the preload. In that case there is no point adding the costly step of installing shims and checking t"he preload.

"Presumably", "pretty close", "pretty sloppy", "no point". Engineers don't work like that.

Roger


 

wrote:

100% correct, Les, in production you would never assemble something, measure and then take apart and add shims, it would take far too long and needs a few bins of shims of different sizes, that might run out at any time. If it needed factory adjustment, they would make an easier method of doing it.

If they don't do it in production then they are unlikely to do it on a service, they would just say the hub or bearings are out of tolerance and say you need a new one.

Robin

There are many instances in car production where tolerances are known  and must be checked to ensure proper working of the unit involved. Yes there are instances where other methods have been adopted, crush tubes on the pinion shaft of a diff. for example, but as Martin supplies shims to alter the pre-load on the king pins then I would suggest, especially as by doing so, "death wobble" is eliminated or at least reduced, then they have a purpose. I will not apologise for being pedantic but I was taught that if a job was worth doing, then do it well.
When I was trialling, we Suzuki boys would laugh at the attitude of the Land/Rover boys because their doctrine was "Oh it will be ok". Famous last words.

Roger
 

I don't disagree that a shim has a purpose, I have used shims myself in other situations, it's just a not production method anyone employs anymore for the reasons set out above.

Mind if you have a Ducati Desmo [Desmodromic Valves, a cam and lever to open the valve and another to close it) motorbike with Bevel head you will know all about shims, they used them in production to set valve clearances among other uses as it was the only way it could work. The bevel heads are amazingly difficult to set up correctly as a result.

Robin

Try to assemble a differential without shims and preloads.

This kind of discussion is pointless and as no one else seems to be interested in joining in I will bow out and let those who wanted the information store it for future use.

Roger

Changed the parking light "bulb" that was blinking cause it is a cheap chinese ebay LED.
But before that i was in a garden lawn where a Vivaro Electric van had sunk into the ground in the thaw and it has rained for days now.
Wife knows I love a bit of rescue so she tipped them of me when she heard they got stuck.

4-low, locked rear diff, cheap snatch strap and several yankings later I had to lower tire pressure in the rear wheels to 0.5 bar and then I got it out.
Loved it even in the pouring rain