3rd broken speed sensor rotor 34983-21E00, why?

[sayani]

Okay, I'm on my third one of these in 2 years and it starting to become an expensive problem. I'm trying to figure out why this part keeps breaking on me and whether it is the fault of the mechanics doing the work or if this part is just so poorly designed that it is going to break each time I have any work done that requires the front wheel to be removed. I had my bike MOT'd in Leicester this morning at a place I've not used before and they failed the bike on three things. Nice guys that they are they said if I paid them £95 in cash they would replace the front wheel bearings, adjust the front headlight, dismantle and regrease the rear brake lever (as the brake light was not instantly switching off) and then my bike would pass it's MOT and I could be on my way. At this point I was starting to worry about ever using this garage but knew that they'd been around for a while and given that I didn't have time to get the work done elsewhere and that I need the bike next week decided to just pay get everything sorted today. Of course, it wasn't going to be that simple. As they were replacing front wheel bearings the speed sensor rotor fell out in pieces (all four tabs!) and they claim it was due to incorrect installation by the last garage when changing the front tyre. After a bit of an argument with them and explaining that this has happened to me twice before and that on the last occasion (about a year ago) the guy I normally use said it was because people aren't careful enough when removing or installing the front wheel. The guy at the garage today first argued that they had done work on lots of SVs and the speed sensor is catagorically not a common fault. After pointing out the problems I'd had and in the past and the number of threads I'd seen previously on here about this issue they did in fairness check this and backtracked on that point but stated that the issue with my speed sensor rotor was not their responsibility and but down to the last garage to install the front wheel and that the problems with the wheel bearings are likely to be related to this and to take the matter up with whoever did the work last time.

So, not a great morning. What should have been a straight forward MOT costing £30 has cost me £95 today and now I've got to source a speed sensor rotor and get that fitted which is probably going to cost me another £50 at least assuming it is just the plastic rotor. What annoys me is that I have no way of knowing whether this could have been avoided - whether the fault lies with the garage who replaced the tyre previously or the garage that's done the work today or if this part really is that prone to breaking - all I know is this morning the speedo was working and now it's not. In fairness the garage I used today have given me a letter stating that the issue was casued by the last garage so I can contact them and see if they will fix this for me which I think is extremely unlikely. I guess I'm just going to end up out of pocket as I can't see either garage admitting fault or helping in any way and I'm gonna end up paying for a new rotor and using another garage to fit it. What really annoyed me today was one of the guys (not even a mechanic and didn't see the work being carried out) raising his voice at me and stating that it was catagorically 100% absolutely not their fault and that I was being rude and unfair to even hint that they should accept any responsibility or liability for this problem. Is it just me that finds that dealing with a garage rarely goes as smoothly as it should and feels like when things do go wrong no one ever takes responsibility or knows how to handle the situation in a fair and honest manner? Or am I being unfair and the fault is really Suzuki's for a poorly designed part?

[CodeJACK]

Sounds like you got ripped by the MOT guys.

To remove the front wheel, you gotta be reeaaalllyyyy careful with the speed sensor bit. The cable must be detached to allow for slack and easy removal without breaking the part.

This happened to me too.

It cost 25 euro for a new one here.

[husky03]

it'll cost you £20.86 from robinsons, get a haynes and you'll stop getting bumped by the garages

[sayani]

it'll cost you £20.86 from robinsons, get a haynes and you'll stop getting bumped by the garages

I have been weaning myself off using garages - got myself a haynes manual and have been doing the servicing myself and any jobs that come up that I feel comfortable at having a go at. But yesterday I had to take the bike for it's MOT and because they already had the bike there and said they could do the work that day I was just being lazy and thought I'd let them get on with it. I couldn't have done the front wheel bearings myself anyway as I don't have the equipment but not sure they really needed doing or if they were having me on. I'd also like to know if anyone thinks their claim that the front wheel bearings were affected by the broken speed sensor rotor make any sense or again if they are just fobbing me off. In fact, here's the actual wording from the letter they gave me:

"We believe that when the front wheel was removed and re-installed to have a replacement tyre fitted that it was done incorrectly. The speedo drive was not located correctly onto the castellations in the wheel therefore leading to the prongs on the drive to snap. This in turn also affected the load on the front wheel bearings causing them to fail its MOT (excessive freeplay and rumble."

Maybe I'm just being overly suspicious of this garage becuase I've not used them before and these problems would have come up where ever I'd had the bike MOT'd.

[husky03]

load of $hite in my opinion-if the tabs break, they break, but the rotor stays connected to the drive itself, i can't see anyway this would effect the bearings-but thats not to say your bearings didn't need replacing in the first place just that there explantion is very shady.

[Dicky Ticker]

Over tightening[Incorrect torque pressure] when replacing the front wheel can result in both damaged bearings and speedo drive.

[lh25]

i found that the notch it sits in on the fork leg made it offset imo so i put mine behind the notches on the fork leg and now it sits straight hope that makes sense

[Mannerheim]

When I changed the front tyre and was installing the wheel back to the bike, I found out that one of four tooth was missing from the sensor. It wasn't on the floor so I thought it was froken with somebody else. I was wondering if speedo is still working, but it is working well. I don't understand how it can work, I would say that one of four "signals" is missing.
Has nobody else found out that you can still use the broken part:confused:

Manual says that front calipers must be taken out when taking wheel off. Maybe somebody last time didn't do it like that and I can imagine getting wheel back is not easy...

[Baldyman]

When mine went for the second time, I glued the rotors back on and it has worked fine for three months now :D
http://forums.sv650.org/showthread.php?t=154262&highlight=rotor

[husky03]

the teeth on the rotor only grip the grooves on the front wheel, aslong as there's one there your speedo will work

[Sid Squid]

The lug on the speedo drive is supposed to go behind the projection on the fork leg, the bit where the wires emerge is not intended to place the drive.
Speedo sensor rotors are fragile and very easily broken by incorrect fitting, but fitting it properly is hardly difficult. Can't see how a broken speedo rotor would duff the bearings, even if it broke up into tiny fragments able to get into the bearing itself it's such a soft material that I sincerely doubt it could cause damage.
You can't duff the bearings or break the rotor by overtightening the spindle, there's a spacer between the beaings and the speedo drive itself is the left hand wheel spacer - when the spindle is tightened the bits get clamped - they don't get closer together.

[Dicky Ticker]

Is that why there is a torque setting for the front spindle? I've been tightening bearings wrong for the last 40years

[flymo]

the newer versions of the speedo rotor seem much more robust than earlier ones, they appear more of a plastic material instead of entirely graphite? Doesnt a part redesign like this support the view that its a faulty part design?

luckily I dont need a speedo on my race bike so I simply threw the knackered one over my shoulder and never looked back, but if they are carefully fitted there should be no reason why they should break.

The wheel spindle on the pointy has a shoulder on it, if you give it too many berries on tightening then as far as I can see the only risk would be damage to the spindle thread or the threaded hole on the fork leg casting that it fits into. The older graphite rotors are extremely fragile, graphite will crack with almost no pressure at all applied so its vital that everything is lined up properly when the wheel goes back on.

Given the nature of where the part is and how easy it is to break during fitment, I would place this at the door of Suzuki. They could have designed this so that the wires exiting the wheel spacer could be disconnected, allowing you to carefully assemble the wheel and spacers before fitting the wheel to the forks and then plugging in the lead. As it stands its a bit of a juggle holding everything in the proper place.

[yorkie_chris]

The lug on the speedo drive is supposed to go behind the projection on the fork leg, the bit where the wires emerge is not intended to place the drive.
Speedo sensor rotors are fragile and very easily broken by incorrect fitting, but fitting it properly is hardly difficult. Can't see how a broken speedo rotor would duff the bearings, even if it broke up into tiny fragments able to get into the bearing itself it's such a soft material that I sincerely doubt it could cause damage.
You can't duff the bearings or break the rotor by overtightening the spindle, there's a spacer between the beaings and the speedo drive itself is the left hand wheel spacer - when the spindle is tightened the bits get clamped - they don't get closer together.

+1

Important bit in bold... otherwise it gets very hard to turn the wheel and stuff starts melting. Even though it looks like the lug is supposed to go in the slot.

Rest is fairly obvious from looking at the parts.

[yorkie_chris]

Is that why there is a torque setting for the front spindle? I've been tightening bearings wrong for the last 40years

There are million and one different bearings and million and one different ways they require tightening.

Spindle doesn't care so long as it isn't about to fall out. On 2gen you could be really precise and calculate exactly how much preload you need on spacer to prevent lateral flex due to cornering forces...
Or just tighten the bugger up so it isn't going to fall out without stripping it...

P.S you use grease on those front spindles you been tightening up for 40 years?

[Dicky Ticker]

So the spacers don't go against the bearings case and will not be affected as the spindle stops you over tightening when you get to the end of the thread and the pre grease packed bearing bearing will not be compressed.
Yes,I normally put a bit of grease on the pinch points of the spindle as it makes it easier to remove next time I take it out and it stops corrosion forming on the end and threads
I always greased my wheel barrow spindle when I serviced it

[yorkie_chris]

The spacers don't go against the bearings case... because the bearings don't have a case. They go against the inner race which is a fair size (relatively) bit of hardened steel
The spindle doesn't get threaded in until the threads stop... you thread it in until the spacer(s) and bearing inner "pack" stops you moving it any further.


So you have been greasing a thread then applying a dry assembly torque given in manual? Why would you want to overtighten things like that for 40 years?

[Sid Squid]

Is that why there is a torque setting for the front spindle?
No, the torque setting is the right amount of tight to satisfy a number of elements, amongst which are; tight enough that the spindle won't come undone in use, and that the assembly is held as rigid as is possible, but not so tight that the threads will be damaged.

If the bearings get stiff when the wheel is torqued then something is fitted wrong, or is already duffed.

I've been tightening bearings wrong for the last 40years
Not because of this.

[northwind]

Overtorque it enough and you'll manage to pull the spindle out of the fork leg mind, I remember a couple of people managing that on here. The bearing's not a cup-and-cone, it doesn't need the right torque, think about how it all bolts together- essentially just a load of spacers just that some of the spacers happen to be a bearing.

[Dicky Ticker]

Fair play to the comments----YOU DO IT YOUR WAY---I prefer to use the torque settings and avoid **** ups like over compression thereby eliminating tight bearings and squeezed speedo sender units as seems to have been the problem in the OP
Yes there are many variations on bearings and types i.e. taper,needle,roller which is why they normally have a torque setting and when you have something like a reduction hub with 5 or 7 planet gears all bearing mounted it is quite important that they all have the same settings.
Most bearings sit in a cage of some sort and even hardened cases will distort with heat caused by bad fitting. Burred threads will give a false torque reading so the grease or oil I use is to clean the thread when I run it on or in before final fitting and I'm pretty sure that very few people, in my experience,wash threads before fitting and apply a dry torque,after all you have the pinch bolts which are there to hold the spindle in position after being fitted and the torque is to ensure you haven't overtightened the assembly

[yorkie_chris]

the torque is to ensure you haven't overtightened the assembly

You understand how a thread works?

You apply a turning moment, component of force goes to axial direction. Your torque setting you apply is split into friction component and axial component.

By using grease you reduce the friction component... which increases the axial component for the same torque setting. Which means you are applying more force than the book says.

[Berlin]

Every budding mechanic should be given a two stroke 50cc engine to assemble and have to do the cylinder head and barrel studs up without a torque wrench.

Its the best way i know if learning how tight "Tight" is without snapping something. Its an art! :)


Spanners are generally Idiot proof. They are the length they are so when its "Tight" using it at the correct hand position its close enough to what the recommended torque setting is for that size bolt. Of course, idoits have a lot of spanner and ratchet extension methods to counteract this rule :)

C

[Dicky Ticker]

Plus nuts bolts and studs are made of and fit into different grade materials being where the experience comes into play.How many times do you read on here about studs being stripped or broken and chewed up heads on nuts and bolts.

An old scrap engine is an ideal place to practice with YOUR spanners as they tend to vary in length

[Dicky Ticker]

YC----AND If you read my thread I said to clean the thread before final fitting so the residue left is minuscule and little enough so as not make any great difference or variation on the torque where as you are advocating no torque setting is required,which is the lesser of two evils?
I would prefer to ride a bike which has had the wheels fitted to the torque settings which according to you maybe fractionally out rather than by somebody who chooses to ignore them and slapped it together till they think "That will do"
This is a bit of experience and practice verses a bit of paper and knowing your cantankerous enjoyment in such things;) I will leave you to practice what you preach
hoping that I never have to ride or drive something you have repaired.:)

[flymo]

....runs off to lookup cantankerous....

[trail guru]

What glue did you use?

I had new tyres fitted and the fitter said the last people to put the front wheel back didn't align the speedo rotor correctly and broke off the tabs. So I was thinking of glueing them back on.

[sprocket]

Had the same problem when I had a front wheel replaced once, didn't go back to that garage again lets say, but sourced a new sensor pretty cheap and replaced. IMO . . someone messed up and charged you for it :( sucks but what are you gonna do . . hope you manage to find a new sensor . . fleabay is normally pretty good :D.

[ophic]

Got same problem. Finally got round to removing the front wheel to find the threaded end of a screw inside my speedo drive. It's smashed a lug and scored some nice gouges in the lugs on the wheel :mad:

I can't for the life of me figure out how it got in there.

[yorkie_chris]

Got to be really careful with pots of grease, always keep the lid on when storing. If you've got a pot open on the bench guaranteed it will catch every bit of swarf and crap going.

[trail guru]

I've replaced the broken rotor with a new one - about £24 - and IMO the lugs are unlikely to get broken on wheel removal. It's also really easy to line up the lugs correctly on refitting the wheel so I guess some mechanics/tyre fitters simply forget, whack the thing on and crunch! There goes the lugs.