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69 Posts
Discussion Starter · #1 ·
As per post title, I know it's all been said before and as SV's are becoming older and less common it's possibly not so important but I just thought I'd post this piece regarding what I did in case anyone new is interested.

Shortly after buying my SV I realised I had a problem with the dreaded 'chudder' and was expecting it at some point during my ownership so wasn't too concerned, I'd also heared that there was a chap not too far from me who modifies them so no problem, just get him to tweak it.

Unfortunately, although I tried all methods of contact I couldn't get any response, as I didn't want to have my bike off the road for a prolonged period at the start of the riding 'season' I decided the best method was simply to get a new basket which I did.

This removed most of the issue but the bike still suffered some unfavourable characteristics around the 2500-3500RPM area so having a used clutch basked available I decided to have a play, what follows is the detail of what I did.

Just to clarify, I'm not indicating I've done anything new here, all (or most) of what I've done had been cribbed from information from modifications discussed in many places on t'Internet.

69 Posts
Discussion Starter · #2 ·

This is covered in many places so I'm not going to say much about this. It's a fairly straightforward proces of drilling out the 3 large rivets which hold the large gear wheel and 2 spring plates (inner and outer) to the Aluminium clutch basket.

One thing which may be worth mentioning is that I made up a bush to fit over the head of the rivets to act as a drill guide which centres the drill on the rivet to prevent drilling off centre.
Unfortunatley I didn't remember to take a photo' of this, maybe try and take one later.
Just have to make do with a photo shortly after drilling off the heads.

Automotive tire Rim Gas Wheel Motor vehicle

Not the mark-up for location on re-assembly and the shiney area under the rivet heads indicating that even though the rivets are a close fit in the holes in the outer spring plate there still seems to be some movement - 'Fretting'

Removing the upper spring plate shows the springs, only the (2) secondary springs have paint marks in this case however I collected the 3 spring types and tie-wrapped each category to prevent mix-ups - Also added a my own marker to the single primary spring.
Automotive tire Alloy wheel Vehicle brake Bicycle part Rim

Removing the gear wheel (and two BellVille washers) reveals the inner spring plate, Market this up to aid re-assembly although it does have a hole which would help with this.
Note that shiney areas around the outer edge where plate has been fretting even more than the outer one.
Automotive tire Alloy wheel Vehicle brake Rim Bicycle part

Likewise on the underside
Wheel Automotive tire Crankset Tire Motor vehicle

Inspecting the Aluminium basket shows damage to the upstands where the gear wheel has been travelling enough to contact with significant force.
Also damage to the spring pockets from the spring ends and/of spring plate.

Automotive tire Fluid Gas Automotive wheel system Engineering

The rivents were then pushed out. Again no picture.


69 Posts
Discussion Starter · #3 ·
Modification - Basket

As one of the often reported issues with these clutches is wear on the central bore from the gear wheel I didn't expect this to be trustworthy so decided to locate the basket on a fixutre on the only other machined features, the three dowel holes.

Here the basket is mounted on the fixture ready for inspection and machining (may even have started machining but it's the first picture I have!).
Automotive tire Product Gear Metalworking Automotive design

I inspected the bore and found that it was not only circular to within a tight tolerance but also central based on the location of the dowel holes. Quite surprised by that.
There was however around 0.1mm clearance to the location diameter on the gear wheel.

Here the basket has been machined out to accept the bronze bush.
Wheel Automotive tire Locking hubs Alloy wheel Motor vehicle

And this is the bush and a tool I made to help insertion.
Household hardware Nickel Gas Adhesive Cylinder

And the bush shrunk fitted into the basket.

Automotive tire Scientific instrument Vehicle Rim Gas

69 Posts
Discussion Starter · #4 ·
Modification - Gear wheel

Unfortunately I don't have acces to a cylindrical grinder so I used a lathe to re-turn the diameter on the gear wheel.
First I turned up a mandrel.

Fluid Bumper Automotive exterior Water Gas

Which I first used to check if the basked location diameter was concentric to the bore. It wasn't, it was just short of 0.1mm off centre. This was dial gauge reading so sounds worse than it is but even 0.02mm is too much in my book.

I than turned the diameter true and to a better finish.
Wheel Crankset Gear Automotive tire Hub gear

Having done that I returned to the basket and finish bored that bronze bush to bore size plus 0.01mm
Rim Gas Nickel Circle Metal

69 Posts
Discussion Starter · #5 ·
Inner spring - Locating central and rotation prevention

At this point I realised that one problem this clutch has which I hadn't originally realised the significance of was the location of the inner spring plate location.
However the more I looked at the assembly the more I thought that this just couldn't be correct. I read back over the many forum threads I'd read and although this is mentioned it does not seem to carry quite the same focus as the central bore issue so put up the following post here:

Request for sanity check on inner spring plate

It just seems crazy to me that the unit should operate in such a way that the gear wheel should routinely strike the Aluminium upstands such that it causes the indentations visible on my clutch and all the others I've seen around the Internet. I also believe this is causing the awful hammering sensation I was feeling with the original clutch over a wider RPM range and even with the new clutch between 2500-3500 or thereabouts.

I was originally going to locate the inner spring plate using some bushes around the upstands (see photo' in previous post), however from the response I got from the above thread it appeared that there was a possibility of severe damage to these posts. For this reason I decided to employ a different method.
I've pinned the plate to the basket.
Wheel Automotive tire Tire Motor vehicle Alloy wheel

After I had done this I found a video on line where someone had riveted the plate on using 3 rivets, so the 6 attachments I've used may be overkill however I couldn't find any follow-up on that video to indicate if it was successful. Mine is so far, fingers crossed it will continue to be.

69 Posts
Discussion Starter · #6 ·
Re-assembly and conclusions

As they always say in the Haynes manuals ‘Re-assembly is the reverse of removal’ and this is pretty much the case here both with the clutch itself and the clutch onto the bike.
Important with the clutch assembly to make sure the drive pin for the oil pump drive gear is installed.

Light Automotive tire Material property Circle Auto part

Otherwise the clutch behaviour will no longer be a worry!

I also checked that I had clearance with my hex-head bolts

Automotive tire Building Gas Wheel Tire

All is good.

The roller bearing which the clutch rides on is a bit odd. Looks like a couple of rollers are missing.
Wheel Automotive tire Motor vehicle Locking hubs Automotive design

This is normal though so nothing to worry about.

On when placing the clutch assembly on the shaft it is first engaged wtih the spring loaded gear on the crank, then rotated to align with the main part of this gear, then tickling the oil-pump drive gear allows the unit to be slid fully home.

Gear Machine Engineering Metal Auto part

Important to make sure the dots on the two parts of the slipper hub assembly are aligned.

Wheel Automotive tire Locking hubs Motor vehicle Rim

Then it's simply a case of torquing up the centre nut, re-loading the plates and bolting up the drive plate.


I've only covered about 100 miles or so but early indications are good, this is the best the bike had ever ridden, I no longer have to carefully ensure that the RPM doesn't drift down towards or bellow 3000 as it will pull quite happily down in this area (even as low as 2000). OK, the engine is not really happy here and doesn't have much grunt (it would struggle to pull a boy-scout of your grandma) but does not sound like there is someone trapped inside trying to hammer their way out. This is much better even than the brand new unit I put on earlier this year (around 2000 miles ago).

This makes me think that the worst aspect of this clutch design is not the centre bearing which seems to get a lot of focus but is actually the 'loose' inner spring plate which only seems to be mentioned in despatches. Due to not correctly locating the contact point on the spring, there is more movement before the springs are loaded and likewise more deflection under maximum load which then allows the gear wheel to contact the upstands on the rear of the hub which is giving this hammering sensation.

I'm not saying that the center bearing is not a problem, just that the rotational movement of the clutch parts contributes more to the overall negaitve feelings I was getting from the bike.

I do think the centre bearing is also important. The other thing I notice riding the bike now is how much smoother it is, even the idle is much better. I thought at first this was my imagination but I'm now confident it was not. I'd say the main contributors to this are:
The basket location diameter running true to its bore - Previously just under 0.1mm runout (T.I.R)
The reduced clearance on the basket bore - Was 0.1 now 0.01mm.
The clutch spring inner location plate running true as now positively located radially & rotationally.

I really feel that this is how the bike was intended to be. Had I test ridden one of these new and found the negative characteristics I would not have bought.
I know the argument would be that my bike is not new and therefore I should not expect it to behave as such but the clutch I used originally was and changing just this one component has transformed the bike from something I'd not purchase to something I probably would.
To put it another way, I was thinking of switching to another bike for next year but now I'm looking at keeping this for a few years more now.
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