Renthal rear sprocket problem

[szrdave]

I'm in the process of fitting a new set of chain and sprockets to the Falco, and have stumbled across a problem.

The replacement Renthal rear sprocket is narrower than the stock sprocket where it mounts to the carrier. This means that the studs protrude through more, and consequently would rub on the inside of the swinging arm if the rear axle was fully tightened

This must be a common problem to anyone fitting Renthal sprockets, but a search doesn't show anything up.

Have you guys come across this before?

The obvious solution is to add some shims to make up the difference, but it's not ideal.

[blinkey501]

I'm in the process of fitting a new set of chain and sprockets to the Falco, and have stumbled across a problem.

The replacement Renthal rear sprocket is narrower than the stock sprocket where it mounts to the carrier. This means that the studs protrude through more, and consequently would rub on the inside of the swinging arm if the rear axle was fully tightened

This must be a common problem to anyone fitting Renthal sprockets, but a search doesn't show anything up.

Have you guys come across this before?

The obvious solution is to add some shims to make up the difference, but it's not ideal.

Looking at this from a fitters point of view i would be tempted to use washers to fill the gap between the bolts and sprocket.
I would not use standard washers though. Go to a bolt stockists and ask for "Hard face washers". This should solve your probem!

[struv]

I cant see how a thinner sprocket can make any difference your swingarm doesent tighten up onto the sprocket .re check how your putting your spacers back in its impossible for a thinner sprocket to cause the studs to hit the arm

[wayno]

Dave, I had exactly the same problem when I fitted a new chain and sprockets. P1ssed me right off as I stripped it all a couple of times before I realised the sprocket was the problem. I ended up making some spacers to take up the slack.

[D-Rider]

Is it worth speaking to renthal?

If the mounting surface is thinner it will give chain alignment problems - which really isn't good.

I think they need to sort this out by either modifying their sprocket design or supplying the necessary spacers.

[wayno]

Alignment isn't an issues, you mount it on the flat face. It's the securing studs that are the problem

[szrdave]

Thanks for the replies guys, I'll pull it all apart again and measure both sprockets.

I'll either add shims or take a bit off the end of the studs depending on how much the difference is.

Struv - The sprocket carrier is fixed in position by the wheel/spacers etc, and the studs that mount the sprocket butt up against the 'inside' of the sprocket with the threaded portion passing through the sprocket and carrier. Any loss of sprocket width will result in the end of the stud protruding through more, even though the carrier doesn't change position.

I think I'll drop Renthal an email and see what their comment is, as you'd have expected them to check this kind of thing!

[D-Rider]

Alignment isn't an issues, you mount it on the flat face. It's the securing studs that are the problem

Ah OK - I get what you are saying - I was assuming it was waisted on both sides.

I do have a renthal on my BST rims but the carrier etc is completely different to that on the Brembo wheels and OZ wheels (requiring a different sprocket) - so I've never had this problem.

[szrdave]

...on my BST rims...

Just measured them up, 7.0mm standard and 4.7mm for the Renthal.

Have also sent Renthal a message so will see if I get a reply.

Off to try and find some 2mm thk washers...

[bigun]

I had Renthal on my Falco (Brembo wheel) and currently have them on my Mille (Oz wheel) without issue on either. I can't remember off hand as I'm at the in-laws at present but is the stud not the same length regardless of how much it protrudes through the nut? Yes, it will come through the nut more with a slimmer sprocket but shouldn't cause issues with the swing arm. If you need me to send a photo of mine I'll take some when I get home tonight.

Paul

[mickt1964]

Hi

Where did you get the sprocket from - I have renthal on my Falco with no problems.
Bought mine from B&C Express.
I would go to your seller and ask them to check what they have sold you, shouldn't have to start adding spacers.

[wayno]

I definitely had the same trouble. Might be worth some of you others spinning the rear and looking at how close your studs are to the swingarm welds. Mine only clashed by about half a mm but clashed enough for me to realise there is a problem. There should be a few mm clearance. If I recall correctly the shape of each individual weld could determine who has a problem and who doesn't.

[szrdave]

Mine is the same as yours wayno, just catches the weld.

Gearing may have an effect if the wheel is moved forwards or backwards it may allow it to miss, or a slightly lower profile weld may give clearance. Or the studs may have 're-profiled' the weld slightly

I checked the part number on mine, there is only one type of 525 sprocket available so they should all be identical.

[beyond]

Balls, I also have the same problem. Off to the shops tomorrow morning to get some washers :/

I measured the protruding thread from the bolt to be about 4mm so I'm going to get the equivalent size washers.

[wayno]

Balls, I also have the same problem. Off to the shops tomorrow morning to get some washers :/

I measured the protruding thread from the bolt to be about 4mm so I'm going to get the equivalent size washers.

4mm sounds a lot, I just spaced mine out the same amount as the recess in the sprocket (2mm if I recall)