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General Category >> Rubber Side Down! >> Is this normal? Countershaft pulley question
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Message started by MotoBuddha on 01/23/11 at 09:39:43

Title: Is this normal? Countershaft pulley question
Post by MotoBuddha on 01/23/11 at 09:39:43

I haven't tried to remove the countershaft pulley yet, but I was cleaning years of neglect and grime from the engine and noticed something odd. The pulley will rotate about 1/4" back and forth while the shaft and nut stay still.

Huh?

Were the pulleys made with lots of slack in the splines? Or are the splines worn? In less that 9k miles?

Title: Re: Is this normal? Countershaft pulley question
Post by Serowbot on 01/23/11 at 09:42:34

You are talkin' 'bout the front one, right?...

That's a problem... Somthin's stripped out...
Hope it's the pulley... ;)...

$75.00 buckeroos at Ron Ayers...
PULLEY COMP,FRO
SKU: 412049
Mfg. Part Number: 27510-24B01
http://www.ronayers.com/ProductDetails/N/687/SKU/412049

Title: Re: Is this normal? Countershaft pulley question
Post by MotoBuddha on 01/23/11 at 10:01:38

I'm converting to chain, so if it's just a worn pulley, no big deal. If it's something else, then >:(

Title: Re: Is this normal? Countershaft pulley question
Post by verslagen1 on 01/23/11 at 10:10:45

2F0D160D201706060A03620 wrote:

I'm converting to chain, so if it's just a worn pulley, no big deal. If it's something else, then >:(

It should be just the pulley.
It's not uncommon for the compression on the pulley to back off after a number of years. Once this happens, the pulley will work back and forth with each pulse of the engine and eat away the splines. If you can move it that much, it's just about done. I got a pulley from a PO that was worn to fine points, while the spindle was fine.

Title: Re: Is this normal? Countershaft pulley question
Post by T2 on 01/23/11 at 20:07:06

I'm just tearing into mine for a RYCA kit. if you get a chance, I'd like to see pictures of the pulley and spindle when you get inside.
Terry

Title: Re: Is this normal? Countershaft pulley question
Post by BuckHMCC on 01/24/11 at 14:41:55

I'm getting ready for a Ryca build, too!

As for the front drive pulley -- mine stripped out about 15K miles. This was with the locknut properly torqued. Fortunately, the splines were not badly damaged. I replaced the pulley with a new one.

After much research I used Loctite 660 Quick Metal Retaining Compound to fill in possible gaps between the splined drive shaft and the new pulley grooves. This Loctite allows for mechanical removal (with only 300F heat which should not damage shaft seals), and is specifically designed for this application.

The pulley has been solid for several thousand miles now.

Photos: http://picasaweb.google.com/gmbhsg/SuzukiSavagePublic?authkey=Gv1sRgCIWagYOk0LqxwgE#

Title: Re: Is this normal? Countershaft pulley question
Post by MotoBuddha on 01/24/11 at 16:01:48

Here are shots of my shaft and pulley splines.

http://i280.photobucket.com/albums/kk182/motobuddha/a8251885.jpg

http://i280.photobucket.com/albums/kk182/motobuddha/68b95c81.jpg

There's a slight step on the outer edge of the shaft splines, probably word by the pulley rotating mack and forth. But I don't think it's enough to worry about.

Man, there's a lot of crud on things.

Title: Re: Is this normal? Countershaft pulley question
Post by T2 on 01/24/11 at 21:18:53

Thanks to both of you for posting pictures. Those will help me evaluate my bike. Am I correct that the shaft would normally be a harder material than the drive pulley?

Title: Re: Is this normal? Countershaft pulley question
Post by justin_o_guy2 on 01/25/11 at 02:12:23

Id expect the shaft to be a good bit harder.

Title: Re: Is this normal? Countershaft pulley question
Post by MotoBuddha on 01/25/11 at 07:51:26

The sprocket went on with a little initial tapping. There doesn't seem to be any slop between it and the shaft, so the wear must have been in the pulley.

http://i280.photobucket.com/albums/kk182/motobuddha/a3720756.jpg

Title: Re: Is this normal? Countershaft pulley question
Post by engineer on 01/25/11 at 13:33:39

That picture of your worn out drive pulley is incredible BuckHMCC. Really gone. The thing about a splined shaft is that keeping the nut good and tight will not prevent that kind of wear. The shaft and pulley must be designed with clearance in between the sides of the splines of the two parts so it can be assembled and then if sharp loads hammer it the thing will slam back and forth and it is going to wear out. The wear rate will increase as the clearance grows because the hammering action becomes greater. That's why they are fine for a long time and then seem to suddenly go. Fortunately they obviously made the pulley with a softer material so the shaft is saved.

Unless this is an exceptional case, this pulley/shaft system is under-designed. One approach would be to simply use a larger diameter shaft and more spline surface area to handle the load. There are other ways to attach a pulley in high torque situations that are better and have been in use for decades. A taper-lock style bushing and key system would be better.

One thought about the chain conversion and I hate to say this since so many have done the conversion. In view of the wear on the OEM pulley I think the drive chain sprocket would benefit from a wide hub, one that covers the full length of the splines. A narrow steel sprocket might start wearing into the splines on the shaft. Chain sprockets are usually made from fairly hard material.

Good luck with that chain conversion. It will be nice to be able to change drive ratios.

Title: Re: Is this normal? Countershaft pulley question
Post by MotoBuddha on 01/25/11 at 14:38:26

High power bikes use chain sprockets on splined shafts without the kind of wear happening on these pulleys. I spend a lot of time over on the owner forum for a particular high powered bike. One common topic is changing final drive ratios. Guys with tens of thousands of miles have never reported problems with worn countershaft sprocket splines. So I think it's probably another case of Suzuki cutting back on specs in order to keep costs down.

Title: Re: Is this normal? Countershaft pulley question
Post by engineer on 01/25/11 at 16:34:29

Yes, I think you are right about the cost factor MotoBuddha. The cam chain and tensioner system is another problem talked about in this forum that seems to fail prematurely. Guys on this forum have made improvements to the tensioner in their home workshops so you have to wonder why Suzuki hasn't done something during all the years they have been making this engine.

It would be fun to tinker with the drive ratio and it is something I might do in the future. I think I'll do a search on the topic. This is a great forum, lots of good technical information.

Title: Re: Is this normal? Countershaft pulley question
Post by Max_Morley on 01/25/11 at 17:39:41

Think about the power impulses on a big single vs a 4 cyl. 1 per 720 degrees in the singe and once every 90 in the 4 cylinder. That is why we also have a rubber dampener system in the rear hub. I would check it for condition as you move the the chain drive. I've had to replace the ones in my 96 bagger in 40K miles. I like to thump vs spin it so that will pound the rubber drive parts harder. Max

Title: Re: Is this normal? Countershaft pulley question
Post by justin_o_guy2 on 01/25/11 at 18:58:34

I think we talked about the cam chain issue some time ago. IIRC, we concluded it wasnt a real maintenance issue years ago, but that they had likely started sourcing cheaper chains & parts in the mix. If I was gonna try to decide when that happned, Id look at when they changed the tensioner spring design & see if that was when, or if the changed the spring to try to compensate for changing to a cheaper chain a coupla years after they created a maintenance headache BY making that change.