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Classic Bike Trackdays

SDR200 clutch basket cush-drive issues

 
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Sat Feb 13, 2016 7:47 am    Post subject: SDR200 clutch basket cush-drive issues Reply with quote

Some of you may have seen my similar post on the TZR250 forum, but I thought I should post here as well, as there are probably more SDR owners present.

Some Yamaha workshop manuals say to replace the clutch basket cush-drive assembly if there is any play. I found about 2mm of play in this DT200R assembly (identical to SDR except for number of gear teeth) and there was also advanced wear on the clutch plate thrust surfaces, so I thought I'd have nothing to lose by dismantling it to see what was inside.



In the opening sentence, I said "some Yamaha workshop manuals" because not all of them mention circumferential play in the cush-drive. There is a picture with caption in the official Yamaha TZR 2MA workshop manual, setting down the requirements for circumferential play in the clutch basket cush-drive. However, there is no such picture or caption in the official Yamaha TZR 1KT workshop manual, even though the 1KT and 2MA use identical clutch basket assemblies.
Just to make sure, I spent an hour or so Sad translating the few short paragraphs of Japanese text adjacent to the pictures dealing with clutch basket examination. The text mainly describes wear or damage that may be encountered on the helical gear teeth and clutch plate thrust surfaces and how to deal with it - nothing about circumferential play in the cush-drive (unless I've missed something). I've also got official Yamaha workshop manuals (in Japanese) for the SDR and DT200R (both 37F and 3ET versions) - any mention of circumferential play is also missing from them. There is also no mention of circumferential play in the Haynes manual for TZR125 & DT125R models, which use a similar clutch arrangement.

At this stage, I am only presuming that the TZR 1KT/2MA cush-drive assembly uses similar parts to the SDR/DTR assembly (my only spare TZR 1KT clutch basket assembly is in excellent condition with no play, so I'd rather not dismantle it).
I have so far stripped three clutch basket assemblies - one DT200R and two SDR. The SDR assemblies both exhibited less play (about 1.5mm) than the DT assembly (about 2mm to 2.5mm), but the play was definitely noticeable. According to the TZR 2MA manual, absolutely no play is permissible. Would anyone like to comment on this?

If play must be eradicated, it can only be done by replacing the six large rubber cushions or buying a complete new assembly (or perhaps by making some modification). The SDR clutch basket assembly is no longer available from Yamaha, although the DT200WR (3XP/4BF) assembly may be compatible (it is still available new and uses the same 37F clutch basket section as the SDR and also a 51-tooth primary driven gear, as per SDR).
Replacement rubber cushions are seemingly difficult to get. I have found no evidence to suggest that Yamaha sells them separately. The closest possibility I have so far found is this: http://www.uppracing.com/item.php?pid=266&cid=71, which states "Banshee, Blaster...". The Banshee and Blaster cushions are different (Blaster cushions are same as SDR, Banshee cushions are same diameter but thinner), but the advertiser hasn't replied to my enquiry for more info after more than ten days Mad .
I have the option to get new rubber cushions especially made, but this will likely involve trouble and expense, as well as some degree of experimenting.


The other aspect of this post is the grooves which appear in the clutch plate thrust surfaces of the clutch basket with continuing use. The three assemblies I have dismantled so far have wear ranging from moderate to advanced. A popular quick fix is to file the surfaces smooth, but this often later increases the rate of wear because of the inaccuracy inherent in filing by hand (i.e. one cannot remove exactly the same amount of material from each surface, leading to some of them bearing more load than others. It is also difficult to file each surface at the correct angle.). Helpfully, replacement machined-from-billet clutch baskets are available from Hinson, Wiseco, Magnum and Performance Engineering (although PE is no longer in business). Unhelpfully, none of these come with new rubber cushions and it seems that none of the aforementioned makers is willing or able to supply them - they expect the user to re-use the original ones. I managed to buy a Hinson basket at a price somewhat cheaper than normal retail, but still expensive. The basket has tapped threads for screws to reassemble it (instead of rivets), but for some silly reason the threads are American Standard instead of Metric (for a bike which is all Metric Rolling Eyes ). Luckily the basket comes with screws...
I understand that a replacement clutch basket is also available under the Pro-X and/or Mitaka brand, but it is die-cast (not machined-from-billet) and also not cheap!
After some more thought (and unfortunately AFTER buying the Hinson basket), I came up with an idea to recondition the original clutch basket portion. I have never seen or heard of this being done before, but I'm sure somebody must have thought of it before me.


The rotary table was set up end-wise on the bed of the mill and the clutch basket loosely clamped into the chuck of the rotary table on a short mandrel. One pair of slots (I chose one with the most wear) in the clutch basket was squared up to the head of the mill and the chuck of the rotary table tightened. Several light cuts were taken in the first slot to gauge the amount of material to be removed. Once a flat surface was obtained, the cutter was withdrawn and the rotary table advanced by 36 degrees. Each slot was machined in turn to provide the uniform end result which is not obtainable by filing. The "other side" of each slot was similarly machined by repeating the process.
About 0.3mm was removed from one side of each slot and about 0.2mm removed from the other (the side which experiences less wear). To set up the mill and machine all the thrust faces of one clutch basket took less than an hour, which should be a lot cheaper than a replacement clutch basket.

I have yet to decide how to reassemble the clutch basket cush-drive assembly, but it will likely be with screws instead of rivets. I would much prefer to have the circumferential play issue sorted before going any further though. To that end, I'd be glad of any info/advice/opinions which forum members may care to offer!

Thanks & regards,
James
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smithyrc30



Joined: 02 Apr 2013
Posts: 8
Location: Thailand

PostPosted: Sat Feb 13, 2016 9:49 am    Post subject: Reply with quote

As you have taken a total of 0.5mm from the fingers, could you get some 0.25mm shim stock, roll it to the inner diameter fit it to the basket, drop it in and then mark the positions of the fingers and then cut between them.

If you fold the rolled shims (not holding on the bit that is going to sit inside the basket) you would then have a steel reaction face for the clutch plates. You the trim off the excess that sticks up. This should give you 10 W shaped shims.

To stop them falling out clean the basket and then RTV the shims to the fingers. It should not need a lot there. A blob at the bottom of the finger in the centre should be enough.

If an additional 0.5mm is going to lock up the plates you can always turn the inside of the fingers to be 0.5mm bigger in diameter.
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Sun Feb 14, 2016 2:14 am    Post subject: Reply with quote

Thanks for the suggestion Smithy - a steel thrust face for the clutch plates would certainly be less prone to wear and hence longer lasting. However, that is not the particular problem I still have to solve. The two "problems" I have encountered are:

1. Circumferential play between the primary driven gear and the clutch basket, possibly caused by the wear, shrinkage or deformation of the six large rubber cushions.
2. Formation of grooves on the clutch plate thrust surfaces of the clutch basket, caused by long-term use/abuse. These grooves hinder movement of the clutch plates, promoting clutch drag.

I am satisfied that I have effectively solved Problem No.2 by accurate machining of the clutch plate thrust surfaces on the clutch basket. Although it is not a perfect solution (in that grooves will slowly start to form again with use), I think it is just the same as fitting a new clutch basket portion. I daresay that having the clutch basket portion anodised may retard groove formation slightly, but I think I'm no worse off than fitting a new clutch basket portion (if this was available from Yamaha as separate part). Making a new clutch basket portion from steel would be a better solution, but it would of course weigh more and be very expensive for a one-off part!
I'm not at all worried about the 0.5mm extra clearance in the clutch plate slots as a result of the machining.

Problem No.1 is still to be solved...that is if it is really a problem (no mention of it in the workshop manuals, except for TZR 2MA). It is this "problem" on which I invite comment, particularly;

Is it really a problem?
If so, where can I obtain new rubber cushions? OR
What effective (and easy) modification can I make to take up the play?

Does anyone have a new or used SDR, DT200R, DT125R or TZR125 clutch basket cush-drive assembly handy? Is there any circumferential play between the clutch basket and primary driven gear? Anyone got any other Yamaha workshop manuals which call attention to the "problem"?

Regards,
James
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2TV owner



Joined: 22 Mar 2012
Posts: 146
Location: West Yorkshire

PostPosted: Mon Feb 15, 2016 3:53 pm    Post subject: Reply with quote

James,

Mine has a bit of radial play in it. But i'm sure some is allowed. Have a look at Youtube Ken O'conner racing. He has some very good videos on there about blasters and clutch baskets. I'm sure he says you are allowed some movement in the basket. He also mentions the Hinson basket and shows you how to modify the stock basket like a Hinson one.
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Wed Feb 17, 2016 1:26 am    Post subject: Reply with quote

2TV owner wrote:
James,

Mine has a bit of radial play in it. But i'm sure some is allowed.


That's good to know Justin...I think Laughing ! Considering the arrangement of the cush-drive parts, I don't see why a small amount of play would be problematic, provided the internal parts are all in good condition (i.e. cushions not disintegrating or badly deformed). However, it would be nice to know why some Yamaha manuals state that only zero play is permissible.


2TV owner wrote:
Have a look at Youtube Ken O'conner racing. He has some very good videos on there about blasters and clutch baskets. I'm sure he says you are allowed some movement in the basket. He also mentions the Hinson basket and shows you how to modify the stock basket like a Hinson one.


Yes, I came across Ken's videos while researching replacement clutch baskets and cushions. I don't remember any mention of allowable movement, so I'll go back through them in case I missed that particular video.


Thanks & regards,
James
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Wed Feb 17, 2016 11:11 pm    Post subject: Reply with quote

I've just had a look at a genuine YFS200 Blaster workshop manual and it DOES specify replacement of the clutch basket cush-drive assembly if there is any circumferential play. Is this over-cautiousness, is it an attempt to increase sales of spare parts or is there a real possibility of damaging the transmission if the circumferential play is not eliminated Confused ??? Why is there no mention of this in the SDR or DTR workshop manuals Confused ???

Ken O'Connor doesn't seem to think circumferential play is a problem, judging by his videos. Anyone else care to offer an opinion?

Regards,
James
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