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The Beta Clutch Fix


dan williams
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2 hours ago, dan williams said:

Anything really different with the 2020?

Aside from the bold new graphics that is.?

No idea.I just got rid of my 2011 Ossa.The Beta will allow to have fun without fear of breaking something i can't fix.

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3 hours ago, ric h said:

I'm thinking that the change made in this video is a better (and easier)  modification.Now if someone can translate! https://advrider.com/f/threads/how-to-correct-beta-clutch-drag.1375397/

Yes we need an English translation, there are some minor details not quite clear also I am not sure the center washer is setup the same on my 2018 300 4T so will chech and get back here with a comment later.

 

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It’s a fairly simple idea. There is only a small amount of throw in the clutch mechanism and tolerances and wear can cause freeplay before engagement which just wastes some of that travel. Hydraulic clutch actuators should compensate to some degree but they seem to not quite get it done. Bultacos used to have a screw to adjust the position of the throwout bearing to compensate for this. Maybe time to see if it’s possible to implement on the EVO. I feel another custom part coming on!

B92109CA-03CE-4058-B371-2E208AF84B97.jpeg

Edited by dan williams
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  • 2 weeks later...

Thanks for posting about the clutch shims. I tried it on my 1996 Beta Techno 250 and it worked great. I can now find neutral or shift gears at a stop. After doing the clutch plate clean up posted by Dan the cold clutch plate sticking was fixed but my clutch dragged so much that it would move the bike forward even with the clutch pulled in and was impossible to find neutral at a stop.  

I used two of these 0.005" thick shims I ordered from McMaster-Carr:

18-8 Stainless Steel Shims for Shortening 16mm Diameter Screw Shoulders, 0.005" Thick

Delivers Tuesday, $6.45 per pack of 5, Part number 91437A555

It turns out that two of these shims are 0.010" or 0.254mm thick and in the video it looks like they tried 0.10mm (not enough), then 0.30mm (apparently too much, although unfortunately I don't understand Japanese) and then settled on 0.20mm thick, so two of these McMaster-Carr shims are very close (0.254mm). 

 

While I had the clutch cover off I added two 1/4" washers on top of the clutch hub posts under each of the 6 clutch spring bolt washers to reduce the preload on the springs and make the clutch easier to actuate and more progressive. Two of these washers stacked up reduces the preload on each spring by 3mm which is the same distance as the nice machined clutch spring spacers that Dan provided an image of on page 25. 

I used two washers, each 1.5mm thick that I ordered from McMaster-Carr:

18-8 Stainless Steel Mil. Spec. Washer Passivated, 1/4" Screw Size, NAS 1149-C0463R

 Delivers Tuesday, $7.08 per pack of 100, Part number 98017A660

 

It took me about an hour last night to make these changes and give the bike a test ride. When I came back inside my wife commented, surely you can't be done already?

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So has anyone done this shim mod and have feedback?  I installed 2 shims at a total of .48 and nothing super overwelming to report.  I am only riding in the street in circles though...and I just tried it for something to do, LOL. 

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On 8/14/2011 at 7:37 PM, hammerski said:

Hi Dan or anyone else with help and ideas! I have a beta 300 factory, and this weekend i had major problems with the clutch suddenly engaging when i rev the engine to the limit. I've also had this problem on earlier betas.. Anyone else experienced this?

The problem is when i'm standing still in front of big steps with short or no space in front and need maximum revs and then quick engagement of the clutch to jump/ride the bike up. the clutch works fine on normal riding, but then at full revs it suddenly engages and sends me crashing into whatever is in front of me.. It's just like i let go of the lever, except i don't, and then of course get REALLY surprised when i start to move (fast)!!

I haven't tried your fix yet, do you think it will help? I'm pretty tired of this happening, so that clutch is being opened tomorrow! I will give the fix a shot anyway, but if anyone have other ideas you are more than welcome! i've also seen people drilling holes in the basket and pressure plate to improve oil flow. Is this a good idea?

thanks,

Martin

I think drilling holes is a bad idea especially if you have not cleaned the glue and polished the tabs. Cleaning the glue will probably fix this issue as the symptoms sound like a lack of oil in between the plates but while you have it in pieces do the washers under the spring bolts, 1.2mm should be good

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3 hours ago, AZB said:

So has anyone done this shim mod and have feedback?  I installed 2 shims at a total of .48 and nothing super overwelming to report.  I am only riding in the street in circles though...and I just tried it for something to do, LOL. 

The hydraulics are compensating you need to put washers under the spring bolts to make any difference, it's simple mechanics ?

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This is just my 10 cents and nothing more so make of what you will.

If you take the time to read this thread you will see the successful people are doing the work. There is no quick fix for mechanical improvements , remove clutch components clean polish and add washers to relieve preload it really is that straightforward.

Don't do the work you won't get results. I did and others tried my bike then immediately did there own with equal benefit.

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7 hours ago, AZB said:

So has anyone done this shim mod and have feedback?  I installed 2 shims at a total of .48 and nothing super overwelming to report.  I am only riding in the street in circles though...and I just tried it for something to do, LOL. 

I've done it a couple of times.

It's just making sure the clutch has it's maximum throw by reducing the reliance on the self adjusting capability of the hydraulics. The difference can be really noticeable but isn't always, depends on what you're starting with.

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