MTC clutch theory

Tech Q&A for the VTX 1800 - PLEASE keep this section tech-oriented only!

MTC clutch theory

Postby big bad » Fri Aug 14, 2009 9:58 pm

Sorry I had to.... I have to slap some stuff together. But opening this up for discussion, Can anyone figure out mechanicly why a bike after rplacing the mtc components will be hard to shift?





Also Bare and Verb rock. I hope verb comes back to this, his reserch has been unparalleled.
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Re: MTC clutch theory

Postby Bareass172 » Sat Aug 15, 2009 6:47 am

Not enough disengagement of the clutch...

To break down all the discussion previously done about this:
  • Too much spring pressure on the pressure plate
  • Too much shim on the springs causing a coil bind situation
  • Possible flex of the pressure plate (unverified)
  • Possible tilt of the pressure plate (unverified how/if this impacts the clutch)
  • Radial expansion of the hydraulic clutch line (proven to reduce disengagement ~10% on stock lines)
  • Old/spongy hydraulic fluid
  • Not enough hydraulic fluid in the master cylinder
  • Worn clutch lever bushings (the brass bushing that directly engages the piston on the master cylinder)

I believe that's a fairly complete list of what can cause problems with disengagement. It has also been theorized that drilling the clutch basket improves oiling of the inner plates, but the jury is still out on that one. Some argue that it allows oil into the clutch basket to help oil the innermost plates, others argue that it allows any oil that might reach the innermost plates to get out. There is no doubt in my mind that the inner plates are not oiled as well as the outers, I've seen inner plates burned and glazed too many times vs. outer plates, I just don't know if the drilling is a sure fix.

Other topics worth reviewing in this discussion:
viewtopic.php?f=86&t=194

http://www.vtxoa.com/forums/showthread.php?t=217471 <----Most important IMO because it has concrete numbers instead of "opinions"

http://www.vtxoa.com/forums/showthread.php?t=100401

http://www.vtxoa.com/forums/showthread.php?t=128965

http://www.vtxoa.com/forums/showthread.php?t=144770

http://www.californiavtxriders.com/phpB ... 26&t=19067
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Re: MTC clutch theory

Postby big bad » Mon Aug 17, 2009 5:49 pm

Thanks bare, I have some reading to do. I have a few Things to discuss as i read. Also I have not put a mtc in mine but i have in anothers with out any after affect.

The first is not directly MTC related but I hope some things will come up to give us a full idea and this will help in understanding what I see.

Barnett springs
I have read many people say theyre junk.... they break. I have read verbs write ups. Gotta say awsome job. I will refrence his work, I know he is far beyond competent, his write up showed how and why, the tools the process the data. I love it. I agree that the Mtc clutch springs are superior to the barnett. They are also longer. This extra length gives them the ability to essetially shift so the top an bottom spring are not concentric with eachother. If the face is high in the back and low in the front, then you tighten them down and the clutch engages them. The compress but the spring has a curve, sring faces are parallel but not positioned directly over each other. Now you have a broken spring.

In this condition the spring gives extra tension, until it hits its yeild point. Thats the point that the spring goes beyond its limits and is never the same again.

A shorter spring at the same rate will have less potential to have the faces nonconcetric.

I wanna take this slow, Im up for testing but I amreally looking for an understanding of how these parts interface and the potentials.
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Re: MTC clutch theory

Postby Bareass172 » Wed Aug 19, 2009 12:09 am

I don't think the Barnett are junk, I just think that given the option of Barnett that "sometimes" break and the MTC's which haven't broken (that I'm aware of) yet - I would choose the MTC. All the usual disclaimers apply, the Barnett's have been on the market and in VTX's much longer than the MTC's - so MTC's could all start breaking too, just not yet - this remains to be seen... Also, when we talk about breakage in Barnett springs we are talking about fractions of 1% of all the springs that are out there.

I like the MTC's over the Barnett also because the springs are, as you said, bigger. It's not just a height issue either, they are a bit wider and seemingly more robust. If you think a picture might help clarify any of this for discussion purposes I have stock springs, Barnett springs, MTC red springs and MTC blue/black springs in the garage. I can take a pic of all of them side by side. ;)
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Re: MTC clutch theory

Postby big bad » Wed Aug 19, 2009 6:34 am

I agree...... but I do not think the spring breakage is chance. Can you see that the spring will have a extreamly greater chance if the faces are not concentric? I ve never had a spring break. A pic would be great. I chuck the springs when they come out.

The idea that the spring is long and will have a greater oppritunity to flex if the faces are not concentric is my main point, the breakage is mininimal but I feel the concentricity on install in to blame for the rare cases. Not application but installation.
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Re: MTC clutch theory

Postby Bareass172 » Thu Aug 20, 2009 7:40 am

I've seen pictures, I just don't recall where. I don't have one, so it must have been on the VTXOA somewhere, if someone had sent me an email with the pic I would have saved it. IIRC the pic I saw actually had 2 broken springs.
I can appreciate what you mean when you talk about the non-concentric forces, I just can't comment with 100% accuracy on it - even with all the clutches I've done over the years I've never paid very close attention to how much "slop" is in this area. I believe that Verbatim may have taken some measurements in this area because he discussed spring tilt and how it impacted tilt on the pressure plate. If you have your clutch apart get a measurement of the bottom of the pressure plate spring bore, I can measure the OD of the 4 different spring types normally used (mentioned above - stock, Barnett and 2 types of MTC). This would at least give an idea of what you're talking about in terms of this non-concentric force.
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Re: MTC clutch theory

Postby big bad » Thu Aug 20, 2009 2:44 pm

Okay this is one peice to the puzzle. Next on the agenda is on shorter springs like mtc's they will align themselves easier because they short, Now Verb was on the mark when the spring guides were discussed. The springs by gravity will be lower than on center a little bit...... possibly as much as 1/16 of an inch or .0625. When you do a cluch note if the spring face against the bolt is on center around the washer. I have pics but...... cant find them. looking



so theres a potential to have the springs on the top twords center of the clutch and the lower springs closer to the out side. leverage is comming back into play
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Re: MTC clutch theory

Postby verbatim » Thu Aug 20, 2009 6:06 pm

Hi B&BB…at Mike’s suggestion, I have had a look at this thread and I thought I’d offer my 2¢ worth on the subject.

First, to the original concern, I don’t think there are any issues with the MTC clutch that will in itself cause disengagement issues. I believe that if disengagement issues arise after installing an MTC clutch, it is because of one of the things listed, and the nature of the MTC clutch (stiffer springs, more pad area etc.) just brings those issues to the surface.

Just to comment a little on Bare’s list, from the data I gathered, I couldn’t find any evidence of pressure plate flex. There was some flex on all configurations measured, but it was fairly consistent regardless of the springs used. Additionally, I have built the MTC up with very little pressure plate tilt on assembly as well as again with considerably more tilt and there was no noticeable difference between the two in performance. I’d also like to add a few more possible causes:

• Warped Steels (or fibers for that matter)
• Insufficient oil circulation (unverified)
• Damaged seals or bores in the master or slave cylinders

Additionally, on the warped steel issue, the Barnet steels are complete crap in my mind. They are not dimpled and as such do not circulate oil as well. When I had my Barnett clutch in, the steels blued and warped badly while I was performing an extended demonstration of slow speed maneuvers at one of the MSF courses I was teaching. I would never use Barnett steels in anything… ever! Warped steels can happen even on the stock setup though.

Now, on to which springs are better. The Barnet springs are closer to stock than the MTC. The Barnett springs are longer and have more coils than the MTC springs. The number of coils is really the determining factor here, not length, since the installed heights will be identical for both springs. The more coils you have, the less stress is placed on them due to a lack of concentricity of the ends (more coils can take up an offset better because the offset is distributed across more coils). The MTC wire diameter is also larger, so that will place more stress on the wire if it’s forced out of concentricity. So in that regard, if the concentricity issue is what caused the Barnett springs failures, the MTC’s should be more prone to failure, not less. To be honest, I don’t believe this to be the root cause of the Barnett spring failures, the ends are held well enough to prevent this from being the failure mode.

There are many other more critical factors that will determine a spring’s life. While it’s true that concentricity of the ends in service is one factor, in this case I don’t believe it’s enough of an offset to be an issue. Other things that factor in are:

• Spring wire diameter
• Coil diameter
• Number of coils (less coils = more stress on the spring)
• Spring wire material

I agree with Bare on his point that we should not be to harsh on the Barnett springs. I don’t believe they are breaking left right and center. The sheer number of springs out there is going to result in a certain number of failures regardless of how good they’re made. There are infantile failures in virtually any part that is manufactured, just look at the variety of failures of components listed on these message boards. It doesn’t mean there is a flaw in the design, it just means that there are enough out there that there is going to be the odd problem. Certainly some parts experience more failures than they should (i.e. flange bearings), but I don’t think the Barnett springs is one of them. As mentioned, there just isn’t enough data on the MTC to judge them yet. Don’t forget, these springs are basically like valve springs…and you know how many more cycles valve springs are going to see versus the clutch, so I don’t think there’s a design issue. Based on my testing data, I decided the MTC’s shimmed to .075 were the best combination for me, and I have to say I’ve been more than happy with the setup. I’ve had no issues at all with shifting or finding neutral and it hooks up great.

My only complaint with the MTC is the same one that others have reported. When first jumping on the bike after letting it sit for a while, the clutch plates stick. After sitting overnight, they are so bad that I can actually turn the motor over a little with the clutch pulled in while in gear with the bike not running. It takes a few rocks back and forth to break them free, and then they’re good for a while. If you don’t do this and you start the bike in neutral, the first shift into first is very harsh…in fact once it stalled the bike. I just have made it a habit to break them first, and then all is good for the day. It’s a pain in the ass, but still worth it for a better clutch.

Just to update here, since I never did update on the VTXOA thread (quite frankly, I just couldn’t bring myself to stirring that up that thread again). I did manufacture better spring guides and tried to install them after a while of riding the MTC clutch even though I was having no issues. I wanted to see if they would correct the pressure plate tilt. Unfortunately, however, when I was taking my original measurements for the guides, I did not factor in that the posts on the inner clutch hub were tapered. I should have known this because it’s a cast component and they need tapers like this to be able to separate the casting pattern mold away from the casting. As a result, my guides didn’t fit and I determined that it was both too complicated to make work, and pretty much unnecessary based on my comparison on how a build with more tilt compared to one with less tilt. I don’t plan to pursue that any further.

My thoughts on installing an MTC clutch are this. You should replace the stock line with a braided line, you should inspect / replace your clutch lever bushing, you should install new OEM steels or at least ensure the existing ones are dead flat (making sure the steels are all installed the same way with the rounded stamped edges facing out), you should shim no more than .075” (my opinion only), and you should flush and bleed the system thoroughly (including back bleeding) with fresh fluid. If you do all these things and you do them properly, I can’t see anyone having a problem with the MTC clutch unless they have one of the other problems listed.
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Re: MTC clutch theory

Postby big bad » Thu Aug 20, 2009 7:29 pm

I agree with everything but what i was looking at as far as concentricity it that wh barnetts when installed are longer. Long enough that you have to push the bolt in and turn it in at the same time.

When you have to compress the spring in by turning the bolt in the washer may or may not rotate. The ones i did the washer didn't rotate. If the spring on the bolt side is off center then when tightned down its still off center unless you actually push of lightly tap it so its centered on the washer. I think the longer the spring the more room for error.

I do beleive this lack of concentricity is the death of the barnett springs, and this theory will parallel the washer/guide you touched on and the tilt of the pressure plate.

What will have a greater level of concentricity between 2 peices a nickel of a 20ft peice of barstock the same diameter?


dose this make sense?

Heres the average clutch install by the average guy, ever look at the spring placement on clutch install? honestly I haven't till i read your write up on mtc clutches

Image

Image

Image

Image
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Re: MTC clutch theory

Postby verbatim » Thu Aug 20, 2009 11:08 pm

You're not going to get any better than that with the MTC springs either. They move off center as well, trust me. I installed them probably over 30 times through the course of my testing. The springs end up all over the place and it's the same with the barnetts as well as the mtc. The fact that when they're installed, they're the same length leads me to the conclusion that IF there were a stress problem causing springs to break due to concentricity issues, the MTC springs would be more prone to break because of the fewer coils given that the concentricity mismatch is the same for both. Install the mtc springs and you'll see what I mean...they don't center themselves any better.

I understand your logic, I just don't agree with it. I'm not exactly sure why you're on a mission to prove that the Barnetts are inherently worse...many many many people have had good success with them and swear by them. The failures have been so small, I consider them to be statistically insignificant. If, in your heart, for whatever reason, you don't feel they are a good design, then use the MTC springs and be done with it.

One more thing to chew on...as I mentioned, the barnett springs are very very similar to the stock springs and the stock springs would therefore be just as prone to moving offset (and they are based on my observations during assembly). How many stock springs are snapping? How many are out there in use?

My opinion is you're chasing your tail on this one...and I'm not even sure why. They all shift just as much.
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Re: MTC clutch theory

Postby verbatim » Thu Aug 20, 2009 11:19 pm

big bad wrote:What will have a greater level of concentricity between 2 peices a nickel of a 20ft peice of barstock the same diameter?

dose this make sense?


Quite frankly...the way this is worded, no I don't understand. And one thing I believe you're missing is that once the springs are installed, the lengths are identical. Even though the MTC's make up distance is less because they're shorter, they still move offset just as much as you're showing in the pictures...and again, I've built it up twice, once making sure the springs are all set nice, and another where they were all over the place. Tilt was worse on the latter, but the clutch performed just as well and is in fact the way it's still built up to this day. There simply isn't enough room for the springs to be that much offset to make any difference in the life of the spring or the performance of the clutch.

You keep referring to the barnett springs as if they are flawed and have a problem. I disagree. One or two reported spring failures out of thousands of installs doesn't make it a design flaw.

I was once as concerned as you about tilt and spring placement. I'm not anymore.
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Re: MTC clutch theory

Postby Bareass172 » Fri Aug 21, 2009 3:05 am

verbatim wrote:One more thing to chew on...as I mentioned, the barnett springs are very very similar to the stock springs and the stock springs would therefore be just as prone to moving offset (and they are based on my observations during assembly). How many stock springs are snapping? How many are out there in use?

This is an excellent point...

verbatim wrote:You keep referring to the barnett springs as if they are flawed and have a problem. I disagree. One or two reported spring failures out of thousands of installs doesn't make it a design flaw.

To be fair I am familiar with about a half-dozen, but still I agree with you 100%. With how many are out there 2, 6 12 failures, whatever, it's insignificant.

I have to agree, and I think it was best put that you're chasing your tail going after spring failures due to concentric issues. I don't want to discourage you from doing whatever you want, it's your time and you never know when you might stumble across something... But I can say that I've built up enough clutches in the past that I don't think spring offset is a major factor at play. I'm sure if Honda thought it was then they would have made guides, because you know they're not paying someone at the factory to straighten each spring manually.

I really feel like the clutch on this bike has been beaten to death. Thanks to guys like Showtime56, Verbatim and others who have done extensive breakdowns, measurements and discussions on this I think we have a lot of insight into different aspects that we didn't have before. I still know that Showtime56 is a bit misguided about his "lifter washers", but I would never fault him for an honest mistake - and his work otherwise was very good and informative. With that said, Verb and I and others have talked and believe that more work could be done, but I think most of it would be repetition to verify existing figures on a different bike - basically, just building supporting evidence.

Run with it all you want BB, I think it would be nice to have a lot of the data compiled in one thread regardless. I just don't know, at this point, what else could be measured, calculated or looked into further than has been done so far. ;)

What's your plan? :huh:
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Re: MTC clutch theory

Postby big bad » Sat Aug 22, 2009 7:34 pm

I guess what im getting at is, The plate is/ was tilted a little. The clutch packs are rubbing on each other to make it hard to shift..... If the plate is tilted and putting pressure on the clutch plateds? lets untilt it.

I would like someone on the next mtc clutch install to center the springs as best they can and see if we get favorable results as I did.
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Re: MTC clutch theory

Postby verbatim » Sat Aug 22, 2009 10:59 pm

And what I'm getting at is I've built it up both ways...carefully without tilt and not carefully with tilt...made no difference in shifting, it was exactly the same. As was mentioned in the other thread, if you wind up your RPM's while you're moving and the clutch is engaged, the pressure plate will be rotating anywhere up to 5750 rpm...at those rotational speeds, the springs inertia will likely force them to the outside anyhow. I honestly don't think the tilt makes a difference from what I've seen. If the clutch is built up correctly and you don't have any other of the mentioned issues going on, I can't see why it would be hard to shift.
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Re: MTC clutch theory

Postby big bad » Mon Aug 24, 2009 8:30 pm

I was under the impression that the mtc clutches are having some problems shifting into neutral at stopsigns is this the case or no? Is it a very slim number? I had a friend of marks ask me why at the mmr.
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Re: MTC clutch theory

Postby Bareass172 » Tue Aug 25, 2009 8:58 am

There are some cases that report this. It is my opinion that these cases are rare, and I believe that most of them are caused by some of the reasons mentioned when this thread started:

  • Too much spring pressure on the pressure plate
  • Too much shim on the springs causing a coil bind situation
  • Radial expansion of the hydraulic clutch line (proven to reduce disengagement ~10% on stock lines)
  • Old/spongy hydraulic fluid
  • Not enough hydraulic fluid in the master cylinder
  • Worn clutch lever bushings (the brass bushing that directly engages the piston on the master cylinder)

In my experience it is usually just as simple as fresh fluid. I have seen more than one bike that had COMPLETE clutch failure, zero disengagement, and when the clutch was bled it went back to working like new. I think that too many people don't believe the fluid can make this big of a difference, but it obviously does.
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Re: MTC clutch theory

Postby big bad » Tue Aug 25, 2009 12:46 pm

Thats interesting with the fluid thing, I would have never dumped mine if i was having the problem. Met a guy at the mmr mark knows him ill pass it along.

The cases you have seen have you known any consistancy in oils among the half dozen?
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Re: MTC clutch theory

Postby IL-Mark » Tue Aug 25, 2009 2:52 pm

Alright my ears are ringing :rofl:

Q. What if the fluid was thicker?....would it have an effect?
Q. Hypothetically speaking, what if the plate had guides that kept it from tilting? Like rods that ran in the same direction as the springs but went through the plate.


:D All I know is that you guys..... :roll: better get this figured out soon cuzzzz my clutch makes noise when its cold as in slips.

OH and BTW I'm one of the guys who have broken one stock spring and 2 Barnett Springs and hope I don't have a third.

Maybe what we need is a clutch cut from a billet with some huge pressure springs to ensure lock up and have air over hydraulic clutch levers. :wall: :rofl:
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Re: MTC clutch theory

Postby Bareass172 » Tue Aug 25, 2009 3:27 pm

big bad wrote:Thats interesting with the fluid thing, I would have never dumped mine if i was having the problem. Met a guy at the mmr mark knows him ill pass it along.

The first time I saw it I expected something more serious, but when I got it I figured I'd bleed it out first to ensure I knew what I was dealing with. As I bled the new fluid in I immediately felt the clutch come back to life, and to my surprise that was all it took to run like new again. Since then, I have always bled first when encountering problems.

big bad wrote:The cases you have seen have you known any consistancy in oils among the half dozen?

To be clear, I have only dealt with 2 complete "failures" due to fluid. Both were MTC clutches, and I relate the issues to the improved grab of the MTC fibers combined with additional spring pressure when using shims. Both worked like new once bled.
When you ask about oils, I can say they were both running Amsoil but am unsure what correlation you're trying to draw with that info...? :huh:

IL-Mark wrote:Q. What if the fluid was thicker?....would it have an effect?

The hydraulic fluid? :huh:
I'm not sure what you're going for here, hydraulic fluid isn't rated by thickness like oil is. :confused:

IL-Mark wrote:Q. Hypothetically speaking, what if the plate had guides that kept it from tilting? Like rods that ran in the same direction as the springs but went through the plate.

You already have this, the 6 "pins" that the springs sit on also guide the pressure plate.

IL-Mark wrote: :D All I know is that you guys..... :roll: better get this figured out soon cuzzzz my clutch makes noise when its cold as in slips.

IMO it is already sorted out in great detail. I'm all for additional discussion, but I believe that we would gain a LOT more from having people take measurements that coincide with what Verbatim and Showtime56 have already done. Measuring clutch pack installed heights, engagement and disengagement distances, spring pressures, radial flex of clutch lines, pressure plate tilt, etc.
I feel that the work that has already been done paints a clear picture of the operation of the clutch in ALL aspects, so additional measurements would either support what we know or prove those things to be wrong - I don't believe there is any aspect of the clutch's operation we've overlooked. Short of an expensive re-engineering of the entire system, the measurements we've compiled allow us to find a delicate balance between the limited fluid displacement of the master/slave cylinder and the appropriate spring pressure on the clutch pack to provide optimal engagement & disengagement of the clutch. ;)
So now we just need more people pulling measurements and compiling data to support and reinforce (or disprove) what we've found so far. :thumb:
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Re: MTC clutch theory

Postby IL-Mark » Tue Aug 25, 2009 4:34 pm

Well, unless I break mine I'm not taking it apart until late fall :roll: :D

I still have to get some shims that I've been to lazy to call about. :wall:

As for the Hydraulic fluid....in my lawn mower I have 2 hydraulic pumps that drive the wheels and blades. The pumps use full synthetic 15-40 motor oil. I just run 20-50 MC oil in it. Just wondering if viscosity would have anything to do with it.
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