Upgrading your clutch springs?? What NOT to buy... MTC

Discussion in 'Rocket Performance' started by Torque addict, Oct 27, 2017.

  1. Torque addict

    Torque addictSupercharged

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    Do NOT waste your money on these!!

    0712151657resize.jpg

    Yes, MTC may make the best fibers. Yes, their $500 billet basket (installed here) is virtually indestructible but their clutch springs are actually WEAKER than stock!! How do I know this you ask? After rebuilding my clutch with all MTC parts it still slipped!! So I was forced to take it all apart again to compare these springs with some others that I had. I took three sets of springs to a machine shop to be tested and also made a phone call to Barnett. Here are the spring rates from weakest to strongest:

    MTC 110 lbs/inch
    Triumph 120 lbs/inch **stock springs T1171201**
    Barnett 170 lbs/inch (not measured - derived from the compressed value below)
    Carpenter 200 lbs/inch

    The MTC and Carpenter springs freestanding height both measured about 1.53" and the compressed height area inside the pressure plate is about 1.03". To get the effective clamping strength of each spring on the pressure plate you subtract the compression height from the freestanding height and multiply by the spring rate. When installed, the stock Triumph springs are going to have a slightly stronger "effective" strength than 120 lbs/inch when compared to the MTC and Carpenter springs because their freestanding height is about 1/16 inch taller than the others so they will compress slightly more.

    MTC 1.53" - 1.03" = .5 inch X 120 = 55 lbs.
    Triumph 1.6" - 1.03" = .57 inch X 120 = 68 lbs.
    Barnett per phone call with Barnett 85 lbs. to compress to 1"
    Carpenter 1.53" - 1.03" = .5 inch X 200 = 100 lbs.

    To determine the amount of force the pressure plate is putting on the fibers and steels multiply by 5 since there are 5 springs

    MTC 55 lbs. X 5 = 275 lbs.
    Triumph 68 lbs. X 5 = 340 lbs.
    Barnett 85 lbs. X 5 = 425 lbs.
    Carpenter 100 lbs. X 5 = 500 lbs.

    So... Carpenter Racing wins again!! I will be re-installing the Carpenter springs and also plan to shim them 1/8 inch which will put an additional 25 lbs of force per spring down on the pressure plate. Yes, they were in there before with some Barnett plates and I thought the springs were Barnett too but that the MTC's must be better. The clutch held but did not function correctly. It needed to be redone and I was told MTC was the way to go. There's more to the story but I will not get into it here.

    With all the ravings on this forum about the MTC clutches I just couldn't believe my clutch slipped when I finally got everything back together. For the record, I am running a turbo with 225 ft/lbs torque at the wheel so getting my clutch to hold has been problematic ever since I bought this bike but there are others here with more torque than that with MTC clutches. I even let these ravings override my suspicions of how easy it was to pull in the clutch lever with the MTC springs. Their fibers must really be the $hit I thought (and still do - it barely slipped with 1/2 the spring pressure I had before with the Barnett fibers). Well, lesson learned. If your clutch is slipping throw everything you can at it. Get the MTC fibers but go with the Carpenter Racing springs. The lever is stiffer but really not that hard to pull in at all IMO.

    I'm half tempted to call MTC and complain that their springs are no better than stock so WTF? But what's the point. My time is better spent typing this up for the R3 community here to be in the know. I could find NOTHING about spring rates, nothing with real hard numbers to compare the available springs on the market, here on the forum or anywhere on the net. Manufacturers also don't advertise the spring rate. Like people are too stupid to understand this stuff or something. I'm also waiting to hear back from TTS on what their spring rate is for the springs in their supercharger kit and will update this thread when I have that info. I'm guessing they're not as strong as the Carpenter springs.

    To clarify and to be fair, Triumph did beef up their clutch springs in 2009 and onward. The MTC's are probably somewhat stronger than the old spring which is Triumph part number T1170028. Also, my MTC springs have been installed and compressed in my clutch for a year now and the Triumph springs are brand new, never used (From the update kit I have). Don't know how much that may effect things. But if you're going to make the best fibers and sell a billet basket that's built like a tank why wouldn't you sell springs that are stronger, or at least equal for crying out loud, than your competitor?

    OK. Rant over.
     
    Last edited: Oct 27, 2017
  2. mr hunt

    mr huntLiving Legend

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    Good onya for doing the maths :thumbsup:

    I went with Barnett springs and fibres/steels in a stock motor and have had slipping problems ever since. From idle it actually hooks OK - but when I go WOT at pretty much any road speed its no good. I'm about the rebuild the box for the second time this year and WAS going to replace the clutch springs with MTC.....
     
  3. IMFASTTOO

    IMFASTTOOLiving Legend

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    WE never had good luck with any of the BARNETT clutches
     
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  4. Torque addict

    Torque addictSupercharged

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    1027171746.jpg

    Here's a pic of the springs that were tested. Value at .5" minus value at .25" multiplied by 4 is the spring rate in lbs/inch. The MTC's actually come in closer to 108 lbs/inch.
     
  5. BigNorm

    BigNormBoobie Inspector

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    That's funny. Now that you mention it I believe my clutch pull was slightly easier after I replaced my fibers and springs with MTC. I'm glad my motor is still stock. keep us posted after you install Carpenter's springs.
     
  6. barbagris

    barbagrisMad Scientist

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    Calling @warp9.9 - God knows how many times he's been in there.
     
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  7. warp9.9

    warp9.9Pocałuj mnie w dupę

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    Warp has never used the MTC springs just the fibers and clutch basket. I still use OEM steels.
     
    Last edited: Oct 28, 2017
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  8. barbagris

    barbagrisMad Scientist

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    Which springs, sir? - I think I know but .......
     
  9. warp9.9

    warp9.9Pocałuj mnie w dupę

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    The ones Bob Carpenter supplied.
     
  10. Torque addict

    Torque addictSupercharged

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    There you have it. No finer endorsement than that folks. MTC fibers/basket + Carpenter springs = Warp worthy clutch.

    I actually remember you saying you were using the Carpenter springs with you MTC fibers. I just had no reason to believe that the MTC springs weren't up to par with the rest of their stuff. Makes no sense. Cost me an unnecessary tear down. But hey, looks like I may have saved @mr hunt a hassle. That's cool.

    This is also now here for anyone to find running a search on the issue.
     
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