Sparks/GT Thunder 8-Plate Clutch- Worth It?

[Quadzilla]

Hey all,

My new motor below runs great but I've always noticed what a POS the 400EX clutch is and the new motor just brings it out more. Shifting under full throttle, the clutch does not engage power back to the next gear right away. It slips for a second. It's always done this on both my EX's (and everyone I've ridden). Speed shifting makes the slippage even worse.

What really got me going was riding a piped and jetted YFZ this past weekend. No, the tranny is not as buttery smooth as a 400EX or Z400 tranny but man-oh-man that clutch, I was in heaven!!! When you shift under full throttle, WHAM it's in the next gear with NO lag or slippage. Even speed shifting is like that, I mean no freaken slipage!!

So which brings me to the subject for this post. Will either the Sparks Racing or GT Thunder 8-plate kits do this for me? The GT Thunder kit cost more but comes with a machined back pressure plate to properly accept the new plates where the Sparks does not. Need to know if you really need this. Hope some of you who have one of these kits can help. Again, my two questions are:

1 - Do the Sparks or GT Thunder kit really make that much of a difference and will they eliminate the lag (or slippage) when shifting on full throttle and/or speed shifting when drag racing?

2 - Is it worth the extra $$$ to go with the GT Thunder kit over the Sparks?

Thanks!!!

[cals400ex]

here is my experience with the sparks:

it works great on a track. you have a lot more travel in the lever that gives you slipping ability. with the stock one its harder to slip a little bit. in other words, it helps get the power to the ground. also, when drag racing i don't have any slipping. however, the stock one disengages earlier and the sparks you nearly have to let the lever all the way out. what this amounts to is that the stock one seems to give me more of a jump when shifting, kind of like a shift kit in a car. the sparks doesn't give that much of a jump. also, the sparks clutch made my bike not shift quite as smooth when just putting around. all in all, i would probably get the sparks again. i was almost expecting more, but that is alright. it has lasted me a long time so i won't complain. but then again, i am not hard on my bike.
sorry if i didn't help much

[3x440ex]

Yep.......mines doing the same thing. I just got my motor back together last week. I was just gonna buy some disc this week and see about finding some heavier clutch springs.

[Quadzilla]

I know a guy that has a 502 and he just put heavier springs in and shims to boot, but has OEM 400EX metal and fiber plates. I have not talked to him in ages and don't even know if I still have his contact info. I wonder if this is the way to go vs the Sparks clutch. Anyone tried just doing this and if so, did it help? After hoping on that YFZ and drag racing it, it really made me see just how bad our 400EX OEM clutch really is.

Yes it is worth the money hands down.

I don't think just adding stiffer springs is going to be the fix for your problem. Having the extra plate helps I"m guessing do to more area for friction. I'd also like to add that i've read when having a built motor and adding a 8 plate setup that stock baskets are close too the exploding point so a good aftermarket basket isn't a bad idea. I added a hinson basket just for the peace of mind.


I'm very VERY pleased with the 8 plate and hinson setup I have. There is NO slippage at all, except for when the rear tires are breakin loose...:D

[TC426EX]

I agree with Rico.... I also am running the 8-plate Hinson set up (which I assume would be similar to either of those), and could not be happier with it. No slippage, and a much easier time shifting under power and clutching into the upper rev range with ease. The 8 plate definitely GRABS and you will love it. Definitely worth the money...

[Quadzilla]

Thanks for the input guys. It went with the GT Thunder setup because of the machined backplate that he includes. Link here---> Click Me (http://www.gtthunder.com/400EXClutchKit.html)

I also saw that Magic Racing is selling billet baskets for $145. I may do that also.... I have high hopes that this will help! Thanks again!

[Chefbigdaddy]

My brother works in the business and claims that all the top fuel drag bikes use stock plates (vesrah I think) and just *** heavy duty springs. If that can handle 300 + hp, it should probably handle a quads as well. Thats what I run in mine a have had no worries.

[Sandragggen]

I had no problems with the stock clutch when I had the 440 but when I jumped up to the 465 the clutch started to slip soon thereafter. I then installed the Sparks 8 plate clutch and have had no slip problems for over a year. I did install Hinson basket at the time of the clutch installation.

JMiller

[Jingle #11]

to add to ricos statement. One of my friends at the track last week was racing and his clutch went out. Btw he's runnin a loaded 440. He had the stock clutch and took it apart and the biggest peice left of the basket was about 1" in diameter. SO get a new clutch and basket when u upgrade engines.

[Quadzilla]

I'm going to order a basket in the a.m. tomorrow. I've seen two brands in my price range, both billet. One is a Magnum and the other is s PE. Both are $139 with free shipping. Hinsons are about $60 or so more and I can't justify it, plus I'm already wwwwway over budget on this project and my wife is about to kill me. Anybody use either of those baskets before?

Originally posted by Quadzilla
plus I'm already wwwwway over budget on this project

Famous last words of an ATV rider...:o

[Doibugu2]

stay away from magnum there products are garbage.

[Quadzilla]

I just ordered the PE. Thanks guys. I'll give a full review once I got it installed...

[cummingetit]

Another way to get an eight plate setup without spending all of the money is go to Honda buy 300ex steel plates because they are are thinner you can add one more. Then you can use 400ex fibers or what I like to use is 250r fibers because there is more material on them. If you can get to know someone at Your Honda shop they can give you a big discount, 20% over cost is like 40% off or more.