Hi Wondering if somebody can help. I have a 2005 Thruxton with BC air box elimination kit and predators (I assume the associated jets as well because this was all fitted when I purchased the bike and had been dyno tuned). The bike had 19,000klm when purchased with a 19th sprocket fitted which I later removed because I felt that on inclines there was a tendency to ride the clutch a bit on take offs. At 21,000klm's I had the bike off the road for about 6 months while I did a cosmetic make over fitting a NH TX half fairing, BC eliminator kit, polishing all the alloy stuff and chroming the steal bits and fitting a T100 engine chrome kit. When I got the bike back on the road I noticed on two occasions coming out of the same round about in 3rd that when I went to give it some stick the clutch slipped. A short shift to 4th and it was fine. Ride along in any gear and hit the throttle and no slip but again same round about (20k into the ride on all occasions) it slipped again so much that I was actually slowing down while reving the tits out of it to convince myself that it was slipping..short shift to fourth and fine. I then thought that my clutched must be worn which at only 21,000 klm's was a bit questionable but I was assuming the previous owner may have stuffed it by having the 19th sprocket fitted (adjustment is fine with 3mm free play and not catching with good cable) so I ordered a barnett kit from BC. When I removed my clutch there was nothing wrong with it, all disc and plates measured up well within spec and the springs were all of the correct height. I still decided to fit the Barnett clutch kit and went for a ride thinking that all would be fine as I assumed that the push rod may have been the problem not being set up correctly (didn't check on disassembly) and may have been binding holding the clutch off slightly from full compression/engagement. What I am finding now is on a couple of occasions 2klm or 20 klm into the ride when I am about to take off basically with the foot still on the ground and the bike stationary as the clutch is dropped it gives like a shutter feeling (two small jerks like it slips but just a bit) and a squeal (Not high pitched) noise like a belt drive engaging, with the bike jerking forward and then it takes off. I have not experienced any off the the 3rd gear slipping just the low down slip. After reading a few sites I am of the belief that the springs in the standard clutch are not up to any sort of horse power improvement (I also have a Standard 2006 T100 15,000Klm on the clock and I have done 8,000 of those without a hassle) and the Thruxton already having a few more as standard is more prone to clutch slipping problems so I may have been able to fix the initial problem with just a heavy duty spring change out (Gold type are in the Barnett kit I fitted.) but now I am having the take off issues which makes me wonder how can a clutch slip in first gear at take off and not higher gears? Could the Barnett clutch be working fine but something going on in the cushion drive?? Somebody posted a similar problem on another site and somebody replied that it was the cushion drive. If so what would make a cushion drive slip like that as it is my understanding that a cushion drive is just blocks of rubber seperating the metal fingers from the hub and the sprocket mount to basically eliminate the harshness of direct drive between the drive sprocket components and the tyre on the ground.....so how can this type of set up actually feel like it is slipping??? It is definitely not tyre slippage as this feels entirely different. I am running Motul 3100 15W50 oil as both my bikes have done since new and this is recommended by the dealer and is one of the oils advisable by Barnett for the Barnett clutch kits. Could my rubber be worn in the cushion drive? Has anybody experienced the same problem and fixed it? Sorry for the novel but it helps to list everything to get a correct answer. Cheers TD
Clutch slipping 05 Thruxton
- Thread starter Twodogs
- Start date
Hmmm, I occasionally get what I think is clutch slip.
On a hard ride, when engine is well warmed up.
It shows itself if I'm tearing out of bends to keep up with other bikes.
I'll be up to full revs.
Doesn't happen all the time, and sounds like the clutch is slipping.
I've had engine work done in the past, and at the same time upgraded the tyres, brakes, suspension, and installed stronger clutch springs.
The Thruxton isn't designed to keep up with sports bikes, so I'm a little more chilled out and selective of who I ride with now!
On a hard ride, when engine is well warmed up.
It shows itself if I'm tearing out of bends to keep up with other bikes.
I'll be up to full revs.
Doesn't happen all the time, and sounds like the clutch is slipping.
I've had engine work done in the past, and at the same time upgraded the tyres, brakes, suspension, and installed stronger clutch springs.
The Thruxton isn't designed to keep up with sports bikes, so I'm a little more chilled out and selective of who I ride with now!
Easy13
Street Tracker
Just my $0.02, could be the clutch springs. Barnett's Green springs are supposed to be much better than the gold ones. I've also heard of people having various issues with Barnett performance clutches; it seems they engage and grip so well, they tend to be a bit brutal on takeoff. Sometimes just changing the brand of oil you use can make a difference as well. I have green springs with the OEM clutch on a 70+ HP '07 Thruxtonated Bonneville with 10k miles. I use Rotella synthetic oil and have no problems. I hope you get it sorted.
chances are it's the springs. Taking a look at the cush drive is easy so it really won't hurt to do it but I can tell that unless you got a defective one, it's fine.
I got 70K hard riding miles on mine and it looks brand new.
You are correct about the stock spring not really being up to the job when HP is bumped up. It is a common problem.
The green springs (no shims) will almost certainly fix the problem.
The hd clutch is nice though. I used a Honda carbon fiber set and to say it is "positive" would be an understatement.
I don't see why the other hd clutches would be different.
(When you changed out the clutch, did you soak the new clutch plates in ATF overnight?)
Also: It is important that the push pin is as free as possible and not binding.
It is unusual that you would have problems on take off but not in the higher gears.
when my clutch started to go it would chatter on take of, sometimes. as it continued to wear it would happen more often. Mostly it was the typical high gear slipping.
I got $1 that says it's the springs.
BlueJ
Blue Haired Freak
+1 on the springs. No way the cush drive could cause anything that feels like clutch slip, unless it's totally effed up and then you'd know it all the time.
It's not mentioned as often as it should be, but basically you do *any* power improvement mods, you should beef up the clutch springs.
It's not mentioned as often as it should be, but basically you do *any* power improvement mods, you should beef up the clutch springs.
thearcticsea
Rocker
How difficult is changing the clutch springs?
It's rather easy.
The only "hard" part is getting the lifter pin to move freely.
There are a couple of tricks to it but it's not hard. Just take a bit of patience.
I found the easiest way to align the pin was to evenly tighten the spring bolts that hold the plate on until almost tight.
Then, very gently use a wide bladed screwdriver to apply slight pressure to move the plate.
As you do this, try to pull the lifter pin in and out. you will be able to tell on which side it is catching and then repeat on that side.
The lifter pin is very tight tolerance so the slightest pressure will make a difference.
It is important that it move freely. Check again after you tighten it all down.
There are several things
1. when you take off the case, keep it oriented as on the bike. The little spring on the lifter arm likes to pop off. It's no big deal if it does but it is just extra steps in the process.
2.DO NOT LOOSE THE WAVE WASHER on the starter gear. MAKE SURE it is in place (use a bit of red grease to glue it down).
As mentioned I have fitted the new barnet clutch which has the gold springs so the 3rd gear slipping has stopped but I have since inherited the take off problem that I have described and I cannot think what it can be and would be surprised if it is the cushion drive but I cannot think what would make the noise or cause the slip (Jerky) feeling on take off??? I did get it to make the noise in the shed when holding on the front brake and releasing/dropping the clutch but not enough to snuff the engine. It made the noise once but wouldn't do it again as if there was some movement in the cushion drive and it was now taken up. I also soaked the clutch pack in oil before installing and according to the kit I think it said 20 minutes was enough time, any longer was not required but I soaked it for a couple of hours and I did adjust the push pin so it moves freely.
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I am going to refit the original clutch (as mentioned is not worn) combined with the gold springs (Possibly even try the green) as I never had a take off problem before fitting the Barnett clutch kit, only the clutch slipping in third gear so I now know the third gear slip is cured which I am of the opinion was achieved by just the heavier springs and hopefully fitting the original clutch will have the take off problem sorted. I have emailed Barnett on several occasions to see what their thoughts are but I have had no replies so I can only assume that now they have my money they don't have to waste their time with any customer follow up. Try to do it this week end and see how it goes. TD
Fitted a set of goodridge springs (10% heavier) and refitted the original clutch and all is good. No slip on take off anymore and third gear slip has not returned. These springs are definitely heavier than the gold Barnett springs. Be interesting now to see if Barnett want to help out with the clutch kit that I now own that is basically useless, they are still yet to reply to any email that I have sent them.