Comet 108-EXP on 800, Scrapping the TRA 7 Options

[DooSask]

Has anyone tried a Comet 108-EXP primary on a Summit 800? I am looking at putting one on my 07 800R.

[Maize583]

Has anyone tried a Comet 108-EXP primary on a Summit 800? I am looking at putting one on my 07 800R.

Why? TRA's are SOOOOOOO much more tunable. Also, Comet just went belly up recently.

[evandaigneault]

I had one on my 07 800R. It worked well, I upgraded to the 4-pro this year because it is more durable than the 108 EXP

[DooSask]

Why? TRA's are SOOOOOOO much more tunable. Also, Comet just went belly up recently.

A few reasons:
1. I am tired of rebuilding my TRA 7 after every 3 rides because of inconsistent RPM's on climbs and having your sled's RPM fall off when you really need it
2. I can't find a good used TRA 3 and Doo wants $1500 for a new TRA 3
3. The comet uses the same priniples and operates the same as the polaris and cat clutches and the guys I ride with always have their clutching dialed in
4. 108-EXP is reasonably priced for a new primary
5. Adjustable weights are available from Thunder Products to give you the tunability

[DooSask]

I had one on my 07 800R. It worked well, I upgraded to the 4-pro this year because it is more durable than the 108 EXP

What were you wearing out on the 108-EXP? What set up were you using with the 108-EXP, spring, weights and at what elevation?

[lund]

I've used the Comet 108exp in the past and yes they are extremely tunable, more so then the TRA. Pretty much any combo can be done on a Comet. They are very much the same as the Cat clutches, most all parts are interchangeable. BUUUUUT the comet is far from durable, and has been known to physically break. The TRA is a superior clutch in every aspect other then tunability.
Personally i would not even consider it, though the 4post Comet could be a good option if you don't care for the TRA.
Its interesting your saying that DOO wants $1500 for a clutch. Why do you want a whole clutch for, didn't your sled come with one. It must of cause you also said your tired of rebuilding it. Last time i rebuilt a TRA it was less then $400, that inclueded all bushings, spring and rollers. Maybe you need a different part supplier. Other then that there is not much else to wear on the TRA if you keep them clean. Occassionaly a ramp or arm might need replacing, but not usually.
If your finding your self tired of rebuilding Doo clutches........wait till you have a Comet on there, you better carry a repair kit with you.
Something else to consider is that Rotax uses its clutch for added low end torque. The rotating weight of the TRA helps the Rotax do this. That is something DOOs are well known for, hard low end excelleration and pull, something you will lose with a Comet spinning at the end of your crank.

Just like you said "YOU HAVE TO PAY TO PLAY"

FYI, Comet industries built Cats clutches for yrs, but under a different quality control. Cats standards were much higher then Comets.

[Paul_Aris]

Someone told me Comet was going out of business. I hope not.

[REV*BARON]

Comet did go belly up. Was told this from Gary at MicroBelmont whom I trust.

If you want a TRA3 clutch....call Emerson Stahl in Proctor MN. He has tons of sleds and parts. Tell him Chuck sent you.

[Maize583]

I've used the Comet 108exp in the past and yes they are extremely tunable, more so then the TRA. Pretty much any combo can be done on a Comet. They are very much the same as the Cat clutches, most all parts are interchangeable. BUUUUUT the comet is far from durable, and has been known to physically break. The TRA is a superior clutch in every aspect other then tunability.
Personally i would not even consider it, though the 4post Comet could be a good option if you don't care for the TRA.
Its interesting your saying that DOO wants $1500 for a clutch. Why do you want a whole clutch for, didn't your sled come with one. It must of cause you also said your tired of rebuilding it. Last time i rebuilt a TRA it was less then $400, that inclueded all bushings, spring and rollers. Maybe you need a different part supplier. Other then that there is not much else to wear on the TRA if you keep them clean. Occassionaly a ramp or arm might need replacing, but not usually.
If your finding your self tired of rebuilding Doo clutches........wait till you have a Comet on there, you better carry a repair kit with you.
Something else to consider is that Rotax uses its clutch for added low end torque. The rotating weight of the TRA helps the Rotax do this. That is something DOOs are well known for, hard low end excelleration and pull, something you will lose with a Comet spinning at the end of your crank.

Just like you said "YOU HAVE TO PAY TO PLAY"

FYI, Comet industries built Cats clutches for yrs, but under a different quality control. Cats standards were much higher then Comets.

I think I am going to have disagree with on COMET being 'more so' tunable than a TRA. With the pin weights, rollers, ramp angles and springs weights, TRA's are EXTREMELY tunable. You can change more variables by changing less parts that you can in a COMET style clutch. You can vary pin weights to change RPMs, you have change complete arms and springs in a COMET style to change anything.

The Thunder gives you more options to mimic the TRA style tuning with variable weights.

If he was losing RPM's, he wasn't tuned properly to begin with. If he has to rebuild it all the time, he definatley needs to be finding out WHY he needs to rebuild it. It isn't the clutches problem, it sounds more like an alignment problem.

Changing clutches isn't going to correct the problem. He needs to find the source of the problem, not just change out clutches. The undue stress put on the clutch isn't going to change by changing the clutches.

Hillclimbers, drag racers and oval track racers (along with millions of sleds sold) don't have these kinds of problems - so you need ask why YOU are having these problems. Chances are it is not the clutch....

[lund]

I think I am going to have disagree with on COMET being 'more so' tunable than a TRA. With the pin weights, rollers, ramp angles and springs weights, TRA's are EXTREMELY tunable. You can change more variables by changing less parts that you can in a COMET style clutch. You can vary pin weights to change RPMs, you have change complete arms and springs in a COMET style to change anything.

The Thunder gives you more options to mimic the TRA style tuning with variable weights.

If he was losing RPM's, he wasn't tuned properly to begin with. If he has to rebuild it all the time, he definatley needs to be finding out WHY he needs to rebuild it. It isn't the clutches problem, it sounds more like an alignment problem.

Changing clutches isn't going to correct the problem. He needs to find the source of the problem, not just change out clutches. The undue stress put on the clutch isn't going to change by changing the clutches.

Hillclimbers, drag racers and oval track racers (along with millions of sleds sold) don't have these kinds of problems - so you need ask why YOU are having these problems. Chances are it is not the clutch....

I agree completely the TRA are very tunable.

[YamaDooPolCat]

I agree completely the TRA are very tunable.

Ya, tuneable like a piano. And just like a piano the TRA goes out of tune if the weather changes or you move it. Tuneability is over rated. I don't want a clutch that has to be tuned constantly. It is simply not a desireable feature. Screw tuning.

Had some bad news today, at least for me. I was supposed to get a 4 post Polar clutch like we had on the 1200 turbo when they made a new batch of 50 new clutches last month, but the batch sold out. So Polar has already started another batch of 50 and I was just told that it looks like all those clutches are all spoken for as well. Oh well, that'll teach me for saying I could wait.

We are taking the sleds out to the mountains tomorrow for some trail work and I'll have to run the Comet 109, no big deal, but it would have been nice .... oh well.

Attached File(s)

 CIMG1333__Small_.JPG ( 66.41K ) Number of downloads: 0

 

[DooSask]

"If he was losing RPM's, he wasn't tuned properly to begin with. If he has to rebuild it all the time, he definatley needs to be finding out WHY he needs to rebuild it. It isn't the clutches problem, it sounds more like an alignment problem."

I have to disagree, once rebuilt either by myself or 2 dealers I have tried, the TRA 7 operates great for the first 200 km and then the fluctuating RPM's at WOT start.

"Changing clutches isn't going to correct the problem. He needs to find the source of the problem, not just change out clutches. The undue stress put on the clutch isn't going to change by changing the clutches."

We have to agree to disagree again, the source of the problem is the thin 10.8mm bushing between the fixed and sliding halves of the primary. I have identified the short fall. The TRA 3 has a bushing which has 50% more bearing surface, over 15mm. The TRA 7 bushing wears very quickly causing the primary to bind under load.

I believe changing the TRA 7 to something else will fix my problems. I have found a TRA 3 and I will give it a kick.

[lund]

Ya, tuneable like a piano. And just like a piano the TRA goes out of tune if the weather changes or you move it. Tuneability is over rated. I don't want a clutch that has to be tuned constantly. It is simply not a desireable feature. Screw tuning.

Had some bad news today, at least for me. I was supposed to get a 4 post Polar clutch like we had on the 1200 turbo when they made a new batch of 50 new clutches last month, but the batch sold out. So Polar has already started another batch of 50 and I was just told that it looks like all those clutches are all spoken for as well. Oh well, that'll teach me for saying I could wait.

We are taking the sleds out to the mountains tomorrow for some trail work and I'll have to run the Comet 109, no big deal, but it would have been nice .... oh well.

Your too funny YDPC, at least i'am actually riding my none tunnable TRA.
So are you STOCK piling on Polar clutches this year so you can get out on a few rides, at least its TUNNABLE HUH. Between the Comet and the Polars you should be ok, just don't forget the TOOLS huh.

Thats ok, somebody has to be the mule for testing while the rest are having fun........good luck

[YamaDooPolCat]

Your too funny YDPC, at least i'am actually riding my none tunnable TRA.
So are you STOCK piling on Polar clutches this year so you can get out on a few rides, at least its TUNNABLE HUH. Between the Comet and the Polars you should be ok, just don't forget the TOOLS huh.

Thats ok, somebody has to be the mule for testing while the rest are having fun........good luck

I also have a Polaris clutch this year as well that I might have occasion to run, if I need a spare. As for fun I always have fun, probably more fun by the looks of the faces of the TRA owners that I have met out in the hills. They suddenly realize that the TRA doesn't tranfere all the power to the track after watching the difference the Polar makes. The difference between the Comet and the TRA isn't that much, but at least the Comet is consistant. Pack a spare black spring though because the Comet spring broke just like the Polar usd to before the cup mod on the spider.

Lund you might not really notice the power loss on that big pig you are riding because it has gobs of power to burn. I'm pretty sure you would turn into a wild-eyed clutch junkie like me if you got a taste of just how much power your tank really has. I'm that junkie now, I'm hooked and can't go back to the TRA, the difference is just that noticeable.

Attached File(s)

 P6221485_ss.jpg ( 63K ) Number of downloads: 0