108EXP clutch setup

[SIIaCanuck]

What weights and springs should I use for initial setup on my 108EXP.

My sled is a 1980 Liquifire. Polaris Indy 400 stator and CDI setup so effectively an HSR ignition. Rest of motor rebuilt stock with new seals/gaskets etc.

1.86 gearing and a Sportfire secondary helix.

I was going to fit B-1 (207802A, 45.7gr) weights and a purple (207888A, 226# / 106#, 96# per inch) spring but I can't find B-1 weights.

I've read that someone else was running C-2 (208964A, 43.4gr) weights and a red (207877A, 254# / 92#, 130# per inch) spring.

I don't know what the differences are between the B and C ramp profiles and weight distribution so I'm not sure how these two setups would differ in response.

In simple terms I live in a quite hilly area and would like stock or higher rpm engagement, quick revving into the power band and faster than stock backshift for the hills (Sporty helix helps). I still like to be able to wring her out on the lake or river but the 20-60mph region is where I spend most of my time.

Advice?

[SIIaCanuck]

OK, anyone who has read my first post again will note that I've edited it severely. I was given some terrible info over the phone and have revised my post to reflect the details on the cam/spring sheets with the clutch.

It looks like the C-2 cam, although 2.3 grams lighter than the B-1, has a similar weight distribution. The lighter preload and higher spring rate of the red spring may well allow the C-2 to engage at a similar point but my gut still says I'll get slightly earlier engagement (something I don't want).

I was also given the wrong spring specs so I'm going to re-check my figures and edit the post again. I'll put a third post up when I've done it so anyone who is mulling over the subject can get back to me then.

[SIIaCanuck]

OK, I've now confirmed the specs of the weights and springs. The B-1 weights are heavier than the C-2 weights. The purple spring has a higher preload than the red but a lower spring rate.

I'd imagine the C-2 / red to have a similar engagement to the B-1 / purple combo but rev faster and have a higher shift rpm (with the same secondary setup). However, I could be wrong and I'd like some advice from someone who has run either combo in an EXT clutch.

[That Girl Racing]

Why the Sportfire cam?

[SIIaCanuck]

Faster backshift, time will tell what the drawbacks might be. Might also experiment with slippery buttons on the stock LF item to see how that alters things.

[That Girl Racing]

IMO the start angle will load a Liquid motor too hard and overshift the clutches off the line and the the finish angle will be too shallow and cause the RPMs to creep on the top end.

[SIIaCanuck]

As far as I'm aware, the start angle is the same as the stock LF helix. It's the finish angle that drops off to 38 degrees. You may be right about the creep at the top end, I'll have to keep an eye on it to see if I end up with an issue.

In another post, I500 says he's running the C-2/red combination with a stock secondary and it works really well. A comment on what engagement RPM and shift speed it's producing would be nice.

[S_Kyle]

According to my fine tune manual the liquifire was 44 degree straight ramp and the sportfire was a compound 32-48 degree.

[SIIaCanuck]

OK, it's been a pain but I've found a set of B-1 weights. Two from one supplier and one from another. Hopefully they'll all arrive in good order and look/weight the same. I've also been informed that the weights that fit the 108EXP (207802A) are the same as the 102c/108c weights (207801A) but without the bushing (giving a 5/16" hole). I've got two of the former and one of the latter coming so I'll know soon if this is true or whether I'll be searching for another weight.

I think I'll shop around for a set of C-2/Red too so I can have a play and see how the two setups compare.

I also found a MAX1105M3 belt. It's 1-3/8" wide and 47-1/4" long. A couple of forum members have reported having good results with this belt, one with the factory secondary and TR800 / 108EXP clutches. This should allow full ratio shifting with these overdrive clutches.

Regarding the Sportfire helix, I looked in my fine tune manual this morning and discovered the same thing. I'd originally thought it was a 44/38 dual slope. It may be better to simply fit good buttons on the stock helix and then play with spring loading to fine tune the backshift characteristics.

I'll still have a play with the dual slope helix out of curiosity but I'll have my stock secondary sat on the shelf ready to put back in if this experiment turns out to be a step too far.

[nick80lf]

I could be wrong here, but if you have an 80 LF secondary. I don't think you'll use the full diameter of the larger primary if you have the 80 limiter washer in the secondary.

Sent from my Motorola RAZR MAXX using Tapatalk 4

[SIIaCanuck]

That's a point I hadn't considered. Thanks for the head's up.

[SIIaCanuck]

Well surprise, surprise. 3 feet of snow, 16th of December and I'm still short one clutch weight.

If I can't get it by tomorrow, I'm going to put the 102 back in and just play with the secondary & gearing. Can't stand having my machine sitting while the snow is beckoning.

[SIIaCanuck]

Finally get the time to do a bit of work on the sled - clutch puller is crap. Labelled for 102, 108C and 108EXP (3/4") clutches but the threaded portion of the puller is wrong and won't engage.

Good news is my new sled lift works great.

[That Girl Racing]

I know I will be told different but the only belt that fits the TR800/108 setup is the 69170. Other belts of course will drive the sled but not to full efficiency. If you move the motor or jackshaft they would be perfect. That while doable is probably not worth the hassle.

[AirborneX4Special]

I had an 80 with a junk 102 and rather than spend more than the price of a 108 rebuilding the 02, I opted for the new 108C. It was plug and play, literally. I had the same questions you guys have but the sled mechanic at my local dealer told me it would be fine. He raced all the Deere sleds including hopped up Sportfires, so I figured he knew what the heck he was talking about. We bolted on the 108C, used the stock secondary and ran.