Got long. Sorry. Hope it helps.

1) Olaf has the best rep around.

2) I didn't accept his advise anyway.

3) I can't help but note he suggested the same springs for you as he did for me at sea level, general purpose, lower engagement with slower shift-out.

4) After a bit of study (see clutch primer) I decided I didn't like his advise, his tack was to general, not in my best interest, and in conflict with my aims.

5) Many here on the forum suggested I was ignoring HPD's advise erronously. I called and asked to talk to Daryl (the man) and received MUCH better answers then I had received from them to that point ( I'd called before and felt I was getting poor answers). We agreed on enough things that I felt his finer tuning points were likely on target, so went with him.

6) I then learned that Rick Ritter Racing sells HPD parts. I'm about sick. Rick is absolutely the best to work with and had I know I'd have HPD bought from him. You should.

7) In my VERY limited opinion:

a. The Aaen blue spring is WAY to tight a secondary and WILL cost you both top speed and acceleration. I consider it a bad choice. No matter what you do you're going to loose about 30% power to altitude. So, no matter what, you're coupling maybe 35 Hp to ground. Keep the stock secondary spring. You won't overpower it with 35hp and more spring just makes the tranny less efficient. You've got enough problems at that height, don't lose more power.

b. I can't comment on the pipe as I don't know what your bottom end power needs are. It seems true that the top end pipes make a lot more power on the top and don't hurt the middle. I do note nobody talks about sub 3K rpm power though, and I think they take a big dive there. I'd consider the power pipe now too, ( i have an HPD trail pipe now) but I'd ask Rick what he thought first. If you use less pipe you need to reduce the preload in the stock spring.

c. Normally I'd say the Aaen green spring is way to stiff, but you are pretty high. Still, I'm leary. I suppose if you DID go with the high end pipe you might need it. Personally, I'd look at the polaris yellow and/or gold. I WOULD alter the weights. Polaris suggest "S" at your altitude, but I think that's a typo. Likely they mean the S53.

d. Get the polaris service manual. it shows spring rates, weights, etc.. for different altitudes.

e. you're going to get stock Hp, at altitude, with a steeper power curve. so same rear spring (as no more grab is needed) a primary spring that forces you up onto the pipe a bit and shifts slower (I've already suggested two), and lighter weights which also do the same. I'd do the springs and then check it out, add the weight after I did a test and if I needed/wanted more rpm.

f. If the read ever does slip I'd goto a dual rate helix before I'd add more rear spring tension. In fact, that's cheap insurance for you right now and won't hurt efficiency.

8) Why aren't you bumping the compression? You need some power help up there bad, and I'd think compression (VERY thin air) would help lots.

9) Call Rick Ritter @618- 644-3212 he knows lots about this and has done it.

10) I could be full of crap. I have very minimal experience with these things, but the fundamentals don't seem too hard.

11) Find a decent tach to help tune it in. Wish I could tell you with what to buy as I need one too. Searching the archives will tell you a sun pro II works. un-uh. Oh, it shows something, but it ain't right... I'm still working on that, but no luck, and their tech support guys aren't to knowlegable. They've going to get an engineer to talk to me, so we'll see. Perhaps their pro line that adjusts to a 2 cylinder setting works.

I hope I've helped. Good luck. CALL RICK. No, I don't get paid. But he's a great guy and takes very good care of his customers.

 

Hey thanks for the info... I hate spending big$ on something that conflicts with my admittedly, very limited observations and was confused by Olaf's clutch recommendations. Also, I believe he said I should use the stock helix - does this make sense? I'll have to clarify with him...

I did call Rick Ritter but he turned me away at the pipe. He says he doesn't have anything for a '99 Xplorer since they changed the engine offset after '98. I figured I'd go to someone that could put the whole speed kit together and chose Aaen.

I'm looking at HSP's billet head to increase compression but thought the pipe and clutch kit would be the best starting place, for now.

Thanks - Dave

 

I'd change the helix now, but then I'd want to slow the shift out rate down a bit as you get closer to rev'd out (remember, you have power problems) and apply a bit more grab on the belt on the upper rpm, thus increasing the chance of allowing you to keep that stock spring. That was the first thing I decided on when I bought kit +.

I'm pretty sure Olaf will convince you he's right, and I do think it'll cost you dearly in speed and acceleration. These things are cheap, so buy a few extra's and see what you think.

You'll find rick can sell you springs, as can hpd, for about half what olaf wants for them.

I'm going out to the airport this weekend and begin testing. While I've bought a full kit and several springs for primary and secondary, I intend to do just what I've told you. I've cleaned up the belt area (I was slipping) and will install a split angle helix. If this stops the slippage I'm not putting in a stiffer rear spring. If it still slips I'll add more spring as is needed. (go buy a decent snap ring tool. Not a plier. Get the twist wrench).

Then I'll re-test and re-record rpm data.

Then I'll try both front/primary springs and record data. Then I'll grind the outer part of the weights a bit to reduce their weight at the upper RPM range, thus increasing my rpm on the big end. Then I'll mull it all over and decide what combination works best. Hopefully one that needs ground weights [img]i/expressions/face-icon-small-smile.gif[/img] If all this fails I'd the heavier weights. Or, if I need lots of secondary spring. You'll do about the same, but you need more rpm all the time, so I'd just get lighter weights first.

Somewhere along the way I may inject enough power to slip the belt forcing a re-do.

Remember, its all about getting the engine to the power band then coupling the power to the wheels with the least amount of loss. Heavy springs create loss (I'm pretty sure), so use the least rear spring you can, then lighten the front weights, then alter the springs and if no much add the heavy weights back... Test lots.

Oh yeah, Bubba's thinking maybe the sun tach works right on his, so I'm rethinking wether I trust it or not.

luck dan

 

A couple of things to remember. Lat time I checked, HPD or anyone else did not publish an in depth book on the functions and tuning of the variable transmission. Olav Aaen was messing with them probably when the others were in elementary school. I would trust what he tells you. Dfischer, You seem to be a little off on the theory of secondary operation. The spring tension is not all the considering factor. The amount of side load by compressing the spring into place and also the actual spring rate has as much to do with it as anything else. As the clutch shifts out, spring tension is decreased. You can have springs with the same load tension but with different rates and side load pressure. Decreasing the pressure on the stock spring is not a good idea. I am staying clear of the tuning of high altitude simply because I am low here and it makes a huge difference in performance. I would stick with what Olav says, and I am sure he would help fine tune if it came to that. Bubba

 

Bubba's points are well made. I could easily be off in any aspect of this. I'm quite new to it. ANYBODY READING THIS SHOULD CONSIDER THAT STRONGLY. One thing everybody says is to call xyz. I do note differences in advise from one shop to another though, and some quite startling. I also encourge you to know enough about it to know when you like what's being sold to you. All of you will have bought something that wasn't quite what you wanted simply because you didn't know enought to protect yuurself from bad advise. My discussion in this and other thread is more about learning and applying it to yout needs then it is "go buy abc".

As resgards the 8000' application, not changing the secondary won't hurt him to try et? I suppose I do tell him to buy the helix that Aaen doesn't stipulate....

I still focus on; The stock red secondary has 22lbs of compression and 213 lbs of torsion. What changed in that bike to need twice the compression and 50% more torsion to overcome (Aaen blue is 45/308)? If he can get back to stock sea level HP levels he'll be doing good. I see only engagement and shift rate, both of which are best addressed in the primary clutch.

As I ramped up on this whole clutching thing I noted several trends shown in the archives. They were:

1) An awfull lot of people get sold the Aaen Green primary and Blue secondary. Sure seems to get used to cure all ills.

2) A too high amount of negative feedback over the high engagement of the green.

3) Lots of feedback talking about top speed loss.

I may have screwed up. I assumed, (well, I did a bit of research too) that this loss of top speed was a result of tranny efficiency loss. The weights in and off themselves can't do that, but we are talking about hundreds of foot pounds of energy being used to compress the prinmary springs, and several hundred more in losses to friction as a result of the secondary. It seems to me you'd use only as much secondary spring as was needed, then look to the primary for the rest.

THIS COULD BE OVERSIMPLIFICATION, but does nicely explain the speed losses. Bubba: Are you telling me I'm off base here?

You're quite correct, I don't have a grasp of the interrelationship of torsional tension vs compression in the secondary. Once I got to this area w/Darryl I defered to his judgement quite easily. Our conversations on that topic was largely:

"Darryl, I'm uncomfortable with the Aaen blue seconday and was thinking more along the lines of the polaris gold, or perhaps the silver/blue". His reponse was essentially: "yes, the Aaen blue is too much spring, but you're not getting the correct torsion rates with the gold. I'd suggest my violet." Right or wrong, I was talking to a guy that was making sense to me, so I defered to his experience.

I truly don't know and openly admit I'm the worst form of hack. Limited knowledge, limited experience, and a big mouth. Still, these things make it into the archives where others will read the try to make decisions. If we can get something in them that addresses root concepts, stimulates thinking and research, and etc... We'll have done more the the dreaded "Put in the white/green/blue" spring responses.

Thanks to all.

dan

 

Hey Dan, dont get me wrong, I like your thinking. Not alot of people these days like to use their brain for what it was meant. I still think you are off somewhat. The primary clutch has 2 MAIN objectives: to control the engine engagement and top rpms. The secondary's main objective is to control the shift. If he does not increase the spring tension and/or rate, his machine will shift out too quickly and pull the motor down because of the lack of power being developed. In the same sense, you could go to a lighter primary weight and slow down the shift phase, right? Wrong. The lighter weights would engage higher, shift later, and move the top rpms of the motor up, reducing power and driveability all around. When dealing with lower HP figures, tuning becomes more critical. Dont forget also that the pretension load can be somewhat adjusted through the secondary clutch assembly even with the stiffer spring. You need a fish scale hook to test and tune with. And to add that alot of negative feedback is coming to these spring combos, I believe that guys are buying springs that their buddies have on a different machine. It works great for them, so why shouldnt it for me? Or they thought if it engages higher, it must run faster. That's why clutch kits come with everything, so they work correctly and backshift correctly while maintaining efficiency and belt life. Simply putting in a stiffer primary spring alone will drastically affect backshifting of the transmission. The primary clutch tries to dis-engage quicker than the secondary can keep up. That produces a free wheel effect. I guess I'm done babbling for now. [img]i/expressions/face-icon-small-happy.gif[/img] Bubba

 

Great job Bubba.

 

OK. Thanks. I'll mull it over some more. thanks for the input. No, I don't take it wrong at all. I appreciate the input. I'm learning from it all.

I confess, I did think if the secondary tension was adequate to control slippage one would tune weights and primary springs to control engagement and shift out. Still don't get why that's wrong, but I'll re-read your posts for a bit and see if I can figure out what I'm missing. I'm still real vague in secondary tension vs compression, so....

Another possible area of confustion for me lies in studying primary spring tables. I'd assumed they acted a bit like a progressive rate spring. Certainly the tables suggest a lot of control in both engagement and shift out forces. This seemed like a macro tuning area for engagement and shiftout. Of course, I also assume overcoming those rates robbed engine power. In candor, I'd assumed the heelclicker and thundershift guys had it right. They seem to suggest tuning engagement and shiftout via placing mass in different parts of the weights. I assumed weight tuning to be more of a micro tuning method.

Ah well.. At some point it becomes more an intellectual time sink then its worth. I do look forward to getting out to the airport and doing some testing. I suspect I'll learn a lot.

All this, and I'm not tuning for maximum performance, but an odd combination of utility, power, and speed. People will think I'm nuts. I may yet grind on the ramps....

Thanks much!

dan

 

hm.. re-read your post a bit more. I see two key thoughts for me to think on. They are:

"The primary clutch has 2 MAIN objectives: to control the engine engagement and top rpms. The secondary's main objective is to control the shift."

and

"In the same sense, you could go to a lighter primary weight and slow down the shift phase, right? Wrong. The lighter weights would engage higher, shift later, and move the top rpms of the motor up, reducing power and driveability all around."

I need to study the former thought some more. Out of the box I'd have simply disagreed. In the latter I agree, assuming by phase I can substitute the word "rate". I gotta confess, that's why I like the double angle helix. I can push the rpm up onto the pipe, hold it higher, and alter the rate a bit with the helix. All without robbing power. I also see where the weight comes from is an issue, as is the curvature of the weight. In any event, your depicition is exactly what I intended to suggest was needed, so again, Caveat emptor...

BTW, did you know HPD suggests snowmobile rate curvatures? Hmm... More to think about. I wonder how I get a curvature table.

Here's a question I've been pondering that may affect this secondary torsion/compression issue, and is likely where I've missed the boat:

How does one, as in conceptually what mechanism, allow the PVT to upshift to high at medium load and medium rpm. Its clear it'll do this at hi-rpm, but PVT seems to be a meachanism designed for constant RPM state. Example: If I wanted to run down a 10 mile ex-rail road path @ medium speed in my 'she i'd lock into 6th, run 50% rpm, and still travel about 45 or so. In a PVT sense I can't think of a way to get it to shift up under mild-load without RPM as I need get the primary weights moving to apply force to upshift. Does the torsion rating of the secondary play a role here? Then, under load I want a downshifit. I need to think about this. herein lies the torsion issue doesn't it?

Remember, for my project, I'm not racing. At any load I WANT early engagement, early upshift, then a upshift delay, then @ hi-rpm the rest of the upshift. But, at medium loads I want it to upshift as far as it can..

And so the question becomes, how does one tune for load rather then via RPM? hmm.. Am I right in saying that's a secondary issue? hm... This is were I'm missing the boat isn't it? I need to undertstand that mechanism a bit more. Of course, maybe it can't do it.

Thanks again. I'll keep thinking.