Well I was bored again today so I opted to go out and rehab a couple Drive clutches. The first was a stock and second was an ALT. Both clutches had a bunch of hours on them. I took two stock ones and combined them into one. I will test it later. The second was a old ALT that was worst for wear. I'll do a write up on it later after I test it a little. I took the driven and set it up using a spring at a free length of 5.80 and no shims. I had posted some info on that in post ride. Then I set this one up with a short spring and no shims. I also change the belt to a double cog type belt.
I'll break it in a little before hammer time. Hope to get out tommorow and run.
Here is a few teaser pics.

Few more pics

a little off topic, but that inside CV boot looks awfully stretched, that was why I was looking for an alternate boot.

You make a valid point on boot. The pic is with shock fully extended. Also the boot is pushed down so I don't rip it working on it.
Here is a pic with it puffed back up the machine is setting back down on the tire. It is still tight.

Here is a pic from the other side that has the EMPI on it.
I posted this pic for a where waldo moment.
Eye spy with my little eye.
Almost a failure.
The reason for pre /post ride walk around.

I had a interesting day today. Got some ridding in and started dialing in the clutch.
Here is a pic of the waldo. If you look at the lower shock bolt, it is not sticking through the back side of the upright. That tells me I did not tighten it up when I did some work on that side. Good thing it did not come out. You should see it like the pic shows as you do a walk around.

Got a shot of the base line run. Found it interesting that it did as expected not only did the rpm and mph reflex the seat of the pants feel and sound of the Engine confirmed the results.

Did a little work this morning to show what and the effects of the old clutch rebuild. As the picture above shows in way of RPM and MPH that is pretty darn close to a stock unit in sand with stock rear tires. This is what I will use for as a base line for a spreadsheet to log information,adjustments and results. Then I can add Adjustments into it and show results against the base line. The first two are the Base Line and a Drive Spring Shimmed .081 the rest remained the same. You can see the results from the math in way of change to the readings displayed on the Vapor unit I use for Data collection.

We can call this step one.
The puck all have 14 disc in them for both runs. So the only change was Shims on the Drive Spring. The result is a Hugh increase in RPM and an sight increase in MPH. I do use an 89 CDI (Capacitor Discharge Ignition) with rev delete other wise a stock CDI (Capacitor Discharge Ignition) unit would cut in and sputter the Engine.

Here are some pics for later discussion.

I deleted a pic and replaced, made a mistake on shim thickness, also changed 13 disc to 14 disc for each pick.

few more pics
As always some loo over my numbers, Please

I will let those numbers soak in a little before moving on. Surprising how much the change in pre-load and run-out poundage on the drive had such a great effect. As you ponder this keep in mind the driven Free Spring Length and the Drive Free Spring Length. One Additional item of note is this is a top end ported Engine and the rpm it is ported for peak power. Here is the port numbers for a reference it may help. This will help align some of the numbers you see on the vapor.

Forgot to add this, sorry:
Primary (drive) Spring Ending Rate = Controls Up Shift, Back Shift & Peak RPM


Softer Primary Spring Ending Rate = Faster Upshift, Slower Backshift, Less Peak RPM

Stiffer Primary Spring Ending Rate = Slower Upshift, Quicker Backshift, More Peak RPM

Went out and remove one shim. Reinstalled clutch with one .046 Spring Shim.
Ran it real quick out front only got about 300 feet hit 47.1 at 7680 before I had to get on the brakes pretty hard. I will need to go back to test area and run to get good data. Then I will exchange the .046 shim for a .035 shim and test.

Did a little informational work today on what I am doing. Put them in pic form for review. I also moved on to step two which is the ratio of the Drive Spring. The Linear Graph shows how poundage throughout shift is applied. The speed spreed sheet pic sows the ratio for each pre-load. This can be compared to the Vapor results. Then I can move on to step three etc.

good stuff, I have a comet 4 pro in my 670, I bought their spring shim set, I think each shim is supposed to bring up the engagement point and carry that through the max RPM by 300 rpm, in actual usage I think it was more on the order of 275 Rpm, I'm sure there are some variances in the springs, weights and between clutches. keep it up.

Thank you, Feel free to post up what ever you have here for data or in separate post and we can link it to this. It may help others dial in there twins.
I have some pics of rework to share. This clutch is about shot.

more pics

more pics

more pics

more pics

last one for now

This is the base line set up ALT

Just did a search when I had my Powerblocs moons ago.
Copy:
Just to add to this,it's advisable to weigh each component,puckblocks,disc weights etc.
I have found some big discrepencies in individual weights.NEVER ASSUME!
Get yaself some digital scales,weight each seperate piece and put in 3 piles.
1st pile put the underweighted ones.
2nd pile the correct weights.
3rd pile the overweight ones.
By using underweight with overweight etc

This way you mix and matchup the diff weights to end up with 3 totally assembled block/weights that are even/same weight.

On my Pilot800,I bought a NEW set of 10-64 Polaris flyweights.
1 was correct weight at 64g,one was underweight by a small amount,and one was a porker 0.5g overweight.  
I weighted these because of what I learned with thePowerblocs and many more components to affect the system.
The blocks over time wear and get damaged and inturn change their own weights.
Mark the blocks with their weight,so you can see over time how they change from original.
End copy.
Have you ever weighed yours?

Great information, Thanks for adding it to the post. I have never weighed them. I will how ever get me a scale and do so on tare down for next set up. The wear on them is great. Wish I could find a place to get new and a new cap. Maybe start looking at e-bay etc.

I see I have some work to be done. According to the spring chart it uses engagement to Load at max speed. Assuming max speed = full shift out on the clutch. Assuming engagement=belt grab, Not installed height. This would require a different set of numbers. The distance from installed to shift out will be different from engagement to max speed. The spring cart tells us the spring travel from engagement to max speed. This number is 68 mm to 41 mm or 27 mm. In order for me to cross reference a spring I need the two numbers.

Time to figure it out and see what the chart provides. If some one wants to take a crack at it go ahead.

No one, come on slackers.With some sort of base line that spring cart does no good. Some one got info on how to apply it.

I took a shot at it. Best Guess
I used Installed Height and Belt at top of pulley

Went out today to get more results. I also ad made a front spring change and a re valve of the front to use as a high clearance set up for rocky woods ridding. Basically stiffened up the valving, stiffer single spring rate with pre load and stiffer rebound valving. I did need to make adjustment to all positions of the shock setting as well as change the caster one full turn out upper front. It had a high speed twitch through the rough as speed rose above 45. This also required a change in the rear setting, two clicks out of the rebound add one high speed comp and one out of slow speed compression. Now it was dial in for rough rocky woods trails and high speed wash with out the twitch.
In the last pic the camber looks off. Its not it the wired camera angle.