Due to the sporadic rpm readings (13,650) I thought I had better take a look. It takes me about 20 min to completely remove and take apart. I was expecting the 8000 rpm setting maybe a spike however not 13,650. So maybe the tires lifted and free spun, tach error,old drive not set up right or opps in driven assembly.

First item of business is to look at the belt. If bad look at drive and driven faces for signs of issue. If that looks good than look at the assembly of drive and driven and parts checking for broke spring, hung puck etc.

The belt was bad. showed signs of slippage, lose of grip, over heat and was coming apart.
The drive and driven both showed signs of slippage. The area of slippage was at engagement and run out. The shifting area (zone) was OK. Both springs were fine Drive assembly looked good. The driven not so good. the issue may be one I created when assembled or The old Seals and o-rings would not hold the grease as it moved in and out (shaft wiper) The driven shows signs of grease being flung outward on the outside of the movable face and on the inside of the sheave faces. and of course I may have packed to much in. I lube them than run them up and down and then wipe off excess before installing the collar seal. Then wipe down after installing the collar seal and running it up and down then clean again. I also clean between the sheaves after running it up and down before installing the spring.
With the amount of fling on the outside and the sand packing in the middle of the sheave is which also ad some fling on it. I would say the seals did poor or I just did not clean good. I reworked it again and double checked my cleaning as I went this time be sure to rule it out. I also ordered new o-rings and found some seals which are on order to get ere next week. Since I will be reworking it again next week I went light on the grease so I can run this weekend. I did order enough to do three drivens. This one, spare one, future one (wife's). Now I can test the set up again.

I arrowed up some of the pics to show the slippage zones

more pics

As you look at the first set of pics you see bad belt. The driven fling on driven face does not really show up in the pics at first glance.

more pics

Now we can start looking at damage and cause

You can see the brown strips where the belt was slipping and see grease fling where the snap ring is on the cap.
If go look at the pics of driven clean up you will clean this clean before install.

In pic 1 you see the fling on the driven outer surface. You can also see the seal has wiped the shaft clean.
In pic 2 you ts arrowed up
In pic 3 you can see the slippage on the driven faces and some fig and the sand build up in the center.

So I say the inner seal is bad and the o-rings are bad. The inner seal allowed grease to squeeze out and fling on the faces causing the bet slippage and pack sand in the center. The o-rings allowed grease to fly out past the collar seal and fling on outer face.

When I get my new parts I think I will do an enhanced post on assembly

Went out today for some more fun. I did confirm the seal is bad on the driven. I have good consistence rpm data now for the HRD drive. The belt did well and only showed minor signs of slippage at top end. This can be fixed pretty easy with a new seal and a shim here and there. I cleaned it up and install a shim on the drive to start with. This sound get me were I want to be on RPM. Then I can shim the driven a little and be good to go. With a HRD you can not only add pre load you can take it a away. You can not do this with an ALT once you all shims are removed from spring plate with out some work. My red over rev light came on more than I like so I will take some pre load away from the drive. This should take care of that. This will load the driven more. As I am driving under hard acceleration if I can see go from blink to a quick solid its to much.

Got in another tank ride of 51 minutes. What a gas hog.

In case you were wondering I rest it before every run. I resets max temp, max speed and max rpm, it does retaine ART or accumulated run time (Engine hours).

Hopefully the seal will come this week before I run again.

Got the seals today. Still waiting on the rest of the parts to put this driven toghter and replace seals and o-rings on the other.

If you still have the driven apart you can try shimming the spring 1/8" to give better hold and back-shift. That way you'll be able to run more weight in your primary clutch pucks which will put more pressure on the belt to not slip and wear like your photo while keeping a similar RPM.

BTW why the heck are you spinning 8400 RPM anyway? The power drop-off after 7500 does not yield well I'm afraid. Are you massively ported for top end? Have you dyno'ed to see if that's a good peak target?

Zero it is rev ported. Did it my self so who knows on power. The driven is at 6-1/4 inch's right now. The HRD has 14 washers in it.
I'll post up a port angle area,rpm for it. Posted in other post.
I did some ridding today since I will not be home Saturday.

The rpm numbers are what the ports can flow at a given angle area.