Warp Drive hub

[sdemeyer]

I'm a little confused on what I have and what I should have. I can't see any way to center the prop hub onto the gearbox flange. I think I'm missing something but ? I talked to WarpDrive and the guy thought maybe I had the wrong hub but I don't think he really understood what I was talking about. I'll try to explain here:

I have a WD 3 blade 68" prop and a 912UL ( older ). I am using the 75mm bolt pattern with 8mm bolts. The gearbox flange "protruding" center measures 35mm wide. The centering hole in the hub measures 47mm. I am guessing the hole in the hub should be nearly the same size as the protruding center of the gearbox flange to keep the hub centered?

Or, should there be some kind of centering pin in the gearbox flange? Without some sort of centering pin the only way I can see to center the hub is with the prop mount bolts, but there is quite a lot of slop.


Thanks,
Scott

[sdemeyer]

Well, a picture is worth a thousand words so here is what I'm referring to.

[sdemeyer]

Evidently, there are supposed to be inserts pressed into the gearbox flange ( as indicated in the photo ). I've been informed that the inserts keep the hub centered to the flange and provide a much stronger method of attachment. It is recommended by WarpDrive to not use the inside set of holes as an attachment point.

Pretty soon I will have replaced / fixed just about everything possible on my KF and it will be brand new! It's been a great learning experience.

[cap01]

scott , you do need the inserts in the gearbox prop flange . mine had been removed and luckily i still had them to reinstall . i went thru this with warpdrive and kitfox to figure out what i needed .

[sdemeyer]

I ordered a set from LEAF. Hopefully they will be here in a few days.

[cap01]

did they have the prop installed using the inner bolt pattern ? i think you need bigger bolts to fit the inserts . i got a set of bolts from warpdrive when i bought the prop . if you need the protractor or the bolt torques let me know

[HighWing]

I wonder. I built in 1993-98 and a couple of days ago I reviewed the engine section of my old manual and there were instructions on how to remove the studs for fitting the Warp hub. The hub and flange were self centering, though. I ran the combination for 900 houirs. Keep in mind that back in the day, Denney and Skyster were shipping 40 kits a month and there are a lot of airplanes out there with the old set-up and I don't recall anything on the lists about related issues.

I guess there is something new now, but I still doubt I would be comfortable using the bolts or studs to center the prop hub. I think I would either opt for a new hub that fit, or get someone to make a bushing that would mate the two up. This is on my mind now as I am in the process of mounting the engine on my new - old - Model IV project. I picked up a 150 hour engine and it was run without the studs. I think I would be comfortable going with I had in the past if the hub was mechanically centered to the hub.

[sdemeyer]

HighWing, I had a lengthy discussion with WarpDrive and they "highly" (almost forcefully ) recommend using the stud inserts, which is reason enough for me to use them. I decided to check the prop because of a menacing vibration issue. The moment I loosened the hub to flange bolts, the prop dropped a lot. I don't think it was even close to being centered on the flange and I could see no way to get it centered. I went ahead and ordered a new hub so we will see if the center hole is small enough to self align with the flange. I am skeptical this will be the case. At any rate I also ordered the inserts, which I will use regardless.

[cap01]

scott , when i installed my warpdrive ,as i can recall, alignment was never an issue . the inserts of the prop flange fit really well in the machined holes in the hub . i think i made up something to press the inserts into the prop flange , they are a tight fit . by the way i noticed on one of your pictures that you have your oil cooler installed , looks good

[catz631]

Scott,
I would be willing to bet you have the wrong hub. I had my Warp off a few weeks ago .My prop hub looks nothing like yours and the center holes in mine line up perfectly. I can set my prop on the prop flange without the bolts and the holes line up perfectly just sitting there with no bolts attached. I believe mine is the HPL hub.8mm bolts are correct for the prop bushings that need to be installed in the hub. The hole in your prop hub and the hole in the prop flange attached to your gear box should both be the same size. I too have an old engine (mid 90's) From the picture of your prop flange it appears someone has sealed some existing holes on the outer ring. Mine are still open. I know with all the holes,it looks like a swiss cheese. This whole thing is a bit confusing but the bottom line is you should be able to pick up the prop and sit it on the flange coming out of your gearbox .The center flange lip,prop hub hole, and the bushings should all align perfectly. Then slide the bolts in.
Dick
912UL