Hey guys I purchased a Dave Brown 2" aluminum spinner. Went to put it on my plane which has a OS 46 with the 1/4 28 thread. Had to buy the adapter nut. So I put that on. My question is with the backer plate prop washer and adapter when I put the spinner on it doesn't quite make contact with the backer plate. Does this make much differece? Does it have to make full contact with the back plate?

Yes the spinner must make full contact with the backplate in the grove or notch depending on how it is made or the spinner will go unstable and violent results may occur.

I don,t use Dave Brown spinners but sometimes with some instalations the adapter can be shortened if needed.

Sorry if i am stating the obvious....you use the adapter nut in place of the OS engine's original prop nut. Maybe thats why your spinner is not going far enough back to meet the plate.

ro347 the spinner actually requires the adapter as there is a bolt that goes through the center of the spinner to hold it on. The shaft from the engine is not tap in the center.
Thanks john. Maybe I can grind it down a little bit in a surface grinder at work. The spinner is about 1/32" of an inch away from the back plate.

I UNDERSTAND THAT....I TOO HAVE A DAVE BROWN SPINNER. OK ...MAYBE I AM NOT EXPLAINING THIS RIGHT. ..

YOU NEED THE SPINNER....THE BACKPLATE....THE PROP....PROP WASHER...AND THE DAVE BROWN ADAPTER NUT - YOU WILL NOT NEED THE NUT THAT THE ENGINE CAME WITH TO HOLD THE PROP IN PLACE. IM FIGURING YOU HAVE ONE TOO MANY NUTS ON YOUR PROP SHAFT.

IF IM NOT MAKING SENSE...OR ITS ME THAT IS NOT GETTING IT...I WILL TAKE A PIC FOR YOU TONIGHT.

Oh ok. No I understand. I don't have the stock nut on at all. The other thing that I think is hanging me up is I also put on a bigger prop than what it came with. This was suggested by one of the trainer at my club. Stock prop was a true turn wood 10x8. I purchased a 11x6 plastic blade that is acutally a little thicker. However the spinner is extremely close to touching the back plate. Can I get away with taking some material of maybe both sides of the adapter to get it to fit?? Keeping everything square will be short work as I work at a machine shop.

HMMMM.....THE SPINNER SHOUD FIT REGARDLESS. IT REALLY ISNT THAT BIG OF A JUMP. IS THE HANG-UP THE SPINNER BEING HELD BACK BY THE 2 SIDES OF THE PROP? OR IS IT HELD UP FROM WITHIN THE SPINNER CONE SOMEWHERE?

I think i got it.......you purchased the wrong Dave Brown adapter for your application....there is a long or short available. EUREKA!

ahh well that might explain it. Hold on a minute (" hey sweetheart I have to order more stuff from tower hobbies) Damn just when I thought I was free and clear. Hey thanks ro. Just a $5 part anyways.

Make sure what you initially got indeed was the long.

I just measured the one I have and the short adapter should measure between 3/4 and 7/8 of an inch.

The answer is in the kit building forum under, Dave Brown Spinner problem. Essentially, the DB short nut doesn't work. Its too long and the 8-32 end only has 3 threads. So, if you attempt to cut 1/8 inch off that end to make it fit, you will remove all 3 threads. The answer is the 1/4-28 short True Turn nut. Its the same length as the DB nut. But it has 8 threads at the 8-32 end. Therefore, you can cut off the 1/8 inch required to make the nut fit and still have 5 threads remaining. I hope this helps.

Pilotfighter hit the nail on the head with his answer.

Yes, the spinner DOES need to be tight against the backplate. If you start the engine without it tight you are risking the entire assembly coming apart and causing injury or damage to persons or property in the area. But the solution is pretty simple. Just cut a little bit off of the center bolt used to mount the spinner. Take off a little bit at a time until you can tighten the spinner all the down to the backplate.

Ken