Installing mounts on the Wren Turbine

[cbergen]

I promised some pics and explanation to Skidds for installing the mounts on his Turbine Engine. While building Michael Gregory's I snapped a few pics.....

I start with the Fwd mount, noting that the curved portion has a bevel on one side. This bevel goes against the engine. I only install 3 of the 3X16 SHCS and washers for now, as we will have to orient this mount to parallel the top of the fan hub.

[cbergen]

The aft mount attaches to the two studs at the back of the gearbox. Wren made a slight change here with the new fuel lubricated gearbox, necessitating slotting the bottom hole of the mount.

Again only snug it down at this point as it will also need to parallel the fan hub. Also, unscrew the studs slightly to ensure the plastic in the locknut engages the threads.

[cbergen]

Installing the fan and hub, remove the existing washer and nut, you will NOT need these. Install the spacer and split collett onto the shaft, seating them all the way down.

Smear a little light oil with your fingertip on the split collet to make seating the fan and hub easier.

[cbergen]

Place the fan and hub over the split collett. Use some blue loctite in the threads of the nut, again put a light smear of oil on the taper of the nut, and thread it onto the shaft into the fan hub.

We make a spanner wrench to use when installing the fan and hub on any of our models. This removes the strain from the crankshaft, piston, gears, whatever, helping to prevent twisted cranks and dents in the tops of pistons!!

It also allows some pretty good tightening of the nut holding the fan and hub on, as well as making removal of the nut much easier. Kevin, I will include this spanner wrench in your kit...

Using a standard 1/2" socket on a 1/4" drive breaker bar, begin snugging up the nut.

[cbergen]

After the first snugging, check the runout with your dial indicator, noting the high side. Notice that I am measuring on the side of the hub, at the top.

With the Wren gearbox, we found that our usual method of tapping the high side of the fan down with a hammer was a poor idea.

Instead i found that slight prying action was all that was needed to bring the high side down. Use a bolt head to pry against, and we're NOT putting any brute force into this, just lift it a little and check the runout.

When you have less than .001 runout ( I can usually get .0005 EASILY), then snug the nut down some more and repeat the process.

With the Spanner wrench you can eventually put some SERIOUS bite on the nut, securing the whole assy quite nicely while keeping the runout at the very minimum. It's important to get this runout to the minimum because we are going to parrallel the fwd and aft mount to the TOP of the hub!!

[Skiddz]

Great Chris...

Looks like you have the same dial indicator I do... Looks like you're clamping the mount in the vice, is that the case and still just the 3 bolts in the mount?

[cbergen]

At this point, the gearbox and turbine are still separated. The AFT mount is attached to the gearbox with the 2 studs.

Or maybe I misunderstand the question?

[cbergen]

After joining the gearbox to the Turbine, you'll now need some way to hold the whole thing level.

This comes under the heading of "It's nice to own a machine shop!!" I have a perfectly flat setup table, joe blocks, and I use a parallell under the front to level the engine fore and aft.

The fore and aft level is less critical for this procedure, eyeballing it is good enough. With the engine mounted in the frames, the fan hub WILL be level fore and aft.

The critical part here is side to side level that needs to be fixed into place using the adjustments built into the mounts. All of this is necessary to have a level surface for the clutch system to mate with. Just like in a nitro or gasser, the fan hub and clutch system need to be level to each other to prevent vibrations. Normally this procedure is done here so the customer does not have to sweat it, but Kevin (Skidds) wanted to build his own engine, and who could say no to those baby blues...

[Skiddz]

Ok, disregard previous question. The lightbulb just went off.

In the 2nd pic above, what's the dial indicator measuring?

[cbergen]

Measure the top face of the fan hub, side to side, adjusting it by loosening the nuts on the studs at the back of the gearbox and rocking the whole engine slightly in the direction needed.

When it's nice and level, tighten the nuts, checking the level again after tightening.

[cbergen]

Gotta give me a chance to finish........

[cbergen]

Now we measure the fwd mount, across the top face, side to side.

Zero the indicator in the middle for a reference point, then move to one side. Loosen the 3 bolts holding the mount in place, slide the mount around the turbine to level the top surface of the mount.

Check the top surface all the way across side to side for level then tighten the bolts down. Check it again after tightening.

[cbergen]

You can now install the additional 2 bolts for the fwd mount, and install your engine into the helicopter.

Easy, right?

[Skiddz]

Looks pretty straight forward.. I'm going to have to plumb up my kitchen table and check to make sure the glass is perfectly flat or go visit my buddy's shop and use one of his benches for that part...

[cbergen]

Your table doesn't have to be perfectly level, just flat.

[lperagallo]

Chris,
Can you have this moved as a sticky post?
It's good info to have on top.

Lou

[cbergen]

It was only intended as an aid for Kevin, but for those doing maintenance on their engines, which require removing the mounts, I agree, it is good info to have on top.

Goin' up!

[Drevil02]

Chris, love the pictures. Can't wait to get the kit!!
Michael

[lperagallo]

Originally Posted by cbergen

It was only intended as an aid for Kevin, but for those doing maintenance on their engines, which require removing the mounts, I agree, it is good info to have on top.

Goin' up!

Chris,

Thanks. You know it's better for us old guys who forget what they did yesterday! I'll remember it was posted, but I'd never find it again. Heck, I've watched you do this twice and still didn't remember it correctly. This way I'll be able to find it quickly and it'll save you the time of explaining it to me again.

Lou

[Skiddz]

Well, amazingly the kitchen table is pretty much dead on level and appears to be absolutely flat when I put a 3' metal straightedge across it from several different directions.

Can't wait to get the goodies and start building..