Question(s) for those who've rebuilt their SN's...

[Michael]

It will be okay. The resistance is all in the compression of the balls by the races. Otherwise the seals and misc. contribute a minor percentage to the rotational torque reading. I can’t see any reason dry filming only the carrier would impact your readings. It is a relatively soft metal, mines brass, and I do see wear. It would be interesting to see your coated carrier after some hard use.

I hope you're right. As I said, my logic was entirely based on exactly what you've said: all the compression on the balls is from the races (why else would they have shims and the belleville washer/spring?). The carrier just keeps the balls in place and transfers the rotational movement from the pulley. No real "drive" pressure.

The shop owner did say that the coating itself will "glaze" but it won't wear off. This is the same coating that you see on piston skirts for high-performance applications. I figure if it won't wear off of a piston skirt, it should be fine on the ball-carrier.

[Michael]

I'm confused on your statement, the ball carrier drives the balls from the input shaft so there is high pressure between the carrier and balls??

No, there is little pressure between the carrier and the balls. All the pressure exists between the bearing races, balls, and impeller shaft. The ball carrier only keeps the balls in place while transferring the pulley's rotational motion. If there IS any pressure between the balls and carrier, it's MUCH less than the pressure between the balls, races, and impeller shaft.

The pressure between the races, balls, and impeller shaft HAS to be there. Otherwise, the drive system wouldn't work. But other than the sideways contact between the ball carrier and the balls themselves, no pressure is needed between the balls and ball carrier which is why I decided to have it dry film lubricated.

Does that clarify things...?

[whodwho]

I think your missing the connection between the input shaft and the ball drive assembly. The input shaft is connected to the ball carrier, the ball carrier drives the balls so they roll and the output/impeller shaft is driven from the balls at the 4.4 step up.

[Michael]

I think your missing the connection between the input shaft and the ball drive assembly. The input shaft is connected to the ball carrier, the ball carrier drives the balls so they roll and the output/impeller shaft is driven from the balls at the 4.4 step up.

I know the input shaft is connected to the ball carrier, and I know the impeller shaft is driven by the drive balls. Have you seen the photo below? Who do you think modeled it?



I'd like to think I have a decent understanding of the components within the ball drive and how they work.

But I don't understand what you're getting at, and what it has to do with applying dry film lubricant to the ball carrier?

[whodwho]

Sorry to have upset you it was not my intention at all. It is just a friendly discussion of a different view on something and sorry if I am not explaining it well and let me know if you are not wanting to discuss it.

It didn't have any to do with the dry film it had to do with the comment "since the ball carrier itself doesn't actually place any pressure on the balls"

As we agree there is good amount rotating resistance of the ball assembly, what and how makes that assembly rotate?

Again feel free to tell me to STFU and delete my posts, it is just meant as a discussion and not an attack :sick:

[Michael]

I'm not upset, and there's no need to apologize.

You're right. My comment about the ball carrier not applying pressure to the drive balls was incorrectly worded. It does indeed apply force to the drive balls as it pushes them around the bearing races and impeller shaft. But that force is linear, along the side of the drive balls. The bearing races apply an axial force to the drive balls which is transferred to the impeller shaft as the balls rotate.

The bottom line: friction between the bearing races, drive balls, and impeller shaft is needed, otherwise the impeller shaft wouldn't spin; friction between the ball carrier and the drive balls isn't needed (or wanted). Or is it?


I'm going back to designing airplanes. At least stuff made sense.

[whodwho]

I agree, the friction between the balls and carrier is not needed or wanted I think your attempt at lowering it is a great idea.

With the balls rotating as the carrier is driving them would seem to have a high friction potential between them. It will be interesting the next time you have it apart if the coating will have held up.

I know they switched between an aluminum carrier and brass/bronze, not sure if that was any attempt at this or just durability?

Again I appreciate your efforts here and documenting it and your CAD project. I have had that pic above as a desktop background since you posted it! :laugh:

And now back to your regularly scheduled program...sorry for the extended detour.

[Michael]

The carrier that I took out of my SN89 was aluminum (probably the original one from the factory) the replacement one that I'm having coated is brass. The reason for the switch was because brass is soft (softer than aluminum and certainly much softer than the drive balls) so it won't score or wear the balls themselves (they see enough pressure from the races and impeller shaft). Durabilty? Don't know... probably more to do with mitigating parts wear. If a drive ball gets scored, it can easily (and quickly) damage the races and impeller shaft. If the 'soft' ball carrier wears, there's little likelihood of that damage propagating anywhere else since the drive balls are harder than the carrier.

Of course, once any damage occurs, it's only a matter of time before everything has to be torn down and rebuilt anyway.

But I agree. It will be interesting to see how the DFL holds up after some time in the blower with regular use. It's too bad I don't have any previous data (oil temps, discharge air temps, etc...) to compare to with respect to these coatings. Would have been great to actually quantify these changes with real numbers. Maybe one of the members here can provide their oil and discharge temp numbers as a comparison? Of course, they'd have to be running the same setup as mine (ie. same pulley sizes, comparable sized engine, same fluid, etc...) to make the comparison of any value.

I'm glad to hear you liked the rendering so much that you've made it your desktop background. But if you like that one, then stay tuned... I've got more renderings coming soon which will blow that one away!

[Michael]

Well, I got the impeller and ball carrier back from the shop today. They look FANTASTIC too! Great work.

Take a look at the ceramic coated on the impeller:




And here's the ball carrier with the dry film lubricant:




Now it's time for the reassembly process to begin.

[Buck-Strickland]

Looks nice. It's a shame to hide the impeller.

What was the cost for the dry film coating on the ball carrier? I'm interested to see how that holds up.

[Michael]

What was the cost for the dry film coating on the ball carrier? I'm interested to see how that holds up.

The dry film lubricant cost me $80. A relatively inexpensive experiment all things considered.

[Charged87GTA]

so if anyone was wondering what would cause a loud buzzing noise from your sn89, this is a pic of the old impeller shaft out of mine lol

[Michael]

This is going to sound like a real 'novice' question, but what do you guys use as an inch-pound torque wrench?

I'm asking because the bolts that hold the input shaft to the ball carrier (which is where I'm starting the reassembly process) need to be torqued to 50 inch-pounds. How are you guys ensuring that torque level? Beam-type torque wrench? Clicker-type? Any particular tool brand you guys favor or use?

All the torque wrenches I've found at the usual retail outlets are all foot-pound units. I already have two foot-pound units, one 3/8" drive and the other 1/2" drive. I just can't seem to find an inch-pound wrench.

[64wagon]

found one new on ebay $60.00 0-60 inch pounds brand Consolidated Devices Inc. it's a bar type.

[suede57ford]

You need to check a Ball in the Bronze Ball Driver(Carrier) slots. Sometimes they are a little tight when brand new. It can throw off your inch pound measurement with all brand new parts.

I 've had to open the slots up just a little to allow the balls to spin smooth when the Ball Driver pushes them.

The best inch pound guage is one with a needle.

You have to turn the blower with the inch pound gauge at a consistent speed and note where the needle is.

I marked my inch pound gauge with a red line in the target tension area so I could see where it was reading easier.