Cooling Fan Balance Questions Options

[aggiezig]

Does anyone happen know how the cooling fans were balanced from the factory?

I took mine apart to refinish (Cerakote!) and very stupidly did not make any index marks for the front "ring" and back fan. I noticed on reassembly that there is a weight crimped under the ring lip, presumably for balance. I'm wondering if these pieces were balanced independently (unlikely) or as a unit...

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.1.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.2.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.3.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.4.jpeg)

Any ideas from 914world on how I may find the right orientation / re-balance? My local machine shop said no dice as far as fitting it on any of their machines (ID of the fan shroud bore is too small).

[930cabman]

I'd bet the assembly was balanced, have you sent the crank for balancing?

[Jack Standz]

Does anyone happen know how the cooling fans were balanced from the factory?

I took mine apart to refinish (Cerakote!) and very stupidly did not make any index marks for the front "ring" and back fan. I noticed on reassembly that there is a weight crimped under the ring lip, presumably for balance. I'm wondering if these pieces were balanced independently (unlikely) or as a unit...

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.1.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.2.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.3.jpeg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-19557-1771437363.4.jpeg)

Any ideas from 914world on how I may find the right orientation / re-balance? My local machine shop said no dice as far as fitting it on any of their machines (ID of the fan shroud bore is too small).

Don’t know what those last couple sentences mean.

It’s a very good idea to balance everything in your motor that rotates. Flywheel, crankshaft, rods, pistons/rings/pins, etc. That means get that fan balanced. Have seen pictures of an exploded fan and it’s not something you’ll enjoy. Dynamic balance all of it and if your shop can’t or won’t do it, send to someone who can (DPR?).

[mgphoto]

If you took the fan apart and didn’t assemble it the exact same way then you have to rebalance the fan, I would include the hub, crank and the rest of the rotating assembly.

[bdstone914]

In addition to balance the ring has to be centered on the fan or it will rub the shroud.
Test fit it and see if it clears. If not loosen the bolts and teap the ring until you have equal clearance on all sides

[TRP]

Oh man, I was going to do the same thing with my fan (Cerakote), but I wanted to figure out how to make sure it was indexed the right way afterwards. In the end I kind of looked at it and said "it'll be fine all dirty".

I did notice that my fan doesn't have any of the timing marks on it, that seems like it's going to be a problem.

[930cabman]

In addition to balance the ring has to be centered on the fan or it will rub the shroud.
Test fit it and see if it clears. If not loosen the bolts and teap the ring until you have equal clearance on all sides

changing the relationship between the hub (fan) and the pulley will affect the balance. It's possible everything will be fine, but it's a gamble. Yes, the clearance must be equal

[stownsen914]

See if you can find any witness marks on the fan for where that crimp was located previously. It may tell you how to clock the fan belt ring.
Also look on your crank where that nub on the bolt triangle was on the crank. It could tell you the correct orientation to bolt the fan to the crank.
Hard to know how everything may have been balanced in the past, but putting it back the same way it was before would be a safe bet.

[Jack Standz]

See if you can find any witness marks on the fan for where that crimp was located previously. It may tell you how to clock the fan belt ring.
Also look on your crank where that nub on the bolt triangle was on the crank. It could tell you the correct orientation to bolt the fan to the crank.
Hard to know how everything may have been balanced in the past, but putting it back the same way it was before would be a safe bet.

Have "built" VW motors in years past without balancing because $$ was tight and didn't have the ability/equipment to do so. Would not build a motor today without dynamically balancing it.

Just bolting parts together and hoping it is balanced is not a "safe bet" nor is it prudent, especially if you plan to wind it up and spin it fast. In the end and over the expected life of your motor, dynamically balancing your motor isn't that expensive anyway. Do it right and you'll have a smooth running motor that will last a long time (everything else done right). Running an out of balance motor is asking for trouble and a reduced lifespan. YMMV.

[rfinegan]

If no one can Zero balance the fan, I would suggest static Balance like a mower blade or wheel/tire. That will get you close.
Then do a dynamic balance with the crank, hub, flywheel and pressure plate. Along with the internal components balance to match each other.

[stownsen914]

Would not build a motor today without dynamically balancing it.

Generally agree. But if the motor isn't apart (was unclear if OP's motor is apart, I may have missed that detail) ... not sure I'd take it apart just to balance the fan if I could figure out how to put it back the same way it came apart.

[Ninja]

That is a neutral balance part; doesn't have a dedicated offset weight.

Any decent balance shop should be able to balance that fine alone.
Edit: As long as they have a method of chucking it up on the balancer, this might be an issue.

On a neutral balance engine proper balancing technique is to balance everything separately THEN bolt it all together and recheck/rebalance.

Most of the time, the crankshaft is balance first, balancer is bolted on and balanced then removed, flywheel is bolted/balanced, followed by pressure plate ALONE.

If a balance shop wants to balance with the disc installed run like HELL!
The disc is considered to be part of the transmission for balancing purposes.

Then it's all bolted together. If it was really done right, it should be CLOSE!

If you're off a little bit do a final assembly adjustment.

If it's a bunch recheck each part to see where you botched it!

The above way is more expensive than merely balancing the assembly as a single piece but allows individual parts replacement (flywheel/clutch/balancer).

On something I cared about I'd have that fan balanced after verifying correct outer ring placement.

[aggiezig]

Lots of great comments, thanks for the replies.

Motor is already built and in the car. Long story short, I am planning to change the fan that is on the car (it was "lightened" and otherwise modified by the PO) with a 100% stock cooling fan.

The entire rotating assembly was dynamically balanced at the time it was built. No, it will not be coming apart again for a rebalance - should be no need as long as the replacement fan is balanced itself.

I purchased and subsequently refinished the above-pictured unit for that purpose. Didn't think about indexing the two pieces until it was too late, that's my mistake.

The issue I've run into is exactly what Ninja mentioned - they had no way of chucking it up in the balancer. Going to have to get creative and come up with some way to balance...

[stownsen914]

Call a shop that specializes in VW / type 4. They will have a crank to bolt it up to and balance for you. Not the perfect solution perhaps, but hopefully better than doing nothing.

[930cabman]

Call a shop that specializes in VW / type 4. They will have a crank to bolt it up to and balance for you. Not the perfect solution perhaps, but hopefully better than doing nothing.

(IMG:style_emoticons/default/agree.gif) probably your best option, assuming the crank is in decent balance, adding the fan will get you close

[Ninja]

One of my all-time mechanical gods is Smoky Yunick...

Early on he built some windage test engines with plexi-glass sides and found that during use oil would "rope" on the spinning bits in strange ways and change position with rpm variations.

It was so much oil that balancing to extremely low tolerances was a complete waste of time in his opinion.

Just something to keep in mind...

[930cabman]

One of my all-time mechanical gods is Smoky Yunick...

Early on he built some windage test engines with plexi-glass sides and found that during use oil would "rope" on the spinning bits in strange ways and change position with rpm variations.

It was so much oil that balancing to extremely low tolerances was a complete waste of time in his opinion.

Just something to keep in mind...

With all respect to Mr Smokey (I met him in his Daytona shop in the 80's) a precise dynamic balance is of utmost importance. In a previous life (career) 1970's I was a balance tech in the Northeast. It's possible the issue going on with the OP is nothing, but worthy of a double check in my opinion