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Restoring Type 4 pulley/fan alignment
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drlong
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PostPosted: Tue Jan 19, 2021 9:54 pm    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

Ray.
I can get it back together in proper timing position. I'm looking for help getting it centered.
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raygreenwood
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PostPosted: Wed Jan 20, 2021 9:12 am    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

drlong wrote:
Ray.
I can get it back together in proper timing position. I'm looking for help getting it centered.


No problem. I will get my address to you shortly. Ray
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PostPosted: Tue Feb 09, 2021 10:52 am    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

This is not going to be a super detailed “how to” like my last one on fans…just more of an update. I have done enough fans over the past 2-3 years (I have about 6 and have done those and a couple more)….that I have this down to a pretty quick and accurate process.

My apologies that this is so wordy and long winded.

So.... drlong sent me his very nice fan…clean and well painted pulley….to re-center. It took me a couple of days to get around to gathering all of the tools and slapping a jig together. My last jig…in this link:

https://www.thesamba.com/vw/forum/viewtopic.php?p=8681745#8681745

….was just the surface of a work table I had and that’s gone.

Making a new jig took maybe 10 minutes. A piece of board, six 5/16” washers, three 5/16” bolts with nuts, two wood screws with washers, a piece of flat steel plate and three 608Z bearings.

Aligning this fan should have been less than an hour’s worth of work. But it got odd.
I have done enough of these fans even since the last time I wrote that “how to” at the link above …that I have it down to a quick process as long as the fan is not beat up….and this one was as close to perfect as you can get.

Usually, it’s just a quick eyeball centering of the pulley, then tightening of the four triple square bolts to maybe 2-3 foot pounds max ....mounting of the hub to the fan…just so it takes modest tapping to move it….then put the hub between the bearings and see how far out the high from the low point is in the to main axes between the bolts…being aware that the high and low spot may actually be in a quadrant between the bolts.

Then… “pre-orient” the pulley…by purposely pushing it all the way toward one bolt….and carefully centering as much as possible between the two bolts that are 90° to either side.

This makes it so that 90% of the “out of whack” is in all one axis. Use the dial gauge only to find out what that total amount is. Then just use the polished end of the 10mm arm on the stand…which is stiffer and less sentitive….as a feeler gauge in the Vee of the pulley. Work in one axis until centered and then check the other axis. Reset the gauge bar and repeat as needed.

However….as I was reading the initial out of round….the tip of the dial indicator kept slipping out of alignment big time. I thought the arm clamp was slipping.

I very quickly realized that pulley was OUT OF PLANE. It was “helicoptering” by about 0.55” to 0.60”. I was thinking the pulley itself was bent.

I took the pulley off and laid it flat on a small granite slab. Worked it around under the dial gauge….and the pulley was pretty damn flat.

So….as I starting taking the hub off, I realized one bolt was really tight in its bore…one was a little tight…and one came out easily. The bolts were rubbing on the bore walls. I should have caught on right away…but seeing that they were not stock bolts….I “assumed” the oversize (to the thread) shank was the culprit.
After polishing the shanks down about 0.010”….they fit far better…but still one was very tight, one was kind of tight and one good. It was at that point I realized …with a quick check with a machinist square…that the horns on the hub had been bent when a PO removed it with a three-arm puller.

I would wager heavily that anyone who has a fairly well centered fan ….that is throwing belts for a mystery reason…..this is your problem. After all this time….with all the removals of these hubs through brutal methods….many of them are bent.

Being off at the edge of the fan…out of plane….by 0.060”…means the side opposite is off by -0.060”. That’s a spread of 0.120”…..that fan at 3000+ rpm will wobble like hell and easily sling a belt.

Really…once you start visually checking it….you can actually easily SEE IT when all three bolts are screwed into the hub without the fan.
So, straightening the hub was actually pretty quick and easy once I thought about how to do it. It took five minutes to get the hub straight enough to get the fan runout to right at +/- 0.0025”.
So….here is the gist of what got done in pictures:

Straightening the hub:

So here is the range of the problem. This bolt #1…is pretty damn straight Still actually bent about .002” but you can barely see it next to the hub.

Image may have been reduced in size. Click image to view fullscreen.


Here I bolt #2. Bent a god deal more.

Image may have been reduced in size. Click image to view fullscreen.


And here is bolt #3….bent quite a bit.

Image may have been reduced in size. Click image to view fullscreen.


To add more insult, #3 is twisted in the other plane as well.

Image may have been reduced in size. Click image to view fullscreen.


And you can see the light gap underneath (sorry for the bad picture)

Image may have been reduced in size. Click image to view fullscreen.


Straightening these is not that hard. Get a class 10.9 bolt, a stack of 8mm washer and 4 nuts. Like this:

Image may have been reduced in size. Click image to view fullscreen.


But screw the bolt all the way in like this (sorry for the crappy picture)…and lock all four nuts and the bolt up tight, tight, tight! You want to make the bolt a unit with the washers and nuts so you do not bent the bolt.

Image may have been reduced in size. Click image to view fullscreen.


I mounted it in a vise with UHMW plastic on one side and aluminum plate on the other You could use all aluminum but do not use a steel plate. Do not damage the machined surfaces. Lock it up VERY tight.

Then use a 13mm socket on a 12-14” extension bar. Just lever it up. I estimate that I used about 30 ft lbs. of force. It took two tweaks on each bent leg and one to the right side for #3.

Image may have been reduced in size. Click image to view fullscreen.


In the end…once mounted, all three bolts should stand right in the enter of their bores like this. This was #3 after straightening by the way.

Image may have been reduced in size. Click image to view fullscreen.


To see what pulley alignment problem this was causing…..
Here is the straight bar in contact with the pulley edge at the highest point for a starting reference.

Image may have been reduced in size. Click image to view fullscreen.


….and here it is 180° opposite at the lowest point. That’s a 0.060” gap.

Image may have been reduced in size. Click image to view fullscreen.


The pulley alignment jig:

Image may have been reduced in size. Click image to view fullscreen.


Its just a piece of 1” x 10” board…with a lag bolt screwed into the wood under each corner so I can level it and to leave room underneath for the bolts and screws going through it.

Image may have been reduced in size. Click image to view fullscreen.


And three 608z or 608zz bearings (skate bearings). The bearing on the right has a slotted hole so I can make it up tight. These are 120° apart. I used the hub to mark their positions.
The bolts are 5/16” with a washer under each bearing and one on the back of the board with a nut for each bearing. Yes, these bearings have less than .0001” radial play. You are side loading them anyway so it does not matter.

The holder for the dial stand is a simple piece of 3/16” steel plate held on with wood screws. You can use a long extension like this or a short. I like the room to work and only use the dial indicator to check limits…not for adjusting. Then I use it again at the end to find out how accurate I could get it.
Image may have been reduced in size. Click image to view fullscreen.


I like this indicator tip. If I had one 1/16” smaller in diameter it would be better. If I can get another of these, I may polish this one down.

Image may have been reduced in size. Click image to view fullscreen.



It fits like the pulley groove like this:

Image may have been reduced in size. Click image to view fullscreen.


Here is the whole set up:

Image may have been reduced in size. Click image to view fullscreen.


Alignment method:

First you find the high and low point on the pulley. By "high and low"...I mean closer and farther away from the indicator.. Mark them. If they are between bolts…re-orient the pulley by eyeball to get it largely oriented in one axis FIRST.

Here is the low/far point with a tape marker:

Image may have been reduced in size. Click image to view fullscreen.


Here is the high/close point (sorry for the bad picture):

Image may have been reduced in size. Click image to view fullscreen.


Notice that the red arrow is pointing to the bolt. We are off...in a slightly off axis manner. So I straightened…pre-oriented it…. a bit more to get it to be primarily off in the axis I am working with.

Then I switch to the straight bar. Notice the 5 lb weight sitting on the center of the fan. Whenever you are moving/turning the fan…keep it pressed down in the center with your hand. When you are setting up the gauge or bar and need both hands….use the weight to hold the fan down.

Image may have been reduced in size. Click image to view fullscreen.


The bar above is shown on the low/far side. By low side I mean that in that picture the pulley is pushed off toward the left away from the arm and stand. So the other side would be very tight against that pin and try to lift the fan out of the bearings.

So…. remember…I already know the fan is about 0.012” off in that direction toward the high side from measuring with the dial indicator. So…. carefully back the rod off about .006”. I can use feeler gauges between the edge of the rod and pulley…. but it’s an odd fit.

Yes…you CAN use the dial indicator…but you keep having to pull the probe away and lock it away while you adjust to keep from banging against the indicator. It easier and faster (for me anyway) to just use a solid pin. Most of this you can see in my other link.

I use a small tool and die adjusting “tapper”.

Image may have been reduced in size. Click image to view fullscreen.


It is a piece of 1” brass rod with a soft rubber end (green) and a hard plastic one (back). Its great for making non-marring tapping adjustments.

Make a couple of quick taps until you either contact or just about contact the pin you moved back by 0.006”.

Then slowly spin the fan 180° to the spot directly opposite of where you are working…noting whether it drags or is tight anywhere on the fan along the way. If it does drag…rotate the other direction where it will not drag. Do not get hung up trying to adjust both axes at once.

As I noted…check 180° out. You want to tap adjust…toward the bar on the stand....just enough to split the difference….several times until the pin/arm fits with the same drag at each end of the axis…right above the bolts in that axis.
Then switch to the other axis. Install the dial gauge first…find out how far it is out….then set up the pin/arm on the low side and back it off half the distance. Repeat what you did above.

THEN…recheck the first axis with the dial indicator. You will usually see that it has moved maybe .001” to .003”. Adjust it again with the pin/arm. Then check the second axis.
It usually takes about two rounds of adjustments for each axis.

THEN…..check on the quadrants in between the bolts. Adjust just like above.
Then check it all with the dial indicator.

When this one was done it was out only a +/- of .003” in one axis. It is probably actually closer than that….but the edge of the pulley is not perfect and you get short spikes of a little more than that which span maybe ¼”….lumps in the paint…..dents etc.

So….last time we ere working with this and in several other threads…we have discussed a lot of method and jigs.

I “think” I can make a simple jig board with a machined cone….that contacts the pulley on its inner diameter….based around a center pin that aligns in the middle of the hub. In reality….only the pulley needs to be set concentric to the hub. Then the fan would be face down and you can simply tighten it from the back.

Image may have been reduced in size. Click image to view fullscreen.

Ray
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brownbus2
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PostPosted: Tue May 04, 2021 1:59 pm    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

So, I in my hyper-enthusiastic clean-my-engine-and-make-it-pretty guerilla mission, I separated the pulley from the fan...of course before reading this thread.

I dont want to risk any damage to the engine or anything really by putting it all back together and finding out the hard way that there is a wobble or misalignment.

Should I try it anyway or is it way safer to just grab one from the classifieds and hope it hasn't been taken apart and reassembled.

Anyone reading this have one to sell that they know had no wobble?
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Zeta
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PostPosted: Fri May 07, 2021 9:09 am    Post subject: Re: Restoring Type 4 pulley/fan balance Reply with quote

SGKent wrote:
Quote:
However, I'm more interested in what to do to fix it


"...Had the balance checked - it was perfect from the factory, put it on and the belt runs true. Also painted the timing mark so it shows up clearly and also put a small paint mark at BDC for valve adjustments.


When you say "had balance checked" did you take to machine shop? A specialist?

Would like to source local options prior to initiating steps.

Thanks,
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edhnb
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PostPosted: Mon Mar 11, 2024 3:35 pm    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

Luckily I did not take the fan/pully apart.. I was going to, but remembered reading something about this, I'm glad I double checked.

I have removed it from the case to clean it. Is there any risk in powder coating it? I am in the middle of powder coating all of the tins, etc.. and would really like to coat the fan as well.

Does anyone see any issues in powder coating an already balanced fan?
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PostPosted: Mon Mar 11, 2024 3:58 pm    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

That depends on how accurately you can control the coating thickness, if one side gets a little more than the other it'll be off balance.
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PostPosted: Mon Mar 11, 2024 4:12 pm    Post subject: Re: Restoring Type 4 pulley/fan alignment Reply with quote

Hopefully I did ok... it's in the oven Shocked
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