| Author |
Message |
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
|
 Posted: Fri May 20, 2016 9:34 am Post subject: Re: Secret squirrel tips |
 |
|
| modok wrote: |
no place for little pin? ok, you'd know better than I, I was just brainstorming.
If you dip it in paint, then spin it, will it balance itself??
HA! |
Likely...yes...it should be close enough in balance. As I noted...the fans are balanced from the factory. Most have a crimped in weight...if they needed one. An overall dip coating with a spin would not be a balance issue.
Yes....locating pins are the way to go. In my long response earlier in this thread....I noted that I went to this method after my very first Rube Goldberg, overly complicated (but effective) method....of making a center jig board.
If you look at the picture of the fan earlier in this thread....see the four nuts around the edge of the black pulley?.....of which only two are visible in the picture?
These four "posts"...which are not fan blades...but streamlined support posts...each has a triple square type 8mm x 1.25 bolt passing through it from the back side of the fan. The square nuts have special washers under them.
When you remove the pulley you can see that there is enough meat on either side of the bolt through hole in these support posts to easily put a 1/32" pin hole...and at best maybe a 1/16" pin hole...but not a 1/8" pin....which would be so much nicer to fit. Its a pain drilling really good 1/32" holes sometimes.
Either way....its the easiest method. Drilling the four pin holes in the steel pulley flange is a good idea anyway. Its very common to eventually break fins from these fans. So...you may need to change a fan out someday and having locating holes already drilled to start the process over helps.
Also related to that last point........a really issue is owners having broken fins because usually a PO tried to turn the fan with a screwdriver....yes...I will admit I broke fins on my very first car when I was in high school because I did this 
So.....many owners are put in the position of having to install an unbroken aluminum part of the fan to their existing pulley if the pulley is badly rusted or bent on a donor replacement fan. With no starting point...getting these put together straight can be tedious.
If one does not have a lathe and does not want to build the jig board I described earlier.....you can also take an engine case and crank if you have one laying around not in use.....slap in some old bearings with heavy grease...and the crank...mount the fan to the hub....mount your dial indicator and place the probe in the center of the fan belt groove...leave the bolts medium tight, turn the crank and adjust with a rubber mallet until it all works. Its not hard...just tedious. Ray |
|
| Back to top |
|
 |
chrisflstf
Samba Member
Joined: February 10, 2004
Posts: 3446
Location: San Diego
|
| Posted: Fri May 20, 2016 5:57 pm Post subject: Re: Secret squirrel tips |
|
|
What would factory specs have been for concentricity of the pulley?
I used to mount/balance scan disks to motor/hub assemblies at work for laser optical systems and could get it down to 2-3 tenths. Just takes some time and patience. Good tools too
I would not use the belt groove as a reference. Unless I knew it didnt have any dirt or debris stuck in it. |
|
| Back to top |
|
|
57BLITZ
Samba Member
Joined: June 12, 2012
Posts: 2385
Location: DEEK - U.S.A.
|
| Posted: Fri May 20, 2016 8:07 pm Post subject: Re: Secret squirrel tips |
|
|
| chrisflstf wrote: |
| . . . could get it down to 2-3 tenths. |
You really mean to say 3 ten-thousandths (0.0003") . . .
NOT 3 tenths (0.300), correct? 
_________________
Jesucristo es mi Seņor y Salvador! |
|
| Back to top |
|
|
chrisflstf
Samba Member
Joined: February 10, 2004
Posts: 3446
Location: San Diego
|
| Posted: Fri May 20, 2016 9:36 pm Post subject: Re: Secret squirrel tips |
|
|
| Yes, .0003", 3 tenths |
|
| Back to top |
|
|
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
|
| Posted: Sat May 21, 2016 7:03 am Post subject: Re: Secret squirrel tips |
|
|
| chrisflstf wrote: |
What would factory specs have been for concentricity of the pulley?
I used to mount/balance scan disks to motor/hub assemblies at work for laser optical systems and could get it down to 2-3 tenths. Just takes some time and patience. Good tools too
I would not use the belt groove as a reference. Unless I knew it didnt have any dirt or debris stuck in it. |
From measuring some very low miles pristine fans years ago that have no vibrations.....about .003" out....maximim.....is what came from the factory from what I have found. Anything more and its bad news. Most are .001" to .002" max.
This is not a type 1 fan. Totally different animal. The type one fan is not attached to the end of the crank. The type 4 is. Then you add sugnificant side load from the alternator pulley.....the vibration is ugly and hard on both the fan and the main bearings.
Also....no....use the pulley V. At this point in time...40+ years old for many.....the pulley edges have too many dents to be a good surface for checking. Ray |
|
| Back to top |
|
|
raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
|
| Posted: Sat May 21, 2016 7:11 am Post subject: Re: Secret squirrel tips |
|
|
| chrisflstf wrote: |
| Yes, .0003", 3 tenths |
Yes.....I got what you meant right away  . Most engineers short hand it to "tenths"......meaning "10/ths of a mil"......or 10 thousandths of an inch.
I have problems getting many of the engineers in my industry acclimated. ...as they keep reducing things to 10ths of a mil.......each of which is 2.54 microns.
We deal in microns ......singular......so stating tolerances like say.....+/- 1/10th of a mil.....is a spread of 5.8 microns......very poor tolerance when you mean thickness is supposed to be 5-6 microns.
These fans don't need to be THAT accurate......but just be aware.....that really the type 4 fan is.....when bolted up.....an extension of the crankshaft. It therefore impinges on the main bearing loading. It needs to be about as concentric in reationship to those bearings.......as the crank itself. Ray |
|
| Back to top |
|
|
57BLITZ
Samba Member
Joined: June 12, 2012
Posts: 2385
Location: DEEK - U.S.A.
|
| Posted: Sat May 21, 2016 9:26 am Post subject: Re: Secret squirrel tips |
|
|
| chrisflstf wrote: |
| Yes, .0003", 3 tenths |
I got what ya meant also . . . it sounds a little funny to me . . . have the pulley centered to about a quarter-inch! 
I'm just a shade-tree, hobby mechanic and I get jealous of folks with nice equipment! 
For my day job, I pretend to be a C.N.C programmer/operator.
In our fabrication work, we can't bother trying to get a tolerance any closer than "a-half-a-thou" . . . our customers don't want to pay for it!
The problem for me is when I am given a customer's print that was drawn by someone that failed to change the C.A.D. program's default setting for tolerances . . . It's always too tight!!!
ALSO . . . Thanks Ray for your insight! I certainly appreciate the time and effort you put into your detailed, informative replies here on The Samba! 
_________________
Jesucristo es mi Seņor y Salvador! |
|
| Back to top |
|
|
BUSBOSS
Samba Member
Joined: January 21, 2009
Posts: 2161
Location: Northern California
|
| Posted: Wed May 25, 2016 9:23 pm Post subject: Re: Secret squirrel tips |
|
|
| raygreenwood wrote: |
I have seen the picture before. I dont think it was his picture.
I think the gist was....how to get hos fan to look nice like that one again.
And...for those who dont know.......if you powdercoat a type 4 fan...you will generally have to get it rebalanced....in the worst case.....but the usual issue is being very careful to mask the rear coupling area where it mounts to the hug.
Any bit of overspray in that area affects how flat it sits on the taper hub. Been there,
Unlike a type 1 fan...because this is attached to the crank on a morse taper ...and its a little different than a type 3 fan....if it gets far enough out of balance it destroys itself...eventually. Sometimes quicker than you think.
The usual problem ...as I mentioned...is not balance though.
The poor diligent unknowing newby owner will note the balance weight position relitive to the sector that contains timing marks...and take it apart to paint and clean....and slap it back together.....not realizing that it will easily be anywhere from dead on to .015" out of round at the pulley.....which screws things up badly. Ray |
As usual, Ray is spot on! Thanks.
_________________
All the redemption I can offer, girl, is beneath this dirty hood
1976 Westfalia
1970 Karmann Ghia Convertible (sold - but not forgotten) |
|
| Back to top |
|
|
|
