WTF! Fan alignment...or misalgnment

[Speed Buggy]

Has any one seen this problem? Did I whack the fan while it was out?

What did I do wrong?

[john walker's workshop]

typical magnesium fan housing crack. how are the webs that support the alternator?

[Walt Fricke]

Is the issue that the fan (and its pulley) seems to sit too deep into the fan housing? And not that broken piece? Did you replace the alternator? Early alternators were shorter. Later alternators are longer so they could make more amps. The early fan housing was not bored as deeply, but the later housings were to accept the longer alternator. If a guy put an early alternator into a later housing, it would sit too deeply in.

The only reason I can think of to want an early alternator is for racing, to reduce the power consumed by the alternator, as they put out a lot more than needed.

You could shim an early alternator out.

[Speed Buggy]

John Walker - I'll check the webs. They didn't appear cracked on a cursory inspection.

Walt Fricke - yes the other issue is the depth of the alternator. I took this one out at disassembly and set it aside. When I put it on I noticed that the sheave sits too deep in the housing. The belt did not rub before when it was running (about 1-1/2 years ago).

[Walt Fricke]

Well, I am at a loss on what to suggest. The fan housing locates pretty positively on that little roll pin sticking out of the case. If you removed the fan housing and alternator as a unit (which is common if you aren't going to fiddle with the alternator), and put it back in without alteration, and the fan pulley doesn't line up with the crank pulley, well I'm out of ideas.

Well, I can almost always think of something, but if you changed the crank pulley, or didn't get it on right with the locating pin where it should be, maybe the crank pulley could be too far out. But that seems pretty unlikely, as how that pulley goes on the crank isn't up there with timing cams or the like.

[Speed Buggy]

I lined it up on the roll pin. It is back so the alt housing doesn't rub on the crank shieve. I'm not sure what's going on. I didn't drop it. Hmmmmm. I'll have to dismantle it and investigate.

[Walt Fricke]

The crank pulley is normally very close to the fan housing. My stock SC's looks like it is about to machine the housing, but it doesn't.

And I'm thinking that the shoulders or whatever you want to call them on the fan housing make a kind of positive location on the case. The pin centers it, and this stuff locates it fore and aft, and the pulleys line up and all is good.

Another mystery - how did it somehow sit too far back?

[pareto]

Speed Buggy, I had the same problem. Seems that I got a late housing and reusing my 81 Sc alternator...when installed it sunk farther than the stock housing.....I got spacers to make up the sunken distance to properly align the pulleys between housing and alternator on each bolt ....cylindrical spacers from McMaster Carr and it has been 25k+ miles since...it has worked well for me. Hope this helps....

[Speed Buggy]

Thanks, I'll have to measure and get the off set for the spacers.

[cmonref]

Speed Buggy,

I'm with Walt -- if you reassembled the same fan housing and alternator that were originally correctly aligned, they will now fit properly. But there is one more thing -- did you reinstall the bushing on the alternator shaft BEFORE you installed the fan?

Or, you put an early alternator into a later fan housing, like has been mentioned above. The difference in setting depth is shown in this picture of the difference in depths of an SC alternator (left) vs a Carrera alternator (right).

[pareto]

Speed Buggy, I think a good start, if u want to go spacer route, is to look at Metric SS 18-8 unthreaded spacer at McMasterr Carr.....I bought it at 8mm so maybe a 9mm better? As 8 mm was still a bit sunken...belt rubbed housing just a bit....I confirmed is a Carrera housing 930 106 102 4R w a 81 external reg alternator.....u need to check diameter of stud and clearance from stud to alt and housing and shave off a bit at opposite sides of spacers, fits nice and tight and provides more stability....worked for me.....good luck

[Speed Buggy]

I replaced the alternator with an internal VR. I thought it was like for like because I made no wiring modifications. I only had the 3 wires and not the 4th with the spade connector. I'll check the housing part number to the parts catalog and see what housing I have. Maybe the PO swaped it out. Hmmmm

[Speed Buggy]

John Walker, the fan webs are not cracked but do have weird lines running in all directions.

[Walt Fricke]

OK, it comes out. You didn't just pull fan and alternator, and try to put back. You didn't just pull fan and alternator, take alternator out, and put alternator back in.

You put in a different alternator. You thought it was the same, but didn't measure.

So, do what CMONREF did in that photo - put new and old side by side. I bet they are different heights. So make a careful measurement, and use that to determine what kind of spacers are needed if your new alternator, with internal VR, is shorter.

If the new alternator is longer, you can either exchange it, or have a machine shop machine your fan housing deeper. Or get a fan housing which is deeper, based on measurements. If your housing measures X, and your alternator is Y longer, you want a fan housing bored to X+Y.

Again, don't rely on parts numbers. The casting numbers on the fan housing bear no particular relationship to part numbers, and certainly not much of a relationship to the depth they are machined to accept the alternator. And parts numbers are just stickers on a part in a warehouse - they don't often show up on the parts themselves.

Do not rely on parts numbers for something like this

[E Sully]

Here is the update information on new alternators.

[Speed Buggy]

Walt, I changed the alternator out two summers ago. I did not check the clearance then and looking at the fan housing now, I can see where the belt was rubbing on it and machined some small "V's". This was a pre engine tear down problem I didn't know I had. Now on to the fix as you gents have outlined. Thank you.

Ed, thanks for the tech bulletin, I also bought a new engine harness and that will help.