Alternator pulley not flush with bottom pulley

Hougaard · 11:23 AM

Hi guys !

I have a problem with my alternator pulley not sitting flush with the bottom pulley on my 911 1974 2,7.

I have tried fitting a new outer part of the upper pulley, changing the belt with a new one, changing the shim setup (6 in in total).

Is it possible to move the alternator forward ... and how do I do it? Can I take it a part and shim the alternator or is there another way?

some people told me I could move the alternator by releasing the belt/clamp sitting around the fan housing ... but no luck doing that - maybe i am doing it wrong ?

Does the alternators vary in depth and axial length? .... was thinking a wrong alternator might have been installed at some point?

Im a bit frustrated after taking it apart and putting it back together again for quite some times the last couple of days... any input is appreciated!

KR Claus

cabmandone · cabmandone's Garage

You should have a stack of shims for the pulley if I recall correctly.
Edit: Looked again and noticed you mentioned the shims. I don't recall there being a way to adjust the alternator forward when I did mine. I'm thinking there are 4 bolts that hold the alternator in place but don't recall exactly anymore.

Take a look at this for washer setup.

https://www.pelicanparts.com/techarticles/911_fan_belt/911_fan_belt.htm

Hougaard · 07-23-2018, 11:08 AM

Hougaard · 07-23-2018, 11:11 AM

Yes I have 6 shims for belt tensioning - Somehow I need to move the fan longer out of the fan housing towards the back of the car.

proporsche · proporsche's Garage

Hi..give us some more info...what year is your 911...what are you doing this for? Replacing rebuild alt? Did you get this for yours? You have send your in as a core???
To me ,you are installing the wrong type of alternator

Ivan

Hougaard · 07-23-2018, 11:22 AM

Sorry for the lack of info

Its a 911 1974 2,7. I bought the car like this - so im currently trying to correct things like this problem

cabmandone · cabmandone's Garage

I think there are different alternators for different housings as well. I'm going to try and find my old thread from when I replaced my alternator. I think it had something to do with the recess the fan rests in.

theiceman · 11:37 AM

1. shims aren't going to do anything.

all shims do really is tighten loosen the belt they well not make it " more parallel"

what exactly is the issue ? is the belt rubbing on the bottom part of the housing ? or does it just not " look right " ?

not sure if its the right alternator but I think 5mm is a huge issue. Like ivan said verify alternator.

if its not rubbing on the bottom of the housing you can definitely loosen the strap and seat the housing further towards the rear, you will have to keep an eye on the distance from the belt to the bottom of the housing though ( just checked my distance , its about 1mm from belt to bottom of housing ). looks like its been that way a while that thing may need some "help" moving.

cabmandone · cabmandone's Garage

Take a look at my post #9 in the thread link below. It shows that the alternators change based on the fan housing.
BTW, the shim setup should change the pulley face since more shims move the pulley fact out which makes the belt looser. Less shims in the center move the pulley face in making the belt tighter. But it shouldn't be as much as he's showing I wouldn't think.

New to 911's have alternator size question

Looks like from the chart linked at post 9 of the thread above you should have a 901.106.101.5R Housing and your alternator should be a 55 amp alternator and should measure 114mm from the nose to mount face.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by Hougaard

Yes I have 6 shims for belt tensioning - Somehow I need to move the fan longer out of the fan housing towards the back of the car.

I struggled with fitting the notch on the bottom of the fan housing that slides over the pin in the case.

I don't even know if you can get as far as you did on re-assembly if you don't get that lined up.

Hougaard · 11:57 AM

#8 The issue is that the belt is pulled in a not desirable angle, I want it to be straight/lined up with the pulley below. The belt is not rubbing the bottom part of the housing, but there is not much to give. I agree 5mm is a huge issue... I have not been driving the car due to this.

I think you might be right, the fan housing may be stuck.

#9 Thanks for the post with the table of alternator sizes! Im sure it will be helpfull. I will try to disassemble again tomorrow and verify the alternator type -
My housing is the right one - but I will have to check the alternator.

#10 I did not assemble this engine

- and from what I understand, the notch in the bottom of the fan housing not being slid completely over the pin, would give me problems in the wrong direction

? My fan is to far away from the rear of the car.

proporsche · proporsche's Garage

as i said ,you have the wrong alternator...
Ivan

Hougaard · 07-23-2018, 12:28 PM

Actually I think I have the wrong housing

... but hey potato potato

The newer 1976 housing and the 55 amp alternator gives me the offset of app. 9 mm as I am struggling with. I guess I will have to get a new old housing to fit my alternator.

theiceman · 07-23-2018, 12:44 PM

Well housings do crack and I wonder If that's what happened. and that was all PO could find or didn't realize the fitment would be different .... or did..

Flat6pac · 07-23-2018, 12:53 PM

You need to know what fan housing you have and which alternator you have.
Start with a picture of the back of the alternator.
Then the thickness of the back of the housing that the alternator sits on. Approx 19 or 25 mm
Both thicknesses are 901 part numbers. Looks like the early alternator is wrong in a 19 mm back thickness of the housing.
Bruce

Jonny H · 07-23-2018, 12:56 PM

There are three housing offsets. Taking the early long hood housing as a datum, the mid year is +10mm and the 3.2 Carrera is +21mm.

I think you have the correct length alternator (or it would be at least 10mm out). Some alternators have a 2mm spacer that sits behind the fan. My SC has it.

zedsn · 07-23-2018, 01:01 PM

I don't know how far you are off but you can loosen your strap and move the fan housing a wee bit.

Jonny H · 07-23-2018, 01:09 PM

^ No. His fan is too far in and probably rubs the belt on the housing. The housing is in the right place but the fan needs spacing out.

Jonny H · 01:14 PM

The riveted part of the fan should be in line with front of the housing.

P.s. Trust me on this , I’ve spent the last year designing an alternator to fit all models!

theiceman · 07-24-2018, 10:03 AM

okay so just for the sake of discuson , and because we are outside of the box thinkers. Could he not space out the alternator say 6 or 7 mm ? or wahever he needed ? would be easier and correct to get the right alternator but I just like thinking about these things.
I first thought about just an offset spacer where the fan mounts, but he would not have enough left on the shaft for the nut and all the hardware.
So what about a plate or large ring of somekind that sits behind the alternator between it and the housing. Not unlike a wheel spacer that just sit where it mounts flush, then just some longer alternator mounting screws. Might be able to do it for a few bucks and some time until he sources correct , and I'm sure expensive alternator.