924Board.org

[MikeJinCO]

Some how I goofed up. When I took the alternator belt off way too long ago to work on the head the belt was a 10mmx880, when I tried to put it back on two days ago the shortest that would fit was a 10x920. It only lines up in the outside(front) groove of my 3 belt chrank pulley(had an air pump and no AC). I did add a cooling cover, but it doesn't run into anything. Any suggestions?

Finally getting reassembled. Will put on a home made starter heat shield today, then the head can go back on.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[musicalannette]

If you have taken anything off of the car (alternator, waterpump, pulleys etc) I would check they are back as they should be, but if I remember coreectly, I used a 925mm long belt when I serviced mine. If your pulleys aren't aligned then I would double check any spacers or washers where you fitted them, if there not pretty well straight it will eat fan belts.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[ideola]

Is this on a 931? The stock configuration as far as I can tell is the three-groove pulley with alt / water pump belt on the outermost groove. The middle groove is for A/C, and I've never determined what the first really small groove is for, although it's conceivable that it's for the air pump.

Additionally, the water pump pulley should have a spacer that is about 2mm thick behind the pulley. The water pump pulley can be installed in either direction depending upon the crank pulley that you have. On a 931, I am pretty certain it must be installed with the deep dish FACING the front of the car in order to line up with the outermost groove on the crank pulley. On some NA's, I've seen the water pump pulley reversed, but I believe the belt will collide with some of the turbo- or CIS-related plumbing on a 931.

Not sure on the diameter of the belt, I'll double check that a little later on and post back if I'm able to find anything conclusive.
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erstwhile owner of just about every 924 variant ever made

[MikeJinCO]

This one is a NA. I never took the water pump off, only the alternator. The original belt probably should have fit, but not to be. I believe the small inner crank pulley drove the air pump. Since the air pump wasn't connected to anything I just pulled it off in its entirety.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[tomcooper]

Casper's and Big Red's alternator belts run in the pulley groove closest to the engine. You have to take off the A/C belt to get the alternator belt on and off. That could be the reason your belt is not long enough. I sometimes have to take the pulley off the water pump but the belt on the pulley and then reinstall the pulley on the water pump. Just depends on how new the belt is.

Tom
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Casper and Big Red, both 1980 NA
Black Bart, 1990 944 S2 Cab

[MikeJinCO]

Now I really don't know what to do. Using the old time-put a straight edge along the sheaves to check alignment method. The water pump pulley and alternator pulley line up. The front crank pulley is about 3/8"(half a belt width including pulley) in front of the water pump pulley. The small pulley is over an inch away. Did these fellows have a reputation for throwing belts? Since I can't really shim the alternator pulley forward very much (water pump would be much easier) it looks like my best option might be to take off the crank pulley and get it machined to match. Suggestions?

Tom on Applebit's website he talked about machining the crank pulley down because he wasn't using either of the large diameter sheaves to reduce the rotating weight. On some of them, like yours, the small pulley must have been aligned to the others.

Slightly different subject. Are replacement rubber bushing for the top alternator bracket available? Mine really have a little too much play in them. Or is the best way to take off the bracket and drill both the bracket and alternator out for a larger bolt like a modern car. I'd probably add material to the bracket for to get a larger bearing area.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[tomcooper]

Mike,

There is a 77 down in storage at Springfield. I'll try and get down there tomorrow morning and take a look and see how it's set up.

For bushing, I go to Autozone and get some windshield wiper transmission bushing they have, cut about half of the inside rubber off so the alternator fits inside the bracket and drill the bushing out to the next size so the mounting bolt will go through.

Tom
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Casper and Big Red, both 1980 NA
Black Bart, 1990 944 S2 Cab

[ideola]

Just a question...when you disassembled stuff earlier, did you happen to remove the crank driver that sits behind the Gilmer pulley? That is the only thing that would account for the crank pulley being off in terms of alignment.

Bear in mind, it's possible that the water pump pulley was installed incorrectly by a PO, so assuming that what was there before is proper is not necessarily a good thing to do. Look at drawing 105-00 in PET. Notice that the pulley is depicted BACKWARD of what one might intuitively think when looking at it...i.e. with the deep dish toward the windshield, not the front of the car. Also, note the spacer (position 1A, part number 046 121 185). AFAIK, not all configurations used this spacer...do you have the spacer for the water pump pulley? Have you tried flipping the pulley around and seeing if it aligns better with the any of the crank grooves?

Also, the alternator bracket that goes on the side of the block has elongated holes and at least two different positions it can be mounted in, so you should first look to see if you can get the water pump pulley to align with the crank by using the spacer or not, and by flipping it over (i.e. four different possible configurations). If it aligns to the crank in one of those configurations, then see if you can mount the alternator bracket forward or back as required using different holes on it.

And FWIW, I can get those rubber bushings (059 903 263 A) for ~$6 each (plus shipping).
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erstwhile owner of just about every 924 variant ever made

[tyfighter123]

Mike,

I believe Dan is right about flipping the pulley around. I had the same problem with my 77'. Just flip it around and it should line up.
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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)

[musicalannette]

Hi,
Sorry to hear the fact that the 925mm long belt I used has confused you more, but if evrything is in the right place and your bottom pulley is the same diameter as mine (single row, no aircon or power steering) then I would imagine it to be around that figure. As for checking the pulley's are lined up, a straight edge isn't the best method here. Take a piece of thinish string and wrap it round the pulley route, stand and look at the string from the side, getting the nearest and furtherst pieces to line up with your eyes (no parallex error) and then you can get a better idea of just how much the belt will have to flex to accomodate any misalignment (sorry I cannot be there, as ok, or not ok, is gained from years of looking at this sort of thing). Half a belts width does sound a bit much and I would look (as the other guys suggested) at possibilites of moving/spacing or turning round the odd pulley, just remember to be lateral thinking, it might be easier to move the other two pulleys' to correct the problem rather than just the one. When the string is straight the pulleys are lined up.

As for the rubber bushings in the alternator (i think that is what you mentioned), mine were pretty much shot, i found some thick nylon plastic I had in the shed, used a hacksaw and file it to shape it and replaced the rubbers.

If I have not understood and it is the cusion fitting on the adjuster of the alternator, then I would look into METALASTIC repllacements. Rubber and metal are not good long term friends, but METALASTIC are a subsiduary of Dunlop, who made the first inflatable tyres, they made a variety of metal/rubber bushings for the automotivve industry and if you get their orginials they will last a lot longer than most aftermarket replacements, probably longer than the original PORSCHE one's, You notice this if you have something like a LOTUS ELAN where it has the craziest drivetrain this side of the moon, they used ROTOFLEX doughnunts instead of a U.J. or C.V.joints, and they only last if they are from MEATLASTIC, so I would look through their stuff if you want to replace any metal/rubber mountings on the car.
Hope this helps
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[musicalannette]

Sorry, as their directors' can't spell, the "proper" name is METALASTIK
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[MikeJinCO]

You all are right as normal, the water pump pullley is on backwards. A PO had replaced the water pump as it is obviously newer. It should just take rearranging the brackets for the alternator. I am just having trouble imagining how someone wouldn't realize something was wrong, when parts started not fitting right.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[MikeJinCO]

Finally found the solution to the puzzle. This is an XH engine that originally had an air pump. The top front alternator mounting bracket that bolts thru the water pump is a U shaped affair with off set feet so that it can only be mounted one way. What I found was that the water pump pulley had been on correctly the first time with the deep dish toward the radiator, it just needed the spacer per the PET behind it . Not having one, I temporarily spaced it out with washers and everything lined up well. I'll figure out the best washer stack and use it until I can come up with a spacer

The belt a 10x920 now rides in the outer approx. 5.5"dia crank pulley. I tried moving the alternator back by moving the top bracket and it seemed to line up with the first small crank pulley groove, but the top front bracket was entirely wrong, PET has two PN's for that bracket.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)