75 l-48 AC mounting

[Ross F.]

After putting my AC compressor back on. It looks like the belt doesn't line up quite right. I noticed in the AIM it shows some spacers that push the compressor forward.
I can't find these in any other documentation, and they were not there when I took it apart.
Is there a way to check the alignment of the AC pulley ? Is there a dimension given for these spacers some where?

thanks

[Joe L.]

Re: 75 l-48 AC mounting

After putting my AC compressor back on. It looks like the belt doesn't line up quite right. I noticed in the AIM it shows some spacers that push the compressor forward.
I can't find these in any other documentation, and they were not there when I took it apart.
Is there a way to check the alignment of the AC pulley ? Is there a dimension given for these spacers some where?

thanks

Ross------

The shims, GM #3852876, are GM-discontinued but are available in reproduction. They're available from Dr. Rebuild and others. I do not know what their thickness is.

The spacers, GM #351689, were never available in SERVICE and I know of no reproductions.

[Ross F.]

Re: 75 l-48 AC mounting

That's pretty much what I thought.
I have a set of the goofy rear shims.
I guess I will just use washers to get the correct spacing. Mic the resulting thickness and make some.

Thanks Joe

[Ross F.]

Re: 75 l-48 AC mounting

Here is a pic, I think the compressor needs to move forward a touch. Belt wobbles coming off the crank pulley.

[Peter G.]

Re: 75 l-48 AC mounting

Ross....nice car!! Why have we never seen this beauty at a NCRS Regional over the years?

[Greg S.]

Re: 75 l-48 AC mounting

Here are some pictures of my 75L82 with AC. I do not have any of the shims in this installation but you can see that the belt is straighter than yours. I think the only way to move the compressor forward would be with shims. The brackets are not going to bend or move. I'm including a picture of the upper pulley for reference. Maybe yours is farther out on the water pump shaft.image.jpgimage.jpgimage.jpgimage.jpgimage.jpg

[Ross F.]

Re: 75 l-48 AC mounting

Greg,
thanks for the picks. I checked my water pump pulley. It's a frog hair off the pump, just like yours.
the AC brackets are a trip to line up. Mine almost looks like it's cocked inward.
nice car btw.

[Joe L.]

Re: 75 l-48 AC mounting

Greg,
thanks for the picks. I checked my water pump pulley. It's a frog hair off the pump, just like yours.
the AC brackets are a trip to line up. Mine almost looks like it's cocked inward.
nice car btw.

Ross------


It's possible the problem is the waterpump hub.

[Ross F.]

Re: 75 l-48 AC mounting

Ok Joe,
do some splanin.. As Ricky Ricardo used to say.
hub? Now you have me worried. I had paragon rebuild the pump for me. And when I got it back, the hub not been pressed deep enough onto the shaft. Or actually, too deep on the shaft. I took a bearing puller and set the hub depth.
the thing is for the belt to straighten out, I would have to press the pulley farther into the pump. And it's tight now.
also the belt gets a low frequency wobble coming off the crank pulley, so I believe the angle is wrong on both.

[Patrick H.]

Re: 75 l-48 AC mounting

Ross,

How did you measure the proper depth for the hub?
The correct measurement would be from the block mounting face to the hub. If you measured the hub to the end of the shaft, then if they replaced the shaft with a longer or shorter one, the measurement will be incorrect.

Patrick

[Ross F.]

Re: 75 l-48 AC mounting

Patrick,
From what I can find the dimension you are referring to is 5 5/8" .
Is that correct for my 1975 L-48?

[Joe L.]

Re: 75 l-48 AC mounting

Patrick,
From what I can find the dimension you are referring to is 5 5/8" .
Is that correct for my 1975 L-48?

Ross------


No, that's the dimension for the 1955-70 pump. I believe the 1971-82 is 5-51/64". I might be able to confirm later on an NOS pump.

It's not just the hub spacing you need to be concerned about. The hub must also be "square" on the shaft. Sometimes this does not happen if a hub is re-used when a pump is rebuilt.

[Greg S.]

Re: 75 l-48 AC mounting

IMG_2536.jpgMaybe this picture will help. The middle of the AC belt on the pulley is 4 to 4 1/16 inch from the front of the intake manifold. See the picture.