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Discussion Starter #1
A three part question...

1. What is the fan belt size on a serries 2 Spider (11.1mmx84 cm?)
2. What is the fan belt size on a series 4 Spider?
3. What is the correct size for a series 2 with an alternator from a Milano?

I ask this because I have installed a new alternator in my series 2, the higher output Bosch model, and the new fanbelt I bought at Centerline is too short, it needs to be about 4 cm longer to give me enough play to adjust the tension correctly.

TIA
 

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Discussion Starter #2
Fan Belt Sizes and Product Codes

I did some research and answered my own question, so I thought I would post the answer in case it is of use to anyone else.

The Product Codes for the fanbelt from a Series 2 Spider are:

Dayco 15320
Goodyear 15325
NAPA 25-08113
GATES 7320

With the Dayco and Goodyear codes the '15' refers to an 11mm wide V-belt series, the later numbers are the length in inches.

When is upgraded my alternator from the older style to a higher output model, the 65 to 75 AMP BOSCH AL16X with the built in regulator, I was able to use the fan and pulley from the old alternator and as per some previous posts had to shave 2 mm from the lower portion of the alternator bracket to avoid having the fan hit the bracket. I replaced the old flimsy wire harness from the regulator and terminal block with a single 6 guage wire from the alternator to the terminal block. The old regulator is trash. The swap also requires a slightly longer fan belt, perhaps two or more inches longer. The correct Dayco numbers for longer belts are:

Dayco 15340 - Two inches longer than 15320
Dayco 15350 - Three inches longer than 15320

I hope this info helps someone else! Cheers.
 

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I just replaced the fan belt on my 74 2L no-air con. The Gates PN I used is:

7325

In Gates' terminology, 325 means 32.5". So the previous Gates PN is for a 32.0" Either one will work, so for people searching, keep that in mind.

I suspect Dayco above is for a 32" as well, and the longer ones support that scheme. And the Goodyear above is like the Gates I chose at 32.5".

I can say that this belt went on pretty easy, and I seem to remember a little struggling to get the belt back on when I have been removing and replacing the alternator. Maybe the 1/2" gives a little more slack and helps installation.
 

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I'd like to update this post with some info. I used the GATES part 7325 (32.5") above and
installing easy, yes. BUT - I later found the belt was not tight and I could not further tighten it.
It is therefore best to use the GATES part 7320 which is 32.0". You have to remove the
lower alternator long bolt to get the belt on though, as the belt is too short to just slip on.
You will be able to get the belt tight, though.
 

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Go to the local parts store and match it up.
 

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My '73 (Series 2) is currently running a Dayco 15325 belt (installed this past summer). The available specs say that it is 32.5” long X 0.44” wide. I am pretty sure I've also used a Gates 7320 in the past too.

What's AC? Is that when you put the top down?....
 
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