Fan belt 17 mm wide: correct length?

[Z320]

Hi there,

anybody knows the correct length of a 17 mm wide fan belt instead the 20 x 900.

Only thing I know is it has to be shorter than 900 mm....

Ciao, Marco

[RobH]

Are you sure it's less than 900 Marco?  I run a 17mm belt on my '3a with an 18ACR alternator. The belt is numbered 17A0965 making it 965mm long.  I wouldn't be able to fit a shorter one as the alternator won't go any closer to the engine block. 

Edited November 28, 2019 by RobH

[Z320]

Hi Rob,

I own a Gares B35 (that's the "17"), 35" x 25,4 mm should be 889 mm.

On it is printed "Li=900 mm", to the B17 data sheet that should be outside lengh 969 mm, probably this is yours 965 mm.

But mine it is too long.

Due to your answer I was in my workshop with a measuring tape: my Gates B35 is outside 975 mm long, that's 6 mm longer...

Because the B/17 runs deeper in the pulleys than the 20 it must be shorter. I guss about (1+1 mm) x 3.14 mm for every 1 mm deeper?

I guess my Gates is 25 mm too long, I can only use it with an enlargement for the generator strap, what I did for a short time some years age.

That's why I ask.

Ciao, Marco

Edited November 29, 2019 by Z320

[BlueTR3A-5EKT]

and that is what the Li in the part number means...length inside.

975 was the specified outside length for a TR fan belt.  Hence the old Unipart pt no GFB 40975.  The first 2 numbers (I think) after GFB (general fan belt) define the width, the remaining numbers are the outer length in mm.   So 20 mm wide 975 long on the outside. Tedious, as all the fan belt measuring equipment I have ever seen measures the length inside.

Peter W

 

Edited November 29, 2019 by BlueTR3A-5EKT

[Z320]

Hi Peter,

thank you for that Info, but my typ 17 x Li 900 is too long, I can not tighten it.

Ciao, Marco

Edit, what I found at eBay is Li 889 and Li 875

 

Edited November 30, 2019 by Z320