Jim :
This is probably too late to be of any interest, but here goes. I checked
three belts in my possession : an unused Gates 695, a used Continental
20x900, and a new Cummins 178539WRZ. I believe the Gates came from Moss
about 7 years ago, the Conti came from them several years before that, and
the Cummins came from the local Cummins dealer about 7 years ago.
The Gates rides way high on the pulleys, and will not fit my car (too
short). It is cogged, .845" wide at the top, .440" thick (at the thickest
point), and appears to have a 34 degree included angle.
The Continental fits almost perfect, the top is very slightly above the
edge of the pulleys. It is smooth, .755" wide at the top, .495 thick, and
appears to have a 34 degree included angle.
The Cummins rides down about 1/8" from the top of the pulleys. It is
cogged, .720" wide at the top, .435" thick, and appears to have a 38 degree
included angle. It's mate has been on my car for about 7 years now, with
no signs of wear. It runs quiet and smooth.
I also checked an original water pump pulley. The top of the friction
surface is .720" wide, with roughly a 1/16" radius on the outer edge. The
bottom of the friction surface is roughly .420" wide (measured at the
lowest point my calipers will reach).
Randall
On Monday, April 05, 1999 2:41 PM, JIM_WALLACE@HP-Canada-om1.om.hp.com
[SMTP:JIM_WALLACE@HP-Canada-om1.om.hp.com] wrote:
>
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> Hi all,
>
> I was just communicating with the right guy from Gates, trying to get the
right
> belt for the TR3a. I have learned the following which may be of interest:
>
> 1. My old belt, which was a Gates 507, is no longer made. It measures 38
3/4"
> outside circumference (OC), and the top width is 0.70 to 0.72" (a bit
hard to
> tell due to wear).
> 2. There are belts available in 11/16 and 3/4" widths, but there is less
of a
> selection in the 3/4" width.
> 3. There are SAE standards for the angles of the walls of pulleys. The
idea is
> that the smaller the diameter of the pulley, the smaller the angle, such
that
> the belt "wedges in" more tightly on a smaller pulley.
> 4. Said angles are:
> up to 4": 34 degrees
> 4" to 6": 36 degrees
> over 6": 38 degrees
> 5. The angle of the belt wall is 38 degress i.e. no wedging action on a
pulley
> >6" diameter.
> 6. The cords that are visible on the sidewall of the belt should run as
close
> to the outer circumference of the pulley as possible. If done perfectly,
the
> top of the belt should actually be just outside the edge of the pulley.
> 7. Notches, or cogs, have been implemented to allow the belt to go around
small
> diameter pulleys.
> 8. Gates is in the middle of converting all their automotive belts to the
> notched, or cogged style.
> 9. Since their distributors carry stock, there's no way to know if you'll
get a
> cogged belt or not if you order one.
> 10. A less popular size is more likely to be available in non-cogged than
a
> popular size.
> 11. An 11/16" width is recommended. An OC of 980 mm (38.6") is the
closest to
> my 38 3/4". There are also 960 mm (37.8") and 990 mm (39.0") available in
the
> 11/16" width.
> 12. In 3/4", the only close one is 980 mm (which is really close anyway).
> 13. So, belt numbers:
> 11/16 x 980 mm: 15A0965
> 11/16 x 960 mm: 15A0945
> 11/16 x 990 mm: 15A0980
> 3/4 x 980 mm: 17A0960
> I know you would expect the 3/4 x 980 to end with 0965, but that's the
way it
> is.
>
> I hope this helps. I still have a quandary about which width to go with.
The
> guy recommends the 15A0965, as it's closest. He said the difference is
really
> minor when you get right down to it.
>
> Regards,
> Jim Wallace
> 60 3
>
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