convert fork spring specs error?

[gearman]

I tested the springs and the manual says 3 and one half inch compression I should get 230 pounds force. Instead I get 145 to 150 pounds. The first five eights compression is 27 pounds which about right. I did calculations and they say my measurements are correct.Any clue as to why the manual says so much higher.It was listed in kg. and pounds.

[gearman]

Can any one help?I believe the T 3 is the same.Does guzziology list the spec?

[rodekyll]

I've got nothing.  I'd speculate that either the book is wrong or your springs are.

[Moto]

I don't find spring rate specs for the T3 in the factory manual, the Haynes manual, or the 1976 Chilton Motorcycle Repair Manual.

The Haynes manual does list two different fork springs for the Convert, and their free lengths (both different from the T3):

V-1000 [by which is meant the Convert, according to the introduction to the book]:
  Part No. 14 52 66 00   421 +/- 2.5mm
  Part No. 18 52 66 00   415 +/- 2.5mm

For comparsion, "all others," meaning the 750 S, 750 S3, 850 T, 850 T3, Le Mans I:
  418.500 - 423.500mm
 
I did find this spring rate description for the loop frame models V700, V750, V800, in the Chilton manual:

"A new spring should be 230 +/- 15 mm, and should be replaced if collapsed more than 3%. With a load of 110 +/- 4 lbs the spring should be 170mm, and with a load of 231 +/- 8 lbs, the spring should be 104mm."

This last paragraph says that a (230 - 170)/25.4 = 2.36 inch compression should give 110 lbs of force, and a (230 - 104)/25.4 = 4.96 inch compression should give 231 lbs. Both those specs imply a rate of 46.6 lbs/in.

Your manual gives a rate of 230/3.5 = 65.7 lbs/in. But your result is about 147.5/3.5 = 42.1 lbs/in.

It is possible the Tonti springs have that much higher a rate. I dunno. Good luck.

Moto

[gearman]

I don't find spring rate specs for the T3 in the factory manual, the Haynes manual, or the 1976 Chilton Motorcycle Repair Manual.

The Haynes manual does list two different fork springs for the Convert, and their free lengths (both different from the T3):

V-1000 [by which is meant the Convert, according to the introduction to the book]:
  Part No. 14 52 66 00   421 +/- 2.5mm
  Part No. 18 52 66 00   415 +/- 2.5mm

For comparsion, "all others," meaning the 750 S, 750 S3, 850 T, 850 T3, Le Mans I:
  418.500 - 423.500mm
 
I did find this spring rate description for the loop frame models V700, V750, V800, in the Chilton manual:

"A new spring should be 230 +/- 15 mm, and should be replaced if collapsed more than 3%. With a load of 110 +/- 4 lbs the spring should be 170mm, and with a load of 231 +/- 8 lbs, the spring should be 104mm."

This last paragraph says that a (230 - 170)/25.4 = 2.36 inch compression should give 110 lbs of force, and a (230 - 104)/25.4 = 4.96 inch compression should give 231 lbs. Both those specs imply a rate of 46.6 lbs/in.

Your manual gives a rate of 230/3.5 = 65.7 lbs/in. But your result is about 147.5/3.5 = 42.1 lbs/in.

It is possible the Tonti springs have that much higher a rate. I dunno. Good luck.

Moto

Thanks, I am mystified.I will call and see if one of the vendors have this info. My dampers lasted less than eight years.