How much rear suspension travel?

[DrCharles]

My '72 Swinger with relocated springs and an 8-3/4 is sitting too low in the rear (fender lips are only about a finger-width above the rim).

I put on Calvert (Rancho 9000) shocks which have just under 8" of travel. (They are 14-1/4" compressed, 22-1/8" extended). They're mounted in the stock location which I estimate is at a 30 degree angle - so that means the rear axle deflection cannot be more than 6-3/4" total. Does this sound right? I thought it could move up and down more than that...

Anyway there are only about 1-1/2" of compression currently available at rest so I know the springs are way too flat. New springs on order. Meanwhile, should I expect the shocks to sit in the middle of their operating range (4" shock travel in either direction)?

 

[brian6pac]

Not sure how you figured that but the more the angle of the shock the less travel of the shock compared to the axle, if the shocks are vertical the 8" travel would be the same as the axle, the more you tilt the shock the shock travel gets less.

 

[DrCharles]

You're right, of course, but I'm not sure why (mathematically)

I'm trying to use trigonometry for the first time in quite a few years ;) The shock is the hypotenuse of a right triangle and the unknown vertical travel is the adjacent side. So 8 * .866 (cosine of 30 degrees included angle) is six-something inches.

Obviously I am modeling it wrong... my lights just came on. The 30 degree angle is only valid at one height. As the shock compresses or extends the angles change. My brain hurts.

Let's do this the easy way - does anyone know how much rear travel a Dart has?

 

[brian6pac]

LOL