1971 K20- project just get driveable!!

[Vintage Windmills]

First off, I got the front axle in, so that's good. Nice to have lockouts and intact axle shafts!

I also had to grind the rivets off the one upper shock mount since they were loose. I replaced with 2 UNF 3/8" bolts.

Then I lost a couple battles this weekend.
The first is the driveshaft is too short to connect by about an inch when the axle is hanging down. I verified the springs were symmetric and they are. I am going to put a '72 front driveshaft on. They are about 2 inches longer for some reason! Here is a pic, the top yoke is off the ochre 71 and the one in the middle is off the 72 rusty parts truck. Not sure what the bottom was from. Notice how the front yoke portion is a longer on the 72. The main body is also longer than the 71. I wanted to just swap front portions but the 72 front is too tight on the 71 main body.



The axle looks like its where it should be, about halfway between front and rear of fender opening


Second battle I lost was with the shocks. The fronts have 9 inches of travel and only about 3.75" of that is usable between resting height and fully compressed. I'd like more like 5-6 inches of compressible travel. Similar situation on rear. I ordered these per Summit's website with a search filter of 2.5" lift. Guess I should have just ordered stock height. That would give me about 6" of compressible and 3" of extension which seems ideal.


Also thinking I should trim the U bolts down some. Speaking of them, I need to find a torque value for them:

[ryanroo]

Originally Posted by Vintage Windmills

Second battle I lost was with the shocks. The fronts have 9 inches of travel and only about 3.75" of that is usable between resting height and fully compressed. I'd like more like 5-6 inches of compressible travel. Similar situation on rear. I ordered these per Summit's website with a search filter of 2.5" lift. Guess I should have just ordered stock height. That would give me about 6" of compressible and 3" of extension which seems ideal.


Also thinking I should trim the U bolts down some. Speaking of them, I need to find a torque value for them:

you dont want to limit the ability of the suspension to droop. with only three inches of downtravel in the shock you will be mechanically limiting it with the shock. that can make for a poor ride and may damage the shock. you also dont want to limit the suspension uptravel with the shock, but if you have a little more shock travel than distance to the snubber you should be good. it sounds like you dont have that.

as for the ubolts, i always make em as tight as i can with an end wrench. then check at 500 miles. and again the next time after that you remember. they will loosen.

[Vintage Windmills]

thx all for torque specs

Originally Posted by ryanroo

you dont want to limit the ability of the suspension to droop. with only three inches of downtravel in the shock you will be mechanically limiting it with the shock.

axle drop from weighted to hanging is only ~2 in front and rear. so I am thinking ~3-4 inches of down shock travel and 5 to 6 upwards would be good. Is that what you are shooting for?

Originally Posted by swamp rat

If you have not already, after you remove the shocks and with wheels on the ground get a measurement on level ground from eye bolt to eye bolt, that's the static sag, then jack up the truck off the wheels and get that measurement that's fully extended dimension.
The formula is posted on my thread to find the remaining usable compression:
http://67-72chevytrucks.com/vboard/s...38#post6389138

Here are the measurements I took on Monday which led me to state in previous post I have 3.75 of usable compression in the front:

Truck on lift, wheels off ground:
front- 19.75 bolt to bolt
rear- 21.25 bolt to bolt

Truck on ground, weight on axles:
front- 17.63
rear- 19.13

shocks extended:
front-22.75
rear- 26

shocks compressed:
front-13.88
rear-15.75

shock travel then ~9 in front and ~10 in rear.
axle drop from weighted to hanging is only ~2 in front and rear. so I am thinking ~4 inches of down shock travel and 5 to 6 upwards would be good. Is that what you are shooting for? I guess the design goal would be to have just enough downward to prevent shocks fully extending when axle bounces down and then all the rest would be for compressive travel. Golden question is just how much further (if any) can the axle go than the axle off ground (dangling) dimension?

Originally Posted by swamp rat

I really don't know why the drive lines would be different unless they have a manual verses auto tranny or a different transfer case.. So the splines are just to tight to swap the slip yokes? I wonder if its just the diameter of the slip shaft or if its the splines? If its the diameter maybe you could just sand it down a little..

axles from exact same trucks, just a year different. need to measure with caliper but will probably just swap whole driveshaft and be done.