1972 jimmy front suspension

[Tomq]

Good morning everyone; I am currently rebuilding my 1972 jimmy, question is after I installed new front leaf springs,the front drive shaft distance suddenly got shorter,making the drive shaft too long? I also noticed that the left side spring shackle is up against the safety block on the frame. Is this right,or is another problem creating this situation,when the jimmy is down on it's weight on the ground? Thanks for looking, Tomq

[Richard]

Originally Posted by Tomq

Good morning everyone; I am currently rebuilding my 1972 jimmy, question is after I installed new front leaf springs,the front drive shaft distance suddenly got shorter,making the drive shaft too long? I also noticed that the left side spring shackle is up against the safety block on the frame. Is this right,or is another problem creating this situation,when the jimmy is down on it's weight on the ground? Thanks for looking, Tomq

If the driveshaft looks shorter (more compressed) than it was, the new springs actually lowered the truck. Or... maybe you have 73+ front springs which would be longer hitting the spring stop and the centering pin would be further back. There is no worries about length on drive shaft with stock spec 72 springs. If axle is in the same place as original it will bottom out the same and shaft will compress enough. I can measure the stock front springs off of my 72 for you if you do not have originals to compare. Check overall length and eyes to center pin.

[A1971Blazer]

Are your new springs stock replacement or lift springs?

[Tomq]

Thanks for the reply to my situation re: front springs and drive shaft.The springs are supposed to be replacement from original. I have one that was not broke, so used that as a model.There is three leafs in the bundle,same as original, same length from center pin to eye, same total length from eye to eye.I have not modified anything to the truck,trying to keep it original! The driveshaft was built by a pro shop with the original as a model,using all measures the same, but the truck shrunk sometime! The wheel measures are stock,center to center. When I jack the frame behind the shackle, I loose the door gaps etc ,maybe need another leaf in bundle?.Thanks for looking Tomqlooking

[A1971Blazer]

OK without seeing it in person or pictures, I'll throw out something else to check.

Check the springs to see if they are the same distance from the spring eye(s) on the end to the center pin on the springs. The wheel would be off center in the fender opening if they were somehow backward?

Are the replacement springs arched upward? The factory ones are and when the spring compresses, the bottom of the rear shackle will move forward.

It just doesn't make sense that the driveshaft would be too long if the axle hasn't moved rearward. Did you have the new driveshaft in place before you replaced the springs?
Are you sure that the driveshaft is compressing properly on the slip joint?

Not trying to question your judgment or ability, just throwing out ideas

The door gaps will change when you jack it up by the frame...that's normal, the frames are really flimsy on these

[Tomq]

To answer your questions, the springs do have some arch to them ,when no weight is applied. Then the springs go almost flat,and the shackle is tight against the "safety block". There is a lot of room to the rubber bump on the frame from the axle and spring mount. The shackle has a tendency to move towards the rear when bounced by hand in the shop. I have not tried to drive anywhere until I fix this problem,Tomq

[Richard]

The stop has slotted holes and can be adjusted. If you have compared the springs and they seem similar. I would refer to the new driveshaft. It has to be different in some way. Note that the stock suspension has limited movement. Maybe 4"-5" from full droop to full bottom. If the new shaft has 1/2"-1" left before fully collapsing there will not be problems

[Tomq]

Thanks everyone for the replies.Spring shop looked this AM and thinks these spring bundles might be too lite for the weight of the truck. Earliest to check is mid Sept, so I guess it is back to the waiting game.He thinks 1 more spring leaf on #2 would solve the problem,and check the arch at the same time. Thanks again for info,Tomq

[Tomq]

Hi everyone; Just a short up-date on situation. I put one more new leaf in the bundle, and that raised the truck approx. 2". The new spring bundle was checked for arch and only had 1/2", so they re-arched [is that a word?] it to 3/4", and along with the new leaf all seems better with the driveshaft length!! Thanks for looking, hope this helps someone down this road!!

[Tomq]

The extra leaf gave me 1400# from the 1100# cap in the original new bundle.Just had to take the truck for a spin and it handled a lot better,and still did not lose the ride feel .