Just got done with a DJM lowering kit for my 68 F100. I now have a serious vibration at about 20mph - 35mph. I think I changed the angle of the rear axle which is producing this. Just looking for confirmation and ideas to fix this. I can lower the front leaf spring bolt to the lower bolt hole in the front hanger if necessary, its just a difficult switch and I'd like some feedback before I do it.
I will post pics and info after I fix this problem.

 

It does sound like you've changed the pinion angle. I have the DJM kit sitting on my garage floor waiting to go in, so I'm very interested to know what problems I may encounter, and how to fix them. Please keep us updated.

 

I lowered mine 7 years ago and I dont have any problems at all. I cant remember if I used a DJM or an AIM kit. Does your kit look like this?









As you can see, mine is in the bottom notch and the bump stop is about 1 inch from the top of the rear end. It rides pretty good but I dont drive my truck on really rough roads around here though, and when I do drive it I baby it. The stance is really good on it so Im not touching it!

 

The overall process is very simple. and I'm happy with the results. It was and is the little things that have been an irritation. I'm new to restoration and this was done in my driveway with hand tools. The first obstacle was the king pins. I had to get new ones, they came with metal bushings. The pin was .859 and the bushings were .844. Long story short I had to order a hand reamer from Grainger 27/32-15/16 and do it myself. There is negative camber on the front wheels, more than I expected. The steering is a little looser than before. Back shackles and hangers went in smoothly. I used a 4" angle grinder to cut off the rivets. Then I took a mini sledge and beat off the hangers from the inside out, easy. Then I ground the rivets flush with the frame and tapped them out with my mini sledge and a 3/8 extension. Install the leaf spring to the hanger first and then mount it to the frame one bolt at a time. I lowered my truck back down with the weight on the rear axle to get it closer. 3-4 hours total. I also put my leaf spring in the top holes closest to the bed to get max. drop. I think the front needs to be lowered back to the bottom hole to help correct the vibration. All in All I am happy! My top fenders ride just below the top of my tires. Looks good. I did cut my front springs a little before this. I'm running 15" stock rims and 225/75 whitewalls.

 

Just remembered I bought an AIM kit.............Im running 215/70R15 T/A's front.....275/60R15 T/A's rear on factory 8 inch wheels.

 

Thanks for the pics. I did notice that your front leaf spring is in the lower hole. I am going to try that first. I did talk to a friend who builds race cars and he said to use shims if it doesnt work.

 

William(2) love the stance of your truck- even on stock size wheels. Looks mean. That's the stance that I am going for. Is that a 3/5 drop or something different? Thanks

 

You need to get shims to adjust your pinion angle.

Summit racing has a nice set.

With the AIM or DJM kit do you need to shorten you driveshafts? I know on my last 07GMC I had to shorten my driveshaft 3/4 of a inch when I made my flip kit just like the "flip-Kit" moves it back by the same amount.

 

Make sure you did not accidentally mis-align the drive shaft splines. There are alignment arrows that need to match up so the drive shaft stays balanced. Ran into this on a truck purchase a few years ago. Took a while to pin point.

 

Mine is almost a 4/5 drop. However, I did not cut the front springs, I used stock ones from another big block truck. I also did not have to do anything to my driveshaft.

 

Did you ever get your drive shaft situation taken care of? I just dropped my truck and did the "top" hole thing too. My drive shaft plum fell off after 30 miles. Wondering if I need to shim to correct pinion angle.

 

I did the front hanger half flip on my 67 longbed and the u-joint was binding in the driveshaft. i removed the rear end and removed the spring hangers one at a time and rotated them back 5 degrees and rewelded them on and everything is fine now . you can also use angle shims to do it but it was quicker for me to just do the welding..

 

Thanks. I ended up cutting 1/2 inch of the drive shaft. Now its great.