shortning frames

[SGibson]

I have often thought of shortning two of my trucks frames, I would think that undoing the r/spring hangers and sliding everything forward to new desired w/b, redrilling and rebolt everything, fab propshaft & lines and lop off excessive overhang would be a no-brainer but a few frameshops I have talked to say saw cut and reweld to desired length, why? one truck is a single frame the other a triple.

 

[dodgenstein]

The area where the springs bolt are humped up higher than the cab frame/front bed area. Moving the perchs forward would lower the front perch, and raise the rear perch. This would do very bad things to pinion angle.

 

[SGibson]

sorry, I meant on reg. truck frames not pick-ups.

 

[JFinke]

They cut and reweld because it's faster and most people are afraid to weld their own frame, thus you will probably have them do it. If you want to do it yourself go for it. Are they aluminum or steel? I assume the single frame may be aluminum, and the tripple is steel. If they are both steel, a magnetic drill will make your life much better. I have done frames both ways and always move the suspension ahead if at all possible. Some tripple frames are only tripple at the suspension and you have to move that piece ahead whith the suspension along with any crossmembers that support the suspension. A lot of the time you can get close to the desired wheelbase by removing one section of the driveline and not have to have any driveline work done. If you cut and weld anything with a double or heavier frame you should always stagger where you cut and weld it back together.



I was going to move the suspention ahead this winter on a KW i bought this summer, but have decided to just add a drop axle and leave it at 144" (oopps 244") Jake

 

[Philip]

Some shops think it is easyer with a welder than redrilling the holes. I prefer to redrill as needed. Its not fun laying under a truck welding frames back together.



If you go to do this. Find somewhere that you can get a reamer to drill the holes with. Using a 5/8's drill bit to make holes in a frame will be hard on your wrists if you don't have a mag drill. A reamer will last longer than a single drill bit on a large amount of holes. It doesn't bind up like drill bits do.

 

[SGibson]

I was thinking of after layout to pilot w/ 1/8" then keep making passes w/ 1/8" increases each time then blockup w/a bushing and final size for a light interference fit w/ a stepped reamer,& deburr. Actually I can remove a length of driveshaft to get my desired w/b on both applications, I guess I'll have to space the carrier bearings down when I do this . I have an old inclineometer from chopper building days lying around somewhere, what degree shouldn't be exceeded? and what is a magnetic drill? the triple is @ the tandem on the 900 and the frame is split on the bottom of the outer frame on both sides @ the tandem unit, the truck used to be a 10yd. mixer so it's hard to picture it overloaded even harder to imagine the 6-71 twisting the frame that much, of course it is old. but to reduce this w/b from current 202" to 175" would leave that cracked section laying in scrapile.

 

[Philip]

Here is a link to one. You might call a local rental shop and see if they do. The one in my area does.



http://www.mytoolstore.com/milwauke/4204-1.html



You would ask about largest angle. I am thinking 12 to 15 degree max in one plane. Its been a long time sence I was in a class that covered it.

 

[JFinke]

A mag drill is the top half of a drill press that has a magnet in the bottom of it. You place it on the frame and turn on the magnet. Mine has an adjustable base so you can fine tune it after the mag is on to center your hole. If you buy (about $1000. 00 min for a good one) or rent one make sure to tie the cords together and use a big circuit. If someone trips on the cord and unplugs it or the breaker trips they fall to the ground. They have an eye to hook a safety chain, but I never bother on a frame as they can't fall far. It's mainly for use on buildings where they can fall a long ways, possibly on someones head. I usually put an old couch cushan under it just in case. I drill each hole in one pass and install that bolt before going to the next. As far as driveline angles go, I'd just drop the remaining 2? to keep a nice even angle. Also make sure the truck is sitting level before you start if you'll be going outside in the dirt.



You can also get by without a mag drill if you have two people. Just put a lung handle on the drill. Then measure around both frame rails and the drill. Get a rope or cable that will reach around all of that and a 2X4. One person can guide the drill with the handle against the ground, tire ect. and run the trigger, while the other applies a pull to the 2X4 to feed the drill into the frame. Before I got the mag drill thats how I did it. Jake