1952 B3b with Cummins 4bt

[Jeff Balazs]

Chris;

Do you have the frame drawings in your manual? If not they are quite useful. Also there is some good supplemental data on the body drawings here in the archives.

 

Jeff

[1952B3b23]

Jeff,

 

I do have those in my manual, i'll have to check how close i am to factory specs. Do you know what an allowable tolerance would be on the measurements, like 1/16" or 1/8"?

 

-Chris

[nowhereman]

it was give or take an 1/8 back then. but figure if your out an 1/8 in the front  out an 1/8 some where else in the middle and out a 1/16 some where else. what are you really out. being a frame guy i know it don't sound like much but it adds up to being out of square. if you need to have it pulled insist on dead on.

[1952B3b23]

Thats very true, may not sound like to much but in the end it all adds up. Being a frame guy how much does it cost to straighten? Im sure it all depends on how twisted and un-square the frame is to start with but im just looking for a ball park figure. I dont know yet if mine needs straightening but at least then i'll know what to expect if it does.

 

Thanks,

 

-Chris

[Jeff Balazs]

Hi Chris;

My frame was pretty tweaked. It had been T-boned right around the front edge of the drivers door. Besides being bowed in there it pushed the opposite side frame member out in the area of the bolt in cross member. The bolt in member was tweaked pretty well too. The real interesting part was that the entire rear end was kicked around almost 2" to the drivers side.

 

What I learned while straightening this out is these frames are not all that stout compared to modern frames. Also while taking diagonals is absolutely necessary they alone won't tell you the whole story. I set up center line reference points which were invaluable. A taut line don't lie ......unlike some measurements. I also made up special fixtures to check the distances between the various cab and bed mounting holes. In the end it was a combination of all these measuring methods that got the frame to a point that I was satisfied with it.

 

Jeff

[1952B3b23]

Wow Jeff sounds like your truck really took a hit at some point in its life. Those are some really good points on taking frame measurements, i like the idea of using the taught line down the centerline of the truck. I need to do some carefull measuring and be sure that i am dealing with a square frame before continuing with the swap. I'll go out to the shop and check this weekend, im keeping my fingers crossed.

 

-Chris

[1952B3b23]

Hey guys,

 

So i was just talking to some other folks on the 4bt swap forum and i brought up how i plan on boxing my frame. They proceeded to tell me that this may not be a good idea because Chrysler Corp issued a Technical Service Bulletin (TSB) saying not to weld on the frames. I guess the reasoning behind it is that the steel used for the frames was heat treated and welding on them will actually reduce the strength. The person followed up by saying that evidence for this is to notice how all the stuff attached to the frames is either bolted or riveted. I feel like i have heard of this TSB before but does it apply to our vintage trucks? I know that there are folks on here that have boxed their pilothouse frames has anybody ever heard of this before? Im hoping that this isnt correct for our era trucks cause if it is im kinda in a pickle here.

 

Thanks in advance and any comments are welcome,

 

-Chris

[Dave72dt]

The TSB deals with the new frames, 03 and up.  Specifics on drilling for those frames limited them to no lorger than 3/4 inch and not on the top or bottom rails but you could throught the sides.   Welding was allowed, recommended not welding near fuel and brake lines, components that could be damaged by the heat needed to be removed, and batteries disconnected.   You know, common sense stuff. 

[1952B3b23]

Thats exactly what i wasnt sure of what years that TSB applied to. I tried searching for more info on it but came up empty handed. Yea all that other stuff is just common sense. I just dont want to think im doing good by boxing the frame when im actually harming something. The guy who told me about this TSB also said you can tell that its heat treated steel because it throws off bluish spraks when grinding on it. Instead of the regular orange colored ones, i dont know how much truth there is to that.

[Dave72dt]

I got nothing but orange when I ground on mine.  Go for it.  Welded like regular mild steel, drills like mild steel.  High tensile would drill and weld differently.

[1952B3b23]

Thats what im thinking to, "go for it"! Now that you mention it, I've actually had to drill and weld on mine to a little and didn't notice any difference then regular steel just like you're saying.

[nowhereman]

03  and up is where you have to be concerned. anything older is business as usual.  just don't over heat it that's where you weaken it's tinsel strength  

[1952B3b23]

Thanks guys, disaster averted

[nowhereman]

Thanks guys, disaster averted

you want to find exact reference points on each side of the frame side to side front to rears. top to bottom measure your length from various points. take at least three cross measurements these like points. (factory jig/alignment holes) start with the front third of the frame at the front jig hole in the frame horn to maybe the spring bolt or first cab mount hole measuring across take that measurement and compare it to the opposite side. then do this to the center  area of the frame front cab mount to rear cab mount. and compare to the opposite side. then do the rear as you did in the other areas. then you need at least four plumb bobs. ( a string, or chain with the weight of a good sized nut on the end of it) tie or attach these down the center of a cross member or a broom handle or such laid across the frame rails every few feet until all four are in place. then get down and sight the  middle and if the frame is straight you will only see one nut in your sight. problems that the frame could have would be sway, mash, sag, twist or be diamond. and not necessarily  just one.. if you need to go to a frame shop they will usually charge an hour and a half labor to set up and measure. they need to do the to determine the situation and decide where to make their pulls and how many. a frame shop should be able to give you a copy of the frames measurements before the pull and a copy of the measurements after the pull. after the frame is back into spec. a prefit of your cab or metal should be done to make sure you wont have any problems later with fit.

[1952B3b23]

Wow looks like theres a ton of measurements that need to be taken to really make sure the frame is square. I'll have to see how i compare to the factory specs, hopefully the old girl doesnt need to go to the chiropractor lol  

 

How much does a typical frame straightening cost, any idea? 

[Young Ed]

Wow looks like theres a ton of measurements that need to be taken to really make sure the frame is square. I'll have to see how i compare to the factory specs, hopefully the old girl doesnt need to go to the chiropractor lol

 

How much does a typical frame straightening cost, any idea? 

 

After I crashed my plymouth I paid $400 to get the front frame horns pulled back straight.

[1952B3b23]

So ive been tossing around the idea of frame boxing over on the 4bt swap forum and some Cummins 4bt gurus dont really think that it is necessary. In fact they think that it would make the condition worse rather than help it. There reasoning is that the frame was originally designed to flex to absorb vibrations and twisting from driving. Once the frame is boxed it becomes much more rigid and those benefits go away. They seem to think that unless i plan to build a race truck or an extreme off road vehicle that it really isnt needed. I still would feel more safe having the front half of the frame boxed where the motor mounts and extending back under the cab. This would make this area more rigid and stable to carry the load of the engine and tranny and help with the torque. I also dont plan on any crazy tuning for the 4bt but it will certainly be making more power than the stock motor. I also know that there are some guys that have put hemis into there trucks and didnt box the frames and seem to not have any problems. What kind of power ratings are the hemi guys getting?

 

I welcome any comments on this guys,

 

-Chris

[1952B3b23]

After I crashed my plymouth I paid $400 to get the front frame horns pulled back straight.

Hmmm that doesnt seem like an outrageous price just to do the front considering labor and all of that. So it would at least be double that for a total straightening id assume.

[Young Ed]

Hmmm that doesnt seem like an outrageous price just to do the front considering labor and all of that. So it would at least be double that for a total straightening id assume.

At least at the shop I used a lot of the price was based on what you brought. If you brought a very stripped down frame that should save you some labor costs of them working around body parts. My car was in running condition but had the bare minimum of a front clip so things weren't in the way.

[Dave72dt]

One of the reasons for checking the frame over close it to look for cracks caused by frame flexing.   We know that can and has happened so adding more torque flex and more vibration into the mix without strenghtneing the frame doesn't make sense to me.  Additonally if you're changing the suspension, that boxing is needed to stabilize steering and handling characteristics.  Vibration needs to be controlled  as much as possible through the engine and trans mounts.  The rest gets transmitted through the frame to every other component on the truck, trying to shake it apart.  Consider the use of Locktite on all fasteners and watch the engine idle speed.  A little faster idle will smooth it out some.

[1952B3b23]

One of the reasons for checking the frame over close it to look for cracks caused by frame flexing.   We know that can and has happened so adding more torque flex and more vibration into the mix without strenghtneing the frame doesn't make sense to me.  Additonally if you're changing the suspension, that boxing is needed to stabilize steering and handling characteristics.  Vibration needs to be controlled  as much as possible through the engine and trans mounts.  The rest gets transmitted through the frame to every other component on the truck, trying to shake it apart.  Consider the use of Locktite on all fasteners and watch the engine idle speed.  A little faster idle will smooth it out some.

 

Thats the same things that are confusing me, but i think anyway you look at it there are more pros than cons to boxing the frame. It will definitely add strenghth which will be needed to hold up to the torque and vibration of the motor. My suspension is going to be about the same setup as stock except for disc brakes in the front along with updated components (tie rod ends, king pins, etc.). The rear end is going to be a 8-3/4 out of a chrysler with the leaf spring set up. The Cummins dont vibrate to bad at the higher RPMs but they are pretty notorious for a good shake at idle. Also they suffer from the "Cummins shake" when you shut them down, i dont know about the brand new motors but even my '03 vibrates a lot at shutdown. I have fluid filled motor mounts that should help cut down transmitted vibrations to the frame, and i also plan to put a fluid damper on it which i heard helps a good deal. Also locktite and lock nuts are going to be a must when it comes to assembly.

[1952B3b23]

I have a question for the guys who did box their frames... what did you do about mounting the cross members for the bed? After boxing there is no longer access to the inside of the C-channel to fasten the bolts. I was thinking about either welding them directly to the frame, or making small rectangular cut outs in the boxing plates so that i can still get in there with a wrench to tighten the bolts. Im leaning towards the rectangular cutouts so that if i have to replace a cross member it will be easier to undo bolts than cut the welds.

[nowhereman]

Wow looks like theres a ton of measurements that need to be taken to really make sure the frame is square. I'll have to see how i compare to the factory specs, hopefully the old girl doesnt need to go to the chiropractor lol

 

How much does a typical frame straightening cost, any idea? 

depends on your geographical area as tp what the labor rates are. anybody shop would be able to tell you what their rate is in your area. for your cross members why not weld the appropriate nuts on the member. that way you just need to put it in position and start your bolts. use some anti-sieze on the threads and you should be good

Edited March 28, 2013 by nowhereman

[Dave72dt]

I'm welding in a 3 sided piece of rectangular tubing on mine so I can't drop the nut and washer inside the frame rail where i can't get it back out.

[wayfarer]

I have a question for the guys who did box their frames... what did you do about mounting the cross members for the bed? After boxing there is no longer access to the inside of the C-channel to fasten the bolts. I was thinking about either welding them directly to the frame, or making small rectangular cut outs in the boxing plates so that i can still get in there with a wrench to tighten the bolts. Im leaning towards the rectangular cutouts so that if i have to replace a cross member it will be easier to undo bolts than cut the welds.

 

You might consider welding a piece of bar stock to the inside of the frame where bolts need to go. Drill and tap the piece for the bolt pattern needed and tack it in place...it should not require massive welds to hold position.