Cross member replacement

[drummerdad]

Im getting ready to start boxing the frame on Isaacs truck in the next week or two, and then we will start on cross members and suspension. I have the corner killer IFS suspension from Uncle Jimmys Jalopies, and the rear triangulated 4-link from Johnny law (ebay).

The truck is a 67 dodge d100. The frame is just the standard truck frame, like a long ladder. The cross members are basically straight. So, the IFS will add a cross member at the motor. The next one back has to be modified or removed, as it was for the bellhousing on the 4 speed. The third will be the transmission tail shaft cross member, so it has to be re-done also. The forth cross member back is where the 4 link frame mounts will have to be. This will raise a few questions.

1) On the 4-link, I dont want to put the long bars (the lower ones) outside the frame rails, or the frame hangers below the frame. The only option is to remove and rebuild the cross member. Ive never done this type of thing. It seems simple enough. Brace the frame, remove the cross member, box the frame, install the 4-link mounts, build a cross member. Does this sound right, basically?

2) I see a lot of guys adding the x shaped center section/cross member, where the drive shaft goes down the middle. Isaacs truck wont be a track truck, but it might get beat on a little. Is this type of cross member necessary? Can I just add some 2 x 3 square tubing with some bracing fore and aft? It might not be too bad to fabricate an x-brace while its apart.

3) The truck probably wont be this far apart again. Im not trying to make a show truck, or anything. But I want it safe, and right. Now is the time to add bracing and cross members. Im sure the h-style ladder frame was best for hauling hay and manure, but I want something that drives well also. Should I make sure there are just as many cross members as there are now? Or can I eliminate a few? Thats a lot of metal there right now. And everything on this truck is thick, old and stubborn.

4) There is a shock mount cross member for the stock suspension. Im almost positive this will not work with the coil overs. Originally it only held the shocks, and the stock leaf spring suspension distributed the load to the leaf hangers. With the 4-link, the weight will be mostly on the shock mounts. So, that means another cross member, with the coil over shock mounts built in, correct?

I would post a picture, but I dont have one of the frame that shows all the cross members. Ill get one this week. I have a link to the folder of pictures for Isaacs truck in my signature. It might make more sense if you look at some of those. I hope these arent annoying newbie questions. If they are, sorry. Ill search more.

[Sbeck09]

I'll do my best to explain my opinions from experience so we don't leave you hanging with no response.

1. The point of attaching points outside of the frame rails is for control over the axle movement. Think of a lever and how much mechanical advantage you gain. Regardless, yes, adding in a cross member to attach the ends would be perfectly fine.

2. The point of the X is to tie each side together. Old trucks had a ton of frame flex. You absolutely could get away with doing straight tubes across, but that's totally dependent on how much flex you feel is acceptable. Even if you don't race it, but like to push it and X might not be a bad idea.

3. In simple terms, more cross members is better. Obviously you get into diminishing returns here, but I certainly wouldn't have less than it came with. Adding the X brace in the middle could save you 1 brace, but you end up with about the same amount of material used so weight is a wash. You aren't dealing with enough weight here to matter on a fun truck.

4. If they had a cross member just for shocks from the factory then I wouldn't think twice about making a stronger version to deal with the MUCH increased loads from coil overs. You don't want your shock mounts flexing. This isn't an area to skimp on materials.

Good luck. There is plenty of info on chassis designs and mods here on just the first page of threads. Feel free to ask more questions as you go along and have specific pics to show what you're working with.

[drummerdad]

Thanks for replying. I went back over a few threads and feel a little better. Im especially interested in the Cottonmouth build, for obvious reasons, but his build is lower than I want to go, and I dont want a v10. I like what he did with the crossmember/driveshaft loop and the diagonal supports on it. I might look at something like that. I dont want to notch the frame that much over the rear axle. I want the bed floor flat. If I wind up notching the frame, Ill raise the entire bed floor, but no more an 2 or 3 inches. I dont know if I like the 4-link bars on the outside of the frame rails. Im going to look into that. I understand the reason, but I want some really wide tires to be honest, and I think the bars will limit tire width. Im sure he plans on racing the truck, and the wider bar set up will help that. Im honestly more worried about it looking right over performance. It needs to be safe and functional, but it has to look right.

I have a lot to learn. By trade I am an avionics installer. I mount and wire aviation equipment in helicopters. I do pretty good forming aircraft grade aluminum, and riveting and wiring. Working with the steel on this frame is new to me. Plus in aviation, we have rules and standards for EVERYTHING. This car stuff is pretty open to personal interpretation most of the time. The 4-link instructions basically say make sure its straight, the bars are parallel to each other, and set the pinion angle where you want it before welding. Thats about it.

[Sbeck09]

Im honestly more worried about it looking right over performance. It needs to be safe and functional, but it has to look right.

This is where most people create problems for themselves down the road. Don't get me wrong, I love for my work to look great in the end, but if you really want a vehicle that drives well you must make that priority #1. How wide of a tire are you planning to run that a 4 link would be the limiting factor?

You being used to dealing with Aviation rules is a good thing here. Attention to detail is crucial when doing suspension. The main reason we don't have a set rule is the difference in chassis. There is standards set by each organization that runs competitive events though so make sure you keep that in mind.

[drummerdad]

After browsing some more build threads, it appears most lower bars are outboard of the frame rails (although I think they were all parallel 4 link, where this is a triangulated). That made me look again at the truck, and I might be okay. The plan is to box the frame, and set the cab and bed on it to lay the suspension out. I have to make sure the static height is right, and the wheels are centered on the wheel well. Ill take a measurement then. I saw a thread with a 68 ford f100 running the bars outside the frame rails, and he was stuffing 335s on the back. I might be okay.

What I meant by my statement was, I know some feel that wheels larger than 18" are a detriment, and Im sure there are others who would question the direction Im going with certain items. Remember, this truck is for Isaac. We spent a lot of time going to car shows, and watching videos and I understood the direction he wanted the truck to go. Im not building this truck for me, thats what the 67 F100 will be. This truck is in honor of him. He wanted 20" wheels, as fat as he could get them, so thats what its getting. He wanted modern amenities, like bluetooth and cruise control, navigation, and A/C, so thats what its getting. He wanted a killer looking truck, with a modern Mopar spin. Something like what the factory would do today, if the engineers had to use a 67 body. Im just trying to find the best, safest most practical way to do it. His dream was to buy a complete hellcat crate from cleveland and pap, and put everything in it he could. I just dont have that kind of money.

Im spending a lot of time trying to catch up on how the cornering guys think. Ive always been a drag racer. I have a ton to learn. You guys will have to keep me in line.

[Adam_T]

I'm not the most experienced guy on here by a lot so I'm sure others could chime in with opinions about this but you have custom front suspension/crewmember, custom rear suspension, want to box the frame, xbrace it, c notch it, and probably custom motor mounts as well. If its pretty much a simple ladder frame why not just start from scratch?

[drummerdad]

They dont make aftermarket frames for the dodges. If it were a chevy, it would be easy. Everything imaginable is available. The fords are not as easy, but there is still an aftermarket. Most of the stuff is bolt on too. The dodge has almost zero aftermarket, so you are on your own. Im also doing this in a two car garage that is half of my basement. Its dangerous welding and grinding, but we try and keep the door open. I dont have the room or experience to build from scratch. This is pushing my boundaries enough as is.

[Angry]

Read your thoughts n plans ....I undersand and agree about things having to look right...but only to a point...My background here is circuit racing,...and trust me if you want it to drive , ride n handle well,...certian suspension links MUST be in certain places..
The wide your shock absorbers are apart the better the truck will handle n drive...leave 4.5 or 5 " of suspenion travle n itll handle good,...less will need shorter stiffer shocks n itll riade riugh and snap out of control easily

Check out No Limits engineering as Rob comes form a racing background and his chassis setups handle really well becaiuse theyre engineered properly.

All the best
..

[drummerdad]

Thanks for the input. I think after looking around the forums and google for a few weeks, Im going to put it outside the frame rails. It will solve a few other problems also. Had I mounted it inboard, one of the cross members would have to move or disappear. Also the shock mount would have been on its original cross member, and its not strong enough for the coil overs. By studying and watching other threads, Im learning. I still have some other things to figure out.

I still dont know about my coil overs. The IFS I bought came with coil overs, but they look cheap. The ends screw on and the adjustable collar doesnt fit the coil spring well, and I dont know, I just dont like them. I have to get coil overs for the 4-link in the back, so I might just buy all 4. My wife will probably kill me.



I also need to figure out if I need sway bars. There are none on it now, front or back, and no provisions.

And what about body mounts? Obviously Im not going to find a kit for this truck. I was thinking about buying some raw bar stock of something like polyurethane or hard rubber, and having them made. I have access to a mill and a lathe, but its limited. The 50 year old rubber was destroyed. Plus the bed was mounted with wooden blocks.

This is my chance to fix some of these nagging issues. I just want to make sure I dont have to go back and redo them.

[Sbeck09]

Glad to hear you're getting a plan into place. It takes a little time digging when no one else has your same setup. Trust me I know. Haha.

I'll go ahead and be the bad influence here....get decent coilovers now. It makes all the difference. ridetech seems to really be fairly priced for giving a TON of options and adjustability. Single adjustables on all 4 corners is only about $1200. You pick the spring rate. That's a killer price for performance monotubes. And they have loads of happy customers that both track and cruise their rides.

I swear I saw a universal body mount from Energy Suspension bushings. Look into that. Way easier than making them yourself. Then you'd only need to cut out a bracket.

[Tincup]

Thanks for the input. I think after looking around the forums and google for a few weeks, Im going to put it outside the frame rails. It will solve a few other problems also. Had I mounted it inboard, one of the cross members would have to move or disappear. Also the shock mount would have been on its original cross member, and its not strong enough for the coil overs. By studying and watching other threads, Im learning. I still have some other things to figure out.

I still dont know about my coil overs. The IFS I bought came with coil overs, but they look cheap. The ends screw on and the adjustable collar doesnt fit the coil spring well, and I dont know, I just dont like them. I have to get coil overs for the 4-link in the back, so I might just buy all 4. My wife will probably kill me.

I also need to figure out if I need sway bars. There are none on it now, front or back, and no provisions.

And what about body mounts? Obviously Im not going to find a kit for this truck. I was thinking about buying some raw bar stock of something like polyurethane or hard rubber, and having them made. I have access to a mill and a lathe, but its limited. The 50 year old rubber was destroyed. Plus the bed was mounted with wooden blocks.

This is my chance to fix some of these nagging issues. I just want to make sure I dont have to go back and redo them.

I'm pretty sure I used a Energy Suspension kit for the urethane body mounts, the kit was for a later model Dodge, but works on the 67. I just made new wood mounts for the bed, the originals lasted 50 years...

[drummerdad]

I'm pretty sure I used a Energy Suspension kit for the urethane body mounts, the kit was for a later model Dodge, but works on the 67. I just made new wood mounts for the bed, the originals lasted 50 years...

Okay, thank you. Ill look into it when Im there on the project. After disassembly and seeing the horrible things that were done, I am having to rethink some of the decisions I had already made.

[79 Camaro]

Just a comment. Before you pull the cab off measure from the rockers to the frame on both sides and record the numbers. It will make the reassembly much easier. Also measure from the front of the cab to some place on the frame to position it front to back.

[drummerdad]

Just a comment. Before you pull the cab off measure from the rockers to the frame on both sides and record the numbers. It will make the reassembly much easier. Also measure from the front of the cab to some place on the frame to position it front to back.

Oops. Too late. It wouldnt have done any good with the frame and the cab mounts that I had to deal with. I did leave the radiator support from the parts truck in place for just that purpose, though. It was the only way I could think to re-position the cab accurately.