SFC Questions (Bad Dog Frame Rails)

[Bartman]

So I'm pretty sure I want to install Bad Dog Frame Rails on my car, but I have a couple of questions.

 

First, when would be the best time to install them? Initially I was thinking about doing this after the body work and paint has been completed, but now I'm thinking I should install the Bad Dog rails first. I was watching a car show on TV and they talked about sagging that can happen on unibody cars, and they claim that most 30 something year old cars will have sagging that can be fixed by installing SFCs. They jacked the car up put jackstands under the frame rails to let the weight of the engine remove the sag from the chassis. Afterwards the door gaps were changed and they claim the doors closed better as well. I'm trying to achieve somewhat uniform door gaps, so if the SFC installation can affect them it would make sense to install them first.

 

My next question is regarding the actual installion. I have a welder with gas, but I don't have much experience welding. Is this something a novice should attempt to do, or would it make more sense to take it to a professional welder? I could at least prep everything and possibly even bolt them in place (like what jmortensen did with his), and then take them to a professeional welder.

 

Of course if there's anyone in the SoCal that has welding skills and can help me out, that would be great!

[JMortensen]

If you can weld on sheetmetal you can put these on yourself. They're not hard to install. Those self tapping screws that I used worked out great, and I think that is preferable to trying to bend the SFC to meet the floor. Also just to clarify, that shot is showing the piece that John @ Bad Dog had made special for me. I guess roostmonkey was the one that did that special part (thanks!!!) but the normal rails have the same flat flange on both sides, not just one side like the one in the picture.

[Bartman]

If you can weld on sheetmetal you can put these on yourself. They're not hard to install. Those self tapping screws that I used worked out great, and I think that is preferable to trying to bend the SFC to meet the floor. Also just to clarify, that shot is showing the piece that John @ Bad Dog had made special for me. I guess roostmonkey was the one that did that special part (thanks!!!) but the normal rails have the same flat flange on both sides, not just one side like the one in the picture.

Okay, so it sounds like if I do some sheetmetal practice I should be ready to tackle this job.

 

I wasn't intending to bend the SFC's to meet the floor...but I am thinking of doing the exact opposite and bending the car to match the SFC's (at least to some extent). This of course is assuming that there is some sagging in the car to start with.

 

Now if I do the welding myself it may not make any sense to install the screws first, because by using the jack stands on the SFC's the engine weight could theoretically remove the sag from the car and allow the Bad Dog Rails to sit flat against the floor.

[JMortensen]

I saw that show you're talking about, I think it was Musclecar, and that was a Nova they were working on. My impression is that those cars sag a lot more than a Z. I don't know where you would want to put the jackstands to "reverse sag" the chassis on a Z. I had the chassis on a rotisserie upside down, so I doubt you could reverse sag it more than that, plus it makes the welding a lot more convenient. I wouldn't suggest you put jackstands under the SFCs, especially if the SFC's weren't already attached to the chassis. I wouldn't worry about sag since the rocker is the primary factor there. I'd worry more about getting the welding right.

[Bartman]

I saw that show you're talking about, I think it was Musclecar, and that was a Nova they were working on. My impression is that those cars sag a lot more than a Z. I don't know where you would want to put the jackstands to "reverse sag" the chassis on a Z. I had the chassis on a rotisserie upside down, so I doubt you could reverse sag it more than that, plus it makes the welding a lot more convenient. I wouldn't suggest you put jackstands under the SFCs, especially if the SFC's weren't already attached to the chassis. I wouldn't worry about sag since the rocker is the primary factor there. I'd worry more about getting the welding right.

Yes, that sounds like the show and episode I was referring to. The top of my doors seems to have closer gaps than the bottom, so I was thinking that a little body sag could be the culprit here. The place I really notice it is just below the window on the rear of the doors...the part thats almost horizontal just above the body line. I can take a picture if it helps.

 

Maybe I should go ahead and buy the Bad Dog Rails and trial fit them to see if I have sagging or not. Auxilary posted that his body was arced and that his car was dropped on the Bad Dog Rails to make the rails arc (I'm assuming the arcing he's referring to is the same thing that I'm calling sag).

 

If my car does have some sag can the Bad Dog Rails be somehow installed in such a way to remove it, like in the MuscleCar episode, or would I be asking too much from them?

[JMortensen]

Don't really know the answer to that one... sorry.

[Bartman]

So I sent an email to John at Bad Dog and here's the reply I got:

 

"As to the sagging issue, the rails will help but you'd need to get the

floor level first. I'd use 1-3 sheets of plywood, some 2X4s and a few

jacks to get it back into shape. I would also look into adding some

structural support inside (from the rockers to the tunnel). Make sure

these don't interfere with the seat brackets."

 

So I think the time to install the rails would be before I finish the paint and body work since it sounds like some adjusting will be needed to install them properly. I'm going to order them soon and take lots of before and after pic's especially of the door gaps. I'll play around with using the weight of the engine to help level the floor as well as working with additional jack stands, plywood and 2x4's as necessary. It sounds like I may need to install additional structural support between the rockers and the tunnel as well.

 

Sounds like this will be another fun project.

[johnc]

Of course if there's anyone in the SoCal that has welding skills and can help me out, that would be great!

 

How soon they forget...

 

I just installed a set on a customer's car and its more work then you think, especially if the underside has had a rough life. Remember to thoroughly clean off the underside of the car, strip the interior, and keep an eye on the sound deadener on the inside of the car when welding. It can catch fire and burn for a short time. Also, if you burn a hole through to the interior the melted sound deadener drips out and screws up the weld.

[Pop N Wood]

I have no idea how you would tell what gaps were due to body sag and what was due to the floor metal being bent.

 

I don't know about you but at one point I used a 5 pound hammer and a block of wood to straighten my stock 240 "sub frame rails" from where I tried to use a floor jack at an autocross. On the plus side by the time I got done hammering the floor all of the interior sound deadener had flaked off in big chunks.

 

I would think Jon's sheet metal screws would be the ticket. When you are done welding the edges of the flange, you can pull the screws and plug weld the holes.

[JMortensen]

I just had another thought... I wouldn't do anything to correct the gaps before you work on the door hinges. I'd be willing to bet that 99% of any changes in the door gaps have to do with worn hinges or poor door alignment.

[deja]

I have my badddogs already, going to install them this weekend, hopefully. Mine do NOT have the bend in them like your picture so I can't use the sheet metal screw idea. Maybe they aren't bent because they are for 280Z instead of a 240Z.

 

My welding expert has suggested stitch welding them against the floor and adding some plug welds along the sides. Any opinions on the plug weld idea?

I have removed all the undercoating from the old frame rails and totally gutted the interior including the old sound deadener. I have beat on the floor attempting to get the old rails as straight as possible, but these things are a mess.

[Bartman]

I just had another thought... I wouldn't do anything to correct the gaps before you work on the door hinges. I'd be willing to bet that 99% of any changes in the door gaps have to do with worn hinges or poor door alignment.

Problems with the door gaps may well be due to worn hinges or poor alignment, but if installing the rails can have any affect on door alignment whatsoever it seems to make sense to me to not mess with anything until after they are installed. If I tried to make adjustments for door gaps first, then I would probably need to do it again after the rails are installed.

I have my badddogs already, going to install them this weekend, hopefully. Mine do NOT have the bend in them like your picture so I can't use the sheet metal screw idea. Maybe they aren't bent because they are for 280Z instead of a 240Z.

...

The 240Z frame rails aren't bent either, but it seems that the floor pan could be. If the floor pan is straight, then the Bad Dog Rails should fit easily.

 

I'm assuming that my floor plan isn't straight and trying to determine the best way to resolve this issue.

[deja]

The 240Z frame rails aren't bent either, but it seems that the floor pan could be. If the floor pan is straight, then the Bad Dog Rails should fit easily.

I'm assuming that my floor plan isn't straight and trying to determine the best way to resolve this issue.

 

According to baddog's pictures the 240Z frames are bent.

 

http://www.baddogparts.com/

[Bartman]

According to baddog's pictures the 240Z frames are bent.

 

http://www.baddogparts.com/

Yes I guess they are bent at the front ends, but I'm referring to the main run with the flanges that run along the bottom of the floor pan. This part is flat and the floor pan that it connects to needs to be flat as well.

[deja]

Yes I guess they are bent at the front ends, but I'm referring to the main run with the flanges that run along the bottom of the floor pan. This part is flat and the floor pan that it connects to needs to be flat as well.

 

Click on the products page link, you can look at bigger pictures, looks to me like the main sections are bent, mine are straight all the way. BTW mine are all one piece.

[gnosez]

Both the 240 and 280 rails have a slight bend in the front section that corresponds to the angle of the frame rails as it transitions into the T/C box area.

 

The 240 rails are flat from there all the way back and are now made with flanges on each side to aid in the welding process.

 

The 280 rails do not have the flanges and mimic the OEM rails as they fit the contour of the 280, which is different that those on the 240s. The portion that fits up against the floor pans is not flat. This contour issue and the fact that fuel and brake lines run along side the passenger side rail make both flanges and optional rear rails (like the one made for 240s) more difficult to design around.

 

We are looking into how we can add an optional rear 280 rail section to our product line but the bottom line seems to be that at the very least the fuel/brake lines must be relocated. Side flanges don't seem to be possible but we're looking at the idea of a series of tabs at a few points along the floor pan. The layout and cuts (phasma) aren't the issue, it's the added steps (bends) to make it work right. Those increase the cost.

[deja]

Both the 240 and 280 rails have a slight bend in the front section that corresponds to the angle of the frame rails as it transitions into the T/C box area.

 

The 240 rails are flat from there all the way back and are now made with flanges on each side to aid in the welding process.

 

The 280 rails do not have the flanges and mimic the OEM rails as they fit the contour of the 280, which is different that those on the 240s. The portion that fits up against the floor pans is not flat. This contour issue and the fact that fuel and brake lines run along side the passenger side rail make both flanges and optional rear rails (like the one made for 240s) more difficult to design around.

 

We are looking into how we can add an optional rear 280 rail section to our product line but the bottom line seems to be that at the very least the fuel/brake lines must be relocated. Side flanges don't seem to be possible but we're looking at the idea of a series of tabs at a few points along the floor pan. The layout and cuts (phasma) aren't the issue, it's the added steps (bends) to make it work right. Those increase the cost.

 

 

Thanks for the input. As bad as my rails and floors are now that contour thing isn't a real issue, LOL. I think we'll be doing a lot of hammering. I'll see how it all goes this weekend.

[johnc]

BD subframes are nice and well made. I just installed a set on a customer's car that had some pretty messed up pans and front rails. I used the BD subframes to get things lined up properly.

[pparaska]

Compared to the work involved with cutting out the floor where the subframe connectors go, making up the 2x3" subframe connectors on my site, and adding gussets like I show to the engine frame rails and T/C buckets, how much LESS work is it to install the BD subframe connectors?

[johnc]

6 to 8 hours from start to finish (uncluding seam sealer and paint) to install the BD subframe connectors on the three cars I've done.