wheelman Posted May 2, 2007 Share Posted May 2, 2007 Bart, I installed frame rails similar to the BD units and to eliminate the sag in my car I supported the car with jackstands at the TC rod buckets in the front and the front diff crossmember in the rear. This put the engine weight in front of the jackstands and reverse sagged the body. Not sure this is the "best" way to do it but I could see the sag change as I lowered the car onto the front jackstands. I also used 2 floor jacks to keep the rails in place while I tacked them in, then removed the jacks and finished the welds. I wish I knew then what I know now about stitch welding instead of seam welding the rails. I seam welded mine but now I know that it would have been stronger long term to stitch weld and use seam sealer. Wheelman Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted May 2, 2007 Share Posted May 2, 2007 Bart,I installed frame rails similar to the BD units and to eliminate the sag in my car I supported the car with jackstands at the TC rod buckets in the front and the front diff crossmember in the rear. This put the engine weight in front of the jackstands and reverse sagged the body. Not sure this is the "best" way to do it but I could see the sag change as I lowered the car onto the front jackstands. I also used 2 floor jacks to keep the rails in place while I tacked them in, then removed the jacks and finished the welds. I wish I knew then what I know now about stitch welding instead of seam welding the rails. I seam welded mine but now I know that it would have been stronger long term to stitch weld and use seam sealer. Wheelman Did you take 6-8 hours like John said, or something less than the 6-8 days it might take a doofus like me? This might be my one "while I'm at it" with this project since I have the interior stripped and the majority of the sound deadening crap gone. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 2, 2007 Share Posted May 2, 2007 Bart,I installed frame rails similar to the BD units and to eliminate the sag in my car I supported the car with jackstands at the TC rod buckets in the front and the front diff crossmember in the rear. This put the engine weight in front of the jackstands and reverse sagged the body. Not sure this is the "best" way to do it but I could see the sag change as I lowered the car onto the front jackstands. I also used 2 floor jacks to keep the rails in place while I tacked them in, then removed the jacks and finished the welds. I wish I knew then what I know now about stitch welding instead of seam welding the rails. I seam welded mine but now I know that it would have been stronger long term to stitch weld and use seam sealer. Well if you put it that way I get it!!! I know that my front end used to sag down probably 1/4 to 1/2" when I put jackstands under the TC buckets. I don't know for sure, but I always figured that this sagging was happening between the firewall and the engine mounts, so I wasn't associating that sag with the SFCs, and I definitely woudn't associate it with the door gaps. I never noticed any sag in the rear, but I guess that doesn't mean that it wasn't happening... I installed braces from the rockers to the frame rails (upper and lower) and did the strut tower to dash bar braces and the strut tower to lower frame rail braces to stiffen this part of the chassis. I also stitch welded the whole car. I don't think the SFCs will really help this issue much. I would suspect that the only part of the SFCs playing a role here will be the short section from in front of the footwells to the back of the TC bucket. Quote Link to comment Share on other sites More sharing options...
Bartman Posted May 2, 2007 Author Share Posted May 2, 2007 Bart,I installed frame rails similar to the BD units and to eliminate the sag in my car I supported the car with jackstands at the TC rod buckets in the front and the front diff crossmember in the rear. This put the engine weight in front of the jackstands and reverse sagged the body. Not sure this is the "best" way to do it but I could see the sag change as I lowered the car onto the front jackstands. I also used 2 floor jacks to keep the rails in place while I tacked them in, then removed the jacks and finished the welds. I wish I knew then what I know now about stitch welding instead of seam welding the rails. I seam welded mine but now I know that it would have been stronger long term to stitch weld and use seam sealer. Wheelman Ken, the way you installed your rails sounds very similar to what was shown in the MuscleCar edisode I watched. When you completed your installation did the new frame rails hold the chassis in the "reverse sagged" position or perhaps somewhere inbetween where it was previously and how it sat on the jackstands? Did you notice any difference in your door gaps and/or how your doors opened and closed once the rails were installed? Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 2, 2007 Share Posted May 2, 2007 I can't really say how much of the reverse "sag" was retained or how it affected the door gaps as the doors need major adjustment anyway, sorry. I can say though that the new rails stiffened the car enough so that if I get my jackstands on an uneven section of my garage floor only 3 will support the car and the 4th is loose. It's always the same section of the floor so I know when I've got the car in the wrong spot and move it so everything is level. It's a bit disconcerting when I bump one of the stands while I'm under the car and it moves. This happens with the front stands under the TC buckets or the engine crossmember. Everyone keep in mind I'm an amateur mechanic and don't always know the best or even correct way to do something, I figure it out as I go. So if JohnC, Doc Hunt, Grumpy, Jon Mortensen or one of many others here say I screwed up what I did, listen to them. I'm only putting myself at risk in my car. Wheelman Quote Link to comment Share on other sites More sharing options...
Bartman Posted May 2, 2007 Author Share Posted May 2, 2007 So I think I'd like to put my car up on jackstands to try and reverse sag the car and see what this does to the operation of my doors as well as any changes in the door gaps. I'll take pictures on and off the jackstands and post them up on this thread. What would be the best position to place the jacks for this experiment? Under the TC rod buckets and front diff mounts like Ken did or somewhere else? I'll try to perform this test sometime this weekend. Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 2, 2007 Share Posted May 2, 2007 Bart, You might try several locations for the front and rear stands. Place them where I did and take some pictures and measurements then move the fronts to the engine crossmember and measure, then place the fronts back on the TC buckets and move the rear to behind or under the diff somewhere and measure again, etc.. I think we'd all be interested to see your results. Wheelman Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 3, 2007 Share Posted May 3, 2007 Everyone keep in mind I'm an amateur mechanic and don't always know the best or even correct way to do something, I figure it out as I go. So if JohnC, Doc Hunt, Grumpy, Jon Mortensen or one of many others here say I screwed up what I did, listen to them. I'm only putting myself at risk in my car. I'm just a dude with a welder too. I just got the welder maybe 2 years ago, and had virtually no previous fabrication experience before that. John is a professional fabricator, and I think Doc has the qualifications to be one as well. Not sure on Grumpy to be honest. I'm not sure I should be lumped in that same category though. I have ideas and I'm implementing them, and I try to think them through, but no engineering degree or certifications or any of that to back my theories up. Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 3, 2007 Share Posted May 3, 2007 Jon, I was just listing the folks on here I respect and that are knowledgable in a given subject, you are one of those. Obviously it's not a comprehensive list as that would be much to long to type in. Wheelman Quote Link to comment Share on other sites More sharing options...
Bartman Posted May 6, 2007 Author Share Posted May 6, 2007 Well I was able to do some testing today and I took pictures as well. For this test I just jacked up the front of the car and placed jack stands under the front of the floor pans. I used two jack stands on each side and put a small board between them to help distribute the load. The rear tires are still on the ground. The door gaps on the front had very little change, but there is a difference on the back side. The gap has the biggest change at the window frame. Pic Below is on the ground. Pic below is on jack stands: I can definitely feel a difference in opening and closing the doors, with it being easier with the car on the ground. Here are pic's of the rear door gap on jack stands: The one below is with the front on the ground You can see in the pic's that not only are the rear door gaps different, but the rear of the door is higher when the car is supported on the jacks. Quote Link to comment Share on other sites More sharing options...
deja Posted May 6, 2007 Share Posted May 6, 2007 Well I was able to do some testing today and I took pictures as well. For this test I just jacked up the front of the car and placed jack stands under the front of the floor pans. I used two jack stands on each side and put a small board between them to help distribute the load.quote] Wow, that does seem to move a lot. I have not noticed that on my 280Z, but I didn't really do any indepth testing either. I got my Baddogs installed yesterday, took a good 6 hours and that doesn't include cleaning the interior and undercoating which I had already done or painting and sealing afterwards. We used a couple hydraulic jacks and some 2x4s to get them as tight to the floor as we could. As you can see from the picts they didn't really go all the way up against the floor, not sure if they are supposed to but the jacks were raising the car and hitting the baddogs with a hammer sounded like they were tight to the bottom of the Z frames. My welding buddy Chris then clamped them tight against the frame with "C" clamps and stitch welded them into place moving the clamps as he went down each frame. As bad as my frames and floors were messed up this could only be a big improvement. I will clean this all up and apply a coat of POR-15 for rust protection. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 6, 2007 Share Posted May 6, 2007 Those are pretty surprising test results. Please repeat after so we can see the change! It still looks to me like the weight of the engine is pulling the front frame rails (and everything else in the front) down. It will be interesting to see if the SFC's can reduce that flex. Quote Link to comment Share on other sites More sharing options...
badjuju Posted June 30, 2007 Share Posted June 30, 2007 Is it totally out of scope for me to want to do this with the motor in the car? I'm planning on jacking it up as high as possible (hopefully finding a lift instead), cleaninggrinding to get a good surface to weld to, and then stitch welding the bad dog rails on. It's a 73 I only have to do the front sections, but I think I'll be doing front and back. My idea is that I just have to jack the car up and weld. Am I going to have to remove suspension parts and the like, to weld underneath them? Quote Link to comment Share on other sites More sharing options...
wheelman Posted July 1, 2007 Share Posted July 1, 2007 Badjuju, If you're installing BadDog rails the most suspension stuff you'll have to remove is the rear swaybar, assuming you have one installed. You'll want to remove as much of the undercoating as you possibly can and all the sound deadening inside the car. To do this you will need to remove the seats, carpeting and the jute mat that might still be in there. I did mine with the complete drivetrain installed and on jackstands. Made for some interesting welding positions but I was able to get it all welded in. Pop, I think it took me about 12 hours including the prep time. Wheelman Quote Link to comment Share on other sites More sharing options...
panachedk Posted August 10, 2007 Share Posted August 10, 2007 alright, my shell is on saw horses right now... any suggestions on how to get them welded in such a way they do their job right? Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted December 2, 2007 Share Posted December 2, 2007 Just found this thread. I'm interested on how the finished product turned out. How did the door gaps come out? Quote Link to comment Share on other sites More sharing options...
Bartman Posted December 3, 2007 Author Share Posted December 3, 2007 Just found this thread. I'm interested on how the finished product turned out. How did the door gaps come out?I haven't completed my installation yet, but I'll post up when I get back to working on my car and get it done. Quote Link to comment Share on other sites More sharing options...
Blown77Z Posted December 25, 2007 Share Posted December 25, 2007 I started removing the underbody coating on my frame rails tonight and have a quick question. Did you guys remove the little tabs/wings when you installed your rails or did you put the rails up flush with them? Here's a pic of the tabs/wings I'm talking about... Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted December 25, 2007 Share Posted December 25, 2007 Blown77Z I assume that is a 280 with the tabs. My 240 didn't have those. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 25, 2007 Share Posted December 25, 2007 I'd cut that thing off if nothing else attaches to it. Quote Link to comment Share on other sites More sharing options...
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