All, I am installing a triangulated 4 link on the rear of my 1956 Dodge 1/2 ton truck. My question is in regards to the lower, outside parallel bar. Is it designed so this lower bar needs to drop a certain amount below the axle or upper angeled bar to work properly? My 4 link is from Ridetech and it appears to be a pretty decent set-up. The axle bracket for the lower bar drops the bar about 5 1/2" below the axle. To make the front end of that bar parallel at ride height, I would need to add about a 2" spacer block between the bottom of my frame and their front mounting bracket. Without a spacer block, the front end of the bar will be too high. My question is, would this be the correct way to proceed with this mount (welding in the 2" block), or could I simply re-drill the holes higher on the axle bracket, bringing the back of the bar up 2" and even with the front without the spacer added? Also, I am looking for the "best" way to do this so the 4 link will work properly. I am not trying to change their design, I simply do not know that much about the 4 link system and want to know the best way to go about this. I read a lot of posts, but didn't find anyone talking about the vertical separation between the mounting points at the axle end. Thanks for the help!! AkBillyBow
The tubes do not need to be level, or parallel to the upper tubes. The way it looks in the picture actually looks pretty good to me. I usually try to have the instant center somewhere in the neighborhood of the back of the camshaft. There are some threads on here that explain instant center, even a nice diagram by Ned Ludd somewhere. Instant center is where a line continued through the lower tube meets a line continued through the upper tube. I hope that helps. I don't claim to be an expert, but I read a lot and have built many cars with triangulated four-links that worked well on the street.
Thanks for the replies. I have seen that diagram before, and it is helpful. I know you will get many different opinions (from what I have already read) to your questions, but "most" of the posts that I have read say to have the lower bar parallel or 1-2 degrees upward in the front at ride height. I see that Ned's drawing does not have it parallel. Where does this leave me? Thanks.
metal man, thanks for your reply. After reading it, I went back out and took a closer look and decided you were right. The angle originally looked too high with the naked eye, so I put the angle finder on it and it read only 2 degrees. I decided to go with that, and it actually worked out good after I tacked it up. I now have another question about the upper bars. Please look at my pics and see if the way I have the upper bars mocked up will work. It is not measured out or squared up, just asking if the placement of the upper bars on the 3rd member will work. The way it is in the mock up gives me 84 degrees between the bars, gives me about 60% length of upper to lower bars, I can adjust the angle of the top bars down in the front to about 15 degrees (not that much needed but is available), and it puts the front mounting location about 18" forward of the axle center. It also (as you can see from the pics) puts the extended intersection of the top bars right at the center of the axle. I am not sure, but I am thinking this could be a good thing, as I believe this represents the actual pivot point. I have not seen anyone do it like this, but I think it may be a great way to mount them. The mounts being forward of the axle center are one of my concerns, as I do not know if this is correct. I had to place them there to obtain the correct length of the upper bars, as well as the correct (close to 90) angle between the top bars. The truck frame is only 36" across (inside), so finding the correct length and angle is kind of hard to achieve when finding a good mounting point on the Dana 60. Mounting them on the axle tubes just doesn't give me enough bar length or enough angle between the bars. What do you think? Anyone have an opinion on this mounting position? Thanks, AkBillyBow
Metalman is correct in that the lower links do not "need" to be level. However, level mounting is the method recommended by many of the manufacturers of these kits (including the guys at Ride Tech). This reduces the amount of roll steer and pinion motion the housing sees as the suspension cycles. There are other forums where this type of suspension is discussed in terms of best handling, and most of the mfr. tech support offered bears this out. Mounting the upper bars slightly forward won't hurt anything. The motion of the housing is determined by the relative lengths and angles, which you seem to have kept to a minimum. Be SURE you know what you are doing when welding those brackets on to that cast center section. That is a tricky process under the best of circumstances.
exwestracer, good point on welding to the cast center section. You have convinced me to purchase / build a truss for the Dana 60 and to mount the upper bars on top of it. That will also move the mounting location back over the axle. Thanks for your help!! AkBillyBow
The off-road guys make a VERY stout rear cover for the 60 that could be used to mount the upper links. This is just one example: 3/8" plate! http://www.ruffstuffspecialties.com/catalog/D6070COV.html
The Jalopy Journal
