From everything I've been reading when it comes to building hot rods if you Z the rear end you don't want to do a Pure 90 degree but instead closer to 45 degree angle for safety reasons. I've been looking at 4 link setups, and on all the places I've looked the 4link kits are meant to be setup with a 90 degree Z. See the below image for example (which is from Chris Alstons Chassis works for a Nostalgia Door slammer. http://www.cachassisworks.com/p-673-nostalgia-1932-34-willysa-arm4-linkmild-steel.aspx I'm trying to map out my chassis and want to make sure I got my head on straight. Thanks for your time and advice. -Brahm
I would think that the more angle that there is the more likely it would be to flex or twist. Most 90 degree four link setups have roll bars with rear down bars to stiffen them.
Me thinks, it's a 22.5 degree cut, at each intersection, in your "Z" section, from the front side of the axle, to the rear side, of the axle......................But there is MUCH more knowledge 'bout that stuff on here,'cause I've never done one!!!!!
Nothing is set in stone, but this is a general run down of what I have in my head. I'm thinking of a 4x2 chassis with a taper down to 3x2 in the front. Suicide spring above front end, and 4link rear. I'm not sure on weight, but I'm shooting for 2750# for the class I'm attempting to build towards..which has me a bit Leary as the spring above kits are rated at 2500# (any thoughts on how to "beef" them up?) . Wheelbase I believe will be around a 116". The car will be caged.
I built my '34 pickup with a 14" 90* Z out back with 2x3 tubing, 112" wheelbase, 2400lbs. I fishplated the joints and gusseted them well. Drove it hard on the street and occaisionally on the track for 12k trouble free miles before I sold it. A 90* may put more stress at the joint than a lesser angle, but if it's of sound construction it will be fine.
A lot depends on what rear suspension you use and how much room you have back there... a 90 is fine... we used 'em a lot on circle track cars but you have to use a good size gusset usually, but not always, made from the same material as the frame.
I have been told that there is a small difference in strength between the two by a couple of well known chassis guys. But neither could produce any sort of physical evidence, and after a couple of beers and some exchange of knowledge, it was decided that the difference of strength wasn't of any benefit or detraction from what we do with our cars. The reason I asked the same question was I just did two back to back builds of Bantam coupes, where every inch you can save is golden. So, now I have one that has been running around for two years, and has lived very nicely through a pretty bad accident,( hit from the side and rolled over, now repaired and back on the road) and one that will soon be on the road. Both have ninety degree kick ups, and I might add, about three inches of extra leg room. I do have to assume that you are talking about two forty-five degree cuts welded together and not those god awful stack them and butt weld them kinda deals that were popular with the rat rod stuff, right?
2750 is still not that heavy. I guess that you could have the spring arched more or add a leaf if you had to. The father that you move the engine (weight) back away from the front spring the lighter the front spring thinks that the vehicle is. I wrote that and read it a few times and it still sounds screwed up but, do you know what I'm trin' to say...? Smokey
Thunderbirdesq,Kroozer,need louvers all have you covered with good info...45 degree gives you a lot of weld surface,four link brackets act as gussets,cage even more strength. It sounds to me like you're goin' in the right direction... Have fun,Smokey
Brahm, unless my understanding is way off base, you don't need a heavier/ beefier spring as it is not supporting the entire 2750#, it will only be holding up a % of the total depending on the weight bias of the car ie 60/40 will have ~60% of the mass on the front end.
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