Kafer Cup Bar - Truss Bar Setup

[Hotrodvw]

I put the floor jack under my sump plate, and lifted until it started to move the car. Basically, I took the weight off of the frame horns, or at least some of it. Zero wheel hop any time.

[Jadewombat]

I was getting some hop, or something bouncing around back there last autocross this past weekend exiting a corner on full-gas. I have a half rollcage in the rear and considering just tying two short pipes from the top of the shocks to the rear cage mounts. Would this work in place of going with the whole truss bar (don't like adding weight to the car if I don't have to)? This is a basically stock engine, BTW.

[Dale M.]

Probably not because truss bar kit actually supports frame horns ( ties them to shock towers) and there for supports motor which in the end stops frame horns from flexing (at least as much)...

Got to say first blast off in the street after getting mine installed there was some wheel hop/shutter, but am unsure if moving motor back a little over 1/8 inch to accommodate brackets it may have changed deflection in bowden tube which may have induced some clutch chatter or what ever.... Going to re-tweak clutch pedal and cable and bowden tube (due to cracked clutch pedal) and will have update soon...

Think "Hotrodvw's" method of "setup" may be way to go.... Any way once things are in place its pretty simple to tweak...

But what do I know... still learning (I think)....

Dale

[Steve Arndt]

Just run some adjustable turnbuckles from the trans mount where the truss bar ties in up to your cage double plates. Ties it all together.

[Hotrodvw]

Dale.........build your own. It's easy!

[Dale M.]

I bought one for $159.... I have no welder or some of the required tools....And I would have to drive at least 40 miles (one way to buy the steel), would have to order the heim joints and bungs anyway so why not just buy one...

Dale

[Hotrodvw]

Sure.... I have about $80 in total materials in mine. What brand, or whose product did you buy?

[Dale M.]

This one.... The 1 one inch 4130 "Chromoly" one... They are out there all the way from $150 to $300... Whose to know which one is best and if it will really help....

http://www.kustom1warehouse.net/Bolt_on ... 518-11.htm

Only whine is this bracket could have been longer to get bolt a little further from trans mount... If I ever have engine out again I think I will have a tab welded to trans mount (mine is a solid mount) or maybe directly to frame horn....

k-cup-bar-2.JPG

Dale

[Hotrodvw]

Let us know how it works.

[Dale M.]

Well I had car out yesterday (illegally on road) but it did not seem to do anything for wheel hop on take off and I could not tell much as road is fairly straight so I could not do much for handling... It will probably be after first of the year before I attend any event and have anything to report... Just wondering if I pull tension of links like you suggest if it will change the wheel hop thing, that I can test (till gendarmes catch me)...

Dale

[Hotrodvw]

No idea.......it'll either hop or it won't. I welded tabs to my solid mount.

[Ol'fogasaurus]

Dale, this is the style truss bar I was looking at but was told by Piledriver and several others that would/could flex; I think the 1" diameter tube might be a bit less flexible than the 3/4" tube might be (wall thickness is also an important part. While it isn’t hefty enough for off-roading (which I really need) it might do for lighter duty work so it might be OK.
The big problem I see with it is that the mounting bracket, on the main tube that goes between the shock towers, sits too far inboard from the shock tower that there can easily be some tube flex induced. If you moved the bracket farther outboard then you would be welding and loading into the threaded area which is much weaker and would fail even with a doubler added… I think. The other thing is that it would be nice to have the angle of the two diagonals sitting at a steeper angle both down and towards the rear to give some additional support to the tubes/horns to eliminate some of the tail wagging that could happen besides the up and down dancing by the engine and transaxle assembly.
Every time this comes up I get thinking about it; today I had an idea that if I get a chance, Iwill try to sketch out and post later on, hopefully today. Maybe it will get someone thinking and they can come up with something better based off it.
As long as the bars are tight they should not allow the engine and transaxle assembly to jump around but the idea of taking a load off the tubes before you tighten them up might help some, worth a try anyway.
Lee

[Ol'fogasaurus]

As I said, this would be a quick sketch. The reason it looks smudgy is the sketch was done on some tracing Mylar I had laying around so I had to put a piece of paper behind it when I scanned it; the ghost image on the other side if the paper is what you are seeing.

Assembly #1 (not identified) is the strut that goes between the two shock mount towers made up of parts #1 thru #3; assembly that is identified as “strut” is made up of similar parts. On the strut I showed some miss-alignment spaces which I think could be a good idea.
Part #4 is made up of a short tube and either two plates cut to shape and welded together into an assembly or two square tubes cut to shape and welded to the tube. I think it would be better to make this a casting though for strength. If you do use the two plates I would box the two pieces together for strength in case of odd loading.

I moved the mounting of the cross strut up so as to get the whole mount closer to the shock tower for some rigidity and a better angle down to the solid motor mount. I think this way that the two struts will work against each other for additional strength and rigidity.
On the solid mount for the transaxle and engine I would also make a double shear mount attached to the solid mount.

I also think that the solid mounts (I’ve seen), either the normal mount or the 10° mount allows for some “S”ing of the mount during side to side loading such as when auto Xing, RR, and off-roading for example; I am not sure about acceleration events though. With no addition support; e.g. Kaffer bar/truss bar, the engine should be able to dance up and down, whip side to side and in the case of serious off-roading rotate in a circle. The engine wants to pivot around the torsion bar where the mounts are welded in. The solid mounts are not designed for the “S”ing problem as they need the mount to be made with stiffening flanges around the perimeter rather than the gaps in the flanges that they now have (or don’t have).
Anyway, food for thought.
Lee

[Dale M.]

Only problem is it would take complete revamp of rear shock towers to move shocks to "outside" of towers and the upper arms of the"yoke" ( your #4) would not clear body... Shock towers would have to be shorter... Then Shorter shocks.... Since I'm not going to pull body off to makes things fit, the premade "kits" fits situation very well....

But anyway "anything" back there will stiffen up the horns and towers vs not having anything back there (I think)...

Dale

[Ol'fogasaurus]

You are right Dale, I did put the shock on the wrong side of the casting (my pan is bare on the driver's side which is what I looked at as the other side is in the dark) as a last minute addition which at the time I knew I shouldn't have done. Granted, the picture is over simplified but I still think the basic concept of the bracket is what needs to be worked on as the mounting of things that allow for beefier components is most of the problem.

And no, I don’t expect you to change things, this was something that I hoped might spur some design work in other directions than we are going right now.

Lee