4-link question (yes another one)

i'm using a kc components triangulated 4-link on my 50 chevy, i chopped 2 inches off of the top bars because it fits better that way (ie..i didn't want the upper frame mounts sticking through the back seat). my question is what should i do to the bottom bars, should i also cut 2in off them as well? whould it hurt anything to leave them alone? if i leave the bottom bars alone how will it affect my suspension, it is bagged so it will have quite a bit of travel.

 

As long as the bottom bars will clear everything there is no reason to shorten them, it wont affect the travel or arc of the suspension enough to make it worthwhile

 

I'm thinking you might of wanted to keep those 2". Those upper bars are already pretty short compared to the bottom.

With the shorter top arms, at the far ends travel, it will tip the rear end too much and change your pinion angle enough to cause some binding/stress on the u-joints, pinion bearing & seals. This is especially true on a bagged car which, like you say, will have a lot of travel - like if you want to drive it really low.

It may also put enough stress on the link mounts to eventually crack them out of the frame.

I have a similar setup on my 40 chevy (which is an amazingly similar frame given the time span between models), but I also did a large kick-up to the rear frame which also led to major changes to the floor/trunk.

A lot of work, but sometimes you have to bite the bullet and do what you need to in order to make a modification work properly.

Then again, maybe I'm just anal

 

well i did a large notch from gambino and i will have to cut the trunk up, but with the length these bars came(seem really long to me)the upper mount would have been sticking out of the bottom cusion of the rear seat. man i hope i didn't mess up when i chopped those off, i thought about it alot an did alot of measuring and i just decided to do it..................as for it being worthwhile to shorten the bottom ones to match would only take me about 1 minute as i have not welded any of my brackets yet

 

I'd give Alex a ringy-dingy before continuing. He can for sure tell you what's right or wrong.

I don't know about your kit, but in mine the upper bars were already pretty short compared to the lower ones.

 

triangulated

 

How long are the bars?

 

You do know that the upper bars can slant back down towards the frame rails and that you do not have to keep them horizontal to the ground like the lower ones, right?

 

24in lowers, and 17in uppers now,, they where 19in

 

well i've done a lot of reading and i thought that idealy i needed them pointed down in the front about 1 and a half degrees......am i wrong?

 

Hmmmm, that does not sound too extreme really, maybe you will be ok.

But really, just to be sure, I'd run it past Alex Gambino - he can confirm one way or another, and then you will know for sure before you get it on the road and find out the hard way.

Nothing sucks worse then having to cut back into something.

 

Thats what I was thinking too....if you are running the upper bars parallel..that would explain why they would end up in the middle of your seat cushion...run them at an angle from the frame rails to the center of the rear end,would probably put the upper brackets towards the rear of the back seat....

 

Nothing sucks worse then having to cut back into something.[/quote]
for sure,,thanks for the help will call Alex

 

if my bottoms are parrellel how much angle could you put on the uppers? i thought that would affect the way it drives like raising the front a whole bunch in acceleration or v.s.

 

If this helps at all, here's what mine ended up like:

 

http://www.jalopyjournal.com/forum/showthread.php?t=202220
Take a look at this tasty thread from Rusk....

 

Now that's some quality info.

I would have killed to have seen that thread back when I was trying to figure mine out.

 

I hear ya...saved my ass...kept bringing the thread back to the top so other people could benefit from it also..but only a few bites.....great info and documentation from Rusk....

 

Here's how mine turned out. These pics are prior to me finishing up the welding and gussets, but you get the idea. PM me if need be.

 

wow out of all the posts i've read somehow i missed that on, thank you

 

Gracias guys,,,what I didn't go into in my thread were the concepts of anti-squat and instant-center that are affected by bar length and angle in relation to the bottom bars. I went for a very simple approach by setting up the bars parallel (advice from Alex Gambino...the best kind )...my car handles VERY well and gets off the line better than with my leaf-spring setup. I did toy with the idea of dropping the pivot points on the frame for my top bars a few degrees to put the instant center around my front bumper...it wouldn't be tough change, but I don't feel I need to.

Here's a cool instant center calculator,,, http://home.earthlink.net/~whshope/id25.html and check out the rest of the info on that site,,,it may be over-complicated for our applications, but if you're into drag-racing, it's pretty cool. I believe the concepts are important to understand, even if you're not planning on employing them.

Another (and easier) trick is to make a replica of your suspension out of dowels to see how shortening the bars affects pinion-angle change through the range of motion and whether or not you have binding issues.

Hope that helps a little.

Bryan

 

hope im not to late ,call me in the morning 408 561 5744 never be afraid to call i always love to help a phone call is only a few min re doing or undoing is hours if i dont answer the first time damb it be persistant were here to help!!!!!