Does anyone have the data to answer these questions:

1. Dia. at largest part of tapered hole on suspension knuckle where the outer rear tie rod fits (84 Vette)

2. How much pressure is put on that rear toe adjust tie rod end under road driving conditions ( probably talking lateral force)

OK, here is why I'm asking. I have an '84 C4 rear end on my 36 Chevy hot rod and I'm having bottoming problems with the outer tie rod end of the toe adjustment hitting the bottom of the frame on bumpy roads. I have Aldan 550# coil over on rear screwed up pretty tight and still bottoming too often.

My options to get more clearance are to
1. C-notch the frame about 1.5 in. on a painted, just finished car, or,
2. put a booted heim joint on the outer toe adjust rod and put it on the bottom side of the suspension knuckle instead of the top. The tapered hole would have to be drilled out and a shoulder bolt used. I would gain about 1/5 in. travel doing that but don't want to create unsafe conditions if there is a lot of torque on that joint.
3. if it is still bottoming I can do both but I really don't wanna take the plasma cutter and welder to a nice painted frame.

Assuming it would be safe I prefer the heim joint solution. No I haven't dealt with the inside joint and shaft issues but have seen kits for changing over for around $300 for both rods, both ends but don't know if they have enough flex to allow upside down install.

Thanks for any help. I will be glad to add any further details if that would help.
Jerry

 

The condition your describing sounds like it has potential to be pretty dangerous if you were to hit a "bigger" bump at any kind of speed.

It can be done but cutting a frame is never a great idea. If it doesn't work out it is hard to "fix" a frame once it has been cut/hammered/rewelded/bent.

If it were me, I'd keep look at the suspension (if your out of threads on the coil over) perhaps go with a slightly stronger/heavier spring to reduce the ease of the suspension's travel. It will be a slightly rougher ride for sure. Wouldn't be a bad idea to install a rubber subber to keep away from the metal to metal contact in the future.

 

Think I would try the heavier spring first also.

 

I will check with Aldan they may have a heavier spring and I can try a longer 15" vs. the 13" shock. The issue there is looks as the 36 has the right 'stance' for a hot rod and raising the rear further isn't desirable from an "looks" point of view. I agree that the last thing I want to do is C-notch the frame. That's the reason I thought about going to a Heim joint and putting it at the bottom of the suspension knuckle toe control. That would gain me about 1.5 inches further travel.
I appreciate the caution re. C-notch and do not approach that option lightly. But C-notch is an accepted practice in pro build shops and were I to do that I would not only close up the hole created by the C-notch with stout 1/8th inch flat bar but 'fish plate' on the sides of the frame as well with 1/8 flat bar. At the point where I could C-notch the frame isn't carrying much weight--maybe 400 lb spread over two frame rails and I would have about 1.5 in. of double plated side rails to carry that.

 

but to me it looks like crap once it is done...and can serve as a constant reminder that someone couldn't measure correctly the first time around.

I imagine you have a custom built frame on this car so many things are possible. I've only "fish" frames when I've completely cut through'em other than that you can usually just remove a small portion for needed clearace and "box" up the remaining surounding portions. Good luck with the project.

 

If you notch the frame for a little extra clearance, and then weld a plate of the same contour as the notch over the hole, you will not lose much stiffness. It will still be plenty strong.

 

I believe you are right about the strength. The discussion here has helped me formulate a plan: 1. Go to heavier springs on the coil overs to reduce sag from weight supported by springs. 2. reverse the rear toe adjustment rod end on the suspension knuckle via a booted heim joint to gain extra clearance. 3. Do the C-notch if 1 and 2 do not entirely solve the problem.

 

Done properly, notching the frame will be OK. You don't want a longer spring. You want a stiffer one. How much travel do you have before it hits?

 

With a driver in the car I have just a hair under 2 inches. I had almost 3 inches when the springs were new but they have settled now after some driving. That's another reason to look at heavier springs as well as C-notch. With the current springs the car settles almost 3 inches after taking it off jack stands. Too much according to Aldan.

 

Why not just add the softest mono-spring and end the problem? Your suspension is too soft....thats all. The heim joints are stronger but they will still beat the frame if the travel bottoms..

 

There isn't any room for a mono spring. This is a 36 Chevy with a custom built fuel tank and between tank and C4 rear suspension there just wasn't enough room.

re. earlier query about amount of suspension travel. It is two inches because the body and frame settle too much. It used to be about 3+ in. but has settled even more down to the two inches. I think the stiffer spring would keep it from settling. If it only settled the 1 to 1.5 in. Aldan recommends I would have more than 3" of travel.

Since I obviously know very little about C4 suspensions, let me ask, if this was a stock setup how much travel would I have? yeah, I know, I should have asked that in the first place.

 

I eliminated the factory toe rods on my 85 and use swerved rods and heim joints along with a fabled up plate that mounted to the rear end. Changing the mounting point from over to under is doable, the only concern I would have is the change it would make in how the suspension travels. I tried to keep the toe rods on mine parallel to the half shafts. With the mounting plate on the deadens you can easily do this.

 

klkordzi, Pics of this would be very helpful. Thanks.
Jerry