Beam Plate Alternative?
Safety Car
Joined: Apr 1999
Posts: 4,623
Likes: 2
From: Ohio
I can't speak for the benefits of them in an automatic, although I would think that it would carry over. I have dealt with Bill (ZF Doc) and he is an extremely knowledgeable guy that has a wealth of experience with ZF C4's. Unfortunately, I didn't have the time to wait when we were putting my engine back in the car, so looking at the potential benefits, we made up something similar, but different. It was pretty obvious that the clamp load with just the head of the bolt, and the washer on the nuts was limited, and the beam was infact "moving". The holes on the beam were at the very beginning stages of elongating by about .070"-.010". Tying the two nuts and bolts together, and spreading the clamping force over a larger area, (on both the top and bottom of the beam) indeed helps to keep the beam solidly in place. I can attest to the fact that not all C-beams are properly aligned, nor torqued when mechanical work is performed. If you ever see your shifter moving vertically under load, I can almost guarantee you that your beam is not properly installed. It's not good enough to get it close enough to align the bolts and torque it into place. If you decide to make them, it's best that the "plates" have some type of "backbone" as ZF Doc's do. Frankly, mine are nowhere near as pretty, nor are they made out of stainless, but they were/are effective in keeping the beam located without excessive torqing of the bolts in (especially) the tailshaft bearing area.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Tying the two nuts and bolts together, and spreading the clamping force over a larger area, (on both the top and bottom of the beam) indeed helps to keep the beam solidly in place.
That's how I figured it was working.
To use the straw example - lubricate your fingers and the straw, and now where does the "twisting" occur? Between the fingers and the straw because the connection is poor.
ZFDoc does not say that they strengthen the beam he says they reduce the flex in the joints.
That's how I figured it was working.
To use the straw example - lubricate your fingers and the straw, and now where does the "twisting" occur? Between the fingers and the straw because the connection is poor.
ZFDoc does not say that they strengthen the beam he says they reduce the flex in the joints.
Instructor
Joined: Sep 2002
Posts: 154
Likes: 1
From: Azle TX
Originally Posted by ski_dwn_it
I am not a structural engineer, but an engineer and looking at the diagram and the way the torque is applied to the C-beam, there is no way in gods green earth those plates are going to stiffen up the C-beam.
The torque to the beam is going to deflect the middle point of the beam. These clamps are merely on the end, where its already at its stiffest point. They do NOTHING for the center of the beam. Therefore if there is going to be flex, then its going to flex with or without them.
Take a straw, hold it at either end and twist the two ends in either direction. The straw will twist in the middle, not at the ends. That is because the ends are already held and strongest and the torque will transfer to the weakest point, or least supported point, which is the midway between the supports.
Granted a straw is different from the C-beam, but the scenerio of what will happen is the same.
These I am sure are nice for putting the bolts back up through and I give the guy credit for putting the time and effort forth to make them. But I would not buy for a second they make the car stiffer.
The torque to the beam is going to deflect the middle point of the beam. These clamps are merely on the end, where its already at its stiffest point. They do NOTHING for the center of the beam. Therefore if there is going to be flex, then its going to flex with or without them.
Take a straw, hold it at either end and twist the two ends in either direction. The straw will twist in the middle, not at the ends. That is because the ends are already held and strongest and the torque will transfer to the weakest point, or least supported point, which is the midway between the supports.
Granted a straw is different from the C-beam, but the scenerio of what will happen is the same.
These I am sure are nice for putting the bolts back up through and I give the guy credit for putting the time and effort forth to make them. But I would not buy for a second they make the car stiffer.
The fact that the rear of the car kicks out to the right is common among C4's. This has to do with the differential and rear suspension design rather than the C beam. This is why we wear out the right side u joints and wheel bearing first because there is more torque to the right rear. The beam plates won't do anything to help this because of the way the rear suspension/drivetrain is designed. They may make it easier to deal with the bolts but to me the most time consuming part is having to drop the exhaust to get to the rear tailshaft bolt. Beam plates don't eliminate that. When I had problems with mine I wound up replacing the bolts with new ones and using loctite (blue) and lockwashers. So far no problems with loosening.
