[Daniel]

In the front end of my 71 Dodge Challenger (340 4-speed) all the following is replaced:
K-frame
Strut rods – Mancini Racing
Torsion bars – Mopar Performance
Upper control rods – Tubular from Magnum Force
Shocks - KYB
Bushings – PST

AND I still have the following 2 problems:
Caster is slightly negative (-1)
Front suspension sinks on driver side. Frame rests on Lower Control Arm snubber as if torsion bar is not able to support weight.

Since everything else is new I am thinking the lower control arms (only things not replaced) have problems (bent or cracked). Any advice is greatly appreciated. Can these things get cracked up and cause all this trouble?

[Brant]

I have an issue with mine right now, it's in the process of being fixed. Turns out it is not uncommon for ebodies to find themselves with a bent lower control arm. This will result in a lower (negative) caster. Source another one that is not bent (thats what I had to do).

The sinking issue ??? maybe your frame has been tweaked a bit. That's my next step - frame measurements. Sorry I don't have an answer for you, as it's a hit and miss thing with me too. Hope I'm OK with the new LCA.

goodluck to both of us.

[dave-r]

Front suspension sinks on driver side. Frame rests on Lower Control Arm snubber as if torsion bar is not able to support weight.

Well you changed the K-frame. You must have had the LCAs in your hand. Did one look damaged or bent compared to the other? You fitted new bushings on the LCA pivots didn't you?

Ah! Don't tell me. You paid money to some grease monkey to do the job for you.

When you say one side drops. What happens when you re-adjust the suspension height so it matches the other side? Does it then settle lower again? If so how? What moves?

If the front suspensin ride height is adjusted too low vs the rear you will loose caster angle.

[Daniel]

Brant,

Thanks for the quick response! I just took a close look at my LCAs and the end tips (lower ball joint mounting point) are turned in the direction of the rear of the car. Is this normal or should they be perfectly straight? Bent to the rear of the car will make a neg Castor.

Thanks,
Daniel

[Daniel]

Hi Dave!

More help thanks! This forum is great! Yep I took the grease monkey route

When I raise the car on the jack and let it down again, the ride height is OK for about 15 min and then it starts to settle down 1 inch. The frame rails are in great shape the new K-frame looks good too. The torsion bar rear mounting point looks good and strong (no shifting). When I adjust the ride height with that bolt in the LCA, again I can raise the ride height for about 15 min before it starts to settle. The car sinks about 1 inch each time and actually is not supported by the snubber just lightly sitting on it. Is it possible there is something not fitting right inside the LCA. I can detect no movement elsewhere.

Also, as I noted above the tips of the LCA are pointed to the rear of the car (look bent to me but I have nothing to compare to). BTW, the reason I needed a new K-frame is because when I was having the front end re-bushed at the shop they found that the sleeve in the K-frame LCA mounting point was cracked out and the torsion bar rattled around in it and opened up the hole.

Thank you!
Daniel

[Daniel]

One more thing. The settling only happens on the driver side, the passenger side maintains proper height. Settling takes about 30 min. I also just found a tear in the metal at the tip of one LCA (ball joint connecting end) and there seems to be a lot of plier marks on the ends of each LCA.

[dave-r]

Ok well you can't tell anything by jacking the car up and letting it settle. You have to let it settle first and THEN adjust the front suspension height with the wheels on the ground.

The front suspension height is adjusted by a big bolt in the bottom of each LCA. Adjust the suspension to the correct level at each side and then see what happens. Bear in mind that the front suspension also effects the rear suspension height.

For example you may find that turning the adjusting bolt on one side higher at the front has less effect on the front height than you expected. But if you then check the diagonally opposite rear wheel you may find that it has dropped in height there. So check all four corners as you adjust each front LCA.

Having said all that I have to say that this talk of cracks and scratches has me worried. If the LCA does have cracks you need this seen too urgently.

The main problem with paying someone to do jobs like this is that even when they are this simple they will cut corners. And if they are not used to Mopar Muscle cars they will make a pigs ear of it 9 times out of 10. They will also replace stuff that didn't need replacing anyway.

Why of earth did you need a new K-frame for instance? Unless you were converting from slant 6 to V8? Did they fit new LCA bushes??

[Daniel]

Dave,

Thank you again for your valuable advice. I have adjusted the ride height in the front with the wheels on the ground.

I noticed that when I jack the car up and let it down gently, there will be some space “x” between LCA snubber and frame. I can apply light downward pressure to the front bumper and watch the distance “x” shrink gently to “x-1inch” so I am assuming this it the torsion bar taking up a certain amount of twist based on the cars weight. There is still space between the LCA snubber and frame and that space remains even if I bounce the front suspension very aggressively. So far so good. (Torsion bars are brand new Mopar Perf).

I do believe my LCAs are in bad shape and bent to the rear of the car (contributing to neg Castor). Attached is an image of one of the LCAs. To me it looks bent and there are gouge marks on the side that make me think someone attempted to straighten them out. One even has a tear in it. Looking for replacements.

[Daniel]

Forgot to answer about the K-frame. Well….. When the suspension was taken apart, the collar in the K-frame into which the LCA pivot goes into (driver side) was cracked out and the hole was worked open from the pivot banging around in there. I imagine the force to accomplish that could also do some damage to the LCAs… Groan…

[919]

make sure the lcarms are pulled all the way down before inserting torsion bars & being sure they are adjusted all the way down when you do