The Dodge Challenger Message Board

I still have my "clunk" and cannot locate it, so I am going to rebuild the front end.

Has anyone used the Polygraphite Performance Bushings? The set is a reasonable price, about $229. I might change the torsion bars while I am at it as they are 30 years old.

The torsion bars do not loose their spring rate like other types of spring. Unless you are going to uprate them with thicker bars I would leave them alone.

I have used the polygraphite bushings and they are great. When it comes to rebuilding the front end it helps to have the correct tool to remove the upper control arm (UCA) ball joint. You will have to make a tool to pull/press the UCA bushings out/in without stressing the UCA.

The lower control arm (LCA) bushing is easy. You take a blow torch to it and set fire to the rubber until you can pull the pivot out. The metal outer cover of the rubber bushing stays in the LCA. You then just clean the remaining rubber out and push the poly bushing in. You need a press to push the pivot back in. I used a jack on it's side in a door frame that was in a brick wall.

Everything else is piss easy!

It looks like the torson bars are on the small side. I think the 440 bars are thicker than the 6 or 318. This car is a clone. Figured if I was going to change it, I might as well do it all at once.

My reference books indicate that the same torsion bars and K-Member were used on all E-Bodies (Slant 6 through 440) with the exception of the 426 Hemi cars which had thicker Torsion bars.

Front torsion bars for Challengers.

All were 41 inches in length. The thickness of the bars were as below in inches.

0.86 for /6
0.88 for small blocks and the 383
0.90 for heavy duty for above
0.92 for police,440 and 426 engines.

Yep, and I am running .88. And I am running the 440. So, I think I might as well replace them. Tried to order them on line, but they do not have the torsion bars listed, so tomorrow.

I ordered the parts today. The supplier, PST sells these in diameters of .100 and up. So, seeings as the stock 440 was .90, that is what I bought.

Two weeks tho, I am not sure I can wait

I'm going for the lowered look for my 74 so would the upgraded torsion bars make the front sit higher? some company makes tubular upper control arms for the use of coil-over springs. I do not want to get rid of my torsion bars but the advertisement mentions your car being lowered but without giving up your suspension travel. is any of this true.

The front end height of any Mopar is easily adjusted with a turn of a screw in the lower control arm. Sometimes they are rusted up some so give them a long soak in release oil overnight. Just make sure you turn them both the same amount because the front can look level but the rear can go crooked.

When you lower the front end height you need to have it professionally alligned by a capable shop.
The caster and camber will change when you lower
a vehicle, causing excessive tire wear.

thats right. they said if I adjusted the torsion bar adjusting screws that it would affect how it handled and how it turned. like the wheels would start to angle in or angle out and it wouldn't turn. they told me not to mess with it. thats just how it had to be because of my torsion bars. thats all they said. thats why I wanted those tubular upper control arms because they said with those it didn't affect any of that.

They said what? Sounds to me like they were trying to sell you a whole bunch of expensive parts you neither need or want on your mopar. The Mopar front suspension design is one of the things Chrysler got very right. It is far superior to coil springs in many ways.

Small adjustments to the front height actually effect the front wheel alignment very little. You would have to make huge changes to the front height to even start to get near the effects they warned you about.
I doubt very much that your front wheel alignment is right anyway. Do you think your car is still at its original factory settings? The rear springs settle, wear in the suspension joints, changes in tyre sizes from stock etc. all change the front wheel settings which, as they came from the factory, were not ideal anyway.

Mopar front wheels have a very simple system to adjust the camber and caster settings. The upper control arm is held in with bolts that go through the control arm bushings and sit in cam-plates. When these are rotated they move each side of the upper control arm in and out to change caster and camber.

For example. If you turn both control arm bushings in or out this moves the control arm in and out from the side of the car effecting camber.
Moving one bushing in and one out makes the center line of the control arm move to the front of the car or to the rear, effecting caster.

Any decent front alignment shop will set this for you very cheaply.

Toe-in is very simple to set on any car of course.

I suggest you set your front and rear ride height to whatever you want and then drive the car to a place where they can align the wheels for you. I also suggest the following settings.

2 degrees positive caster.
1 degree negative camber
3/32" toe in.

That will get it handling well.

so I can adjust the height to what I want by the torsion bars and then the alignment shop will adjust the wheel angle by the upper control arms? yeah? I'm fairly certain I understand what you are talking about, and it does make sense to me. I will talk to them about it.thanks

I went to the Magnmforce website and this is what they said. you will probably tell me that these are good but I can do the same thing with the screws, right. I just want it to be smooth.

"Almost any Mopar owner that has lowered their car even slightly by turning the torsion bars down a few turns has come across the problem of not having enough suspension adjustability after doing so. In trying to get the camber back to specs all of the available caster is lost, resulting in less stability at high speeds. MAGNUMFORCE Tubular upper control arms reduce this by relocating the ball joint further out and toward the rear to begin with which regains that adjustability and more. They also use original style ball joints and urethane bushings for ease of replacement. Most cars will end up with 3-5 degrees of total positive caster, relative to ride height and the condition of the existing mounts."

They are trying to sell their product that is indeed very good - if you were a circuit racer. What they are saying is kind of true except for that first line "Almost any Mopar owner that has lowered their car even slightly by turning the torsion bars down a few turns has come across the problem of not having enough suspension adjustability after doing so. That is total bollocks!

You don't need any more than 2 degrees caster on anything other than a serious circuit car. I have my car lowered and the alignment is fine.

Where you possibly could get into trouble is if you drop the front a lot but leave or even jack-up the rear '70s style. This will loose you caster angle big time. It is very bad for handling. But if the front and rear are still their relative heights to each other you are fine.
So don't be silly with the angle of the car.

If for some reason you could not get enough caster angle you can also get off-set bushings to do the same thing that they are selling. Only a lot cheaper.

Don't waste your money buying things you don't need for your car. Set your ride height, get it set to the settings I gave you, and drive it!

thank you very much for your help. i appreciate it.

Now another question. After getting my rims and tires, I wanted to have it aligned again and lowered a little. I had the same guy do it, and Everything went very well. we got it lowered a and everything is level. but he said that I was maxed out on my "strut arm bar". I also had him work on my powersteering. I mentioned that it had not originally come on there and he told me that I was at"-.5 caster" on my strut arm bar and it would be better to have "+.5 to 1 caster". he said that it was maxed out and with non-powersteering from the factory they set it more negative so it would be easier to turn. He said that we could grind down the back bushing to gain more room to screw it in but see if there was a different bar first. Is there is a different bar? Did I explain this right, anyone?

The UPPER CONTROL ARM or UCA as I will call it from now on has two bushings that can be rotated. As the bolts that hold them sit in little cams they move the UCA in and out as they turn. This makes the UCA move in and out as well causing changes in CAMBER.



But if you rotate the rear bush so the arm on that side moves back and rotate the forward bush so that that side of the arm moves out, then you get positive CASTER.



You should be able to get at least 2 degrees positive caster with the stock UCA. That will be enough.

I am ashamed to confess that I spoiled a set of brand new front tires because of wrong wheel alignment. Between diagnosing wrong alignment (al little wear on a unusual place) and the second check were only some 1500 kms, but that appeared enough to destroy the tires. They still appear new when standing next to the car, but the inner half inch of the roadhugging surface is worn to the thread (canvas comming out…). Remarkably handling felt not that bad at all. (I know what good handling is, did y’all know that one would loose a 350++ horsepower all R/T options Challenger with a 79 cui 70 horsepower koni equiped 15 year old $400 European family car in a VERY CURVY neighbourhood in a Dutch city in no time on handling only?)
Dave, as for wheel alignment specifications you suggested:

-quote-
2 degrees positive caster.
1 degree negative camber
3/32" toe in.

That will get it handling well.
-unquote

My 1970 Dodge Service Manual states on page 2-14:

Camber -Left-------------------------- +1/4 ° to +3/4 ° (1/2 ° preferred)
Camber -Right-------------------------- 0 ° to +1/2 ° (1/4 ° preferred)
(Caster -Manual Steering-------------- 0 ° to –1 ° (-1/2 ° preferred))
Caster -Power Steering----------------- +1/4 to + 1-1/4 ° (+3/4 ° preferred)
Height standard AND Heavy Duty (??) -- 1-3/16” +/- 1/8”
Side to side Difference maximum 1/8”
Toe-in ------------------------------- 3/32 to 5/32”(1/8 preferred)

The differences with your (Daves) suggestion are astounding. Is this difference explicable from the suspected American preference of straight ahead stability at the cost of curve handling versus the more curvy European compromise, or is something wrong here?

BTW, I have a set of Polygraphite Bushings I inherited from the previous owner, who did not have them mounted yet as the currently mounted original rubber ones are still in exellent shape. Would in this case mounting them change the alignment noticably?

Ok guys ’n girls, I will start her up right now to get a new set of tires.

To fit the Poly bushings (you must fit upper as well as lower) you will have to take the suspension apart so it will need alignment again.

I have stated many times that the factory settings are no good for handling.

The settings I suggest are used on my car and work well. However I did not make them up. I researched this in some detail for years before I reached a specification for both alignment and spring rates. You will find that many sports cars will have settings like this.

I was worried that motorway (freeway) driving with 1 degree negative camber would result in the inner edge wearing more than the outer but there is no sign of this happening yet. I will be doing a LOT of miles this year so I will let you know if this happens.