Need a few questions answered from the handling gurus please

[benno505]

Hey Guys, Just setting up my suspension again and again as I don't like the way it feels, it drives nice in a straight line and holds the corners but if you hit a bump it feels like the car is going to spin out sometimes if your going over 150km/h.
Firstly I will tell you what I have then ask the questions.

68 dodge charger with a custom coil overs k member UCA and LCA are both adjustable as well as the adjustability on the factory cam bolts it is a magnumforce unit here is a rough pic
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and the rear is an UNEQUAL length 4 link also a magnumforce unit with all 4 link bars adjustable here is a rough pic.

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Now I have the front end aligned pretty good, I started on one side and made the other side camber, castor and toe the same which are: +5* castor, -1.5* camber and 1.5mm toe in to start with.

now to get the rear end perfect because I don't really trust a 40ish year old chassis
*would I plumb bob centre line of front wheels down to the ground and get both back wheels same length each side? or is there a better method?
*also how do I work out the correct pinion angle and where do you take the angle from?
* another problem I keep having trouble with is I set the front end up and go for a ride then come back home and the camber moves from where I set it, it is quit annoying, maybe I need to brace the area up a bit.

* 1 last question, I noticed after I setup the front end this time as it uses a mustang II rack and pinion the passenger front wheel has about 1/4" of play ( movement ) without moving the opposite wheel if you know what I mean. would the rack be damaged? or is there a way to adjust that out? the rack has only seen 3000miles

here is a pic of my ride
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[dragonfly jones]

Thats one awsome looking car.

[Bonehead]

Cant help you with your question but DANG! That's a beautiful Mopar!

[benno505]

Thanks

[benno505]

123

[marolf101x]

Ok, let's brake this down a little as you asked a number of non related questions in your first post. . .

"if you hit a bump it feels like the car is going to spin out sometimes if your going over 150km/h."
for the US that's almost 100mph. My first question is are you on a track when you are going that fast? Does the car have the same "uneasy" feeling if you are going slower and hit the same bump? Have you checked bumpsteer?

"now to get the rear end perfect because I don't really trust a 40ish year old chassis
*would I plumb bob centre line of front wheels down to the ground and get both back wheels same length each side? or is there a better method?"
the easiest thing to do is take it to an alignment shop that has a newer "laser" machine. They can see all kinds of things.
If you want to do it at home here's a pretty decent article about "squaring" a race car that will help get you there:
http://www.longacreracing.com/articles/text/Squaring.pdf

"*also how do I work out the correct pinion angle and where do you take the angle from?"
Typically pinion angle is 3 degrees down on the transmission, and 3 degrees up on the rear. The rule of thumb is that the engine and rear diff need to be equal, but opposite, angles at ride height. Just google "setting pinion angle" and you'll find way more info than you need.


"* another problem I keep having trouble with is I set the front end up and go for a ride then come back home and the camber moves from where I set it, it is quit annoying, maybe I need to brace the area up a bit."
If you set something on the suspension and it moves there is something terribly wrong!!! You need to speak to the manufacturer of the system to see what is going on, and have them fix it.


"* 1 last question, I noticed after I setup the front end this time as it uses a mustang II rack and pinion the passenger front wheel has about 1/4" of play ( movement ) without moving the opposite wheel if you know what I mean. would the rack be damaged? or is there a way to adjust that out? the rack has only seen 3000miles"
The only way to figure out what is moving is to put the car on a lift, get under it and start moving parts. Move the wheel and see what else moves. If one side of the rack moves, and the other doesn't, it's likely a rack issue. If only the tire moves it's likely a bearing or tie rod issue.

[benno505]

the uneasy feeling is on a track and only when going fast, the rear end sways around over a bump. I am not sure about checking bumpsteer?

I have been under the car and it is the passenger side of the rack, the tie rod moves in and out of the rack housing about 1/2" nothing else moves. So I take it the rack need attention, probably easier to put a new one in I take it?

Thanks for the help.

[iadr]

the uneasy feeling is on a track and only when going fast, the rear end sways around over a bump. I am not sure about checking bumpsteer?

I have been under the car and it is the passenger side of the rack, the tie rod moves in and out of the rack housing about 1/2" nothing else moves. So I take it the rack need attention, probably easier to put a new one in I take it?

Thanks for the help.

Usually on a stock steering set up, that would be diagnosed as wear in the inner tie rod. Wear is unlikely in 3000... so could be a defect or could be another type of internal failure of the rack (rare).

You need an open minded, smart alignment guy. Your updates have made the car much more like a current suspension that like the original vintage set up. At least initially, you don't necessarily have to go to a race car specialist.

Sorry if I missed this- but was there a brand name of the front set up?

[benno505]

Usually on a stock steering set up, that would be diagnosed as wear in the inner tie rod. Wear is unlikely in 3000... so could be a defect or could be another type of internal failure of the rack (rare).

You need an open minded, smart alignment guy. Your updates have made the car much more like a current suspension that like the original vintage set up. At least initially, you don't necessarily have to go to a race car specialist.

Sorry if I missed this- but was there a brand name of the front set up?

I pulled apart the rack, the ball end of the passenger side tie rod has a fair amount of play, I can buy that part instead of a full rack so all good there. Because of the massive amounts of adjustability in my suspension I don't really like letting dodgy people do it and I try to do it all myself, I do have a few wheel alignment tools and feel fairly confident I can do it.
the front end is a magnumforce unit.
www.magnumforce.com

I will also say my car is more of a street car, not much track time

Here is another thread I started shortly after this one, I found the QA1 shocks poly bushes blown out and housing damaged, and also the upper ball joint on the driver side is gone, Car has only done 4000 miles approx., with no hard driving, I don't understand it.
https://www.pro-touring.com/threads/106746-Any-QA1-reps-here

[FlyDoc]

A bad inner tie rod end will cause the car to feel loose, or out of control at times.
your suspension settings changing after driving could be,.. chassis flex or movement, did you buy the car done or did you restore the car? if you did not do the work you could have some rust issues covered by undercoating. not getting adjustment points tight. for setup I would find a shop that will set to your specks, and uses a lazier system to square every thing up.
but I would think fixing the rack will have a positive out come for you.

[benno505]

Built myself, 0 rust, 0 body movement, bought some new cam bolts and fixing the front end, hopefully all good from here on, once I get new shocks, hopefully replaced by the manufacturer