Adjustable upper control arms

[Tic's60]

Just musing around with this question. Why do you need adjustable upper control arms after you set you pinion angle?
Unless you racing pretty much all the time trying to get that extra bit I just dont see a need. Once set it's set.
Shocks - sure. The double adjustables look like they would help tons.
Pan hard bar - sure. You need to be able to adjust this to center up everything.

Just musing...

 

[bubbletop1961]

You nailed it. setting pinion angle. They are also stronger. No rubber bushings for flex. In just makes it easier to set pinion angle.

 

[walkerheaders]

and of course to add pre-load to the right upper like you always do on a 4link car.

 

[Tic's60]

and of course to add pre-load to the right upper like you always do on a 4link car.

So in other words you could use One adjustable? I ordered all Polyurethane Control Arm Bushings from Energy Suspension today as well.

 

[Fathead Racing]

I am in the process of making my own adjustable Uppers with a pair of Jegster upper control arms from a 79 Malibu. I will also be raising the upper mounting points on the rear housing.

 

[SHAWN B]

Tic,

How are you setting your pinion angle if the arms aren't adjustable?

-Shawn B.

 

[Tic's60]

Tic,

How are you setting your pinion angle if the arms aren't adjustable?

-Shawn B.

They are but you have to use shims behind the mount plate on the frame. Not fun to do I hear.

Fatride - are they pretty close to the same length?

 

[Garbageman]

I've just added adjustables but I moved the mounting points on the frame up one inch. I set the pinion angle down 2 degrees. I haven't been to the track yet to test it but I've been told I could go down as much as 6 degrees to help traction. The adjustable upper arms will be easier to make corrections with than adding shims.

Paul

 

[Fathead Racing]

They are but you have to use shims behind the mount plate on the frame. Not fun to do I hear.

Fatride - are they pretty close to the same length?

The Jegster Malibu arms are about an inch or so short but that doesn't matter. I will cut the arm and add a left and a right hand theaded insert in each piece. Add a jamb nut and good to go. I am probably making this sound simpler than it will acually be : I just think this will be a better setup overall for the street strip. When I add the 1 3/4" location height there will still be the stock location hole and I can change back and forth if needed

 

[Fathead Racing]

I've just added adjustables but I moved the mounting points on the frame up one inch. I set the pinion angle down 2 degrees. I haven't been to the track yet to test it but I've been told I could go down as much as 6 degrees to help traction. The adjustable upper arms will be easier to make corrections with than adding shims.

Paul

How does changing the pinnion angle help traction? My understanding on the pinnion angle is to just have enough angle so when you launch the pinnion comes up to zero, Zero angle takes less HP to turn the driveline. Under low load conditions (cruise) the pinnion angle should be around 4 dgs to keep the joint working or the bearings will take a crap! Tell me more

 

[models916]

garbageman?

Won't moving the upper frame mount up cause rear to squat? I would think down on the forward mount or up on the rear axle mount would be the way.

 

[yellow wagon]

Won't moving the upper frame mount up cause rear to squat? I would think down on the forward mount or up on the rear axle mount would be the way.

I would think the same????

 

[boxerdog]

I'm no drag racer

but I think (memory is not that hot) raising the axle mount will shorten the side view swing arm, moving the instant center closer to the rear end. I would think this would help plant the rear end.

I'd also think that raising the frame mount might have the opposite effect.

And...back to Panhard bars, I had hoped to set up an adjustable bar with a Nascar style multi-hole or slider mount on the frame end to vary the frame mounting height, but trying to keep the bar around axle-high and relatively flat...any feedback on this plan???

 

[bubbletop1961]

fatride

some one correct me if im wrong. Think of it as a teeter totter. As the front pinion rises. it rotates the housing which pushes down at the rear tires. also raising the mount at the upper point changes the instant center. It brings the center back closer to the rear tires. Which is more aggressive.

 

[bubbletop1961]

http://www.348-409.com/forum/showthread.php?t=8799&page=2&highlight=wheel

Here is a link to where I posted my drawing of instant center. It isnt a exact drawing. Some measurements were taken with a tape measure. The 2 blue lines are the angle of the factory control arms. The red is the new angle of the upper after raising the mount 2". see how much it changed the instant center.

 

[Tic's60]

This has been some top notch information herebang I'll probably build mine up as best as I can in the time I have this year and go full on four link with coils this winter.

Other than search is there a spot here where you can archive build up documents for stuff like this? The search is ok but if there was one spot

 

[boxerdog]

Bubbletop, if I hear you correctly, you are raising the frame mounts of the lower arm up?? Now that would work, I think!


If not, I am still scribbling on a napkin....

 

[Garbageman]

I probably used the wrong term, "traction". From what I've been learning from others and reading it is the pre load of the rearend that I am after. Fatride, you are right in what you said about pinion angle and that is what I hope to accomplish. And, as Bubbletop's drawing points out (I saw a similar drawing in a suspension tuning book) moving the control arms to cross section the cars center point is ideal, but a lot of work. I was told one inch up on the upper control arm will help in setting the pinion angle pre load.

But what the hell do I know. Sometimes to much information is dangerous if left in the wrong hands. If it doesn't give me the desired effect I will change it again, it's only metal.

Paul

 

[bubbletop1961]

Bubbletop, if I hear you correctly, you are raising the frame mounts of the lower arm up?? Now that would work, I think!


If not, I am still scribbling on a napkin....

I raised the mount on the rear end. Like the pic aubrey posted the other day. But instead of a welded bracket, I made a bolt on bracket to fit the rear. Little bit of work, but fun. It was easy to install while the rear was still in the car. Your idea of raising the foward mount of the lower arm would acomplish the same thing. Just a different way of getting there. Your trying to point the front of the control arms towards each other if your looking at them from the side. Ive also heard (myth???) that you should keep the lower arm Parallel to the ground. Any one else ever heard that? I couldve had to many buds that day. You never know.

The pics of the bracket are in the link I already posted. Just under the drawing.

 

[boxerdog]

Bubbletop,
Now I see your picture! It was one of those communication things that happen online...we both have the same idea exactly. Ideally, I think the lower arms would be flat or neutral to minimize wheelbase changes as the car rolls in a turn, but for drag racing?? There are a lot of guys on this site that have "been there, done that" and I'd be interested in what they are doing...it might be simplest to leave the lowers alone and create a bunch of adjustment on the upper(s) for pinion angle and anti-squat.

thanks!