Stock front suspension questions

Guys I'm going to install a set of adjustable strut rods on my 69 street/strip Dart and have a few questions. The car is 3350# in street trim and has a 434" R1 small block and has ran 6.40 in the 1/8 and I expect to be in the .30's this year.

How do you set the ride height? I know the adjuster bolts raise and lower the front. But where do you measure on each side? The MP chassis manual says to start with 1/2" between the rubber bumper and it's stop and go up from there.

I suspect I have a bad torsion bar on the drivers side as it takes more turns of the bolt to show up in measurements. The passengers side responds to small adjustments. I always bounce the car after making an adjustment.

The car currently has .850" bars on it and I have a set of .870" bars that I can install. The car should run 10.0's or teens and according MP chassis manual it don't need /6 bars. Do y'all think the .870" bars will work or do I need to find another set of .850" bars?

Does rake angle help stock suspension cars? With 5/8" lowering blocks in the rear my car only has 1/4" or so measured at the pinch weld in front of the rear tires and behind the front tires.

Thanks, Justin

I'm almost exactly where you are and we are both to the point where the "outdated" chassis manual no longer suffices.

I do the 2" from the bump stop setting as well but I use /6 torsion bars. It seems to work well and did the 1.37 60 ft. late in the year with stock auspension and nothing more than 90/10 shocks up front. I question if I'm at the point where I need to limit the travel (upper bumpers removed now) and go to the 70/30 setting to keep it down in front and spend more energy moving forward instead of transferring weight rearward?

I've been 1.37 but it was with the 408. This motor is probably 100 hp more and has been a best of 1.40. There is a new Coan 8" converter sitting in the shop floor waiting to go in that hopefully wil help my 60'. About two years ago I installed Viking double adjustables all around to replace the CE three ways on the front and Calvert nine ways on the rear. I had a bad shock on both ends so I spent a little more money on a decent shock.

My old '69 Dart was a simple backhalf car with ladder bars and stock front suspension.
It had more motor than your car, but for what it is worth. I was doing 1.2x sixty foot times (torqueflite), and running low 9 seconds (5.80's 1/8).
I really liked when I changed the upper control arms to get some caster in the steering. It was about zero before, and with 3 degrees the car went straighter, did a more stable burnout, etc.

That car had 0.87" torsion bars (with a big block engine) and they worked good.
Now at my power level I was limiting travel to control the wheel stands...

Basically stock door cars are drivers side heavy. If the rear suspension is set with any right rear preload the left front will be heavy. Either the torsion bar will need to be adjusted more or the front may set crooked. With proper preload the car may end up high on the right anyway. Always start on a level surface. When setting torsion bars its best to have the rear jacked off the ground. This needs to be done in the center on the chassis. Don't lift at the suspension. Now with the drivers weight in the car level the front of the car Then set the car back down and add whatever preload you desire in the rear. Why do it this way? Because weight will jack diagonally. if you load the left front it adds weight to the right rear. Lets say you just level the front with a 4 wheels on the ground. Adjusting extra twist at the left front torsion bar now has added weight to the right rear. Scaling the car may look great. Now we go to the track. The car wheelies. Remember all that load from the left front torsion bar being added to the right rear? Its gone. If you've got a hard hooking quick car its going to the right. Watch a bunch of cars at the starting ling. Many will need quick corrections to stay straight after very short distant wheelies. Many times my car will carry the wheels 50-60ft. Trust me I scaled the car on all 4 wheels for its 1st outing. Looked great. When it wheelied, it headed for the wall.
Doug

Thanks Doug, I was hoping you would chime in. I'm guessing that by jacking the rear up you take away any influence the pre load on the rear has on the front? My car has Cal-Tracs with mono leafs. Currently the pivot link has about a dimes thickness gap between it and the spring.

Thanks, Justin

Jim, who's upper control arms did you use?

Thanks, Justin

So what do you guys think about using the .870 torsion bars?

Smaller diameter will have a lighter rate. Thus more stored energy to help pitch rotation. Unless it dead hooks with no chassis movement the softer the better. Now if your car dead hooks with very little travel then stiffer or limiting the travel may result in quicker 60ft. Are you looking for all out ET or a predictable bracket car?
Doug

I don't bracket race anymore, pretty much just run heads up street car shoot out stuff. Currently my car has radials so how the track is prepped has all to do with how it hooks. Most likely my new tires will be bias, they are not as dependent on track prep.

I know where a set of /6 bars are but don't know if they are .850" or .830". I'll call tomorrow.

doug what's your thoughts on adjustable upper control arms?


Thanks Justin

FWIW : I waited until I had time to measure the bars on my SB Duster (username pic).
It's run the .790 bars for decades, Jack Arnew upper arms (widened, more caster, 0 camber), and modified SS rear leafs.
Upper arms travel-limited using a 1" spacer, car sits with a rake, about 1" off lower arm bumpers.
Footbrake car, 5.38s & 13x31s, pretty light ("extra-legal" ) on the nose from its SS days.
Pitch rotation no problem: with a 460-HP 358 (11.40s) & 4400 stall it'd hike the fronts 6-8" and leave hard.
I got greedy, 640-HP 368, 6000 stall, and put it on the rear bumper for 300 feet.
OK, really good pitch rotation ! - added wheelie bars, low 10s @ 128 or so.
Wheelie bars set 10" off ground, hits 'em every time.
On a good day it'll carry the wheels 100 feet out, sets down nice, goes straight as a string with about 7 deg + caster.
(Don't stick your wrist between the steering wheel spokes when the wheel unwinds in the pits...)
BUT. Car has never seen street use.
Bought a B-body that had .850 bars in front, street-driven, LF was adjusted to the limit; my guess is street use killed it.
Hopefully you can extrapolate the above to be useful in your application.

The aftermarket uppers are a good solution for lack of Caster.. Many times offset upper bushings will get you what you need. Remember positive caster is lost when the chassis is raked forward. However going down the track with nose up, that reduces rake angle. Maybe 2-3 degrees? Never really measured it. My car has 2 1/2 degrees positive caster with a like amount of chassis rake. Going down track the car is near level. So I would imagine in reality it has closer to 5 degrees. Stock upper arms. Another note; as you add positive caster the outer tie rod mounting points drop. This can affect bump steer. Depending on the car it could hurt it or help it.
Doug