Chassis Tuning

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Archeryguy02

Archeryguy02

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I have searched quite a bit for good info regarding chassis tuning(maybe I am not searching for the right things) and cant find any direct instruction regarding adjusting my torsion bars to improve weight transfer and traction. I spoke to the guys at Calvert and they told me I needed the front suspension to be 5" from full extension at rest but I am sure that was with their mono leafs and caltracs. I am running SS springs which I have read work on a totally different philosophy from what I have read.

Below is my set up, I know my converter is tight and I don't want to change it at this point. I have put some 90/10 front shocks on the front as well as lowered the ride height in the front since the last time at the track. I am going again this weekend and want to have better idea of how I can adjust my torsion bars at the track to help the car launch.

Thank you.

As cast Speedmaster heads, I bought the castings and had my engine builder put them together.
1968 Valiant full interior and glass minus radio. Gonna guess its around 3200 with me in it.
LA 360 stock crank and rods
Icon 741 pistons about 10.6:1
Oregon Cam Grinding 242/248 @ .050" .600" lift solid roller cam
performer RPM, 750 double pumper
Stock type 273 type adjustable rockers 1.5 ratio
Doug's Headers with a 17" header extension and some turn downs, no mufflers or exhaust yet.
Lock up 904 from a 1982 Cordoba with a TF2 shift kit
A PTC lock up converter that was supposed to stall at 3500 but is a bit tight at 2800 which is likely keeping this car out of the 11's at this point.
8.8" ford explorer rear end 3.73 Limited slip
Super Stock springs, slant six torsion bars, Mancini bolt on subframe connectors welded in.
26x8.5 Mickey T pro drag radial

First weekend out it ran a 12.20 @ 114.37mph with a dismal 60' of 1.900
 
Getting good front end travel (aka, the 5" thing Calvert was talking about) applies to your setup as well. Are you currency having traction issues, or does the 60' just suck? If it is just the latter, then you really need a good converter to improve the 60'.
 
Find the smallest diameter torsion bars, that fit your chassis. That will start you on the right path then, you will need to find the things you need to loosen up the motion of every moving part of the front end. Don’t surrender reliability for freedom of the suspension parts. The hardest piece of the puzzle is making the toe stay reasonable throughout full travel, of the front suspension.
 
flyfish said:
Getting good front end travel (aka, the 5" thing Calvert was talking about) applies to your setup as well. Are you currency having traction issues, or does the 60' just suck? If it is just the latter, then you really need a good converter to improve the 60'.
Click to expand...
It would spin occasionally, I am thinking I was too light on the burnouts. My last pass I did a longer burnout and it improved. I really just want the car to be consistent at this point since I am running a 12.0 and slower bracket.
 
sst3193 said:
Find the smallest diameter torsion bars, that fit your chassis. That will start you on the right path then, you will need to find the things you need to loosen up the motion of every moving part of the front end. Don’t surrender reliability for freedom of the suspension parts. The hardest piece of the puzzle is making the toe stay reasonable throughout full travel, of the front suspension.
Click to expand...
I am already running /6 bars
 
If it flashes at 2800 you need to get looser.... That may help things all the way around.... Have you talked to PTC about changing the one you have? They are good people to deal with or was the case with me in the past....

JW
 
Batteries in the trunk?? Does it have long, or extended rear drag shocks?? You have to let the SS springs do their thing without topping out the shocks. My gut says you need a slightly taller gear, and a slightly higher stall. But that cars already going pretty good you know??
 
SLOPAR72 said:
If it flashes at 2800 you need to get looser.... That may help things all the way around.... Have you talked to PTC about changing the one you have? They are good people to deal with or was the case with me in the past....

JW
Click to expand...
No I have not talked to PTC yet, I ordered from John Cope. Its a lock up and I was told they were going to make it as loose as possible to begin with.
 
Then you are started in the correct direction. I replaced the bushings in the front of mine and used urethane with lots of silicone grease. I know lots of guy’s don’t like urethane but, with a 440 sitting on top of them they done me proud. The ball joints in mine were nice and free originals that, had no slop. I eventually changed the upper control arms to arms with rod ends instead of bushings.
 
Archeryguy02 said:
No I have not talked to PTC yet, I ordered from John Cope. Its a lock up and I was told they were going to make it as loose as possible to begin with.
Click to expand...


Have you rebuilt the front end yet? Worn out bushings will bind up the suspension and you want get any pitch rotation.

Your shocks are not very good, but someone will come along and say they’ve 5.90’s at 235 plus with them. Don’t believe it.
 
So does lowering the front end (loosening torsion rods) help with weight transfer out of the hole?
I figured raising the front would get you a better holeshot by cutting weight transfer time.
 
Lefty71 said:
Batteries in the trunk?? Does it have long, or extended rear drag shocks?? You have to let the SS springs do their thing without topping out the shocks. My gut says you need a slightly taller gear, and a slightly higher stall. But that cars already going pretty good you know??
Click to expand...
Battery is upfront, its still a street car and I dont want a switch until its not. I checked the rear shocks and they are about an inch longer than what the rear end hangs fully extended. I have a low first gear in the 904 in the car so I am not sure a gear change will matter, with the tire I have I am turning ove4 5500 at the stripe so there isn't a long way to go. I am pretty happy with the car overall but looking for information as how to tune the chassis to improve my 60'.
 
Topless69 said:
So does lowering the front end (loosening torsion rods) help with weight transfer out of the hole?
I figured raising the front would get you a better holeshot by cutting weight transfer time.
Click to expand...
I thought so too, I raised it the last trip to the track and it seemed to help. Since then I spoke to a friend who has been drag racing for years and also calvert who both tell me I need to lower it in the front. So here I am looking for more opinions especially those running torsion bar with SS spring cars.
 
yellow rose said:
Have you rebuilt the front end yet? Worn out bushings will bind up the suspension and you want get any pitch rotation.

Your shocks are not very good, but someone will come along and say they’ve 5.90’s at 235 plus with them. Don’t believe it.
Click to expand...
I rebuilt the front end with all Moog components when I converted to disk brakes, it probably has a few hundred miles on it. It had cheap street shocks on it, I put on competition engineering 90/10's over the weekend which I have not run yet.
 
Archeryguy02 said:
No I have not talked to PTC yet, I ordered from John Cope. Its a lock up and I was told they were going to make it as loose as possible to begin with.
Click to expand...

The converter game.... It's probably more wrong than right out the gate. Since you are bracket racing focus on repeat, repeat, repeat. If the Converter is too tight your Et's will move around some. To each his own but you need to trim atleast 2.5 tenths off that 60ft. Are you locking the Converter up? 12.0's and 114mph means you have some steam on top or your locking the Converter up.

JW
 
SLOPAR72 said:
The converter game.... It's probably more wrong than right out the gate. Since you are bracket racing focus on repeat, repeat, repeat. If the Converter is too tight your Et's will move around some. To each his own but you need to trim atleast 2.5 tenths off that 60ft. Are you locking the Converter up? 12.0's and 114mph means you have some steam on top or your locking the Converter up.

JW
Click to expand...
In this 12.0 and slower bracket it is kind of nice since most the cars right at 12.0-12.1 are faster cars detuned to run slower than 12.0 I have plenty of power to wheel race them at the end of the track. It seems I take off then they pass me and I catch them around 1000' providing I have cut a better light.

The converter only locks up in high gear, its the mopar factory lock up from the late 70's early 80's.
 
Archeryguy02 said:
In this 12.0 and slower bracket it is kind of nice since most the cars right at 12.0-12.1 are faster cars detuned to run slower than 12.0 I have plenty of power to wheel race them at the end of the track. It seems I take off then they pass me and I catch them around 1000' providing I have cut a better light.

The converter only locks up in high gear, its the mopar factory lock up from the late 70's early 80's.
Click to expand...

The lockup can throw in an additional 2-4mph in my experience..... Just an FYI. Get that 60 down and you are easily in the 11's.... With consistency.

JW
 
While traction and converter have a lot to do with 60' times, you can't forget about the carb. MPH seems good, but a lot can be hiding in the carb. Jet for MPH, squirters & pump cams for 60'.

* Is the squirter size too big (rich) or too small (lean) off the line?
* Is the duration of the squirt too long (gets rich) or too short (goes lean) before the main circuit takes over.
* Do both primaries & secondaries stop squirting at the same time to keep the A/F ratio consistent in the cylinders.

Naturally, the car has to hook consistently to see differences in any mechanical changes. Weather changes between runs or visits to the track also has to be considered, as well as what you are doing. (Launch rpm, shift points, water temp, etc.) No easy answer to tuning. Just gotta learn/know what the carb is doing and how your changes affect it. But I learned a lot with a playback tach, a lot of which wasn't what I "perceived" during a run.

Adding weight with a battery or legal & safely mounted ballast can help consistency by reducing spin. Will come in handy X2 if you get faster consistently but want to stay in the 12's.
 
Archeryguy02 said:
I have searched quite a bit for good info regarding chassis tuning(maybe I am not searching for the right things) and cant find any direct instruction regarding adjusting my torsion bars to improve weight transfer and traction. I spoke to the guys at Calvert and they told me I needed the front suspension to be 5" from full extension at rest but I am sure that was with their mono leafs and caltracs. I am running SS springs which I have read work on a totally different philosophy from what I have read.

Below is my set up, I know my converter is tight and I don't want to change it at this point. I have put some 90/10 front shocks on the front as well as lowered the ride height in the front since the last time at the track. I am going again this weekend and want to have better idea of how I can adjust my torsion bars at the track to help the car launch.

Thank you.

As cast Speedmaster heads, I bought the castings and had my engine builder put them together.
1968 Valiant full interior and glass minus radio. Gonna guess its around 3200 with me in it.
LA 360 stock crank and rods
Icon 741 pistons about 10.6:1
Oregon Cam Grinding 242/248 @ .050" .600" lift solid roller cam
performer RPM, 750 double pumper
Stock type 273 type adjustable rockers 1.5 ratio
Doug's Headers with a 17" header extension and some turn downs, no mufflers or exhaust yet.
Lock up 904 from a 1982 Cordoba with a TF2 shift kit
A PTC lock up converter that was supposed to stall at 3500 but is a bit tight at 2800 which is likely keeping this car out of the 11's at this point.
8.8" ford explorer rear end 3.73 Limited slip
Super Stock springs, slant six torsion bars, Mancini bolt on subframe connectors welded in.
26x8.5 Mickey T pro drag radial

First weekend out it ran a 12.20 @ 114.37mph with a dismal 60' of 1.900
Click to expand...
I like books. I learned a lot (from not knowing jack to having more than a clue!) using this one.
05052E70-50EA-4CC2-9677-27B82EFAFC80.jpeg
 
Archeryguy02 said:
I have searched quite a bit for good info regarding chassis tuning(maybe I am not searching for the right things) and cant find any direct instruction regarding adjusting my torsion bars to improve weight transfer and traction. I spoke to the guys at Calvert and they told me I needed the front suspension to be 5" from full extension at rest but I am sure that was with their mono leafs and caltracs. I am running SS springs which I have read work on a totally different philosophy from what I have read.

Below is my set up, I know my converter is tight and I don't want to change it at this point. I have put some 90/10 front shocks on the front as well as lowered the ride height in the front since the last time at the track. I am going again this weekend and want to have better idea of how I can adjust my torsion bars at the track to help the car launch.

Thank you.

As cast Speedmaster heads, I bought the castings and had my engine builder put them together.
1968 Valiant full interior and glass minus radio. Gonna guess its around 3200 with me in it.
LA 360 stock crank and rods
Icon 741 pistons about 10.6:1
Oregon Cam Grinding 242/248 @ .050" .600" lift solid roller cam
performer RPM, 750 double pumper
Stock type 273 type adjustable rockers 1.5 ratio
Doug's Headers with a 17" header extension and some turn downs, no mufflers or exhaust yet.
Lock up 904 from a 1982 Cordoba with a TF2 shift kit
A PTC lock up converter that was supposed to stall at 3500 but is a bit tight at 2800 which is likely keeping this car out of the 11's at this point.
8.8" ford explorer rear end 3.73 Limited slip
Super Stock springs, slant six torsion bars, Mancini bolt on subframe connectors welded in.
26x8.5 Mickey T pro drag radial

First weekend out it ran a 12.20 @ 114.37mph with a dismal 60' of 1.900
Click to expand...
What part number "Super Stock" springs are you running?
What rear spring shackle?
What rear spring front mount? Stock or dual hole? If dual hole, which hole is it in?
Are you running an old school pinion snubber with those rear springs?
What is the launch technique; I assume foot braking it, so what RPM do you hold on the starting line before launch?
Is there a picture available from the side to show the stance, or a video of the launch?
Does it ever have full traction? What is the 60' foot time with full traction?
 
Bobzilla said:
What part number "Super Stock" springs are you running?
What rear spring shackle?
What rear spring front mount? Stock or dual hole? If dual hole, which hole is it in?
Are you running an old school pinion snubber with those rear springs?
What is the launch technique; I assume foot braking it, so what RPM do you hold on the starting line before launch?
Is there a picture available from the side to show the stance, or a video of the launch?
Does it ever have full traction? What is the 60' foot time with full traction?
Click to expand...
002/003
stock type shackle
stock front mount
no snubber,
foot brake to 2000 rpm
no video, the last pass the car made I had the torsion bars cranked up and it was almost level stance.
full traction(as best I can perceive in the car) is 1.900
 
street car with a 600 lift roller?
AD57FB01-1335-4D64-99C1-C7C7342C8E72.png

with out a cam change all you can do is work on carb & cam timing
This car needs to cross at6400 rpm
our over cammed /under stalled cars always went more consistent with less burnout
Your new shorter tires will hook fine
 
Deweywinger&howe said:
street car with a 600 lift roller?
View attachment 1715740572
with out a cam change all you can do is work on carb & cam timing
This car needs to cross at6400 rpm
our over cammed /under stalled cars always went more consistent with less burnout
Your new shorter tires will hook fine
Click to expand...
I'm confused...what's wrong with a "street car with a 600 lift roller"?

My street/race car has healthy solid flat tappet cam with 264/268° @ 0.05, 0.621/0.632 lift in it...I drive it all over town...I even drive to the race track, lay down low 10 second passes and drive home again.

The OP really just needs more converter (like an 8" with 4500+ stall)
 
12many said:
I like books. I learned a lot (from not knowing jack to having more than a clue!) using this one.View attachment 1715739086
Click to expand...

There is nothing wrong with this book or any other chassis book out there..................But!
I have yet to find one that has more, them one Paragraph, on SS Spring chassis tuning.

Lower front end to allow at least 5" of UP Travel from resting height. (I know it sounds backwards, but it allows you to throw the weight from the front end to the rear faster) Remember this will mess up your front end alignment. (reset your toe after adj and you will be fine). consider an alignment after your satisfied on the ride height.

I don't think you can get a descent and efficient Stall Converter with a "Lock Up" 904. (3500-4000 stall)

Is your stall low because you don't have enough timing in it, or full advance of the timing coming in to slow??

Low first gear help a lot when you have a tall gear.

I had vary little traction issues until i went from a 2800 stall to a 4200.

408/727/4.56 gears 28/10.0/15 M/T Slick.
Yes, SS Spring, Torsion bar suspension on a 3800 pound car.

Now let me ask you a question.
When you stall it up to 2000 rpm.......is it loading the rear end? Do you feel the rear end start to rise?? If so try leaving at a lower rpm (If its slipping of the line) and see if you get a better 60" time.
 
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