0 minutes ago in Project Cars
We find some oddities underneath our 350Z.
I am thinking of upgrading my torsion bars on my scamp...I found some that are significantly larger than my stockers (it has a slant six by the way so it has the smallet .84 diameter bars i think) How hard of a job is this??? I am prepared to deal with rust! The one thing I am not real sure on is how the tension is set. Any ideas or suggestions?
Tension is set at the lower control arm. There is an adjuster screw that sticks out of the bottom of the control arm. It's about 1/3 of the way from where the control arm mounts to the K-member. It's probably a little rusty. Soak it with your favorite rust penetrate then back it off. I coat mine with some antisieze with I put them back together.
The service manual calls for a special tool to remove the bars. They are available aftermarket now but I've never had to use one. This is what I do to pull the T-bars out:
Preferably on a flat level surface measure the bumper height on each side of the car. I'll mark the spots with some masking tape and write the measurements there.
With the car on jackstands under the chassis, mark the adjusters on the threaded portion with a crayon where they meet the control arm. This will be your reference point on where to wind them back in.
Unwind the adjuster screws as far as they will go. You don't need to remove them, just take them to the point where they are dangling there.
Remove the retaining clips at the rear of the bar where the bars pass through the trans crossmember. They're probably caked in grease and road grime so you might need to dig them out.
Undo the lower control arm nut. It's in the front of the K-member where the stud from the lower control arm passes through. Do not completely remove the the nut. Leave it on by a few threads.
Place a pry bar between the lower control arm and K-member and lightly pry the control arm toward the back of the car. You'll probably hear a popping sound when you do. This is the tension from the lower control arm bushing letting go. This is normal.
With the tension removed from the lower control arm, grab the torsion bar and slide it back. It should go pretty easily. Just pass the bar through the crossmember.
Take a look at the end of the torsion bar you just took out. The crossmember end should have the part number on it. I need to double-check but I think the driver's side gets the one ending in the odd part number and the passenger side gets the even. The hex ends are offset so take a look at that as you take the bar out of the car.
Before going back together clean out the mount in the crossmember and control arm. Inspect the crossmember for rust through or cracks around the torsion bar mounts.
Take a look at the lower control arm bushings. They are usually neglected and worn out. If so this would be a good time to consider replacing them.
Clean the adjusters but don't loose your reference marks. Apply some antisieze and put them back in the control arms a few threads.
Take a look at the replacement bars you got for any signs of damage. Smooth out and burrs with some emery cloth and shoot them with some spray paint to protect them. Grease the ends of the bars and reassemble in the reverse of above.
Run the adjuster screws back up to the markings. If you are using another set of factory bars this will get you pretty close to where your ride height was. If they are the larger Mopar Performance bars or other aftermarket bars this may not hold true.
Cycle the suspension a few times (maybe a ride around the block) then park the car in the same position where you measured the bumper height. Adjust the torsion bars to get you back to the same height you started with. Adjust a little at a time, cycle, and remeasure.
It sounds like a whole lot more work than what it is. What size are the new bars?
Slightly off topic, but not really. What are the advantages of a torsion bar over a coil over?
carguy123 wrote: Slightly off topic, but not really. What are the advantages of a torsion bar over a coil over?
I could see the torsion bars being easier to package. Going a little extreme, you could argue that the torsion bars also slightly lower the center of gravity.
What ever you do DO NOT put a pipe wrench on the bars to act aa a pulling point it will dig in to the bars and leave stress raisers. Other then that point do as instructed above.
Thank you rob mopar! that is what i was needing to know. I have been looking at several sets of bars...I found some aftermarket ones on ebay I think they were a .92 - should really stifen up the front end, I would think! I was originally thinking of just getting some v-8 bars for better handling now and maybe a future transplant. I would like to autocross the car more...I have done some in the past...it was scary...fun!
dwarf, thaks...i could see me doing that!
I actually just got a set of pry bars for christmas...sounds like a good time to try em out
0.920" sounds good. I have 0.870" bars on my Dart and they aren't all that stiff - guess they had different standards for stiff then. Probably because the tires wouldn't allow that much grip anyway.
I have a tip for how to get stubborn torsion bars out. Get a cable clamp from the hardware store. They look something like this:
Clamp it around the torsion bar, and use a bottle jack on the lower control arm to push on the cable clamp. That'll pop out even the most stubborn T-bar. Also, they're made of softer material than a pipe wrench and are a lot less likely to scratch the bar.
The .920" bars are what I'm running in my '68 Barracuda. They ride nice on the street but are significantly firmer than the stock V8 bars. My buddy ran that size in his slant 6 Scamp and that car rode fine.
They are one step larger than the factory big block bars. I might upgrade them later to something larger. MP discontinued all the larger bars but Firm Feel Inc. makes a variety of bigger bars now.
Matt's cable clamp idea is a good one. I've seen some horrible methods to remove torsion bars like the pipe wrench 44Dwarf mentioned. The factory service manual calls for a tool that sandwiches around the bar then you smack it with a hammer. I think that scared people away from messing with torsion bar front ends.
Rob_Mopar wrote: The .920" bars are what I'm running in my '68 Barracuda.
Ooh! Ooh! I had a 68 340S Cuda - - - - - - when they were new. It was the first car I bought myself.
I loved it.
Mine was some special model from the factory that was an automatic with the 4 speed cam. It came as a stripper and even had a bench seat. Mopar was always making some sort of special drag models back then. It was very seldom I was beaten "up the hill" (the street strip we used).
I traded it in for a Hemi Cuda and then an AAR Cuda.
I ran 6cyl bars in my 67 dart with a monster B1 headed 383. Lunched great! but i would never try to corner with it... 3500 stall converter, 9inch ford rear spooled and 12 inches of rubber on each rear and skinny fronts made it fun in the pits.
I miss those days.
Ride height on A-body Mopars:
Measure from a level floor to the lowest point of the lower control arm height adjustment blade, and from the floor to the lowest point of the steering knuckle arm on the same side. The difference is the ride height for that side. Repeat for the other side.
You can measure bumper height, but there's no guarantee that your bumper is square with your chassis now or in the future.
carguy123 said: ... what are the advantages of a torsion bar over a coil over?
I put "340" bars (0.870") in my '64. That and KYB shocks stiffened the ride up a lot, but I wouldn't mind heavier bars next time around.
carguy123 wrote: Ooh! Ooh! I had a 68 340S Cuda - - - - - - when they were new. It was the first car I bought myself. I loved it.
My Fastback is a couple years older than me, but I love it too.
slantvaliant wrote: Ride height on A-body Mopars: Measure from a level floor to the lowest point of the lower control arm height adjustment blade, and from the floor to the lowest point of the steering knuckle arm on the same side. The difference is the ride height for that side. Repeat for the other side. You can measure bumper height, but there's no guarantee that your bumper is square with your chassis now or in the future.
Yes, the control arm measurements are the correct way to do it, but I use the bumper height on each side as a quick reference. If the swap is being done in the same afternoon the bumper height should be consistent enough (unless something went terribly wrong on the ride around the block!) to get in the right ballpark.
An alignment using the factory method to confirm ride height is a good idea once everything is back together.
carguy123 wrote: What are the advantages of a torsion bar over a coil over?
Other advantages to torsion bars are height adjustments, and at least in the case of these Mopars swapping the bars out without having to disassemble the whole front suspension. Or have a coil spring take an unintended flight.
I was wondering if there were enough advantages for me to consider a torsion bar suspension on a small Lotus 7 type car.
One reason some Mopar guys go to coilover conversions is for header clearance under the car. On a Locost or similar car, the exhaust usually exits to the side, but space is still tight parallel to the engine. I'd like to see a design ... Transverse torsion bars could be used in the rear. A recent issue of Street Rodder had a rod chassis build with torsion bars all around. Hmmm ....
Thanks, I came up with the cable clamp idea after looking around a hardware store trying to find the closest equivalent to the factory tool. The tool itself, for those who have their own milling machine, is two blocks of aluminum with a V-grove down the middle, held together with four bolts.
Listening to all of you talk makes me want to go get an old Scamp. I still think a Scamp, a 360, some sort of forced induction puts you well on the way to a competitive challenge car.
Try changing the torsion bars in a 944. You have to take the whole rear end apart! Indexing them means virtually complete disassembly and moving the engagement splines by one tooth and then putting it all back together.
Would the torsion bar need to be on the bottom A arm or could it go on the top? That'd solve some space constraints and accessibility.
I hadn't thought of torsion bars on the rear.
carguy123 wrote: Would the torsion bar need to be on the bottom A arm or could it go on the top? That'd solve some space constraints and accessibility.
In theory, it could go in on the upper A-arm. The A-arms and ball joints would need to be designed to have the upper arm carry the weight, of course, but that could be done. In practice, the upper A-arms often mount at an angle for anti-dive geometry and have the alignment adjusting built into the UCA mount. So you would need to slope the t-bars downward (or put a funny slope in the LCA if you want anti-dive) and put the adjustment on the LCA to pull this off.
dean1484 wrote: Listening to all of you talk makes me want to go get an old Scamp. I still think a Scamp, a 360, some sort of forced induction puts you well on the way to a competitive challenge car.My buddies ran an intercooled Procharger on a 360 in a '70 Dart with a 4-speed. They ran One Lap in '98 & '99 and did pretty well. I've been collecting Challenge friendly pieces for something similar, but finding a sound shell in the rust belt isn't as easy.
dean1484 wrote: Try changing the torsion bars in a 944. You have to take the whole rear end apart! Indexing them means virtually complete disassembly and moving the engagement splines by one tooth and then putting it all back together.
That just fixed any itch I had for a 944. I'll stick with my '87 Daytona, the body lines are similar enough if you squint, and the suspension is easy enough.
MadScientistMatt wrote: In practice, the upper A-arms often mount at an angle for anti-dive geometry and have the alignment adjusting built into the UCA mount. So you would need to slope the t-bars downward
Are you saying mounting the front upper A arm with the back mounting point lower than the front gives anti-dive?
Wouldn't that just mess up the motion of upper and lower pair?
To some extent, yes - and that is how they are set up on an A-body from the factory if you look closely. It's not sloped very much but it's there.
I never noticed that and I'd have never thought of that.
dean1484 wrote: Listening to all of you talk makes me want to go get an old Scamp. I still think a Scamp, a 360, some sort of forced induction puts you well on the way to a competitive challenge car.
Same here, but any A body would work, But a Demon is my #1 pick.
Narrow bodies (60-66) are the lightest and have the smallest cross section for aero. The later cars got heavier and heavier with options, emissions, and safety equipment. 63-72's can accept a lot of the later suspension and brake parts for upgrades, and aftermarket upgrades are available.. 64 and up had a v8 option, although exhaust plumbing can be a little tight. And, of course, '64 Valiants are the prettiest of the lot.
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