Lowering set up?

[35th-ANV-SS]

I am not sure that a full-length torque arm has the option of mounting off the trans. It may only be available for the tunnel mounted torque arms.

[bpopham22]

I'm pretty sure umi has a bracket that gets it off the tail shaft for a full length ta.

[35th-ANV-SS]

I thought there was, but quickly looking through kyspeeds website, I didn't see one. I would call Mark and ask. A full-length will transmit less road noise and will suit you better for the street...but again, get the front mount of the TA off the transmission tail shaft if possible with a full-length.

[j nix]

From reading up on UMIs site, this is what I got from it. Now this suspension project is just getting more and more expensive. I will do everything eventually and I do t kill my car when I drive it now. So what can I get away with. What is absolutely necessary to get now. It sounds like if I get the the adjustable torque arm that is tranny mounted, I can get the relo bracket later and the torque arm should fit on it. The bracket should work with any torque arm that is mounted in the stock location. Does this sound right?

[j nix]

But I get it that I would have to buy a full length TA when I get the relo bracket

[bpopham22]

I have the umi full length and it works just fine, check out ws6 store for that bracket. I have the umi adjustable full length on the tailshaft and I haven't had any issues,but I'm only at bolt on power for now.

[j nix]

I only have bolt ons and not all of them and not all small mods yet either. I am just trying to get the suspension in good shape and better than stock. The ride sucks, my shocks are completely gone. That is how this started. I figured do new LCAs and sways, and I have 2 point SFCs and strut tower brace. Haven't put any of this on yet though. Want to get it all here first. Figured I would get lowering springs since I would have everything apart, then of course came LCA relo brackets, now TA and relo brackets for that. It just doesn't stop.

[35th-ANV-SS]

You are right...it doesn't stop...see my sig

[j nix]

I am really surprised that you only have 330 rwhp with your set up.

[35th-ANV-SS]

I am really surprised that you only have 330 rwhp with your set up.

I have no power mods except LTs and exhaust. That is also on a Mustang DYNO and through a 9" rear-end, which is the least efficient.

[j nix]

How much HP does your SS come with stock?

[parnelligq]

Get the arm that mounts on a crossmember. It does not cost much more and also gives a place to mount a drive shaft loop. Both are safety issues and better for your launch. Why do a mod twice? You always build stronger than what you need. Just saying, build it right or not at all.

[j nix]

I agree about building it right. I already added alot to this phase that wasn't originally planned. I am just going to do whatever I need to. I want to have a strong, tight suspension when I am done. What exactly is a drive shaft loop?

[parnelligq]

Its a metal strap in the shape of a "U" that bolts on just behind the front u-joint. This in the event that your u-joint lets go while making a pass. Without the loop the front of the drive shaft, the shaft digs into the blacktop poll vaulting the ass end up. The ass end coming up four or five feet at 70+ mph and you go end over. These are NHRA required for a reason. Its about a half pound of strap that can save you and your ride on or off the track. Once you have the cross member you can make your own loop. LOW cost insurance.

[35th-ANV-SS]

How much HP does your SS come with stock?

The ls1 was rated from GM at 325HP to the crank, which would be about 280rwhp to the wheels. This is a conservative guess.

[j nix]

I talked to Sam Strano today. He said he won't have any springs for 6 weeks. I am going to install the LS1 Prokit, I already bought. I can always do stranos later if I don't like the Prokit. He also said he didn't change the TA on his car or relocate the LCAs. He said the only thing you need in an adjustable PHB. The other stuff is preference. He said some times the pinion angle might get better after lowering. All our cars Will be a little different. Also that he has only ever seen 2 tail shafts ever break. So I think I will hold off on the Adjustable TA and relocation bracket until after I get everything I have on and see what I think. Thanks for all the advice. Very educating. I might have to learn from some mistakes as well.

[35th-ANV-SS]

Interesting. I've seen more broken ones than that just from this site. I'm not arguing with Sam, he knows his stuff, just saying.

But just food for thought. The stock TA from the factory is set to -2 degrees. Read this if you want some more knowledge.

Both, pinion angle and instant center are effected by the torque arm. Lowering the car will effect both.

Negative pinion angle is when the nose of the carrier housing (the pinion area) is pointing down towards the ground instead of parallel with the tailshaft of the transmission. Positive pinion angle is when the carrier housing & pinion are pointing up from the parallel line.
Pinion angle is measured at the pinion when the vehicle is sitting at rest and is the angle of the pinion, it is not necessarily the angle of the torque arm.

If you do not change the outside diameter of the rear tires, and you lower the vehicle with springs then the rear axle is still at the same height from the ground, but the front torque arm mount is lower in relation to both the ground and the rear axle. Since the rear of the torque arm is solidly attached to the rear axle, If you lower the front of the torque arm that will twist the front of the axle down. This would cause negative pinion angle. To return the pinon angle to 0° or to just make the pinion angle adjustable you can use a torque arm with a turnbuckle or threaded rod-end at the rear axle end of the torque arm. This will allow for adjustment of the pinion angle in relation to the trannies tailshaft. You can also change pinion angle by moving the front mount of the torque arm up or down but that also changes the point known as the instant center.
Ideally you want 0° pinion angle at all times.
When using constant velocity U-joint driveshafts, both ends must be at the same angle (0° difference) to maintain constant velocity. Any angle difference, positive or negative will cause driveshaft U-joint binding with pulsing and surging. This will eat U-joints over time and the vibration, pulsing and surging will cause traction loss and the binding wll slow the car.
Drag cars are set up with negative pinion angle when at rest (usually around -4° or so) so that when the axle twists under extreme force from acceleration and the pinion moves up towards the floor board the pinion angle will be 0°. The idea is to have 0° pinion angle while accelerating so there is no surging, pulsing or binding in the driveline. If the pinion has positive angle (angled up) when at rest and then when under acceleration it moves up more, that would throw the driveshaft and U-joints way out of line and cause a very large amount of bind and surge.

Now for the fun stuff:

Where the instant center is effects traction much more than pinion angle. When the rear axle twists under acceleration it applies a rotating force on the control arms and the torque arm. This force pushes up and back on the body of car. The point at which this force is concentrated is called the instant center Moving the instant center back will push up on the car body over the rear tires, forcing the tires down into the pavement. Think about doing pushups. Your arms lift your shoulders away from the ground while pushing your hands into the ground. Moving the instant center up in relation to the cars center of gravity will help transfer more of the front weight of the car onto the back tires.

Finding the instant center is easy on a car with a four-link rear suspension. Draw a straight line through the center of the front and rear bushings of the upper rear control arms to the front of the car. Do the same thing for the lower rear control arm. The point where the lines cross is the instant center.
Move the mounting location of either the front or rear mounting location of either the upper or lower control arms and you will move the instant center. The front and rear mounting points of both the upper and lower rear control arms of a four link are static. Their bushings pivot around bolts and have no forward or backward movement.
The front and rear mounting location of the rear control arms on an F-body is also static. The rear mount of the torque arm is also static but the torque arms front mount is not. The front of the torque arm not only rotates in the bushing but it also slides forward and backward in the mount. This makes it a little more difficult to find the instant center in an F-body, but it is still the same basic relationship between the torque arm and the control arms. In simplest terms the torque arm more or less replaces the upper control arms of a four-link.

On an F body, instant center is affected by the angle of the torque arm (front mount height in relation to the axle), the length of its front mounting location from the rear axle, and the angle (front and rear mounting locations) of the rear control arms.

When Tory moved his front torque arm mount up he moved his instant center upwards, in relation to the center of gravity, helping to transfer more of the weight of the car onto the rear tires. Moving the front of the torque arm up twists the axle and would cause positive pinion angle. When you add the natural twist of the axle when under acceleration it would go even more positive causing bind and pulsing in the U-joints. The pinion angle would then need to be adjusted to compensate unless the car had too much negative pinion angle before moving the front torque arm mount up.

If you lower an F-body you lower the front mount of the torque arm in relation to the rear mount of the torque arm, moving the instant center down. You also move the front mounting location of the rear control arm down in relation to its rear mount. Due to the short length of the rear control arms their angle changes drastically. This moves the instant center way further forward and way, way down. This will seriously hurt traction. A lowered car needs to have the mount of the axle end of the rear control arm lowered also to correct the instant center geometry.

I am more concerned about the things I mention because my car will be running 500+rwhp in a month or so. For bolt on power being used only on the street without any hard launches at the track you are probably fine.

[j nix]

That was some a pretty sweet explanation. I actually understood everything you wrote. So, sitting in my garage i have new LCAs and relocation brackets. I haven't decided if I need a torque arm yet. I guess I won't be sure until I check my cars pinion angle. How do I check it?

[35th-ANV-SS]

http://www.wolferacecraft.com/pinionangle.aspx

[j nix]

I really appreciate your quick response with straight forward answers. I am soaking it all up. Are these Wolfe parts worth the money? Are my Bilstein shocks and Eibach prokit springs and all the UMI, SFCs, LCAs, phb and sways good quality to be putting on my car. Or am I doing it wrong?