Torque Arm For the Cobra
 

I have been wanting to get a Maximum Motorsports torque arm for the Cobra for a long time now but at $650 for the heavy duty one I just can't afford one. So I have been thinking about building my own. My first idea was to use the bushing and mount from a radius arm of an Explorer or Ranger. However, after talking to Guy one day he offered up his Maximum Motorsports HD one for me to copy.

I then spoke to GTR about ordering the hardware kit from Maximum Motorsports to make it easier on me. The hardware kit comes with the poly bushing, bolt, spacer, U-bolts and everything else that I would need to install it. That way I only needed to build the torque arm and cross member.

I've been slowly working on it for the passed few weeks because I'm still in a cast with a fractured ankle. I already had a 2.5 x .250 square tube left over from building the bumper on the Explorer. So that's what I used for the arm. It's thicker wall than the Maximum Motorsports one but with the way I drive I didn't think that was a bad thing.

Here's mine next to the MM piece. Mine is the same length and the bolt mount is at the same angle.





I still need to make the axle mounts and the arms that go between as well as the front mounts but I'll need to do that on the Cobra.

Next I started making the cross member. I started out with a 5ft piece of 4in x .250 plate that I bought for $15. I traced the MM cross member onto the plate and then cut it out. This took me a long time (about 10 hours) since I was using a sawzall, angle grinder, drill and jigsaw to cut them out.

The tools I used.









Front and back pieces shaped together.

















I still need to drill and tap it for a zerk fitting and then install a freeze plug to the back of the center tube.

Little late now, but John is not far from you and AFIK has a plasma cutter.

He does, it was a Harbor Freight one. I have a couple of friends that have them too but I didn't want to bother anyone and I don't mind the work. Besides, Amy wasn't all that happy about me welding with my cast. I couldn't imagine what she would say if I told her I was going to go use a plasma cutter.

I got a little done today. First, I measured where the zerk fitting was on the MM cross member. Then I drilled and tapped mine in the same location. After that I deburred the hole, sanded the inside of the tube and installed the zerk fitting.



I then drilled the holes in the axle mounts. I used a set of leaf spring mounts that I bought for the Explorer when I did the solid axle swap and ended up not using.

I didn't notice that the front of your arm is that much deeper than the MM one. I know on the gray car I scraped it on a few steep driveways, nearly stalled it a few times. Just a heads up.

Nice work!

Thanks. I went to the doctors today and my foot is healing nicely so I got the cast off. I still can't run yet but he said I can start walking but not to over do it. He has me in a brace for four more weeks but said after that I can start running again. That also means I can't drive the Cobra for four more weeks because of the boot I'm in. That works out though because I need to pull the intake to have it machined anyways.

We still on for Saturday?

Yes. Speaking of that, if you tack the subframe connectors on make sure that you sand the paint off the areas to be welded first. It's hard to do that once they're in place.

Nice job Ron! Wanna make me some? lol

Do you even drive your car? :pot_stir:

Building this is a pain in the butt and I don't want to do it again. I wish I wasn't poor so I could have just bought a Maximum Motorsports one. Oh well, at least I can build one.

I just have a little update. I spent a couple of hours on Sunday getting everything lined up and the cross member tabs secured with C clamps. Then tonight I welded all the tabs in place. Next up will be lining the TA up so that I can make the rear arms and setting the pinion angle so I can make the front ones.

Looking good Ron!

Thanks Adam. Hopefully it performs as good as everyone says it will.

If you made any jigs or templates, you could more easily make and install more for cash moneys. :)

I copied Maximum Motorsports torque arm. It would be illegal to make them to sell and I wouldn't do that.

Is the design patented?

It doesn't look like it but I wouldn't do it anyways. I'm okay with building it for myself but that's it.

It is, MM has sued over it before.

I got a little more done today. I cut the tubing for the axle brackets and got them welded on. Then I cut the tubing for the front of the housing to set the pinion angle. I only got the drivers side done though. Tomorrow I'll make the one for the passenger side. And then finish welding them to the arm.

Sorry for the bad pictures, I'll take better ones tomorrow.

I made the pinion angle bracket for the passenger side and took a bunch of pictures this time to show what I put into making it. Once I got it all made and partially welded I dropped the TA and crossmember so I could fully weld the brackets. I was finishing up the top sides when I ran out of shielding gas. So I'll have to go down Tuesday some time and get a refill so I can finish up.

This is how I start. I measure from the diff to the arm and then cut a piece of 2in plate to use to find the angle for the top and bottom. I hold the piece in place and then use a protractor to get the angles. Then I transfer the angle to the tubing and then cut it.



After that I cut a 4in piece of round tube for the bolt and bolt it to the diff. I drilled the holes out to 1/2 for the bolt so that it would sit centered. then I hold the tubing for the bracket up to it so I can mark it to cut the hole for the round tube.















Once I have the hole cut out I bolt the round tube back up and then hold the bracket in place so that I can tack it.





Then I pull it down so I can weld it.



I then bolt it back up so that I can weld it to the TA.



I only weld the sides because the top and bottom welds come out better with it off the car.





You can see in this picture when I ran out of gas.



Here's what it look like so far.



I also picked up a freeze plug for the crossmember so I installed that.



The final thing I did today was drilled the 9/16 holes in the diff and then cut the back of the TA to give it a little more ground clearance.

Great work Ron! It will be interesting to see what you think of the performance gain when you are all done and romping on it. I want to do this eventually when the Mach gets a blower, maybe even sooner.

I plan to take it to Adams Motorsport Park after to see what it will do. I ran the Cobra on the street tires and I was running 49.xx so I'll do the same and see what improvement it makes. The torque arm is supposed to give it more bite and at AMP I spend most of my time in 2nd gear which would just spin before.

I went and got more Argon today so I could finish up the welding. Tonight I made a gusset for the passenger side pinion bracket because I didn't like how little of the round tube was welded to the rectangular tube.

You can see in this picture how little is connected.



So I made this.





Once I had that made I finished welding everything up.









I also partially painted it. I'll finish it up tomorrow night.

Don't forget that once it's installed you'll need to significantly increase the rear spring rate.

I know. I just don't know what springs to go with. Right now I have MM Road & Track springs but I don't have any idea what the rates are. Plus I have Tokico Blue shocks right now but I want to change them to Koni SA to match the front ones.

You'll need to change all the springs and there's a pretty good chance that with the added rear grip the car will oversteer more. Rear wheel rate of 300-550lbs will be needed with a front rate of 750-900 for absolute best handling with a trade off in ride quality over 750.

Here is a list of non MM springs that commonly pop up used, mix and match to save some coin.

Aftermarket Spring Rates
Manufacturer/Part Info Front Spring Rate (lb/in) Rear Spring Rate (lb/in)

Ford Racing B Springs (M5300B) 425-530 (progressive) 200-300 (progressive, solid axle)

Ford Racing C Springs (M5300C) 650 (linear) 200-300 (progressive, solid axle)

Ford Racing F Springs (M5300F) 460-570 (progressive) 170-310 (progressive, solid axle)

Ford Racing G Springs (M5300G) 500-570 (progressive) 170-310 (progressive, solid axle)

Eibach Pro-Kit Springs (94-04 Mustangs) 425-530 (progressive) 200-300 (progressive, solid axle)

Eibach Sportline Springs (79-04 Mustangs) 425-630 (progressive) 140-295 (progressive, solid axle)

H&R Sport Springs (94-04 Mustangs) 490-575 (progressive) 205-250 (progressive, solid axle)

H&R Sport Springs (99-04 Cobra) 700-760 (progressive) 685 (linear, IRS)

H&R Super Sport Springs (94-04 Mustangs) 700-760 (progressive) 275-300 (progressive, solid axle)

H&R Race Springs (79-04 Mustangs) 750-850 (progressive) 260-280 (progressive, solid axle)

H&R Race Springs (99-04 Cobra) 750-850 (progressive) 770 (linear, IRS)

Steeda Sport Springs (79-04 Mustangs) 650 (linear) 200-250 (progressive, solid axle)

Steeda Sport Springs (03-04 Cobra) 720-780 (progressive) 650-790 (progressive, IRS)

Steeda Competition Springs (79-04 Mustangs) 750-850 (progressive) 250 (linear, solid axle)

StangSuspension Springs (94-04 Mustangs) 490-575 (progressive) 205-250 (progressive, solid axle)

You make me jealous. I wish I knew how to weld. :thumbs_up:

Ditto :(

Your issue is your welder. You just need to practice with it to get use to how it welds.

Finished installing the TA today. I won't know how it drives until I put the intake manifold back on the car. I ordered the gaskets for it and they will be here next Tuesday. I didn't modify the exhaust so I'll see if it drags or rattles when I drive it. If it does then I'll modify it later.

My intake gaskets came today so I got the lower intake put on tonight. I'll try to finish it up tomorrow if I have time.

:popcorn:

WOW! What a difference! I finished installing the intake, distributor, etc. and then took it for a test drive. Nothing clanked or rattled which I was concerned about with how close things were. Now for how it feels. It definitely brakes much better than before the TA. Before when I would brake hard the front tires would chatter with the ABS and the back end would rise limiting the effectiveness of the rear tires. Now the back barely raises and the rear tires chatter with the ABS.

On acceleration it no longer spins in 3rd gear. It still spins in 2nd gear but it bites more. Before the TA if I rolled into the throttle in 2nd it would just blow the tires and not move as quickly. It also doesn't step out as uncontrollably as it did before when accelerating in 2nd on a left hand turn. It seems slower and more controlled.

As for rolling in corners I didn't really think it felt that bad but I'm also used to my Explorer that leans like crazy. Still, I only took one corner at a decent pace and that was a right hand sweeper on a freeway on ramp. Again, it didn't feel like it was rolling all that much to me and felt very planted.

My strongest memory of being in the car with you at Adams, other than impending death, was a feeling of under steer. How about that? Maybe you won't know until you're really pushing towards its limits. How bout from a hard dig? Better, worse (because of limited weight transfer?), neutral?

Everyone says that understeer will be worse because the back has so much more traction but I won't know until I get it to Adam's. Like you said, you don't feel that until you're pushing it which I can't do on the street.

I can't test it from a hard dig because it just blows the tires off in first. The only way to test that compared to before is to put my slicks on which I did do once so I at least know what it felt like before. With the 347 it would spin the slicks through 1st and most of 2nd on the slicks. I'll have to test that one day.

What kind of tire you running up front and what's the limit in width? Without checking I think the new Z28 track car is running like 305s all around or something nutty like that. If it understeers and you have tire to gain, you could always go wider, stickier and with a different camber setup I guess.

I have three sets of rim for the Cobra. One set are 98 Cobra rims which came on the car when I bought it. They are 8.5x17 front and rear. The second set original Steeda Ultralites which are 9.5x17 front and 10.5x17 rear. The last set are stock SN95 GT rims (2) that I have my M/T slicks mounted to. I used to run the Steeda rims with street tires and had 245/45/17 NT01 mounted on the Cobra rims for the track. That's the tire I had when you and I went to Adam's. However, I'm now running a 255/45/17 on the Cobra rims for the street. I still need to buy some NT01 for the track that will be mounted on the Steeda rims and I'll be going to a 275/40/17 on the front and a 315/35/17 in the rear.

Right now my Camber is set at -2 degrees which I run all the time. I've been told that the car will work best with somewhere between -2.5 - 3.0 but I haven't tried that yet. I do plan on going over to Crest Chevrolet one day with Phil and using their alignment rack to set the camber up at -2.5 and -3 so that I can mark my caster/camber plates so for all three so I can easily change it at the track to test. That way I can change it back to the -2 I run on the street.

You can accommodate the understeer by tuning the swaybars a bit. I have all the MM alignment goodies, we can measure the bumpsteer and c/c and find out were the issues are and find a cost effective alternative to doing what I did. I know MM likes to run the sway bars softer, with more spring pressure and minimal rebound but it rides like shit when you aren't pushing it to its limits.

I'll be taking you up on that offer. I spoke to Gonzalo at GTR who called MM yesterday to discuss what my car has now and what they recommend. They said the front springs I have now have a spring rate of 680 - 780 and that their TA spring 42TA5 would be a perfect match for them. However, my current rear shocks won't control them so I need to get rear shocks first and then upgrade the springs. I can't afford to do both at the same time so I'm going to get the shocks first and then do the springs later. Gonzalo is going to get me a price on Koni SA shocks to match the struts I have in the front.