Broken Parts

[coyled]

Anybody else constantly breaking parts? I have broken, the rear end mount(IRS) twice, tranny broken and fixed twice, then blew it to pieces at willow(third gear), sheared a 31 apline stub axle, broke a billit hub in 2 pieces, broke the mount on a pro shock, broke motor mounts. The motor(358ci, 660hp) has been flawless, no broken parts yet, but it has been eating parts behind it as you all can see. Anybody else or just me? scott

[ST]

Obviously too much power for the drivetrain.
Maybe there's a way to slightly detune the motor a bit.(did I say that?) If you're running 660 hp I'm surprised you get even get enough traction to hook up at all. I'm all for horsepower but "balance" is the key.

[John McMahon]

No need for that much power in a Cobra, just about anything over 425 is a waste because its damn tough to get it to the rear wheels.

I have a 486HP 351W in my Cobra and realized I would need a HD tranny. So I went with the Richmond Gear.

Then again.....in my Mustang with a 500HP 351W, I have the Tremec 5 speed and no problems.

ST is right though, you may be trying to put way too much torque through the drivetrain. Again, it all depends on what you're doing with it and what components you're using.

JM

[RACER X #99]

Scott,
Perhaps you could switch to one of those 427 side oilers and then you would not be putting so much strain on the drive line.
Of course you would not be kicking ass like you now do.
Just a thought.
McCranky

[coyled]

Guys, With the goodyear bias ply slicks, the car hooks up fine above 40 mph on a road course so traction is not an issue or a problem.This too much power thing, I don't agree with not from a traction stand point. From a too much car for the driver or parts eating standpoint, I could agree. I am not going to detune the motor. John, your richmond is stronger than a tremec but I have driven 2 richmond cars and they would not shift fast at all. Up or down, the tremec shifts fast. I think, as you guys have stated, its the power that does it. Cranky, the best part so far, knock on wood, is, as much as I have thrashed this car, the motor has had zero problems. The cup style motor and a pro builder is the way to go, if you want the motor to last. I do appreciate your thoughtfull as always big block suggestion. scott

[John McMahon]

Scott,

Richmonds as I understand it, need a couple of thousand miles to break them in.

I do agree, they don't shift as fast though.

Maybe if you slow down the shifts...you'll break less parts!

[coyled]

John, I know what richmond claims on the break in. I have driven these with 10,000 miles and it is still slow. When I shift, its like giving a kid medicine, its going in the easy way or the hard way, but its going in fast. The jerrico is the way to go but I still street drive mine. scott

[Back in Black]

This is why I went with the 9 inch Ford straight axle. But there are options to beef up your IRS rear end, and other tranny options too (I am going with the Richmond Overdrive 6 speed, and figure the right lube should help in there, after break-in) also using the latest Centerforce 2 dual friction clutch and all related goodies.

Rear end options:

http://www.cwiinc.com/ (This is one bad A$$ rear end!)

http://www.cobracountry.com/amp/home.html

AND:
http://www.performancemarket.com/rearend.htm

Hope that helps. The 31 spline standard axles are nowhere tough enough for your app. I went with Strange Engineering 33 spline *Street Pro* axles, and SE posi modular differential.

[Ikestaa]

I'd say shifting slow is better than no transmission at all

[coyled]

I have a stonger bracket to support the rear end along with solid bushings up top. The axles are better and hardend. The tranny is the tremec tko road race version, D&D has not seen one break, yet. Hardend and better axles, may have been worn out along with a shock mount . I think I may have it coverd.The one issue I think is a design flaw is the hub. The inner and outer bearings are inside of the wheel 6 pin mounting. I think the outside bearing should be outside of the flat spot where the back of the rim mounts. The set up on cobra country is my set up. I guess that the jag's are the same way. Mine is a 9 inch center also. The biilit hub broke in half which is beyond me other than the design flaw. The car started hunting on acceleration/deceleration so I knew right away. Thamks for the help. scott

[Junket]

Just out of curisosity I want to get a Richmond 6sp for my toy are you guys runing the Richmond 4-5-or 6sp have about 450HP+- the tek at Richmond said 450 ft.# in there 1st gear with 3.27 ratio. and is this unit slow on the shift?
Thanks Ken McMahan

[RACER X #99]

Scott,
It seems like the components are just not up to the abuse you are giving them. Just like the pro racers you will have to find different parts(heavier duty) that can stand the abuse. Those parts could probably last forever on the strip and street but road racing is the real test of durability. While I don't have any solutions perhaps the supplier of the rear end components can suggest a heavy duty replacement assembly. Those 9" Ford independant rears were from CWI weren't they? I don't ever remember hearing of a 660 hp road racing Cobra so you are probably going to be the guy that sets the bar for the rest of us.
Good luck,
McCranky

BTW are you still planning on Elkhart Lake in Sept.?

[427sharpe]

With this kind of repetitive failures, i'd say something has got to be set up wrong...perhaps hardware failures or too much movement in the rear end. I put a lot of strain on my drivetrain, and have had only 1 failure--a twisted axle. I would go back thru the car and make sure that there is no play anywhere, and replace every nut and bolt with AN hardware. Certainly a competent machine shop should be able to produce a billet steel hub carrier with bigger bearings....if your pockets are deep enough! I wonder if the center section is moving too much under load......

[coyled]

The rear end is solid mounted now, top to bottom. The bigger hub/bearing may not matter as the outside bearing is still on the inside of the rim mount. It would be better if the bearing were on the outside of the wheel moumt, like a front hub. I guess The bottom line is to check and re check if you thrash your cobra with a high hp motor. Cranky, I will be at road america in september. scott

[a427sc]

Scott,
Just food for thought. With all the stress that motor puts the driveline through, maybe all-solid mounts aren't the best idea. The more you lock things up, the more the stress migrates to other "weak" spots. Unless you have installed something like an 8 point cage to stiffen the whole chassis, the original type frame will flex throughout the car, causing local fractures and misalignment. A little "give" in some areas might be helpful. As for the trans, What do they use in Trans-Am, GT1, W/C roadracing etc? Surely isn't a Tremec. The Jericho works fine on the street, just use the clutch like normal and there is no problem. So who can hear a little extra gear whine over all the other music that ride generates.

Amazingly for once, I have to agree with Cranky, dump that little motor and get an FE. I'd be honored to help you with your search for a well sorted big block car, although it would be glass instead of aluminum. Due to my increasing reliance on Depends, Malox, and thicker glasses, I need to move on to a less demanding ride. Maybe we could come to a mutually positive solution?

McFEZ

[Cobranut]

Scott,

It sounds like you have too much traction.


Do what I do, run BFG Euro T/A bricks and you'll never develop enough grip to break anything. (That is, unless the thing gets away from you and hits something.)

But seriously, I roadrace a Legends car, and I'm continually finding weak points. My aim is whenever something breaks, fix it stronger that it was before and move on to the next weakest point.

We last ran at Kershaw, SC and of the 13 or so Legends there, I think there were 4 broken axles due to the rumble strips along the track edges. I quickly learned to stay off the danged things, and whenever I did hit one, I just lifted and coasted across. (Better to lose a position than to go out broken.)
When I got home and inspected the car, I found a cracked frame member at the top rearend link attachment. The rules allow us to double-shear that mouont, so when I fixed it, I did just that. (Next on my list is to double-shear all the rearend links.)

Another point, always inspect the car after every event. Tighten all suspension and steering related fasteners, clean and lube everything. This often allows you to find small things before they turn into big things. High performance cars demand a LOT of maintenance if they're to be safe and reliable.

Good luck,

[coyled]

David, I run the greasy(no traction) bfg's on the street and your right, nothing will break running those tires. I do tighten and check every nut and bolt before each track event, thats how I have managed to catch lots of things. Mcfez, the rear end is fairly stiff now, it does not move around like it used to. The big block idea sounds good. Now, my car has a push during corner entry which I have learned to roll into the throttle before the apex and the cobra will turn once the rear end rotates. Now with that big heavy block of a motor, it will probably push a lot more and then when I roll into the throttle, I will not have the power of the 358ci so the rear end won't rotate, and I head for the wall. I would be faster on the downhill(more weight) section though. scott

[SCOBRAC]

You really need an FE motor.. My 425 hp will not spin fast enough to break anything..