Will a 9" live axle Cobra w/ spool ever turn into corners?

[Double Venom]

Oooooh, I did go back and you did say 31 Spline! Now I assume it is a Ford 9" ??

DV

[Richard Hudgins]

Craig,

JBL has not made a RHD version. But it would be quite simple to do.

As the car is symmetrical, one would only have to put the pedal box on the right hand side and the engine bay side skins would have to be swapped, (For the steering shaft slot) and a RHD rack installed. (I think that Flaming river makes one.)

[Excaliber]

DV

Thanks for the up-date on the name! Helical gears NOT clutches, thats the ticket! I WILL be getting one. I think the sticky "racing" tires and road racing is what blew out my unit. I won't rebuild it, got to move up to something stronger.

DPIracingproducts.com offers what "appears" to be a helical unit (listed under differentials) for $650. I will call them to get more details. Being in Hawaii the shipping costs could be a LOT, wish I could find something "local", ha ha!

Ernie

[cobrashoch]

750HP - RE; Pro gears - I'm no expert but I think it has more to do with the angle the gears are cut and the radius the teeth are. (more straight cut?) I didn't know pro gears are softer to. All I know is at ratios over 430 on a 9 inch ring gear there sure are a lot more smaller teeth and in my case the wear went away with the pro gears. Take DV up on his offer. If you don't I will pay a visit to his shop soon and we will have a community rear end out there!
Excaliber - Be carefull when buying this rear end as there are many styles of lockers out there that have close style names. To make matters worse the tru-trac is sold under several different names too!

cobrashock

[Venom S]

I just ordered a 9" rear end with FOX mounts for my FFR. When I told the tech guy at Currie Enterprises what I was building, and what I was going to do with it, he quickly recommended the Tru-Trac. So, I'm going with that, 3.50:1 gears, 31-spline race axles, and 12" Wilwood brakes.

It will be here 30 September, Can't wait!!

Venom_S

[flipper35]

I think DV may be off on one little thing. if the "Tru-Lock" is similar to the "Sure Grip" for the Dana and what we called the "Detroit Locker" in days of old, it is locked as you drive and the clicking you hear is the unit releasing under tight corners. It is certainly the best setup. My understanding of a 'Limited Slip" is that is still a one-legger but that it transfers power to the one with the most traction, which would be your outside tire in a corner.

[Double Venom]

Flipper,
It is NOT a Detroit Locker. Detroit made this just for "us". At least that is what they told me. The Auburns weren't worth a damn on a road course or autocross. (We blew ours in a DV on a second turn in Texas!) And, those were Auburns words not mine. Mild street or dragracing only with an Auburn and they are NOT rebuildable!

The Tru-Track, as mentioned does not use cluthces of any type, just gears. Maybe I should dig mine out from under the work bench and take some close up pictures of it.

750.......Still waiting for an answer

DV

PS.. this is the same unit that was in the 9" that we ripped in half!
I'll let you make sure there are no unwanted pieces in it! Some spray cleaner and an air hose should do it!

[Richard Hudgins]

Hi Folks,

I think that DV is speaking of the Gleason/Torsen unit. When I was with Toyota (1978-84) the inventors/founders of the company brought in a unit for us to test in a FJ-40. The unit was crude, the machining on the gears was horrible, but they were really trying to get a OEM to look at it. It sat in my office for at least a year before I finally got the guys in the tech center to install it. They did and It worked quite well. However, at the time the inventors had no company and no way to produce a production unit. But, this is a good old example of the American dream and they kept at it. Toyota now uses these in a number of their vehicles.

You may wish to visit Technical discussion of the Torsen diff to learn how this unit works.

Or look at the white paper at: Torsen technical

Also, visit Torsen home page for application details.

I would recommend this unit for most every use in a normal Cobra.

[Excaliber]

Cobrashoch,,,,man I hear you about "names" sounding the same but the Diff's are......well....different!

I have heard of the Gleason/Torsen unit, do you think that IS the technology used in the Tru-Trak unit? Wow, this is WAY confusing!

Venom S,,,sounds like Currie Enterprises has a handle on the CORRECT name and CORRECT unit. Man I'm down to WHO do I call to GET ONE! And I want to be SURE it is like the one DV is talking about, gears not clutches with a name like Tru-Trak! I'll search for Currie Enterprises web site? Or can you just post the phone number or a link (in case I can't find them)? Do I get a discount for being a Cobraclub member? HA HA!

OH! This IS for a road racing application! This IS the correct (best) unit for this application?

Ernie

[750hp]

DV - you really are something else! I don't think it would be right of me to borrow parts that I know would see some pretty extreme duty in my car. Thank you ever so much, but I really can't accept.... Once again, your willingness to help others astounds me I'll have a bit of a think about exactly how much money is required to finish the car, and if there's enough left in the piggy bank I might see if you're interested in selling yours??? Sorry that I didn't reply earlier, but I only get to a computer once per day - usually sometime after 10.30pm here.

Richard - thanks for all the links! It was interesting to read about the process of selecting an appropriate bias ratio for the Torsen. I'll thoroughly read all the articles after I print them out. I'm not trying to be smart here, but is there any application that the Torsen unit wouldn't suit a Cobra? Any chassis styles or racing categories? Looking at your chassis - my supercharger/intercooler arrangement would foul on more things than it would clear, but that would give me a good excuse to go the twin turbocharged route! Ahhhh.... power AND handling!!! Geez, I haven't even driven my car yet, and I already don't like the chassis dynamics

[John McMahon]

Richard and DV,

I am in the midst of rebuilding the rear on my track only '88 Mustang. This car is used purely for road racing.

I have a converted 8.8 open rear using a Power Trax unit with 3.73 gearing. The teeth on the unit wore out and needs to be replaced.

I ordered both a replacement Power Trax unit as well as the Traction Lok unit from Ford Motorports. I continue to get feedback from many about the prose and cons of both.

My question is...from a road racing perspective, which unit will work better on a road course???? I hear differing opinions on the traction available with both.

I was happy with the Power Trax unit, it lasted me 2.5 years of hard racing and I don't know how long it had been in the car before. I have never used the Traction Lok unit. My problem is, I am a "Dear in Headlights" when it comes to the Ford 8.8 rears.

Any advice from you gents would be greatly appreciated.

JM

[Double Venom]

750!

Don't you know it is impolite to turn down a legitamate and sincere offer to help?

It is actually almost an insult...If you turn it down I loose face!

Give me your damned address and I'll ship it. (Unless you don't want to pay the shipping? ) "They" told me we could NOT break this unit. If you do.. ok, it's broke! Tell you what...if you like it, it works, blah, blah, apply the money to next years trip!

Now that is fair and equeal.

What's the shipping address?

DV

[Double Venom]

John,
We posted at the same time..almost.

All I can tell you is what we have learned from my DV. On the dragstrip I have never, and I mean NEVER had a car launch like this one did with this unit. First time out...I wasn't even thinking about the new center section, I launched like normal at 4,800 to 5,200. Unbeknownst to me, I apparently have always countered steered at launch in anticipation of the torque.

I launched and damned near hit the inside wall just past the tree! I thought something had broke, I really did. Saved the car, lost the race and after much checking, finding nothing wrong it finally dawned on me about the rear change!

Took another pass, only this time with full senses and a light touch on the wheel, I still wanted to steer right, but the car went straigt. I kid you not, before I ripped the housing in half, you could almost come off the pad with full slicks and never touch the wheel until the front wheels came back down! (It also totally eliminated our "left" front wheel lift! Now both front wheels, at least with the eye, lift the same time and same height.)

As far as road racing goes, Jay, our driver, Honda's Pro Road Rally Driver (and a guy you fellas are going to be hearing much more about in a short time to come) swears by the unit. I can't give you driving experience since he does all of the roundy round "stuff", but every time he takes the car on the track he is either setting records or coming in with times so fast he would win a full class or two above what they put us in.

There you have it. Back to the corner.

DV

[Venom S]

Currie Enterprises

http://www.currieenterprises.com/

Venom_S

[David Borden]

Craig,

I have not read the 3 full pages.. but hopefully you have decided NOT to use a locker or a spool. Im with DV.

Lockers do not belong on short wheel base high HP cars when used for the curves. You have to be a very good driver to make it work and be safe at the limit.... and I dont believe you can with your chosen rear suspension setup.

If I remember correctly, you are running the Stock FFR rear suspension now that you have decided against the IRS stuff.

That combined with a locker or spool and your HP level will most likely get you hurt. I am not kidding... or exagerating. If you push that car in the corners, it will bite you.

You have huge HP and now have the decided on most ill handling FFR rear suspension option.

Dont mean to spout off or come down on you.. .. BUT there a number of folks giving advice I just dont think is sound for your situation.

Peace,

David

[flipper35]

Sorry DV, I gues you did say gears no clutches. My bad.

[Richard Hudgins]

Hi folks,

First let me state that I really do not understand why everyone is so down on spools or no-differential final drives. I would like to hear from folks that have driven such cars, on a road course, why they feel that they are so bad.

David,

I quote "Lockers do not belong on short wheel base high HP cars when used for the curves."

Why? What cars have you driven on a road course with a spool? I have never had a problem with them. A proper diff is better, but in my day there were no diffs that could take the power and live for a 2 hour race.

Examples of cars that I have driven with spools.

1. Porsche 935 2250 lbs. 89.75 wheelbase, 500>750 hp. (depending on where you set the boost.) A pure joy to drive once you got onto the power delivery issues.

2. McLaren M8 . 1750 lbs. 92 wheelbase 700+ hp. Really a cool car to drive and the motor was excellent in power delivery.

3. Lola T300 1550 lbs. 94 Wheelbase, 550 hp. Ok to drive but the chassis was really flexible and you had to be careful not to have the bodywork and chassis pinch you under the arm due to flex.

I quote: "Dont mean to spout off or come down on you.. .. BUT there a number of folks giving advice I just dont think is sound for your situation. "


As I am the only one here who has said anything positive about a spool you must be talking about my advice. Well, I am sure that you are correct. I know nothing about the FFR car and you do. ( I did not know that Craig had one.)

Therefore, I bow to your experience with the FFR and its needs and I feel that Craig should listen to your advice instead of mine due to your greater experience with the design.

Congrats on your times. It is always fun to go faster. By the way, with 675 springs in the front, what are your wheel rates?

[David Borden]

Richard,

I was rushed when I made the post and did not think it though. I just saw a bunch of posts on lockers and spools.

You are the last person I would accuse of giving out bad advice. I respect your product and its design and your input on the forum.. so I appologies if it came across that way.

So back to what I was trying to say and did so poorly...

All my suggestions and opinions are based on this situation only and not generalizations...

My point was... Craig is putting a heavy 9 inch rear in his car and not the IRS. From what I gather he is using the stock FFR rear setup that uses the mustang quadra bind design. Frankly it only belongs on the street. Its the budget rear setup and has huge compromises on the track.

Add to that the older less rigid chassis, short wheel base, HUGE HP, limmited track experience(this is my assumption and appologize if wrong), Poor rear suspension geometry, short wheel base, and a locker or spool.

I just dont think its smart. I was talking specifically to Craig and his car and situation. Call it intuition. I just think he has really done a neat job this far on his ride and would hate to see him hurt it up based on generalized advice. I have seen a few guy wad up there cars due to high HP and poor chassis setup.

I agree, if he was running the 3 link or IRS with the appropriate bars, wheel rates, and stiffened up the chassis to the new design, had a number of year under his belt, he could be sucessfull with those diffs. However, there is new technology available that is better and not that much more money. The locker will unsettle the car when it locks and releases, the spool will force the car to drift and slide when cornered at speed.

Heck, I run the stock mustang traction lock. It lasts an entire season and costs $70.00 to rebuild at home.

From your list of cars, your a guy that knows how to do that with high HP cars designed for road racing.. and my assumption is you are an accomplished driver to be behind the wheel of cars such as those. I also assume those cars were setup and prepared with the same care as the JBL's you build.

That is very different that a guy with a new car looking for some track time with a car that is not optimized for it.

.... and my wheel rates on the spec racer are... 247lbs in bump and roll in the front, about 400lbs in bump and 224lbs in roll in the rear. currently no sway bars are legal, and the shock are set valving. the rear frequency is high, but seems to work well for the no-bar compromise we have now. The Spec car chassis rigidity is within your suggested acceptable range.

Peace.. and sorry for the missunderstanding.

David

[750hp]

DV - you're just too much!!! I've sent you an email
Your despcription of the 1/4 mile launches left a funny vision in my head of a wheelstanding Cobra with the crazy driver holding his hands above his head as though he's on a rollercoaster ride

David - thanks for your concerns for my safety. I've been having a few of those myself lately. As such, a chrome moly roll cage is next on my list of things to do before I drive the car. Scott (OZVENOM) just won't get off my case until a roll bar is in place. Richard's correct in saying that my car isn't a FFR. It's just another Cobra body with a custom chassis underneath it. While I do have a 9", I have a single coil-over per side, with a Mumford link to locate it all and a Z-bar (4 link, but upper bars go backwards through the trunk) The bars are horizontal. See the attached photo if it works... While my chassis should be alright (though not even approaching a JBL), my recent driving experience has been more 1/4 mile oriented. Driving at 120" wheelbase streetcar at 100+mph sideways on a 1/4 mile track is WAY easier than drifting a 90" Cobra through a corner in my opinion. After some work on the setup, and after getting a feel for the way the car reacts, I think I should have a fun package - but one that still demands some restraint....

Richard - anytime a 935, M8 and a Lola are mentioned in the same breath, you have my attention. Tell us that you've driven them all, and now you're just teasing us..... If money were no object - I'd have the 510 cube M8D from the Matthews Collection in my garage. I wonder if he's sold it yet???

Thanks!

[cobrashoch]

Craig - The piece of mind you will get with a proper rollbar setup is priceless. Don't even think about it, just do it! Let us know how DV's rear end works out too.
cobrashock