Ford 9 in. Locker or no locker?

KingCobra · #1 (**permalink**) 07-18-2003, 10:08 PM

I recently jumped into the Cobra ring big time. I have a West Coast roller on it way. I will install a 460/535 with a Tremec (Viper) 6 speed and a four point held Ford 9 in. with a 3.50 r an P. I have been out of the race car scene for about four grown son years and was, I say was, a Chevy guy.
So here is my question. Will this car preform adquatly without a posi or locker? I have been told that unless I just realy try smoke the tires that the car will launch fine with a open differential if the tire pressire is adjusted to get equal grab. Is the extra expense of a locker worth it.

Also I have been told that a locker will have a negative impact on road performance due to the light of the Cobra?????

Ibr8k4vetts · #2 (**permalink**) 07-18-2003, 11:55 PM

A locker would be CRAZY on the street, IMHO

. I have a posi And it still spins around corners just putting.
Mike

Excaliber · #3 (**permalink**) 07-19-2003, 12:59 AM

I assume King Cobra is asking about a "posi" or "detroit locker" vs an "open diff". The word "locker" in my mind suggests a "spool".

The GOOD thing about an "open" rear is the car is FAR LESS likely to swap ends on you when you DON'T want it to. The Bad news is, the car is far less likely to swap ends on you when you DO WANT it to.

I like playing with throttle over steer, which a "posi" type unit allows for. It's pretty hard to get the back end "dancing" from side to to side with an open rear. And with 400+ horse it will be "difficult" to get it to hook up by just playing with tire pressures.

The only "problem" I have with posi type units is:

They WILL bite you in the ass by snapping out the rear end under even MODERATE accelleration when you LEAST expect it. The car is MUCH more likely to get out of control with one.

As my posi unit is now essentially "blown" it's like I have an "open diff". Running SCCA events or open track road course this is a MAJOR problem. And hooking up in straight line is not easy! You WILL get one tire wheel spin.

Now on the street, I LOVE the open diff. Much more enjoyable to just "drive" and not worry constantly about "throttle position" and the potential for a "spin out" right in the middle of an intersection.

.........maybe I'll quit racing and buy some car wax..........

Ernie

Back in Black · #4 (**permalink**) 07-19-2003, 09:49 AM

It's a Strange Engineering 9 inch posi unit with SE 33 spline pro street axles. Actually, with the super sticky Pirelli P-Zero tires, I have great traction, and beyond 2nd gear it's difficult to spin the tires unless you pop the clutch or something. I do attribute some of that to the excellent P-Zeros, which are almost 1 foot wide in the rear, but the posi is awesome, and it's very predictable, when you do lose traction.

cobrashoch · #5 (**permalink**) 07-22-2003, 04:47 PM

King Cobra- I have ran a Locker for years and around these parts they have had a very unwarranted black eye. To the chase, and in a word you have options. The locker you most likely remember from the 60's was a Auburn Detroit Locker that was used in Ford muscle cars of old. It is indstructable in a cobra, and the weight of the car makes no differance. They are noisy though, and ratchet(click,click) around turns. If you road race them they tend to grab hard coming out of a turn so you need to be aware of that. If you use the Ford verson of a posi rear (traction-lock) the chances are you will have problems with the clutches every 2 or 3 years or so, but on the other side of that, clutches are relatively cheap to replace. HI Ernie!
So much for the old stuff, todays lockers are much better, and for a Cobra the winner of the MANY types of differentals out there seems to be a true-trac (sp). I believe it has a 80/20 aspect ratio with adjustable full lock. Ed Combs aka Double Venom was the first to talk of this locker on this forum, so a site search will give you much information. All lockers are not the same and a off road magizine will show you lots of other options in the adds. Don't forget to buy performance axles for safety, and if you order a rear end a 31 spline axle is the mininum, a 35 spline is better.. As for me, I can't tear up my Auburn locker and have been VERY happy with it. And believe me, boy have I tried. 1250 drag slicks anyone?
cobrashock

KingCobra · #6 (**permalink**) 07-23-2003, 06:45 PM

Thanks fellows for the advice. I think at this time, I'll concentrate on getting my car on the road. After I drive her a while I understand better if I'll need more traction than the open dif can provide. Besides my pocketbook is smarting big time!

XXQQQME · #7 (**permalink**) 07-28-2003, 07:52 AM

KC,
When are you taking delivery on your West Coast? Betchya can't wait!!!! Mine is in Canada being painted at the sending of this message. I'm ready to finally finish this baby!!!

_____________
XXQQQME or CODEBLU
or ASPMAN. . . not sure yet!

427sharpe · #8 (**permalink**) 08-01-2003, 09:14 PM

I have a Detroit Locker in my EM, and have since 1983 when I built the car. No problems, and love that traction!

James Neal · #9 (**permalink**) 08-03-2003, 07:33 AM

Any of the high end units are more than adequate in a 2,400 lb. Cobra and the reaction is very predictable. Allthough there very noisy,but thats why you drive a cobra. Auburns are pretty hot here in these parts, Mustang boys love em! High Bob. I ran a Detroit in my Camaro before I went to a spool, it was great for the street, Allthough a rebuilt posi works well for a couple a years till it needs a rebuild.400-500 burnouts.Cheap to rebuild if you have done it before.I personally would'nt run a open, there useless and not meant for a performance machine. Spools aren't for the street allthough some clowns run them,they must like the sound of the tires scratching and jumping when making a two-mile an hour turn.