Changeing reaer end gears, Is LS worth the extra dollars

[cobrak]

I Have 3:10 Rear End Gears And Will Be Changing Them To 3:64 Or 3:73. The Standard Bmw Rear Diffs Are Very Easy To Come By And Are Inexspensive. The Limited Slip Diffs Are Hard To Find Especially In The Gear Ratio Of Ones Choice. Upgradeing The Gears To Limited Slip Is Exspensive, Is It Worth The Exspense?


Cobrak

[Excaliber]

If your going to do any laps on a road course type track you really have no option. Got to have LS or better.

If your just going in a straight line, cruising town, etc. open diff should be "ok", but not the best solution.

[tonyd]

I too would like to change the rear end to 3:73, how esy are they to come by,where are they? and about how much? I want to just street cruise so non LS is fine.
Let me know.
Cheers Tonyd

[Jerry Clayton]

For cars that are driven only on nice days LS probably isn't nessary, but for driving in inclement weather it could be a help( muddy roads, snow, sleet.Etc)

Drag racing, LS or a spool is generally used but a vehicle's suspension can be tuned to work without it---

Road racing---another whole ball game--LS can become one of the hardest elements to tune around--causing an unbalance on turn-in or exit

I, for example would try to work around an open rear----

Jerry

[Bailey]

I have a LS 3:64, tied to a 408W and T-56. I wouldn't have it any other way.

[ROUSHAC]

Bear with me for a moment here. I also apologize for the length.

I have had extensive experience with offroading Jeeps and have used open diffs, limited slips, Detroit automatic lockers, and ARB air lockers. Driving on the street taking turns, it is very easy to chirp or even spin the tires even on dry pavement even with a just modest amount of extra gas with limited slips and especially lockers. If it's wet out on the street, you may suddenly find yourself looking at where you just came from repeatedly if you give it too much gas in a turn with some type of locker. The ARB's are great because you can go from a full locker to open diffs with the flip of a switch. However, it is good tires that make the real difference even on the trails. I've seen people with the right tires for the conditions and open diffs go places you would not believe. Neither could the guys with the lockers and the wrong tires who couldn't clear the same obstacle.

That said, most of us drive our Cobras only in good weather most of the time. I have an open diff and Nitto Drag Radials in the rear and leave two tracks on dry pavement if i get vigourous with the loud pedal. I suspect that other sticky tires like the new Goodyears would do as well. They do not really like wet roads, so I slow down accordingly when it's wet out.

Poor dry traction tires probably will break one tire free with an open diff even on dry pavement. A limited slip will help, but good tires are the real secret to traction. That's why they use wet and dry compounds on race tires depending on conditions. As Mr. T used to say "Pity the Fool" who chooses the wrong tire on race day.

Also, the skill and experience of the driver make more difference than any other factor (even tires) on road or off.

Everything in life is a compromise. If you want to do burnouts, only do them on dry pavement with good dry tires. If you want to drive fast when traction is not great, get good rain tires. The dry tires suck in the wet, and the wet tires suck in the dry. As to open or limited slips on the street, I do not think they make that much difference if you are using the appropriate tire for the conditions, but the open diff is less likely to cause problems for most drivers.

As to racing, I defer to Excaliber's opinion about lockers especially with experienced drivers. I suspect that the RIGHT tires will make a lot of difference even in those conditions. Considering that most of those who race their Cobras still drive them on the streets, YOU have to decide what YOU want to do and get the approriate equipment to do that particular job well.

Good luck!

Cheers!
Dave

[Excaliber]

Tuning the rear end needs. Our track here is short, twisty right and left, lot of body roll in the corners. Inside tire going up in smoke coming out of one these is pretty common. Some guys use 'throttle over steer' to bring the back end around. A tricky manuever, that virtually requires some kind of taction controlled LS, locker, etc. type rear end.

But what if it were a longer course, with more sweeping corners? An open diff might be fine. Limited slip is most forgiving for overall driving conditions, a 'spool' being the harshest and least forgiving. There are several rear end traction enhancement devices in between.

...and we haven't even opened the gear ratio can of worms depending on WHICH track!

When GM first started using an LS type rear end on their cars (70's I believe) law suits followed almost immediatly. People weren't used to the 'back end' coming around on them. It's much easier for that to happen with an LS type rear. Of course the benefit is greater traction under a wider variety of conditions.

[ROUSHAC]

Excaliber,

Well said, and much more briefly than me.

Cheers!
Dave

[cobrak]

Other then Backdrafts, don't most Cobras have LS. Be it in a Jag IRS, 8.8 or 9.0 rear?

CobraK