DRAG BURNOUTS & LSD'S*a must read*

[Bluepower]

I have seen in many occassions during AFF drag days and regular street meets that people are really getting into the sport of drag racing with their streeters and enjoying themselves.

This is awesome - but I have a handy tip for the "street" cars that are equipped with modern LSD differentials.

Ever seen the guy at the drags with the LSD differential, but then you see it "singling out" (i.e only one wheel smoking).

THIS IS DESTROYING THE LSD UNIT, POTENTIALLY COSTING YOU $$$$!!

A limited slip differential is just that - limited slip. It is designed for driver comfort and control when applying differential (a turn, which will by nature of physics cause the INSIDE wheel to make fewer turns than the outside wheel.)

The slip inside the LSD is featured by a set of wave washers in the Dana M86 as fitted to all B series FPV, V8 and T6 applications, and tapered friction cones 80 series Borg warner style unit in the NA BA6 and AU and earlier series.

The LSD is only designed to be "working" on a turn as stated above - so here is why a big long burnout or "donuts" are no good.

Scenario 1 - You are in the water, ripping it up, your mates are watching, your blood is pumping, there are at least 4-20 gorgeous girls watching, you are feeling at least ten feet tall.

So you get em nice and hot, and decide to move forward into the dry stuff.

WELL,


what is about to happen is this - whilst both wheels may be spinning freely, the moment the car meets"dry land", ONE wheel usually hits the dry stuff first, followed by the other, which may still be in the water.

Usually, 9 times out of 10 and depending upon car weight and power, the wheel in the DRY has to make a bigger effort to turn. If that effort cannot be sustained, the wheel will lock and stop (the start of the one wheel burnout) and ALL the power will be diverted to the wheel that is enjoying less friction.

Meaning, a cone or clutch inside the LSD unit can go from 0 rpm to 4-8000rpm in an instant, creating heat that will permanently damage an LSD.

Ok - i hear you guys piping up "my mate has an LSD and such and such re-built it and tightened it up, and it limo's fine, etc etc."

They can continually work - but the shock load can "peen" the cones in an 80 series Borg warner unit, and will unload the concave preload on a DanaM86 wave washer in a B series.

Either way, it is wearing out your LSD prematurely. Sooner or later, your "mate" will be up for some $$$. Seeing the diff man for an LSD repair is like seeing the Tax man. You dont WANT to do it, but if you want smooth sailing, you HAVE to do it!

Now, im happy to rebuild diffs as long as guys break them - but in this day and age is is important to get the most from your dollar.

How do i do a burnout? well, its no longer called a burnout, the new word is simply a "BURN".

1 - pull into the water evenly, i.e both wheels in same amount of water - the guy at the startling normally does a pretty good job of this, and will wave you out and back in if you have fudged it.

2 - light it up, but keep the car in the water, burn the tyres until you see smoke, and slowly creep forward.

BUT

from this point, if the car is equipped with a spool, throw your foot down hard and do a "power" burn, (spools are not legal for road use)

If it has an LSD, pull most of the throttle back, let the car go forward to dryness then LIFT.

If the car wants to go sideways in the burn, get off it - if a wheel grabs dry, you will be in big diff trouble one day............better to save it then doing a one wheel hero burn, which should sound like the sound of a cash register ringing the bells.......

I hope this helps you guys - building all our own Diffs and LSD's in house and racing them has taught us this valuable info - hope it can help you guys.

See you at the track! :eclipsee_