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_

[XRchic]

Thanks Chris, good advice. Ill bear that in mind with my new LSD!

[Redrum]

Thanks Chris, another thing to file away for day at Heathcote soon. So much too learn.

[XRQTOR]

NO donuts, yea right where the fun in that.

[ClassicAU]

Thats some great advice Chris, great of you to enlighten us all! Ripping a big smoky is so much fun, but also so expensive as well! I must admit upgrading to a LSD took me a bit of getting used to, especially in the wet. But as you said, they are designed for safety. Great write up!

Evan

[naughts]

I put M/T steet E/T's behind by XBGT with LSD.
2 burnouts and up for new clutches. Tyres got sticky, One more than the other.
Started to single spin and glazed the clutch pack.
Lesson learn't.
I had no real trouble with normal radials, but the switch to some sticky tyres cost me.

[SPK-250]

My missus broke my Borg Warner LSD at the drags and the axle. She left the hole and "Happy Wheeled" and when she hit 2nd the passenger side tried to slip but the VHT would'nt let it and it ripped my clutches to peices and broke an axle. But it is all good and tight now, almost locker style without the corner skidding.

[RG]

Thanks for that info, very valuable with the drag day coming up.

[Jason[98.EL]]

Originally Posted by 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_

absolutly brilliant information

just a quick question though

what about the people with single spinners

if we get both spinning and heaps of tyre smoke are we doing damage to our diff as well

jason

[needfordspeed]

Cheers for the info, i'm sure it'll save alot of people money down the track!

[bigAl]

Thats some great information there Chris, as i have been one of those racers with little experience doing the burn incorrectly :(

Thankyou for sharing that with us, i will put the new information into practice next time im at the strip.

[GT595]

First hand on what you were on about Chris......

Just had the Diff rebuilt today - the LSD was fubar'ed as the cluch plates were fried - $2800 big ones (with 4.10 replacement included )......so not too bad for complete new internals.... from Craig - Southern Diffs - good bloke....

Atleast it is done now and will have enough driven k's to smoke them at Heathcote once again........ (making sure I get off the throttle prior the dry stuff of course.....)

Cheers
Damo

[GRNKPR]

sorry lost ya when ya mentioned the pretty girls

[T3rminator]

I have a manual and found that when I do a small burnout the car will inevitably move forward slightly or sideways. I have not tried heel and toe (keeping one foot on the break). Its something i want to try next time but just trying to get the technique right is pretty difficult. Is this the best way to do a burnout whilst keeping the car stationary for manual? Are there any other methods?

Usually when i start to loose the backend i stop my burnout....this can be within 3-5 seconds.

[XRQTOR]

Originally Posted by fullthrottle

I have a manual and found that when I do a small burnout the car will inevitably move forward slightly or sideways. I have not tried heel and toe (keeping one foot on the break). Its something i want to try next time but just trying to get the technique right is pretty difficult. Is this the best way to do a burnout whilst keeping the car stationary for manual? Are there any other methods?

Usually when i start to loose the backend i stop my burnout....this can be within 3-5 seconds.

Yep thats the way for a big burnout.

[philstoj]

Originally Posted by fullthrottle

I have a manual and found that when I do a small burnout the car will inevitably move forward slightly or sideways. I have not tried heel and toe (keeping one foot on the break). Its something i want to try next time but just trying to get the technique right is pretty difficult. Is this the best way to do a burnout whilst keeping the car stationary for manual? Are there any other methods?

Usually when i start to loose the backend i stop my burnout....this can be within 3-5 seconds.

Its no different than doing a brakey with an auto, but you have to drop the clutch to get it to start.

Thats how i do it, though i use second gear for burnouts, about 3500 rpm, drop the clutch, foot on brake and hold revs to 3500 at least till they start smoking up, then off with the brake and let it come out of the burnout.

[T3rminator]

brake with left or right?

(Obviously I'm not a hoon)

[XRQTOR]

Originally Posted by fullthrottle

brake with left or right?

(Obviously I'm not a hoon)

i'd use your left cause the right should be on the gas.

[T3rminator]

lol. Sorry that came out wrong. The reason I ask about the right is because thats what the heel and toe technique woudl use. But dam difficult to master for a newbee like me.

[philstoj]

Originally Posted by fullthrottle

brake with left or right?

(Obviously I'm not a hoon)

LOL mate, what are you implying?

[XRQTOR]

Originally Posted by philstoj

Its no different than doing a brakey with an auto, but you have to drop the clutch to get it to start.

Thats how i do it, though i use second gear for burnouts, about 3500 rpm, drop the clutch, foot on brake and hold revs to 3500 at least till they start smoking up, then off with the brake and let it come out of the burnout.

If i cruise up to about 35oorpm in 2nd and stand on it it'll spin then slowly bring on the brakes, with brand rubber it wont work but after about 2oook's it'll do it every time. I used to love doing it, the look on peoples faces when your cruising along at 6o odd k's and stand on it with the car billowing massive amounts of tire smoke. WIthout getting on the brakes the car would want to acc to quickly and just doesnt have the same effect.

[philstoj]

Originally Posted by XRQTOR

If i cruise up to about 35oorpm in 2nd and stand on it it'll spin then slowly bring on the brakes, with brand rubber it wont work but after about 2oook's it'll do it every time. I used to love doing it, the look on peoples faces when your cruising along at 6o odd k's and stand on it with the car billowing massive amounts of tire smoke. WIthout getting on the brakes the car would want to acc to quickly and just doesnt have the same effect.

LOL, mine wont do that, its only a 5L, and hasnt got a supercharger on it hahahaha, though in the wet, its a different story :

[XRQTOR]

Originally Posted by philstoj

LOL, mine wont do that, its only a 5L, and hasnt got a supercharger on it hahahaha, though in the wet, its a different story :

Oh yea, well about 3ooorpm used to be enough in my EF xr8.

[philstoj]

Originally Posted by XRQTOR

Oh yea, well about 3ooorpm used to be enough in my EF xr8.

In 4th at 100kph in the wet hahahahaha, of course at a racetrack.

[Craig]

Originally Posted by fullthrottle

I have a manual and found that when I do a small burnout the car will inevitably move forward slightly or sideways. I have not tried heel and toe (keeping one foot on the break). Its something i want to try next time but just trying to get the technique right is pretty difficult. Is this the best way to do a burnout whilst keeping the car stationary for manual? Are there any other methods?

Usually when i start to loose the backend i stop my burnout....this can be within 3-5 seconds.

Manuals are easier to do burnouts IMO, have the car in 2nd gear, rev it up to around 3 - 4000 rpm, drop the clutch, the wheels will spin and then move you left foot over to the brake pedal, then it's very very important in a manual to either watch your speedo or angle your mirrors at the back wheels to make sure that the tyres are turning, too many people THINK they are doing a burnout but are in fact just sitting there spinning there clutch.

Once the tyres are spinning nicely and your not over revving release your left foot and slowly move forward to get out of the wet stuff and try to leave 2 nice rubber marks on the race track.

If the car moves sideways don't be too concerned just keep it under control with your steering wheel.

Cheers Craig

[Stevo]

Good right up chris!

[outback_ute]

Originally Posted by Craig@ACE

too many people THINK they are doing a burnout but are in fact just sitting there spinning there clutch.

Eg the bloke in the BA GT at Deca... ended badly

[mcflux]

Excellent writeup!

brake with left or right?

Just remember that you tend to use your left foot a lot heavier on the padels than the right. You may be surprised the first time you use your left foot on the brake padel instead of the clutch. I'd advise against left-foot-braking in traffic because the person behind you may run into your toll bar ;)

[Pursuit250]

Originally Posted by Craig@ACE

Manuals are easier to do burnouts IMO, have the car in 2nd gear, rev it up to around 3 - 4000 rpm, drop the clutch, the wheels will spin and then move you left foot over to the brake pedal, then it's very very important in a manual to either watch your speedo or angle your mirrors at the back wheels to make sure that the tyres are turning, too many people THINK they are doing a burnout but are in fact just sitting there spinning there clutch.

Once the tyres are spinning nicely and your not over revving release your left foot and slowly move forward to get out of the wet stuff and try to leave 2 nice rubber marks on the race track.

I need to do some serious practice this weekend because from what guys are telling me my feet will be dancing all over the place. I think I'm best just getting to the line. I'm likely to apply too much brake and stall it in the wet patch (and no one likes being left in the wet patch ).

[Craig]

Originally Posted by outback_ute

Eg the bloke in the BA GT at Deca... ended badly

Yes that's a classic example.

For those that don't know a chap let his mate have a spin at DECA and thought he was cool spinning the wheels but was in fact spinning the c r a p out of his clutch.....the result a clutch that exploded and took just about everything out in the clutch area and some, around $15K damage, gearbox, engine block (it blew off half the block at the back), starter motor, exhaust, some wiring, 1 x side skirt and a few other things i can't remember.

All in all a VERY expensive lesson.

Even when watching drag racing you will never see me anywhere near the clutch area in the burnout area or when the car is launching, it's very dangerous.