[400 plus]

Maybe I caused my 400 turbo tranny problem. What is the best way to do an automatic tranny burn out???

[redsmokin76]

Start in second gear and up shift as soon as you can, drive out of water area and ease off throttle as tires hook up. No first gear burnouts especially in th350, and don't plant your foot as tires hook and load as you drive out. Top gear burnouts are the safest if you have enough power to start off in top with, and try to stay of the limiter hard. Well that's what I do and been told by others there may be other techniques out there as well.
Cheers Steve

[screamingchief]

That ^^^^ x2.

Or if the car does'nt have enough power to do 'em that way,keep it really short and stay in low gear and dont upshift @ all.

Best: High gear only.
Better: Second quickly into high gear.
Acceptable: Low gear only.

As stated,always ease up as you're coming outta the burnout,never let it "hook" after the burnout while it's still under full power,as I've heard that's really hard on the stator in the converter.

Also,dont pedal the car in second gear if you can avoid it,that's really hard on the int. sprag.

That's also why no 1-2 shifts during the burnout,that too kills the int. sprag.

FWIW

Bret P.

[6TEE8GTO]

Unless you have a manual valve body, how can you start in "high" gear? You can't force the trans into high from a dead stop without a manual valve body.

[screamingchief]

There are modifications that can be made to an auto shift valvebody that allows full manual control when it's in the manual detents.

Most hi-perf valvebody re-program kits include such,and it's also pretty easy to DIY too.

The caveat is that you have to be careful when downshifting,as it works both ways,and downshifting into a lower range while @ higher speeds can be a dicey proposition.

But anyone with a lick of common sense should know such and act accordingly and not throw it into manual low @ 80-100 MPH.

Bret P.

[6TEE8GTO]

Originally Posted by screamingchief

There are modifications that can be made to an auto shift valvebody that allows full manual control when it's in the manual detents.

I get that, but.... On a auto-shift valve body, "D" is the same manual detent as "third" or "high", so how would you be able to still have full automatic operation if you can place the shifter in the D position from a dead stop and be staring in third/high gear?

You have to have a manual valve body to be able to start out in third. I must be missing something here...

[tc]

I do not have a manual valve body, I place the shifter in D. I'm sure the trans starts out in 1st doing the burnout, but have been told the trans will upshift by itself during the burnout.

I give about 1/2 throttle ( maybe more ) to get the rpm's up to 5000. That lasts about 1 second and then the rpm's drop to 3500-4000 for the next 2 seconds. I usually give it more throttle when the rpm's drop to 3500 to keep it at 4000. Then I let off the brake ( homemade line lock ) and ease off the throttle for a full second as the car moves forward. The tire are still spinning for most of that that full second.

The idea is not have the tires hook at the end of the burnout while you have a bunch of throttle ( rpm's )in the engine ( what I have been told ). This is with street DOT tires. My friend with slicks, has the rpms go up after the line lock is released, but the tires do not grab at the end of his roll out.

[screamingchief]

Originally Posted by 6TEE8GTO

I get that, but.... On a auto-shift valve body, "D" is the same manual detent as "third" or "high", so how would you be able to still have full automatic operation if you can place the shifter in the D position from a dead stop and be staring in third/high gear?

You have to have a manual valve body to be able to start out in third. I must be missing something here...

Yeah true,I thought you were talking about doing the 2-3 burnouts.

I was in a hurry to log off and I guess I misinterpreted your initial question,my bad.



Bret P.

[screamingchief]

Oh yeah,BTW,you'll need the manual control mods to effectively "hold" it in low gear too,that is if one opts to go that route,otherwise an unmodified trans can do what's called a "forced upshift" during a low gear only burnout.

But yeah,high gear only is typically a full manual VB deal.

As I said earlier,the whole concept is to avoid any & all 1-2 shifts during the burnout,how one chooses to achieve that goal varies,but the goal remains the same regardless.

HTH

Bret P.

[lust4speed]

A short 1-2 up-shift during the initial burnout isn't going to be putting very much stress on the trans at all - probably much less than the 1-2 shift going down the track. A question might be whether there is more stress on the trans by starting in 1st and shifting to 2nd, or if the initial hit to break the tires loose in 2nd isn't really shortening the trans life more.

[redsmokin76]

With a line lock and in the water, even a lower horsepower car should be able to do a skid in second gear, and if it can't then you probably shouldn't be concerned about hurting the tranny.
Cheers Steve

[screamingchief]

Originally Posted by lust4speed

A short 1-2 up-shift during the initial burnout isn't going to be putting very much stress on the trans at all - probably much less than the 1-2 shift going down the track. A question might be whether there is more stress on the trans by starting in 1st and shifting to 2nd, or if the initial hit to break the tires loose in 2nd isn't really shortening the trans life more.

Problem is,during a burnout,the trans is'nt loaded all that consistently/evenly,especially during any shifts,and that's what kills the int. sprag,pretty much the same deal with pedaling the car in second gear,that on-off-on uneven loading basically hammers the int. sprag race(s) eventually wearing/brinnelling them via higher than intended shock loads,and then the sprag assy. as a whole is prone to fail.

Shifts are never instantaneous,there is always a time component involved between one gear disengaging and the next gear engaging,in the trans business lingo that's called the shift "overlap" timing,it's that millisecond where all the trouble arises as it relates to a 1-2 shift during burnouts.

Plain & simple,a whole lotta guys have learned this deal the hard way,once they know to avoid the 1-2 shifts during burnout (and avoid pedaling it in 2nd gear),soon as they do that,they find that the trans seems to live significantly longer.

In doing the 2-3 burnout deal,the goal is to shift into high gear almost immediately after the tires start spinning,ie: get it into high gear ASAP,and by starting it in second gear (assuming it's done properly) the sprag should pretty much be loaded as evenly as it possibly can be.

The trans should be shifted into second gear back in the staging lanes before pulling into the waterbox,so the sprag has a chance to be evenly loaded before initiating the burnout.

Only way the "initial hit" would affect that deal (starting in 2nd for a 2-3 burnout) would be if the driver somehow hesitated or lifted during that split second.

And remember,an engine is typically making less HP/TRQ during said initial "hit" as opposed to how much HP/TRQ it'll be making at the higher RPM when any shifts are occuring during the burnout.

The primary difference is this: One cant avoid the 1-2 shift during their run,but they can avoid doing a 1-2 shift during the burnout.

Bret P.

[400 plus]

I have no manual VB and yeah I figured my spending to much time in second gear screwed up my tranny! Will have it rebuilt Monday tho.

[SWEETJUDGE]

line lock with a rev limiter.... consistentcy is the name of the game.

[Region Warrior]

How much power and size tires 400 Plus?

No manual v/b here either with Hoosier L50-16's QPT's(to big for mine actually).
Before a rev limiter, i'd leave it drive, go about 1/2 throttle and let it roll out and let off same time after see'n smoke in mirror.
With todays tires, no need for a John Force deal unless you have mega power and steam rollers.

[Region Warrior]

Screamingchief, sent a pm.
No hurry on reply.
Thanks.

[400 plus]

625 HP with either a 28/9/15 MT slicks or 275/60/15 MT drag radials and I do have a Digital 6 MSD box set at 6400