Manual trans guys -- tips for launching?

[Jim_PA]

I'm all ready for Friday night, got my line lock installed, lots of tuning, and fixed an ignition problem.

How are you launching?

I'm planning to get to the line, set the lock, bring it to about 3500 RPM or so, and keep it about there until I see the lights start going...

Once the lights move, I'll bring the clutch out a bit until I feel it grab, -- let the line lock go, relase the clutch, and floor the bastard at the same time? Then I suppose I'll just keep it floored, and flat shift the whole way through 4th. Seems to be faster that way.

How do you do it? Any tips?

[swb85]

Gonna take lots of trial/error to see what your combo likes. I don't like the idea of using the line lock at the line and riding the clutch, you're gonna put a bunch of heat in it that way. What clutch do you have? Certain disc materials are forgiving enough to slip like that and some aren't. I've got a single disc 6 puck in my camaro and if I slip it I'll kill it, so my launches go like:

-line lock, 2nd gear burnout for 4-count, release lock and roll out till it grabs
-stage
-bring rpm to 7000
-when last amber lights, sidestep clutch & mash gas
-right foot doesn't move till the win light comes on

To get your best 60ft with 3 pedals, you can't dead hook or it'll bog. Something's gotta slip, either the clutch or the tires. I like to get 2-3 revolutions of the tires off the line. Takes lots of playing with suspension and tire pressure to make it happen. To be the most consistent, a two step rev limiter is a good idea (I'm getting one next season). Good luck!

EDIT: Here's an in-car vid of the passes I made last week

HPT 10-1-09 video by jmm98ls1 - Photobucket

[Jim_PA]

Originally Posted by swb85

Gonna take lots of trial/error to see what your combo likes. I don't like the idea of using the line lock at the line and riding the clutch, you're gonna put a bunch of heat in it that way. What clutch do you have? Certain disc materials are forgiving enough to slip like that and some aren't. I've got a single disc 6 puck in my camaro and if I slip it I'll kill it, so my launches go like:

-line lock, 2nd gear burnout for 4-count, release lock and roll out till it grabs
-stage
-bring rpm to 7000
-when last amber lights, sidestep clutch & mash gas
-right foot doesn't move till the win light comes on

Well, I wasn't really planning on riding the clutch for an extended period of time, I was just going to hold around 3500, and let it out until I felt it was engaging (just to pre-load the drivetrain), then let go of the linelock, and drop the hammer. I've been told you'll find the weakest link in your drivetrain by dumping the clutch on an un-loaded drivetrain, and I don't feel lucky enough to do that with the mostly stock components in mine.

The clutch is a Zoom stock upgrade type... I think it's organic, and advertises 30-40% more holding power, or something to that effect. I'm running 26x9 hoosier slicks, I was going to start the pressure at 25, and drop it from there if it spins.

Originally Posted by swb85

To get your best 60ft with 3 pedals, you can't dead hook or it'll bog. Something's gotta slip, either the clutch or the tires. I like to get 2-3 revolutions of the tires off the line. Takes lots of playing with suspension and tire pressure to make it happen. To be the most consistent, a two step rev limiter is a good idea (I'm getting one next season). Good luck!

The clutch did slip a little bit last time at the track. Either the clutch slipped or I spun the tires on the wheels a little bit, but I have a feeling it was clutch slippage. Yeah, I don't think I'll get to the point of a 2-step, but I do have a single step rev limiter anyway...

Originally Posted by swb85

EDIT: Here's an in-car vid of the passes I made last week

HPT 10-1-09 video by jmm98ls1 - Photobucket

I'll be anxious to see that, can't seem to get it here...

[hotrod 80]

HPT 10-1-09 video by jmm98ls1 - Photobucket

[/QUOTE]

Wow , tell me that things got a 9" in it .

[Wild83C10]

Originally Posted by swb85

, you can't dead hook or it'll bog. Something's gotta slip, either the clutch or the tires.

Yeah something better slip or something will break. But like you said, trial and error, if you really want to cut your best times you need to get plenty of track time.

What do you have done to the tranny? I'm trying to figure out what to do to beef up my TKO.

[Jim_PA]

Originally Posted by Wild83C10

Yeah something better slip or something will break. But like you said, trial and error, if you really want to cut your best times you need to get plenty of track time.

What do you have done to the tranny? I'm trying to figure out what to do to beef up my TKO.

Stock super T-10, re-built it myself

But I'll assume you were talking to the other guy

[swb85]

Originally Posted by hotrod 80

Wow , tell me that things got a 9" in it .

lol, moser 9" w/35 spline axles, detroit locker & richmond 4.33's. You'd need a big magnet to pick up all the 10 bolt after one launch like that.

Originally Posted by Wild83C10

Yeah something better slip or something will break. But like you said, trial and error, if you really want to cut your best times you need to get plenty of track time.

What do you have done to the tranny? I'm trying to figure out what to do to beef up my TKO.

I built the trans with carbon blocker rings, steel 3/4 fork, billet synchro keys, bronze fork pads throughout. Pretty much every upgrade part available from tremec minus the viper main shaft.

[wheatlandbrawler]

depends on what your stuff can handle, does the truck have enough suspension to handle a 3,500 launch? but other then that its just a slew of test and tunes till you get it dialed in. no body can tell you how to drive your own truck.

[Jim_PA]

Originally Posted by wheatlandbrawler

depends on what your stuff can handle, does the truck have enough suspension to handle a 3,500 launch? but other then that its just a slew of test and tunes till you get it dialed in. no body can tell you how to drive your own truck.

I wasn't really looking for how to drive, just some general tips for launching with a manual trans.

3000 - 3500 launches seemed to work well last time. A little slippage somewhere, but I was happy something was giving a little, and it wasn't my driveshaft, rear, or trans

[wheatlandbrawler]

Originally Posted by Jim_PA

I wasn't really looking for how to drive, just some general tips for launching with a manual trans.

3000 - 3500 launches seemed to work well last time. A little slippage somewhere, but I was happy something was giving a little, and it wasn't my driveshaft, rear, or trans

haha sorry about that prolly wasnt rite choice of words, i also run a manual trans i just put a richmond 5 speed in my truck. i have quite a bit of suspension work, a 9'' and spool and 33 spline axles and on hoosiers i cant get it to hook at 3,500 when i race i hit the box hit the line lock pop the clutch at 4grand and feather it 5 times and roll out. and i launch at 3grand in second.

BTW RICHMOND 5 SPEEDS ARE A HUGE WASTE OF MONEY. for the same price i could have went with a t56 or a 4l80e.

[wheatlandbrawler]

oh hey SWB, that video was nutz we live an hour away from each other ... a little more we should meet up and go Cruise before the winter really starts to HIT.

[CreditGod]

1. Tire pressure is one thing it lets the torque give for a fraction of a second so that your tires don't spin try 12-15psi

2. Summit racing has a product called slide-a-link this is an awesome bolt on works like a four link with a pan hard bar

3. Side step it meaning rap the rpms up and with half your foot on the clutch when you are ready to launch let the clutch pedal slip out from under your foot it should happen in about 1/1000 of a second. But if you don't have a good rear end and a scatter shield this will break stuff.

[BossHogg69]

Originally Posted by wheatlandbrawler

BTW RICHMOND 5 SPEEDS ARE A HUGE WASTE OF MONEY. for the same price i could have went with a t56 or a 4l80e.

I hate to hear that, since they're expensive - that's a lot of money to spend and not be happy. what do you not like about it?

[Wild83C10]

Originally Posted by CreditGod

2. Summit racing has a product called slide-a-link this is an awesome bolt on works like a four link with a pan hard bar

I doubt he has leaf springs and he would be better off with the caltracs.

[Jim_PA]

Just saw the video. I don't even want to know how many parts would fly if I attempted that.

[BossHogg69]

Originally Posted by Jim_PA

Just saw the video. I don't even want to know how many parts would fly if I attempted that.

Yeah, those 7k rpm clutch drops made my jaw drop!

Wild83C10 - you must be about to 'pour the coals' to that TKO if you're worried about breaking that bad boy!

[Wild83C10]

Originally Posted by BossHogg69

Wild83C10 - you must be about to 'pour the coals' to that TKO if you're worried about breaking that bad boy!

I am, 383 with a turbo. Should be fun. Although I wont be running it out to 7k like I do know. The trans has been fine so far, but it doesn't like those 7k shifts too much.

[Jim_PA]

Well, no better times. Best was a 14.3

Still couldn't blast off a sub 2.0 60' time. Gearing and weight seem to be my worst enemy. Then again ... another 75 HP or so wouldn't hurt.

[383Ram]

Wow, thats all you can get from that combo? Something seems terribly wrong there. I would say at least a mid-high 13 from that setup. Can you post up the time incrimentals from the slip? I would think your gearing is fine, obviously weight can be an issue. How much gas are you carrying on board during a run? remeber that weighs 7lbs per gallon. 14 gallons and your already at 98 lbs.

Anyways, like was said above, you need wheel speed,, you need the wheel to try and turn ever so slightly--almost breaking loose but not quite. So traction is going to play a big part here. When i had a stick setup with caltracs, i learned alot from John Calvert (maker of caltracs). When you launch, keep your foot on the pedal but basically let the clutch push your foot up. This way its not a true sidestep which is hard on parts, but its still enough to shock the tires to get a little spin. Obviously you need good tires too.

Also,, i am a firm believer in preloading the rear as you stated. I did it this way. Did burnout, power out of it to the line. Ever so slightly add some brake pressure to the line lock again to add some drag and let the clutch out to bump the car into the stage and prestage. This does two things. It keeps the car from rolling and preloads the drivetrain enough to set the bulbs. As soon as you get it the lights, get your launch rpm on and launch.

I used to launch at 4500-5000 in a car--the truck is unknown at this point. I ran Hoosier QTP at 22psi. It would wrinkle the tires real nice and go 1.72 60ft. I broke parts---lots of them during this time as i figured all this out. I twisted housings (8 3/4 mopar), broke gears, clutches, transmission gears and axles. In the end i learned a couple of things--build a BEEFY rear---i ended up with a Dana 60. If you run soft tires on the street, a spool is fine--if not, a locker is the way to go. Big axles such as 35 spline are probably what your going to need. A centerforce DF is not the best of choices, i'd rather have a cheap disc and the DF hat to get some slippage if i had to use that stuff.

I hope some of this helps.

[383Ram]

I know i just made mention of some big dollar parts, what i am trying to say that i know wasn't clear, is that you have to fine the balance in your setup---yea, this may lead to some parts breaking. Its really a fine line. I dont know where you race, but if you can take a day off from work for a test and tune where you can get in a good 6-10 runs, this is what you need. At our track here, your lucky to get two or three on a normal weekend test and tune.

I would be more interested in hearing the entire combination of the truck so we can maybe help you on your budget.

[Jim_PA]

I will give you a detailed run-down...

Stock body 68 C10 long bed. I think it weighed in at 4450 with me in it.

Stock cooling system, 5 blade clutch fan.

355 ci stock bottom end and rods (balanced), hyperutonic(sp?) pistons, 4 valve reliefs, 9.9:1 static compression ratio.

Cam is a Comp Cams Magnum 270H

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,800-5,800
Intake Duration at 050 inch Lift 224
Exhaust Duration at 050 inch Lift 224
Duration at 050 inch Lift 224 int./224 exh.
Advertised Intake Duration 270
Advertised Exhaust Duration 270
Advertised Duration 270 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.470 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.470 in.
Valve Lift with Factory Rocker Arm Ratio 0.470 int./0.470 exh. lift
Lobe Separation (degrees) 110

Comp Pro Magnum Roller Rockers 1.52 ratio

Heads are Edelbrock Performer RPM #60899

185cc Intake Ports
64cc Combustion Chambers
2.020''/1.600'' Valves
1.460'' Valve Springs, .575'' Max Lift

Thorley Tri-Y headers, full 2.5" mandrel bent Magnaflow header back kit with X-pipe.

MSD Digitial E-curve distributor, running 16 deg initial advance, 20 deg mechanical 36 degrees all in at 3,000 RPM. (also running 10 deg vacuum advance but of course that doesn't matter...)

MSD blaster 2 and 8.5MM wires

Performer RPM Q-Jet intake

Custom tuned 800 CFM Q-jet. AFR all the way down the track was right in the 12.8 - 13.2 range. There were no apparent carburetion issues. Secondaries are able to open to a full 90deg within 2 seconds (I can't imagine there is much more I can do with the carb. It seems pretty much perfect...)

Stock '71 12 bolt 3:73 rear with a early-mid 60's posi unit (no problems with the posi...)

78 Super T-10 trans, Ratio: 2.64, 1.75, 1.33, 1.00

Stock 2-piece driveshaft

26X9 Hoosier Slicks (I was running them at 20 PSI)

I had zero traction issues off the line. I tried dumping the clutch around 3500. End result was the truck falling on it's face, then surging. Best feel off the line was fast clutch release while mashing the throttle, but still, something is missing, as 60' times were right in the high 2.1x range in 5 runs.

Here's my best 1/4 E.T. timeslip of the night ( I couldn't care any less about R/T... I was focusing on getting this pig off the line, but I couldn't seem to do that either )

Cecil County Dragway:

R/T .641
60' 2.161
330 5.979
1/8 9.174
MPH 76.57
1000 11.968
1/4 14.384
MPH 92.88

All my trap speeds were high 92's to 94.

At the end of the track, I was just getting out of 3rd gear. I wasn't lifting off the throttle to shift either. Just tapping the clutch and rowing through the gears. I was shifting right around 58-5900 RPM.

What's troubling to me is that 3 years ago, when I was running Hooker competition full length headers and 2.5" exhaust with no X-pipe, and almost no other changes, my best MPH was 98. I am starting to believe that the Thorley Tri-Y's took away 3-4MPH.

I'm seriously considering going back to full-length headers and maybe going to a larger cam from Lunati.

I'm completely open to ideas, but I truly believe the truck isn't going to get any better without some changes. The truck is running great, and it's a blast to drive around, so part of me says just enjoy it the way it is... the devil on my shoulder tells me to make some changes.

[PhilaTruck]

Originally Posted by Jim_PA

Thorley Tri-Y headers, full 2.5" mandrel bent Magnaflow header back kit with X-pipe.

Just saw a post linking a CHP article by Lemon Headers. Page 3 talks about Tri-Ys and how finicky they can be. I dunno if he's just blowing smoke, but you're times may be telling.

[Jim_PA]

Tell me what you think about swapping to this cam:

http://www.lunatipower.com/Product.aspx?id=2326&gid=297

Is it worth it?

[383Ram]

with that cam, you basically moving the power band range up. I dont think i'd use that cam. I didnt realize your truck is as heavy as i thought either.

The combination looks good, after looking over it all, your really not that far off on the 60' times. Your e.ts throughout are a just slightly low, but it is MPH good which means its making power. As you guess the 60' is whats holding you back (although with that much weight in the truck i don't think its going to go too much faster).

I guess my next question is what do you really want to do with the truck. More race or more street. What realistic percentages of each would you say. Also, do you have an idea in your head of a realistic track time if that is what your after?

As far as getting back to the 60ft deal, if it bogs at 3500, i say launch higher---but you better make sure the rest of the driveline can handle it. Alternativly, maybe try and raise the tire pressure some, to try and get a touch of wheel spin---thus creating wheel speed right off the line. This is a very fine line to maintain. Or you can try and slipping the clutch a bit off the line at 3500 or higher rpm rather than dumping it. Unfortunatly it is just a trial and error thing, but for the MPH your running, your probably only going to best a 60' in the mid to high 1.90's.

Let me know your thoughts.

Also, if it was my truck, all i would change is making it a 383, and keeping it everything else---excpt the Q-jet, but i am a holley guy myself. Torque is king,, your going to need some to move 2+ tons.

[Jim_PA]

Originally Posted by 383Ram

I guess my next question is what do you really want to do with the truck. More race or more street. What realistic percentages of each would you say. Also, do you have an idea in your head of a realistic track time if that is what your after?

It's a toy. I drive it mainly on the street, and it does run great for what I do with it. But of course there's always that bug that gets to me about my buddy with the 83 SWB stepside with a 290 horse GM crate that ran a 13.9 the same night my best was a 14.3.... But his is fully prepped with 4:56 gears, fuell cell, and probably weighs 800lbs or so less than mine. I go to the track maybe twice a year. I think his best 60' was a 1.9.

I think if I got this truck consistently in the high 13's, I would be satisfied. This is really all about keeping up with the Jones', and if I get myself into the 13's, he'll probably add spray, and go into the low 13's... but that's just the way these things work


I am gathering parts for a frame-up build of a 68 SWB truck, and who knows what kind of powerplant I'll dream up for it. That project is so far out that I don't think I can stay content with this one for that long

Originally Posted by 383Ram

Also, if it was my truck, all i would change is making it a 383, and keeping it everything else---excpt the Q-jet, but i am a holley guy myself. Torque is king,, your going to need some to move 2+ tons.

The 383 is water under the bridge with this one. I agree, I would be better off with it, but I'm not going to put that kind of $$$ into this, especially since the engine has maybe 10,000 miles on it since it was built.

The Qjet will stay. Once I got my head around tuning it, I really can't imagine any carb would make it run as good, and be as responsive as this one.

If the cam swap is a bad idea, I think I'll start saving the pennies for a TKO-500. It would give me a better 1st gear for the launch ( I think first is somewhere around 3.27.) And it would give me the overdrive I could really use for my street driving.