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Mike S · 02-04-2008, 08:53 PM

I was wondering if anyone is useing a linkage throttle stop for launching their car on a trans brake. I tried the 2-step, but learned my lesson with 2-step and low rpm. I am leaning to that as the cause of me cracking my block at the main cap threads. I am thinking of useing the throttle stop to hold rpms while on the trans brake. Wanted to see if anyone has done this here. Here is a question for you, If you are alowed a trans brake and 2-step but no electronics would you be alowed a throttle stop with no electronic (just for launching)? Another question for anyone useing this method, how fast do they open? Will they open fast enough for a .500 pro tree?
thanks Mike

FBNRacing · 02-04-2008, 09:40 PM

Mike why do you blame the 2 step for busting the block?

Rex

Mike S · 02-04-2008, 10:17 PM

Engine was fine. Put the trans brake and 2 step on over the winter. Tried it out in the driveway a few times and made 5 passes at the track. Found copper in the oil filter. When I took engine apart found the block cracked all the way down the bolt hole on no. 2 main (studded 2 bolt). Foreced bearing into the crank. I was talking to a couple racers and they both said low rpm on the 2-step (under 3000) puts a lot of load and vibration into the crank that would stess the block and caps. I figured they where right after all you are holding a 1050 holly wide open for 3000 rpms. made sence to me after all this is my first encounter with a brake and 2-step. I do have studded 4 bolt mains now.
Just to clarifie for those who know me. That was 2 years ago. I am finally getting the engine back together.
Mike

FBNRacing · 02-05-2008, 12:41 AM

Mike, they work ok for what you want to do but not that good at a throttle stop. Mostly its when people try to open them slowly they find inconsistanceys. itallian Stallion (member of this board) had a couple he was trying to sell.

Rex

grnmnstr · 02-05-2008, 02:28 AM

Mike,

I have always used the starting line enhancer that Biondo sells. After this disengages, it goes on the 2 step for one amber. It is very consistent.

I agree that that the 2 step is not very good for the bottom end. The SLE minimizes the amount of time the motor is on the 2 step.

Go to Biondo's website. It explains how it works.

fasteddy · 02-05-2008, 10:52 AM

The use of a throttle stop is not legal in some clases. It does not matter what you use it for. I believe that any mechanical device for the purpose of launching may be not legal? Not sure on this. TIKI?

Dave Polichena · 02-05-2008, 01:37 PM

When I'm in bracket mode i just mat it when the tree starts coming down.

mikejub · 02-05-2008, 03:06 PM

Is this a problem unique to a trans brake applicaton? Just wired a 2-Step into my line lock button on a 4-spd car. Expecting to launch 3000 to 4000 rpm. But Mike S experience has me a little concerned.

Kelvin Poe · 02-05-2008, 03:45 PM

I've been running a set-up like this for years on a studded 2-bolt main 455 block with no problems. I run a 3800rpm chip in the 2-step for launch. Once I am staged, I hit the transbrake button and put the pedal to the floor. The car sits there at idle until the first light comes on, then I release the buttom and it goes wide open pretty much instantly. So, I'm only sitting at 3800 on the 2-step for as long as it takes for the lights to go down and not while I'm sitting there staged, waiting. And yes, they are fast enough that they won't effect your lights on a .500 tree. I'm now running a IAII aluminum block, though, but I still have that shortblock in the corner.

Kelvin

Probird · 07:32 PM

Quote:

Originally Posted by mikejub

Is this a problem unique to a trans brake applicaton? Just wired a 2-Step into my line lock button on a 4-spd car. Expecting to launch 3000 to 4000 rpm. But Mike S experience has me a little concerned.

I've got close to 500 passes on my block right now all using a 2-step set at 3800. Knock on wood I haven't had any problems like Mike S. had. Makes me think that there was something else going on there. I wouldn't get too concerned. I let go of the button on the top bulb and then matt the throttle or I matt it on the top bulb and let go on the bottom bulb depending on which class I'm running. It doesn't spend very much time on the 2-step at all.

marks73ta · 02-05-2008, 09:02 PM

Kelvin Poe. I looked at your pic of the "bird. I had an original '72 TA in Lucerne and it brought back many good memories. If you have some better pics of your car can you contact me and send a shot or two? If you would rather not contact me I fully understand. Just wanted a better look at your car. Thanks Kelvin. Mark L

Tempting · 02-05-2008, 09:08 PM

Mike, It's good to see your getting your motor back together. We missed seeing you at Atco the last few outings. Since I've seen you last I started using a 2-step and a trans brake at the Pontiac events. I too was told that leaving at 3000 and under on a brake can do some damage. Have you tried at a higher RPM? I'm leaving at 3600 and have had no problems (two seasons so far). I tried 3800 & 4000 with the same results. You should have better results than me anyway since your car is much lighter. See you out there!

Jamey

Jim Zeek · 02-05-2008, 09:46 PM

I idle in to stage. Hit transbrake button. Release on first bulb still at idle. Mat it on second bulb to 5300 on 2 step. Transbrake releases and hits convertor to 5600. Shift at 6300 and go thru at 6900. 8.70's @ 156+. Filled and 4 bolt studded 455 block. 4.25 stroke, 4.185 bore, 7 inch BME rods, light SRP pistons. Over 200 passes, no problems.

racegto65 · 02-05-2008, 09:57 PM

Quote:

Originally Posted by Jim Zeek

I idle in to stage. Hit transbrake button. Release on first bulb still at idle. Mat it on second bulb to 5300 on 2 step. Transbrake releases and hits convertor to 5600. Shift at 6300 and go thru at 6900. 8.70's @ 156+. Filled and 4 bolt studded 455 block. 4.25 stroke, 4.185 bore, 7 inch BME rods, light SRP pistons. Over 200 passes, no problems.

Pretty much the same for me. Light both bulbs,set transbrake,wait for second amber,go against convertor(about 4800rpm) on the 2 step and release on third amber. 9.30's@142 and have been using the same 455,filled,4 bolt studded block for years.Just had apart for inspection and reused all the bearings from last season.

Mike S · 02-05-2008, 10:43 PM

I think I will try the 2-step again this time. I do have 4 bolt mains and a filled block now. I definitly will not set the 2-step at 2500 again. Think that was my probem. The reason I set it low was , It was my first time useing a brake. I didn't want to break anything first time out. This time I will try 4000. I am just affraid of how much shock the stock supension can handel.

I am trying to get the car together for March 30. I will be running 10.00 index races that use a .500 pro tree.
Mike

Probird · 02-05-2008, 11:10 PM

The higher you leave the less you flash the convertor. I don't know but have been told that if you are having traction problems try leaving higher on the convertor. I've never seen much difference from 3800 to 4400 so I just leave it at 3800. I know it leaves harder than when it is footbraked though.

Kelvin Poe · 02-06-2008, 01:26 AM

marks73ta,
I sent you a P.M.

Kelvin

BruceWilkie · 02-07-2008, 01:27 PM

Type of rev limiter could affect durability. Dropping random cylinders vs all of them at once will certainly have an effect. Dont know how much effect with a transbrake but have noticed my Accel 300+ box hitting the rev limiter at a test setting of 5000 rpm doesnt feel as abrupt as my old MSD. Could it make a difference at low speed? I dont have anything more than a guess that it would to offer.

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