I am sure you guys will be able to fill me in on something that has bugged me for some time now. A newbie to drag racing a while back I took my '65 Cutlass to a social day of drag racing at the Meremere drag strip an hour or so from home. The engine is the original 330ci with an RPM intake, 600cfm carb and high output HEI. I wasn't very happy with acceleration out of the hole so I thought I would try and get up on the torque converter (stock) to get the car moving faster. What happened was that I could not keep the car stationary and I slowly but surely moved forward until I broke the beam. The look on the guy's face who was running it was kind of special! The brakes are good, power boosted with a front disc brake conversion and the engine is rated at 360ft lbs at 3600rpm so nothing big. I have a nice TCI converter sitting in a box which I think is a 2600rpm version. My questions are is this a common sort of thing? With the new torque converter installed will this mean that this crabbing will just happen at a higher rpm than previous? I have a line lock to go in when I make the new brake lines but I am not sure whether using it will make the situation worse as the car will only have the front brakes operating if I try the same thing. Any opinions gladly received.
Norm
New Zealand

 

With front disc's it should be pretty easy to overcome the rear drum brakes.
What prop valve did you use?

 

I don't know what valve was used as the disc brake conversion was done in the USA before I bought the car here in NZ.

 

Yes this is common.

Yes it will most likely happen at a higher RPM Depending on the converters.

 

Stock converter AND transmission? If both that would have a two speed variable vane "Switch Pitch" torque converter.

 

Nice, and as I understand it Meremere is a very fast track.

Yes that has happened to me as well. Getting on the converter on a fast track can be challenging because of the great prep. A healthy V8 will overcome the rear brakes holding ability but the trackbite will minimize wheelspin and force the car forward as possible.

I question how good the brakes are... on the street it may feel good but track testing exposes all issues. The 87 442 that I tested a lot, never crept forward that I can recall. And its born with an aggressive converter. Brakes where factory setup disc front, drum rear. But my 69 does creep forward on the line, and no matter how much brake pedal pressure I seem to apply it still happens. So I just stopped doing it because I didn't enjoy wasting passes.

Now what does your 65 and my 69 have in common. They both received aftermarket disc conversions prior to our ownerships. And I can tell you beyond a shadow of a doubt that the stock 442 stopped far better than the 69 and the 69 was converted to 4 wheel disc.

The line lock may do the trick as its more effective than our leg pressure jostling could ever be. But on stockish cars like ours I wouldn't think its necessary once you find a sweet spot. Now on a built high performance powertrain a transbrake would be the way to go.

 

To reiterate.

"The age-old practice of foot-braking the torque converter by applying the brakes while increasing throttle is only marginally effective. Eventually engine torque overcomes the ability of the wheel brakes to resist axle-shaft rotation, and the tires either break traction and spin or the car creeps forward before you want it to."

Hot Rod Magazine May 2002

Their test car was a 400 hp 400 lb ft small block dyno proven, with a 10-inch Super Street Fighter torque converter (3600-3800 flash stall on a slower car)

"With plenty of VHT on the track and a hot burnout, the converter foot-braked to 3,400 rpm before the 27x10.00-15 slicks began to churn."

Hot Rod Magazine May 2002 https://www.hotrod.com/how-to/tci-tr...es-review-tech

Regarding flash stall https://www.motortrend.com/how-to/ca...rque-converter

 

Try dropping a couple pounds (kiloPascals?) of air out of the front tires. While higher pressure reduces rolling resistance, it also decreases the contact patch. I can push the front on line lock in a burnout if they're over 30psi.

 

One trick the Grand National guys used was to install wheel cylinders for a same year station wagon. The wheel cylinder pistons were bigger, applying more brake shoe pressure for the same brake line pressure. That made it easier to get up on the converter and spool the turbo without overpowering the front brakes.

 

That's good to know. What is the workaround for this type of situation? I guess with racecars it's a transbrake. but for street cars racing is the answer a higher stall TC?

 

BTW that's a very impressive 350ci you have in your car.

 

Thanks for your reply. My hopes are that with the TCI converter installed it will let me get more RPM up before the creeping starts.

 

Great info, thanks. I based brakes "good" because the car goes straight through WOF (Warrant of Fitness) checks no problem. They drive the car onto a set of (computerized) rollers and apply the brakes after which they have data for each wheel's braking ability. Do you guys in the US have to have your cars tested periodically like us Kiwis? It used to be every 6 months but it's been changed to every year now.