Drag Racing Discussions > Front Engine Dragsters

1/8th mile gears

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retroboy:
Howdy.
Following from my post about gears and tyres what are you guys running on the 1/8 mile? A Mate has a set of 5.0 gears gathering dust and I'm thinking 6500 RPM through the top end would see me right.  I had a look at a couple of online calculators but don't really think they are very accurate.  Here's my story :-  I have a 366 Chrysler basic engine - standard heads. Should make 400 - 420 HP 400 Ft/Lbs with a carb. My TF904 has a 2.45 1st gear. Currently 4.3 diff and 31" tyre. I lashed out on an 8" converter that has 5200 stall but because of Torqueflight transmissions willingness to literally explode I'm not using a trans brake and the the car isn't heavy enough to get the converter to flash up properly.  Most of the basic 1/8th mile cars in my area are using 1/4 mile gears so I figure the only way I can get around 'em from the back of the qualifying order is to beat 'em in the first half of the track hence the change to a lower gear set. Any thoughs and no I don't see a powerglide in my future. What Tyres Gears Rpm are you guys running in your little guy 1/8th mile combos.
Cheers

wideopen231:
Since you don't agree with calculators this may not be worth anything. My drag simulator and Wallace both say that 4.80 is max gear for 6500 rpm setup. Not sure why  no PG comment.IMO the weight savings alone would help not to mention a lot of rotating mass removed.For  400 or so hp motor a PG is fAIRLY CHEAP BUILD.You could use a 1.76 gear with mostly factory stuff and few upgrades.

retroboy:
Hi Wideopen. I went from a clutch 904 to a PG 35 years ago and the PG was a dull rid like my first wife. I'll be honest this whole gears and converter thing has me bluffed. The calculators seem to give high expectations ?
Cheers

dusterdave173:
I raced a Torqueflite for over 25 years  here is the scoop
Never--Ever do a burnout in first gear PERIOD! Always start in second and go to 3rd as soon as tire speed is up and you will never hurt a TF.
When you do a burnout in first and the tires bite--the over running clutch or sprag comes to an instant stop
and as it is pressed into the case on a 727 it is easily damaged so that the next run it fails --then there is no control so it will spin the guts the engine RPM x the rear gear ratio usually over 20K RPM range and Kaboom!!  very simple to avoid
904 has a stronger deal on the sprag and usually is much tougher to hurt than a 727
You are correct in that there are not very good transbrakes for the TF--when the button is pressed it does not set instantly like a glide and when they do they change over the evening as fluid temp increases so not useful for winning a bracket race but should do OK for what you want
also 904 converter hubs are easy to crack--you can replace with thicker hub and machine down the support--easy to do or just replace the cracked hub every now and then--even when cracked they rarely fail there
Rick Allison at A&A transmission in Indiana is the DADDY of TF parts makers and TF knowledge--most builders get parts from Rick--he is the worlds BEST TF guru  Not cheap but simply the best parts and tech available
Wallace Racing Calculators--online-- just google are the very best out there--we use them every single day

George:
We have run very well with the PG (1.80). A 600+ hp SBC, injected on methanol, 4.88., 12X31 tires @ 1500 pounds went low 5.0s on 1/8 mile. I suggest you put the 5.0 gear in and go try it.

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