Author Topic: which rear gear?  (Read 494 times)

Offline wideopen231

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which rear gear?
« on: July 11, 2022, 04:09:00 PM »
Ok with very few runs on gear in car it is showing that it was used gear when I put it in.  Not enough runs to decide if like the gear or not. Been running 4.11. More info.1.69 low gear 32 tall tire and chance of 33 in future. Figure I need to be 3.89 to 4.30 and that is why the 4.11 a mid-range start. Car has not been violent or stupid acting. Shake issue especially T-n-T track which normally sucks anyway.  The engine is 975 hp about 900 tq. car weight around 1750# on starting line. Should be adding 75 give or take a few . if new pistons  and rings ever get here. With cost of Pro Gear would like to guess dead on. 

So 3.89,4.11 or 4.30? Remembering 1.69 low.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline tcoupekyle

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Re: which rear gear?
« Reply #1 on: July 12, 2022, 11:04:58 AM »
My car was similar setup 1.69 low 1100hp bbc at 1680lbs. Didnít make a ton of runs with the setup but it seemed to like the 4:11 at the time I was running a 16x33 tire and it like to shake like crazy.
 The previous owner of the car tested and like a 3.89 but he was operating a blown sbc.

Offline wideopen231

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Re: which rear gear?
« Reply #2 on: July 18, 2022, 01:40:50 PM »
Maybe wrong here.Very little fed tuning to go on. From guys, I have talked with Feds are not really happy with a lot of tire. Wheel speed is king when it comes to smooth runs. Frank Park's told me the M/T's will be a problem. Said he could not get enough wheel speed with his motor leaving at 9200  with them. Wondering where best to spend money on gear or tires. If go tires I might need smaller wheels for 33x 15x 12 M-H's.

Kyle going off blower car stuff, so take it for what it is worth. Shake normally come from too little tire speed. So how do you choose gear. Lower will hit tire harder but less wheel spd in rlation to engine rpm. Of coarse opposite true but require more power to get tire going. Got to love this stuff or just stupid to spend the money we do. LOL
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: which rear gear?
« Reply #3 on: July 18, 2022, 02:12:51 PM »
Sitting hear brain in gear(maybe) and butt not. Running numbers with a drive shaft spd of 140 rpm you will get 2 tire roations more with the 3.89 compared to 4.11. Ok it only r tire rpm  but figure in roll out and it is lot of distance if engine can pull it
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: which rear gear?
« Reply #4 on: July 18, 2022, 05:39:25 PM »
Well decision made for me. Had a guy offer up a 10 or 12 run gear cheap. So going to find out which one works better.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline tcoupekyle

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Re: which rear gear?
« Reply #5 on: July 19, 2022, 05:51:18 PM »
Let us know how it goes!

Offline xlr8

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Re: which rear gear?
« Reply #6 on: July 20, 2022, 11:49:46 AM »
Sorry, I'm just fascinated at anyone leaving at 9200 rpm. My pontiac powered fed blows the tires off at 6000 rpm launch. I'm at 4600 rpm now.
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Offline wideopen231

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Re: which rear gear?
« Reply #7 on: July 20, 2022, 01:17:58 PM »
All in how car is designed and setup. My car is built with 6600 leave as target. Cam choice,converter stall,fuel system and engine position are just a few parts of that.

 I am more facinated that the engines live. I use to love to watch the modified class with SBC turning 12k plus on starting line.You could hear the crank going oh xxxx not again.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot