Thread: gear ratio

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I have a 2500lb car that runs low 11s. My problem is slow 60ft times. 1.7 I'm running 4.11s now with a glide and 32" tires. Would 5.14s be a better choice?

That's a major drop. What stall covnerter are you using, do you have a trans brake and what RPM are you seeing going through the lights? Would also help to know what motor and what RPM you can turn.

Pat

4500 stall, no trans brake . Going through the lights at 7300. The motor is a 355

If you are going through the lights at 7300 with 4.11s and a 32" tall tire, you are either pulling some serious MPH, 165+, or something is slipping badly. What's your trap speed? Running low 11s, your trap speed should be between 115 and 120 and RPM between 5000-5200. I would be very suspicious of your torque converter if the RPM is much higher than that. What kind of 60' time do you think you should have? If the TC is slipping that badly on the big end, it could be costing you off the line as well.

For reference, at 120 RPM with 5.14 gears and your 32" tire your rpm should be about 6500.

Hope that helps

Pat

could the bands be slipping?

Sounds more like the clutch pack is slipping...im no expert though.

Couldnt hurt to check the torque on the band. But i would think the apply piston may not be compressing the frictions enough or the frictions and steels are worn. Alot of passes on the tranny?

there are more than a few passes on the tranny. I just want to get throught the next few races then do a rebuild

Originally posted by Pappy1
there are more than a few passes on the tranny. I just want to get throught the next few races then do a rebuild

What kinda frictions and steels do you have? are they stock or the thin ones where you can fit 8 of them instead of the standard 5 i think. Thats probably whats happening, they are worn and starting to slip. if your band was slipping you would be having problems shifting more than likely. i would replace it also, a good set of raybestos frictions and steels with a good kevlar band and a hardend clutch hub, resurface the clutch drum, hell sandpaper it, change out the spring for the pump so it bumps the pressure up a little bit and give a little more apply pressure and you would be good to go. For a quick fix and only a quick fix like for a couple more runs i would pull the valve body and change the pump bypass spring out to a little heavier one to give you more apply pressure and maybe just maybe it'll make up for the worn frictions and steels for a few more runs. but i wouldnt push it too long. Just a bandaid but it should work

Ran Super Chevy over the weekend. Went 3 rounds with a best of 11.02 60ft time1.64. Still going through the traps at 7500

You absolutely have a slippage problem.

RPM= (MPH x gear ratio/ tire diameter) x 336

1.64 seconds isn't that bad for a 11 second car. I found out years ago that tires can make a BIG difference. I ran a front engined dragster and called Good Year about the best tire for the car. I went from 9.83 E.T to 9.30 by changing to the right slick.

I run low 11s with a glide also. 4.33 gears 28" slicks 1.72 60' 122 mph, cross the stripe @ 6900. leave the tree @ 3000, ET changes with the weather, but always 122 mph @ 6900

I picked up some on my 60ft times since I went to 4.56. low 1.6s. rpm still7200 in the traps. Still working on another glide with 1.80 gears. that should help some