I'm moving to Orlando, FL this summer, and I'm thinking about getting some new gears put in my '81. I just had a new engine put in, a 383 with 550 hp, but the rear end ratio right now I believe is 3.08. I have the original sheet the came with the car when first bought from the dealership, and it says it comes with the "optional performance gears" in it, but it sure doesnt' feel like it. I can hardly get the tires to squeal from stand still, so I know the gears must be low. The person who built my engine said he put an engine exactly mine in a camaro, and when dyno'd it had 550hp, and ran a 10 second 1/4 mile, so I know that's what I have, but it sure doesn't feel like that much. I think with better gears it will be better, but by how much?

Well, since I'll just be driving around town in Orlando, I was thinking about getting the 3.70 (I think that's number?), but how much will my top speed be reduced? I have the original transmission, TH-350, so will it handle the horsepower as well with the higher gears than the lower ones? I plan on drag racing it a bit, so I want it to run a good 1/4 mile. But then again, should I get the 3.53 (again, the number?), and get better gas mileage, and better top speed, and better driving on the interstate if I ever go on a trip in it? What will the top speed be like with both of those gears? Also, how much might it cost to get the gear change done by soneone who knows what they're doing? Well, thanks for the help!, I need all I can get.


[Modified by lanceh007, 11:47 PM 6/5/2002]

 

In 81 according to my book the ratios were either 2.72 or 2.87. Both of these gears are very poor for performance. The rear you have is not like the 63 -79 cars so the ratios will be different. I think yours a=has the Dana rear in it. Gears are available for the rear just not sure of the ratios. Yes a 3.55 would be a huge improvement over what you have. It will limit the topend some but are you going to Bonneville or drag racing. Plenty of cars have seen many highway miles with 3.55. Your gas mileage will suffer a bit but performance always costs something.

 

When you get here make sure to hook up with the Misfits, the Orlando/Tampa area guys get together fairly often and have a lot of fun and they're a great group.

I changed my stock 81 gears for 3.55's when I still had the old 350 tranny, I didn't much care for them as the rpm's were too much for me and it made highway driving no fun but they were great around town, gas milage totally sucked. Now that I have a 700r4 tranny I feel they were a very good choice for highway and city driving, I actually got over 20mpg on a trip to the museum. But all that went to hell when I put in a 383 :D

If you are not doing the gear swap yourself give Art at Van Steel a call, plus it's not too far of a drive from Orlando.

 

Get the 3:73's for sure......I sure am glad that I did.....it really changed the entire mood of the car.....I do not do a lot of highway driving though...but it is not that bad at speed...It launches Quite nice now :cheers: :yesnod:

 

I just changed out my 3.07's for 3.73's but I also installed a 700R4. In my opinion, the 3.73's would be too deep to use without having overdrive. (depending on intended use of car)
I don't like the way my new gears feel without the O.D. while crusing at 60-70 mph in third gear (1 to 1. non-O.D.). 3.55's would be the lowest gear (highest numerically) that I would use without overdrive and they would also be GREAT if you ever decide to install an overdrive transmission.
My original 3.07's felt OK with after installing the 700R4 exept in overdrive where the rpm's felt a bit too low during cruise speeds for my engine combination. The 3.73's put my cruise rpm's in a better range w/O.D.
Seems like you would be able to blow the tires off the rims from a standstill with the amount of power your engine is supposed to make. Are you running the stock stall converter? (low stall speed)

 

I'm with MIKER on this one. 3.55's are as low as I'd go without an OD trans. They're a little high for the dragstrip (especially with a small block), but will still work on the street. If it will live it's life at the track, 3.70's or even 4.11's are the way to go. I ran 3.70's in my GTO on short slicks and cleared the line @ 5000 RPM with a THM 400 trans. Anything will be better than what you have. Does the engine come to life once you get it going? Adding a higher stall converter would probably make a big difference as well.

Hans

 

The stall converter is stock, so I know that it's not very good. If I were to put a new stall converter in, would the transmission have more trouble keeping up with the horsepower? Would it be easier to damage the transmission?

 

Horspower doesn't break rear ends, torque does. Keep that in mind.
Well I've driven SEVERAL cars with an excess of 500hp, and believe me, you feel it, best way to know is to get it dynoed.
Gears and a larger stall will really get you moving.

 

go with the 3:73's. Just plan on a 200R4 in the near future. If I was single and my wife wasnt making me sell her thats what would be my next investment. I run about 3400 rpm at 70 right now and I do a lot of highway driving.

 

thanks for the help so far. I guess my main question is how much would it cost to get those gears put in by someone who knows what they're doing? I will also get the exact specs of the cam, heads and everything else by probably friday.

 

Do it yourself I did.... It is not that hard but you will need a helper or two to help put the Pumpkin back in

 

Well, I guess the first thing to do is to get a new stall converter. What stall speed would you suggest? I'm going to talk to the dude who put the engine in tommorow, and see if he will put a new one in, even though he's said I shouldn't. :confused: He says it will just put more pressure on the tranny, and could mess it up if I were to launch hard. What do you think? :confused: Also, how will the stall converter help me? Will it make my 1/4 mile time any faster?


[Modified by lanceh007, 10:12 PM 6/6/2002]