Hi everyone, I have a 71 gs that I'm pretty sure still has the factory rear end in it. It was an original 350 car I've talked to a few people on what the gearing may be in it. Every one seems to be thinking around 2:73. Also I'm doing a 4l60e trans swap in it and I'm looking to change the gearing and put a posi in it I want the car to be somthing I can drive to the beach and back and also go to the drag strip so what do y'all think I best bet on gearing would be?
I do not think you can be so vague on a ratio.... Question to answer before deciding. What is best for YOU personally. Not everyone wants all high power performance low end. Smaller cammed v8s can do very nicely with 3.23 3.42 AND OD which will be very nice on the freeway and of course with a OD 200 or 700 will have a great 1st gear of 2.75 or 3.06 so you really need to ask what you want your car to do for you. There is not a best ratio for everyone. IF you want the maximum performance for the track and still usable driving on the freeway ... ?? Still a customer choice. What one person thinks is too many RPMS on the freeway another will be it is fine... Right? Best thing to do is Pick a RPM you want to be at on the freeway and go that route. 2500 3000 etc? Then get the ratio that will give you the acceptable RPM at a given MPH you like to drive at most on the freeway. Good luck. PERSONALLY - I like the 3.55 and my 700R4 set-up. I do have 3.73 gears in it now, but will probably go back....just wanted my 12.50 run for the record. I only have a 212 duration @ .050 cam so it has quite a bit of torque and gearing is not needed as much for the street for acceleration and burn out FUN etc. Just more to chew on. Jim J D
He has an 8.5",so his options are 3:08,3:23,3:42,3:73,and possibly 3:90. I know 3:55 is a good ratio,but it's not worth mentioning when you can't get that gear for an 8.5".
Something I cant understand, if you have a decent 455 combo, with th-400 or th350, and 3.08s, that combo will almost always turn in 12 second quarter times, and run down hiway at 70mph with a decent rpm, Why is it so popular to spend 2-4k on a overdrive trans, pull out the 2.73-3.23 gears, spend another 2k on 3.73-4.10s, to wind up with the exact same cruise rpm, mileage, and quarter mile ET?
Anyone looking for 3.55 gearing can run a 28" tire with the 3.73's. That results in effective gearing of 3.54.
Yes,that's one way of doing it. As as far as why people go through the effort to change transmissions and gearing: Some do it for personal preference,and others do it to get everything they can out of their car,for performance and drivability. Yes,I could run a 3:08,but it would be a dud at the track. Gearing is a Torque multiplier,a form of leverage. A steeper rear gear,along with the steeper 1st gear of an overdrive will do wonders. Adding the 4th gear to bring the cruising rpm back down is icing on the cake. I myself still run stroker big blocks,with Muncie 4-spds and TH400's and 3:55,3:64,3:73's,and I can do everything I need with those,but I can see how overdrive would make it even better,especially with the higher speed limits on the highways.
