There was a post in rambling recently regarding how different gear ratios effects top end rpm. Anyone happen to have this info? I can't find it.

I am trying to decide between a 3:55 and a 4:11 gear set, with posi unti I will install tomorrow.

I am running TH400/400+.060/between 067 and 068 cam/stock Quad/255/60/15's...

Any/all input is welcome.

Greg

Smitty has this link, I do have it somewhere but cant find it.

If you're looking for opinions, here's mine. Unless you are a hardcore racer, go for the 3:55's. Otherwise your motor will be screaming at any speeds over 50. I have 3:23's (with 205-70-14 tires) and it runs pretty high RPM at highway speeds, about 3000 at 60 MPH. (Make that 3000 RPM at 70, per Smitty's calculator below. Apparently I tend to exagerate )

Greg , I`d not use any gears that low that you cant go at least 70 w/o burning her up....
think of that you may want to go 'cruising' w others some time....

we have Stacy in our group who bought a car w a 4spd Richmond and a very low gear...when we were out cruising we always had to wait on him,, here he comes screaming down the street at 65 at 4000rpms...needless to say he`s changing out his gearing...he wants to be able go cruising with us...I`m not sure what Lees gearing is but he got 14 mpg at 70 mph going to Corpus with us last summer...and his is a 11 sec car!

personnally I like cruising so I dont mind my 2.56 rear...I get around 9 -10 mpg in town and 14-15 at 70 on hwy...
I can travel 85+- at 3000 rpms55-60 at 2000

I can still get there fairly quick...when driving with Stacy , yes he`ll beat me the first 15-20 yds , but then I`m gone and he`ll never catch up! LOL

and if I remember right Stacy`s is 4.11..?

Greg what you have to ask yourself is do I want a racer or a cruiser ?
If cruiser then I'd opt for the 3:55

I have a 3:90 posi with a 4 speed in my bird and it really runs high r.p.m.'s
I almost regret it sometimes when I do any highway driving.

I tried 3;55's and 4;11's at the track and the car had a better quarter mile time with the 3;55's. So, I ask, why 4;11's?

Greg - I've got an Excel spreadsheet that calculates engine RPM as a function of tire size and rear end ratio for a variety of different transmissions. PM me your e-mail address and I'll send it to you.

My ears are burnin' - who mentioned me?
try this: http://www.700r4.com/speedoCalc/rpmcalc.shtml

Lookin' like the 3:55 is gonna get installed. Anyone need aset of 4:11's...and 4:88's?

4:88??? Is that for stump pullin?

sell those 4.88 to some one with a monster truck! might be good for "tractor pull"! LOL

OK. The 3:55's and Auburn posi carrier are in! Talk about a project! Took me about 3-4 hours with professional help. So, now I get 2 stripes and a "hop" when I floor it! Not too big a difference in "seat of the pants" feel. But, I need to brake it in before I push it too hard.