I picked up a new set of tires for my '67... as you can see in my signature the car is very original and one day (in a few years) I want to put it back to "perfect condition" but for now I have fixed most of the little things and we carefully use it for family weekend cruising around town on summer weekends. I have the factory rear with non-posi 3.31 gears. I am thinking about upgrading to a posi rear with 3.73's BUT, eventually, I want to put it back to original during my full resto.

Should I purchase a full new rearend with 3.73 gears, posi and mono leaf purches so that I can clean up and "hang up" the untouched original?
OR
Should I take out (and save) the date coded 3.31's and replace with 3.73 gears and posi for a few years only to switch it back again.

Anyone advise on the best place to purchase or know of anyone willing to sell used posi/gears OR a full 3.73 posi rear? I'll even give them back in a few years! :D

Hey Vince. May I ask why you want to do this? I guess unless you want to do a bunch of burnouts or take it to the strip, I'm not sure I'd bother.

While a different car, I had a '68 LeMans with the original 350 that had an absurdly high gear ratio (not sure what it was but had to be at least 3.73:1), and it was cool starting off the line, but you'd get to 4th gear in a hurry and wouldn't be going all that fast. Then you'd just get a high winding sound, especially when you were on the freeway due to the RPM being so high. It wasn't fun driving over 60mph at all.

In any event, good luck if you choose to go with the 3.73s. If it were me, seeing as your car is so original, I'd keep it as such. So, if that means buying an entire rear end, that's what I'd do and leave the original untouched.

I think I'd add the posi and leave the 3.31's in.

i think i'd add the posi and leave the 3.31's in.

x2

This guy probably gets little to no tire smoking burnouts with 3.31's that's the reason for the 3.73's!....And yes, you need the posi!

I had 3.73's in my car and went down to 3.31's. I have a 4 speed and find the 3.31's much better for street use.

Unless you're going to drag race the car, I'd stay with 3.31's.

I would also like to know why you want to go with 3.73s and a posi. It seems like the car is going to be restored and changing the gears is only going to creat more work. If it was mine and I was going to do anything to it I would just add the posi and keep the 3.31 in it. If you are not doing burnouts, having trouble with traction or drag racing then I wouldn't do anything at all to it.


If you need parts let me know. I can get you a new Eaton posi, and I will be rebuilding an original 3 series Eaton soon to sell. I may be building a '67 12 bolt soon also, so if you want to swap the complete rear end I might be able to help with that too.

Here is what I was thinking... the 3.31 ratio works for me but if I was going to take make a change OR get a new rear end I thought I might step up the gear ratio to something with a little more of a jump like a 3.73 posi that was the standard performance gear for a 67 SS. I was also thinking that if I add a posi etc. it might not be the worst idea to keep the date original gears "safe" in a box or "hung up" with my original rear.

The real reason is that my worst fear might be realized. I can see it now... punk kid in a honda... my 3 year old son cheering me on from the back seat, as he aways does, saying "go super fast daddy"... I then spin ONE tire and off to a sluggish start... with my original rearend gears grinding together for the last time... the honda is the first one through the lights... my son would ask me why the "puddle jupper" was faster then me, could spin it's tires, and why I was crying.

Ok, back to reality, that might be a stretch but we've all felt the pressure. I live in a fairly small city and the only time I make it to the highway is for 5+ miles on the way to work once in a while. That being said, I baby the car and it hasn't seen very much RPM so I don't really want a gear ratio that is too high. I know I don't want over a 3.73 but from the posts that I read I didn't think it would be too bad. What RPM should I expect in 4th gear with 3.73 going 60mph? Thanks for the input so far and either way, I could definately use an eaton posi unit, or a complete set up if I go that route. Thanks for the offer and please send me a PM with the details. What should I do?

The 3.31 is a very good and popular ratio. I wouldn't take it out. I had a '72 SS 454 4 speed Chevelle and a '67 SS 396 Powerglide Chevelle that had the 3.31 gears and I liked the gears in both of them. I would just put in a 3 series Eaton and be done with it. A new Eaton is about $420 plus shipping. Bearings and shims for the installation are about $40.

Your car if it has stock painted steel wheels and dog-dish hub-caps should have D-70 Redlines on it b/c that's the way mine came when I ordered standard wheels and tires on my car back then.

And I'm here to say that my 350SS/RS, M-20, 3.31 posi car could spin them as far as I held my foot down going up through the gears!!

Oh, and btw, I call my car a 350SS/RS b/c I checked the SS line before I checked the RS line!! I wanted the big engine before the fancy body stuff...

If you have nerve enough to hammer her, it will run VERY WELL w/ just the 3.31's after you cure it's terrible wheel-hop! Boy, how I know!!

Install a pair of slappers and coil-over, shock overload springs and tune slap and preload side to side and GO!! She will leave like a "Rabbit outta the chute at the Dog Track"!!!!!

And you can tell when you have enough power in her stock-bodied b/c the drivers side rear window "V" will start to crack!!! A crack appears, add S/F/C's and continue beating on her!! he, He!!

pdq67

Ha Ha... That's awesome! :D

I still have the white walls and wheel covers on the car because that is what the original owner replace the redlines with. I just ordered a set of 15" chrome rally wheels and BFG TA's for it and they should be here late next week. My son, age 3, wanted me to have white letters like "The King" from Disney's Cars movie and it will probably be his car in 15 years anyway or at least a '67 ss coupe. I plan to order a set of the D-70's to put on with my wheel covers when it all goes back to showroom original. But, until then, a few improvements here and there to make driving her a little more fun, for under 1000 miles each year, will sure help.

And yes the wheel hop is a killer... My car is a late December build car so it got the bracket for the radius rod welded to the rear end but missed the date for the radius rod install... This always makes for some good conversation but obviously I still get the wheel hop. No major suspension upgrades etc. for me as that sounds like too much $ and work to put back to stock.
You can take off like the dog and I will hop off the light like the rabbit with my 3.31's with posi in the factory setup.. :beers:

A Sat. will do you fine to cure her hop!

Slapper Lakewoods that are long enough to slap right under the bottom middle of each spring eye, even if you have to extend them.

And coil-over, overload shocks are easy to R&R and adjust.

My car w/ my 406 and big L-60's that measure a modern 298/53-14 would hunker down in back, launch and raise up in front around the C/G and take off like said Rabbit!

pdq67

The Competition Engineering bars are the right length to hit under the spring eye.

Oooop's missed this, "standard performance gear for a 67 SS.".

Stock line not checked is the 3.31!

And imho, it is dead-nuts on for tire burning as well as road racing. Just keep the tires at like a stock of 25.3" to .5" in dia....

Sure a shorter gear will go harder, but gas mileage and rpm ring in your ears at 70 mph on the hwy will suffer!!

pdq67

Oooop's missed this, "standard performance gear for a 67 SS.". Stock line not checked is the 3.31!
pdq67

I did know that the "standard" gear for an SS in '67 was the 3.31 but were there optional check boxes for the other ratios? I know I read something about a performance gear. Come to think of it, I bet that was for the Z28. Thanks for the correction!
For now I am going to leave the factory rear and continue to take it easy on her. One day I will have 2 Camaros in the garage. One cruiser convertible and one coupe for the strip.
I'll buy another lotto ticket tonight... wish me luck!