I tend to go a bit conservative on gears, especially since I like to push the speed limit on the highway.
My 66 GP 427 4 speed was 3.31 and I would have liked a touch more except when I was on the Interstate and wanted to drive 70 or more. Then that was enough gear.
If you do lots of short trips I'd agree with the 3.55 idea. Lots of longer runs, then 3.31 makes more sense.
3:55's are probably easier to find ? I have to take car to Chatham to get it installed.. 11teen hours away Tiny can swap it but does not have shims, or dial indicator no one aroundhere can do it.. thanks
Wouldn't it be nice if I could mix and match to come up with a 3.63.
I figure I'm going to tear the donor apart and inspect it all, then pull my carrier and have a look before I decide. Going from 3.08 to 3.36 is not a huge change so I might as well just go with whichever set looks best.
I agree that with a 1:1 tranny, the 3.31's are better on the highway. If you drive around town mostly, you can get away with up to 3.73's but any long road trips start to get a little tiring. I find 4.11's and higher get old even around town...
but if you go 3.73 like Carl's Ventura say and put in an OD unit usually .7 so thats like a 2.61 ratio less the lockup convertor feature so you are close to a 2.50 in a non-lockup say and the 700R4 has a much better 1st gear so thats maybe like a 3.9 outa the hole ...
i wouldnt mix and match gears unless you are mudbogging cause the noise will be terrible. I would not even recommend putting anything less than a new crown and p as you will never match the gear pattern so its quiet. Most guys have a tough time changing bearings out and still getting the match right.... my2 bits
I hear you Elroy. I've been lucky in the past swapping rear end components without the growl & whine (but always kept used the crown gear & pinion as a matched set). But I also recognize it has been mostly good luck and not good mechanics! I didn't even have a dial gauge back when I was doing this all the time. Bolt it in, see how it feels as it rotates, put some die on the gears, roll it over and have a look at the pattern. If it matched the existing wear pattern, I'd button it up, fill her with oil and be back on the road. If the pattern was off, I'd play with shims to get it to match. If I remember correctly, I think I used to start with the shims that came out of the housing I was trying to get running. My thinking was that it was more likely the carriers would be machined the same - more likely to have variations in the machining of the housing. If things didn't line up with that approach,, I'd install the shims from the donor rear end. Usually, one of the two would get me there.
I'll likely proceed as I said earlier - use whichever gear set looks best. If she growls or whines, it'll be a good excuse to go for those 3.73's!
steeper is always better!!hahaha!! I had 4.56, but they were too steep for a stocker BBC... I have a nice nearly new set of Strange 4.10's for an 8.2 that I would sell if you're interested...
the 10 bolt i have in my Acadian is original and had 3.08 gears but the possi gears in there now are 3.31 ratio from a wrecked 65 chevelle station wagon just swapped ring and pinion and the shims, but i did replace the clutch packs and bearings ,make sure to put in the possi additive after your done . with 14 inch tires its almost exactly like 4.11s on a 15 inch tire :) with a muncie 4 speed i can still cruise at 60 mph . you should be happy with the overdrive im thinkin !
Tiny can swap it but does not have shims, or dial indicator no one aroundhere can do it.. thanks