ok here is my problem i have a 64 chevy c-10 350 with a turbo 350 behind it. its an auto 3 speed and my problem is it runs at way to high r.p.m. at even 60mph. so what should i do? new trans.? im not sure what the rear end is geared at thanks for any help
An overdrive transmission (700R4 or 200R4) would solve the problem, but a new set of rear gears is probably a cheaper solution. I would say 3.08 or 3.23 gears would work well.
Do you know what rpm your engine is running at 60? What is the rpm? If you don't have a tach, get one. If you are not used to driving old, non-overdrive hot rods, you can have the impression that the rpm's are too high, when really they are not. You need to determine your axle ratio, too. Being a truck it could be pretty low (numerically high), in which case a switch to higher gears or to an overdrive tranny would solve the issue.
I had the same problem with my 66 when I got it going. My rear was a 4.56, engine was 350, 350 trans, and 255/60/15s in the rear. I made a serious miscalculation. Would only do about 70, but got there pretty good. Try an overdrive trans 700r4 or 200r4 would work. They also lock up the converter and that will help greatly. Good luck with the truck.
Right on. My coupe has a th350 and 241 gears with a 26 inch tall tire. rpms are about 1750 at 55 mph. My old chevy truck had a Super T-10 4 speed(still a 1 to 1 final) and 373's with a 28 inch tall tire. Rpms were around 2500 at 55 mph if I remember right. An over drive would have made them almost the sameish as far as rpm ranges.
IM very inteersted in this thread. i wanna get a 59 pick up and use it as my dd so seeing all these combos really helps me out. LOL i'm probably gonna use a 305 engine though. But as for fitting up, a SBC is a SBC and all things should bolt up. Right?
I'd be willing to bet you have 4.11 gears in that off the top of my head. Swapping to taller gears will make a huge difference. But don't take my word for it, find out what gears you have, then use one of the online calculators to figure out what set would work best for you...
I had a '64 C-10 with a 350, and stock 3-spd trans. 12-bolt with 3.55 gears. It would purr at 80mph on 255/60/15 tires out back, probably around 3500 rpm. 3.08's or 3.27's might get you where you want to be. I chose the 3.55:1 ratio for a bit more pep on the low end. If you don't have the tools to do a gear swap, a complete rear end swap from a later model truck would be easier, plus you can get 5-lug axles for more wheel options.
most of those stock rears had 3.73-4.11. if yours already has a "newer" trans (350) then you could use a 200r (same length as a 350). my '64 panel has a 6 cyl and stock 3 on the tree, it was screaming at 70mph. i found a newer o/d manual trans and now i can go 75 easy (2500 rpm). or a gear swap to a 3.00 would be good (a little cheaper).
I'd say go with the gear change. It is easy to do and is much easier to find around here for me than a 200 or 700R4 trans AND you don't have to worry about screwing up a TV cable if you don't have it set right to begin with. A 69-70 truck rear end should work for you and not be a big deal to change. You'll still keep your 6 lugs as well. Most of the 71 up 3/4 ton or 4x4 trucks still have 6 lugs also. You might find one under an old pick up bed trailer to use!!
Find out exactly what gears that you have. If you go to the 3.08 ratio rear you will feel the difference around town. Gas mileage will be better on the road but worse around town. If your gears aren't way out there...4.11 or worse then an over drive trans might be a better bang for you buck. The current lower gears will still help you get away from the stop lights economically and the extra over drive gear will knock the Rs down for mileage on the road. Around here changing rear gears can be very costly unless you are lucky. Make sure you spend your money wisely. JMO
mess with your gearing before you buy a new trans that would be a waist of time and money, cuase your gearing will still be to high in the rear.
the cheapest solution is tire size, a 255/60 is not very tall, especially for a truck. you have lots of room, try a 285/70, it'll make a huge difference...
ok thank you all for your help im going to hit up some salvage yards this week to see if i cant find a newer rear i think i know where a 70 is. but im also going to save up some cash to get a 700r4 just because why not do both right
Uhh, you dont need a newer rear end, just better highway gears. And if you go to say a 3.08 and THEN add a 700r4 your overdrive will be useless at anything under 125mph! One or the other, unless you want the OD with stump pulling gears later.
It hasnt been mentioned yet but if your looking into higher highway speeds, you also might want to update your braking system the faster you go, the faster you gotta stop
I'm a great fan of the 200R4 - as others have said, same length as a 350, so you can use your existing driveshaft without paying to have it shortened - which you would have to with a 700R4, but you'll have to move the tranny mount 1 3/4 further back. Lock up converter will drop your cruising rpm another 150-200 rpm. Go to www.currieenterprises.com and click on the center icon, then go to calculators on the right hand side of the main page - you can figure out anything you want from there. You will retain your current performance in gears one thru three and drop your rpm in fourth. You will not retain your performance if you simply change the final drive ratio. As for those who say the 200R4 is okay for a mild horsepower application, I have a built 200R4 with manual lockup converter in a blown and intercooled LT1 383 stroker powered car with sticky Hoosiers on the rear. The car has somewhere north of 650 hp and the trans has been installed for 12 years. I have never had a problem, even when leaning on it hard.
Just stay off the by-pass and stick to old 71! There's more old cars on business 71 anyway! You might try Horn's salvage on Habberton Road in Springdale, if they haven't crushed out everything.
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