Rear End Gears

[Ol' Blue_59]

Well my '59 Chevy has 390 rear end gears in it and not much for crusing for 45-50 mph. The 235 is just wound pretty tight. So I'm thinking of putting different gears in it. I just had the original rear end rebuilt in it so now is the time to change the gears. I was wondering what gears I should go with and where I can get them from for a desent price. I have a 4 speed manual if ya need to know the tranny. Thanks, Toby

[solidaxel]

Have you thought about a Tremac 5 speed and keep those 390s you will think you put a new engine in!!!

[Ol' Blue_59]

I'm never gonna take the 235 out! This truck I am gonna keep as original as possible. So what about this Tremac 5 speed?

[solidaxel]

check out www.classicchevy5speed.com

I have the TKO600 and love it, it shifts like butter and the overdrive is smooth as silk, you just have to be going more than 50MPH with the 3:73 so your 390 would be perfect,
Do you have a open drive shaft?

[Ol' Blue_59]

Yeah that transmission would be great, but trying to afford it would be also! I kinda on a budget and paying $2500 verses 300-400 for new gears, i think i'm gonna have to go with the gears. Saw some 338's the other day...would those be too fast?

[5Mike7]

I ran 3.54's in my '59 with a 235, granny 4 speed. I'd have liked to try something in the 3.0-3.25 range though...but taking off in 2nd might have been hard on the clutch...the engine had plenty of power to keep the 3.54's running up hills, loaded, etc.

[Ol' Blue_59]

So where is a good place to look for these gears. I thinking that somewhere in the 350's would be a good set. I want something that is going to be able to do 75 mph on the interstate so I hope these will work. So where do I start looking?

[wild one]

What about a T5 transmission out of a S10? These are over drive five speed transmissions that have been used in trucks and vans for years. One of my buddies just did this very swap into his 57 1/2 ton - best part about this swap is that the parts are available at wrecking yards for cheap. He invested less than $500.00 total for this swap, which included having his drive shaft redone. You can find more info on - http://www.stovebolt.com/bboard/cgi-bin/ultimatebb.cgi - just do a search for T5 swap. Good luck with your project!

[northerngmc]

Patrick's http://www.patricksantiquecars.com/index.htm sell a kit that I think is a 3.55 rear gear that is a swap out.

[5Mike7]

I'd definitely do the T5 swap before buying aftermarket gears...just my opinion..

I pulled my rear-Dana 44_ from a early 60's GMC, relocated the spring pads, put new bearings/seal clutch pack in it-all for about 200 bucks (paid 50 for the rear, another 150 in parts to freshen it)

There's also a plethora of newer rears that are 6 lug and will work.

[Ol' Blue_59]

I looked at that website and they have a complete kit with 3:38:1 gears. Would those gears be too fast for my 235 or just right? I just want something that I case cruise between 60-70 with the engine not being so rapped up as it is the the 390s.

[5Mike7]

If you're 235 is in decent shape, no issues to run the 3.38's ( I know mine would have had no issues with them), but consider the cost of the gear and cost to have them installed/etc, if you can't do it yourself.

Then compare to converting to a T5.

[Ol' Blue_59]

I just had my 235 overhauled a couple years ago and I don't drive it hard. About 45-50 all the faster I go. Will the 338's allow me to curse at 65-70 without the six banger being rapped up too far? I mean going 65 with the 390's has it wound fairly good.

[northerngmc]

What about brakes?

I have also considered upgrading my final drive ratio so I am not screaming my 235 in my 59 GMC down the road. BUT I have concerns about going 70 mph with 50 year old brake and steering technology.

Where these trucks ever meant to go that fast?

[solidaxel]

Didn't have many choices if it was all DOWNHILL!!!!
Just make sure the tires are in good shape and balanced, the wind noise gets a little worse over 70mph !!!

[5Mike7]

You can do the math on speed, check it through a gear/RPM calculator.

You're 235 shouldn't have an issue running 3000 RPM all day long.


Brakes-problem with our drum/drum brakes are two fold...

The rears love to lock up, and brake fade is a nature of the beast...have to rememeber the roads traveled, etc with trucks in the 50's, speed wasn't much of an issue to deal with, a lot less traffic, etc.

If I were to build a daily driver TF again, it'd have to be disc in front and power brakes...then again if I lived in some area that didn't have much traffic I probably wouldn't be concerned about it...I heard there are still places like that around

[JIMBO59]

put the original rear end away and get a 78 camaro rear end with 3.08 gear ratio. my buddies truck runs like a champ with it.plenty of those rear ends around in the boneyards.

[solidaxel]

Why limit the Camaro to a 78, I think they were all about the same width, and the automatics were almost always a higher ratio (lower number). I think some were even in the high twos, like a 2:74, and whith one of those you could even use 1st gear !! You would not have the 6 lug axles with the Camaro, but steel wheels are inexpensive and lots around for a chevy.

[1-ton of fun]

or have the axles redrilled for the six lug pattern. it may be cheaper than new wheels/tires.

[Ol' Blue_59]

That's all great guys, but the only thing is I just put all new bearings, races, oil, seals, etc. into the original rear end. I just want to change the gears in it, thats all. So will the 3:38s be a lot better compared to the 390s. I have very little knowledge about rear ends.

[1-ton of fun]

put all your info in this calc. it will tell you the change in rpms:

http://golenengineservice.com/calc/calcrpm.htm

[solidaxel]

Changing rear end gears is quite a process even for the experienced (expensive)!!!

[cajundragger]

I got 4.56 gears and a 6 speed...haha

but I deff recomend a good trans..like a T5 or t56...