Trans ideas

[67 Ol' Bess]

Hello there, I am new here (though I've been a member for a few months, I've just gotten around to posting).

Here is my deal. I just lost 2nd gear in my saginaw 4 speed. Can I fix it? Sure. But I'm using this as an excuse to get what I'm really after.

About the truck: 67 Chevy C20. 8 different shades of blue and primer gray. Mildly worked 350, full exhaust, Holley double pump. It's got the 4 speed turd box that is hooked up to some steep 4:10 gears in the rear.

My dilemma: cruising down the highway (at 55 MPG) my tach reads 3250. I swear to you that I can watch the gas disappear as the needle drops. I get about 7 mpg on a good day. And the gas mileage isn't even really the problem. I'm more worried about the undue stress that is being caused to my motor for long periods of time. Not to mention the glass packs are ridiculous at high rpm's.

My thoughts: bump the gear ratio a bit, to say 3:73. Drop a 5 or 6 speed manual trans to replace the turd that is currently taking up space under the truck.

My next dilemma: I don't know which trans is best for my money. I was told an NV 3500, but they are a bit pricey. I can afford it, but I know I will likely have to get a new drive shaft measured up and made as well. Can I just go with a t5? They are a little cheaper, which would leave some room to do a couple of other things that have to get done. Like paint, for example.

Any thoughts you could share would be beneficial. I haven't even had the truck a year yet, and am not that familiar.

[BustedCrank]

Changing the rear ratio will help a lot. Although, I would go a little lower (numerically) to make the swap worthwhile.

Or leave the rear as it is and swap in an overdrive transmission. Both would be best for mileage.

I would recommend staying away from the nv3500 as it was mostly behind the v6s in the s10 pickups/blazers. Not going to survive long behind a 350.

The t5 is a little better, it was behind a lot of 305s in its day, but they didn't use it behind many 350s for fear it wouldn't hold the torque for very long. If you do go the t5 route, i would suggest looking for the wct5 (world class). It was the stronger of the t5s and will survive behind a mild 350 if you dont beat on it too hard.

Another option is the nv4500 which is what they used in the full size trucks behind the smallblocks, big block, and diesel. Not a performance transmission as far as smooth, fast shifts for "playful" driving. And aside from the 5th gear nut coming loose (mostly when its behind the cummins, but is also easily rectified), they are pretty stout transmissions.

T56 out of a 93+ camaro could be an option, they are a little pricey, but the double overdrive is nice, and they are completely capable of living behind a smallblock.

[jocko]

I would not use a T5 for a C20, especially with 4.10's, not strong enough. T56 or TKO if you must row your own, my 2 cents anyway. If money is not an object, why not make the switch over to a 2004R or something like that (not that it's THAT expensive)?

[GASoline71]

Being a 3/4 ton is your dilema... It's a hauler and a puller. You need something stout like a M465 or something along those lines. On your engine, I see the alternator is on the wrong side, so the engine might be a swap, or someone put all different pulleys and a long water ppump on the original engine.

Some cats hot rod 8 luggers... but it's usually for pullin'...

Gary

[67 Ol' Bess]

Thanks for the info. I do use it for hauling, but it's also my hot rod. I can't afford anything else, and love the truck. So, it's a hot-rod-hauler. I'm fine with it, and I don't mind being different.

The guy that owned it before me did a number on the pulleys. He offered to give me the original set up (along with headlight bezels and a few other items, but then never heard from the guy again).

You'll also notice the a/c unit--which is just used as an accessory to make the belts work.

I've been looking at t56 transmissions for a while, as an f body enthusiast, it's what I've always had in my Camaro and Trans Am's. But I don't think it is very cost effective. I am looking for something that shifts smooth for when I get on it, but is price effective, that will hold up under pressure.

I definitely want to "row my own" gears. So going the auto route is out. If I need to stick with a 4 speed, I guess I'll go the rock crusher route and drop the gear ratio a bit more. Maybe I'll go to 3:42's. Not very many options, but a big decision to make.

Once again, thanks for the replies.

[WIDESIDE72]

NV4500 is my suggestion
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[SS Tim]

There are different ways to go and I'd see what was available locally for a deal.

The NV3500 is too light of a truck transmission for a 4k lb plus truck even before you load it up to the series GVW of 7500 or GCW 11K.

The T5 and T56 are car transmissions and are input limited in stock form on all but the latest application (post 2000).

As always there are aftermarket upgrades you may have success with.

In your case a NV4500 may prove to be a good trans swap but clutch decisions and other choices.

The stock SM465 with a Gear Vendors O/D and gear splitter is a great combo and work well in these trucks. They can often be found used.

The Ranger manual overdrive (Advance Adapters) that bolts between the bellhousing and the trans. (again SM465) is another alternative unless you see a big block in your future.