4 Speed Swap

[EClawz]

Hi everyone! I am new to the Chevy truck world and need some help! I recently purchased a 1964 C20 as a fun project to work on in my "Free time" This truck has a 283 and I believe the SM420 and 4:10's? What I would like is to be able to daily the thing and be reliable enough to go to school and back when I need or to the woman's place (both about 200 miles one way) The issue: Granny Low & no O/D. Most of this trucks life while I own it will be on highway and interstate(Hopefully) so 45-75 mph. I am not sure the best route to go with being able to obtain comfortable driving rpm's at 75 or so while still being able to actually drive the thing with some amount of power. I've looked into tranny swaps and it's a bit more of a headache than I want but could be convinced otherwise IF it doenst cost an arm and a leg! I am on a budget being a college student and all... the other option I looked into was a R&P swap, much easier and cheaper. Any and all advice is welcome and appreciated! Thank you - Eric

[jayoldschool]

TH200-4R or TH700R4 for auto, or T5 for manual. All can be done on a junkyard budget. There are how-tos here on the forum for each.

[EClawz]

No autos gotta keep a manual... my current daily is an 04' ranger 3.0 with 71k on it so I want something with so balls and a manual. Ive thought about a T5 but have heard/seen many issues with them in trucks and v8's even though this one isnt a large v8 nor does it have a ton of power...for now. Can you get a T5 with out haveinhg to do a hydraulic clutch conversion??

[jtrichard]

Originally Posted by EClawz

Can you get a T5 with out having to do a hydraulic clutch conversion??

YES ................
Here is a good write up on T5
http://67-72chevytrucks.com/vboard/s...d.php?t=482069

[TwoFiftyShifter]

Axle swap is my vote. 73-87 with 3.42 gears 8 lug. Some even had 3.23 gears.

[franken]

The C20 or 3/4 ton rating, engine, trans and rear were all designed to work together when the truck was built. In 64 you could legally drive 70 on a 4 lane undivided road, but gas was cheap and no one thought much about RPM, or gas.

A 3/4 ton wasn't really made to make frequent 200 mile trips, but not long after there were camper specials with about that combo running around, probably w/ a bigger engine.

You need to find the rear diff ratio first.

A T5 is a poor choice because its known to be weak in any form. In a 4000lb brick?
For one the 283 may not be able to push the truck around and 2nd it may die.

A 73+ diff will have wider spring perches, different shock mounts and the WMS may be wider. Not to mention its probably a trailing arm rear, so a 73+ will definitely need mods since they were all leaf spring setups. Maybe better to swap the R&P. I'd look into what rear diff you have. My guess is an HO52/72, which is great, but getting gears, and maybe brake drums could be a problem. Brake conversions are out there, but research the R&P swap to lower numbers.

The NV4500 is a good trans and may almost bolt in but some creativity would be required. The 96 and up ones have an somewhat usable and synchroed 1st (Earlier ones had a granny 1st/low like the 420/465). They can be had as cores for cheap if you troll CL (I picked one up for $75) but its rare. They also have some issues and generally need a rebuild. You may want to look into the overall length of the SM420 and that of various NV4500s. Some 4500s were slip yoke output and some were a U-joint output. What's your trans? If the trans length is similar, and the outputs the same, you may save by not changing the driveshaft. You should get the Advance adaptors conversion guide and catalog.

People have redrilled the existing BH for the NV4500 and bolted from the inside out. This means your original bell, and clutch can be used.

The NV3500 is also a truck trans that can work, but its not strong, think 1/2 ton, but better than a T5. Same ideas above apply to swapping most any trans.

Finally, it may be cheaper to pick up a tiny beater car and eat the insurance money...

[spookylynx]

look around for an old Saginaw 4sp out of a Camaro or Firebird. They are around, people will say they are weak, but as long as your not bang shifting the thing off a red light you'll be fine.

[TJ's Chevy]

NV3500 is also a good swap. It's a 5 speed though.

[Tazimafied]

That Saganaw is still going to have a 1:1 final drive ratio leading to a gear swap.

Ever thought about one of these? It will give you another shifter to play with and splits all you gears giving you an 8 speed with overdrive. You will have to shorten your drive shaft about 7" though.

[EClawz]

Thank you for all of the input! I am on vacation and have only owned the truck for a week so not a ton of info yet. A R&P swap would be the most favorable if a decent set of low gears would be available. I would love a torque splitter but that is more than I bought the truck for so kind of out of the question right now.
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[Captainfab]

If your '64 C20 has the Eaton HO52/72, which it more than likely does, there are no new gears available for those. If you can find a good used 3rd member, the highest gears you are going to find are 4.10's. The most cost effective option for you is a differential swap. Find a Gm 10.5" 14 bolt, or even the 9.5" SF 14 bolt with 3.73's or higher and install that under your truck. Be aware that cutting and welding will be necessary. If you do go that route, I do make trailing arm mounts specifically for the 14 bolt.

Also a taller rear tire will help reduce the rpm's. A 235/85R16 is about 32" tall.

Originally Posted by EClawz

Thank you for all of the input! I am on vacation and have only owned the truck for a week so not a ton of info yet. A R&P swap would be the most favorable if a decent set of low gears would be available. I would love a torque splitter but that is more than I bought the truck for so kind of out of the question right now.
Posted via Mobile Device

[EClawz]

Axle swap sounds like a decent start.. what would be the difficulties of doing it and keeping leafspring setup? sounds like potentially less work but have not seen any threads on it. Are there any pros or cons associated with keeping leafs over the factory trailing arm and coil spring? What would be the best and least expensive axle, Dana 60, 14b out of a...?

Also found a nv3500 out of an 88' for $400 for any and all parts. Thoughts?

[cryowagon]

I drove a 1967 F-250 (I know) for years with a four speed and 4.10 gears. Made many 200+ mile trips with no problems. Though with the engine churning 3500 rpm's at 70 and 4000 at 80, it was loud. I usually kept it about 75 - 78 mph. Gas mileage was anywhere from 7 to 9 mpg or so with a good tail wind.

[Captainfab]

I think keeping the trailing arms and coils will be easier and less expensive than trying to convert to leaf springs. The coils are going to ride better IMO. If you could find a Dana 60 from a '67-'72 C20, that would be a direct bolt in. The big block trucks were available with the optional 3.54 gears. Otherwise I think that a '73" 14 bolt would be easy to find and not too expensive.

Here's a thread that shows a 14 bolt swap.

http://www.67-72chevytrucks.com/vboa...d.php?t=624445

Yes you could change the trans to a NV3500, but you will have to remove your current bellhousing crossmember and install a trans crossmember at the rear of the NV3500. You will also have to convert to a hydraulic clutch. The booster bracket kit that I make and sell for the hydraulic clutch conversion is $223.85 shipped.

Originally Posted by EClawz

Axle swap sounds like a decent start.. what would be the difficulties of doing it and keeping leafspring setup? sounds like potentially less work but have not seen any threads on it. Are there any pros or cons associated with keeping leafs over the factory trailing arm and coil spring? What would be the best and least expensive axle, Dana 60, 14b out of a...?

Also found a nv3500 out of an 88' for $400 for any and all parts. Thoughts?

[nail pounder]

I have a 350sb w/ NV3500 & 235/85/16 in my stock 66 C20 (ho52 rear) and it'll cruise 70 all day long @2400, first gear is still pretty low so a rear end will be in my future eventually.

[EClawz]

Originally Posted by nail pounder

I have a 350sb w/ NV3500 & 235/85/16 in my stock 66 C20 (ho52 rear) and it'll cruise 70 all day long @2400, first gear is still pretty low so a rear end will be in my future eventually.

Could you give me more details about your truck? Where you got the motor and trans, how the swap was, what sort of troubles you encountered.... anything would be helpful!

[nail pounder]

I didn't do mine, but I know there are threads on the swap. I was lucky enough to pick up this gem for $2500 with the motor & trans in it. It had really small tires & needed some love. With the help of my daughter, alot of elbow grease and another $2600 here it is.