The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Help with K20 axle ratio?

Help with K20 ratio?

I just noticed in research that the K20 has a 4:57 ratio and my intent was to have a 4wd for the road and every day use. How easy and available is it to swap out Gears? The K10 original equipment is 3.73 but it may be nice to have 3.07 for gas mileage. Need to figure the ratio's using the 292cid with 4sp with P235/15 tires.

I can get a set of axles from an early 80 or late 70 K10 as another option. Don't know yet on the ratio. Or I could modify one of my S10 4wd but is not designed for the weight of the truck but guessing according to the charts that the width may be close to the 1964. I could adapt something from a newer full size independent suspension Chevy with the front drive of the S10.

I may be confused but that is usually how I start things.

I'm through with computer controlled vehicles so I will build my own that I understand.

...It's STOPPING these trucks from freeway speeds that can be a problem, especially since we now are used to disk brake, ABS equipped vehicles.

I'm not sure on gear sets for the 5200lb rear axle, but with the LT 235/85-R16 tires my 283 equipped K20 would roll right along at 60-65. Beware that that Rockwell T-221 Transfer case whines a bit at speed.

I think that were I building a daily driver, I'd at least swap the T221 for a NP-205, is it? T'case. I understand that they are are more highway friendly.

Once again, it's stopping these things in a straight line from freeway speeds.

I would advise against trying anything with S10 or the '88 and late IFS 4x4 systems, unless you're planning a complete frame swap. Much of the suspension systems that go along with those drive axles would take much more work that it's worth to adapt to the early frame. A better choice would be to get a matched set of '73-'87 axles, which can be easily adapted to your existing leaf spring setup. Gearsets are readily available for them, and even with stock gearing, 4.10 and 3.73 are rather common. An additional plus, the later open knuckle front end will have disk brakes and a slightly tighter turning radius. You will want to run at least a 16" wheel with those if you stay with the 3/4 ton, 15" wheels will not clear the calipers. If you go 1/2 ton, stay away from the 3.08 ratio if you plan on any kind of work with the truck, snow plow/off roading. The 3.08 gear is not robust enough to handle it.
I do agree with the 205 swap, it is a drive through type transfer case, eliminating much of the extra friction in the drive system. Look for one from a '70s Dodge, they were mounted as a divorced style 'case, just like the original T221. The NP 203 with a part time conversion would be another viable choice, again, look for the Dodge variant (Boyce equipment used to have them for a reasonable price).

an easier 205 to put in is out of a 70's IHC scout or p/u. with dodge you have to get rid of those oddball yokes on them. if you can even get a r/side drop 205 you can rob the pieces from a l/hand drop 205(ford) and put in the r/side case. the output ratio between a t221 and a 205 are both the same; so if your t221 is in good shape ,run it .
if you cann get a 205 from an ihc make sure thathat you get all of the IHC mounting stuff; it will help with the installation
ron

Thanks - Great input. My intro is " 1964 2wd and 1965 4wd project"

I have a 87 K30 for my farm truck. That will do all the work. I found this 1964 C10 in great body shape but need a 4wd to get in and out of home in the winter. I found the K20 in a junk yard and it is suppose to have a good frame, so I wanted to combine the two. The whole truck will be rebuilt to a new looking and mechanical vehicle.

I have a 77 K20 with 4.56 axles (All Rusted out) Drove that for about 12 years but gas mileage was around 8 mpg. That was a very strong truck. The 350 motor and transmission is till in good shape. Then I bought the 87 K30.

I want to Build this as a luxury truck and probably put a Silverado logo on it with all the 1964 trim package. I'm thinking about adapting a 1970 Chevelle Grill and dual head light to this truck. Probably even a SS logo on the grill. I need to see if the grill will modify in and look right. If not I will go with a chrome front end.

I called a parts dealer on the K20 axle and the initial understanding is I might not be able to swap out the gears so it might call for another set of axles which I can get from a friends older truck.

QUESTION -> Is their any reasonable reason why I can't mount two other Chevrolet 4wd axles?

QUESTION -> The 205 transfer is mounted on the transmission Correct?? Would this be the same Transfer as on my 1977 K20?

I'm getting the 1965 K20 as a 4wd base and just use different axles? The Transfer of the 1965 is mounted on the Frame Correct? Maybe that is where the noise is coming from?

I originally was going to mount a 4wd under the 1964 but with the coil spring suspension I figured I would need the mounting hardware from the 1965 K20. Then it was suggested that I use the frame to. The K20 has the 292 4sp which I prefer over the 230 3 spd on column.

That 292 is a great motor I have one in my 1965 C60 and that is still running today. Never fails to start and it will lug a load. I hauled a load of crusher dust for the driveway, it was heavy but the truck took it with no problem other than there was not enough brake to handle it. I wouldn't do that again. I put a big load on and did not realize how much heavier than gravel it was.

I'm not really that confused. I grew up in a Chevy Dealership since 1968. I'm just trying to figure out my plan. I haven't got these two trucks home yet. I'm getting the 1964 this coming weekend and have to wait for spring to get the K20 out because the junk yard is all snowed in for the winter. I'm gong to drive the 1964 C10 until I get the frame setup (Sand blast, paint, rebuild engine, trans, transfer, axles) Then I will work on new paint and restoring C10 body for mounting.

LongBox, I missed the idea you promoted and you missed what I posted. I can get Axles from a friends K10 and the year is unknown but it is either late 1970 or early 1980 and the ratio will not be the 4.56 but what is normally under a 1/2 ton.

I'm not afraid of a little 4wd noise I like trucks not cars. Right now I'm running a K30 and that is rougher than a son of a B. Especially here in Maine with the frost heaves.

all told I would run k20 axles from 73-87. larger brakes, better axle brgs and there is a multitude of ratios. the transfer case which was discussed earlier (205) would be an independent t/c, not like the one that is attached to the trans
ron

Your K20 is more than likely a 14Bolt full float. It's probably the same rearend that's in the K30 also. You can get 3.73 and 3.42 gears for it fairly reasonable. Rockauto has a USA Standard 3.73 gearset for $150 bucks. The 3.42 is a little harder to come by, but you can expect to pay around $300 for it. If your carrier bearings are good you can get by pinion just a pinion install kit rather than the full rebuild kit, saving some $$.

As far as axle bearings go, the real advantage is the full floating hubs.

http://eastcoastgearsupply.com/i-12009997-gm-10-5-14-bolt-ring-pinion-3-42-oe.html

Gotcha LongBox, Sorry.

I'm missing something though -- That 205 is listed as used by Chevrolet from 69 -mid 80 -- What is the difference to other manufacturers mentioned?

I talked to Phil and his truck is a 82 K-10 ..or.. My 77 K20 w/4.56 axle -> I could use one of those. -- But cannot use the 1965 292/4sp/&Transfer -- with 205 -- ?? because K10 or K20 transmission is matted 205 transfer ??

??- Does bell housing of 1965 292 cid bolt up to 79 and 80's transmission -- need to check.

I do want to explore somehow to put an independent suspension under the 1964/65 to gain a smoother ride. -- Need to ensure keeping truck level on the road and same track width.

On the Dodge and International, as well as some Ford products, the transfer case was mounted separately from the transmission, very similar to how the stock transfer case is in the '66 and earlier 4x4s. The later GMs have the transfer case mounted directly to the transmission with an adapter. The SM420 was never used with an integrated transfer case from the factory, however, I do believe that Advanced Adapters might make one for it. The later 4 speed trucks generally used the SM465, which has a synchronized first gear. It also has a slightly larger front bearing retainer, which would require either milling the retainer or the index bore of the bellhousing to work with the stock bellhousing in a 65. Some trucks from the early '80s also used the MY6 4 speed, which has an overdrive 4th gear. I can't say for sure about the bolt pattern or the retainer size, as I've never really messed with those all that much.

Either you forgot to type 'non' or you are confusied.

Well, maybe not confused, but definitely mistaken in this case . Could have sworn First was syncro in those.

Hello and I'm Back.

I've noted down the comments, descriptions and advice and studying those to incorporate my plan thanks very much. for a good start

I just finished the purchase of the 2 trucks. The 1964 is not in as good of shape as pictured but worth the $3000.00 and will go through a complete remodel, but I will drive it until I get the 4wd and frame set up and then move the body over with a full paint and rebuild. The 4wd is a 1966 K20 292 4sp with 4:56 axles. The axle is the one with the bolt on front and rear pan. The transmission is missing the gear shift.

Now I've got to make some choices. Do I rebuild the original equipment and install higher gears. The engine, trans, transfer, Frame and axles all look in good shape. The frame has no rot and the shackles and springs are very good. Or I can install a 350 Auto mated to transfer and use newer model axles. The 350 is out of a 1977 K20 with C6P chassis and I remember that I was told it was a 4 bolt Main. It is whether I want an automatic or standard.

I studied the independent front suspension and it will be to much engineering to accomplish.

I will need to add power steering and power Brakes, Any advice would be good. And I will change the springs to give a better ride as it won't be used for a work truck. I have my K30 for that.

I have the shop and assembly manuals and been reading those and studying the rebuild projects on the trucks. Right now I'm compiling my Todo list of items to build the truck that will make a good statement for a Custom Chevrolet Truck with all the trimmings.

So Thank you for your advice and input. And I will figure out how to post pictures as the project progresses

Swap the crossmember from the 77?