K10 to K20 Conversion

[hotrodpc]

I have an 85 K10 that I am going to be building soon. It currenty has the stock 10bolt 3.08 front and rear diffs. I already have 14bolt FF 4.10 and keeping my eye out for an 8 Lug D44 or D60 with 4.10's for the front diff. I am sure I can bolt these axles to the same springs already in the truck. I also at some point intend to do a 6 inch suspension lift. I know in 2wd models, the 3/4 ton springs are longer than the 1/2 ton springs. I believe its 4 inch longer for the 3/4 ton.
Questions are, Is this true for the 4x4 models too? Are the rear springs longer? Can I remove the rear springs hangers from a 2WD 3/4 and is the 4x4 K10 frame punched for the 3/4 ton hangers where I can use hardened bolts to mount the 3/4 ton rear spring hangers in a K10 frame???
How about the front spring differances between K10 and K20??? Is there any differance at all?

Anything else I am forgetting for a K10 to K20 converson? Brakes will come on the diffs already, and maybe upgrade the master cylinder if there is a differance, and likely going to use bigger driveshafts too.

[hotrodpc]

Yikes !!! 25 views and 0 response. I assume that means noone knows?  It took me awhile, but I finally was able to find out the info myself. So for those who may be interested in knowing....

Front Leaf Springs
K10, K20, and K30 Use the same springs. Differance is, they come in 2 leaf, 3 leaf or 4 leaf set up. All 3 set ups are interchangeable between all 3 models.
I'd imagine the K30 comes in the 4 leaf set up, but the K10 and K20 could be either the 2 or 3 set up depending on heavy duty RPO code or not.

Rear Leaf Spring 2WD C10, C20, C30.
C10 can be 52 inch or 56 inch springs. Depending on Heavy Duty RPO code.
C20 is 56 inch springs. # of leafs and thickness of spring pack depends on RPO code, ie... Smooth Ride, Heavy Duty etc.
C30 is 56 inch springs. # of leafs and thickness of spring pack depends on RPO code. 10 Leafs is Heavy Duty 1 ton.

Rear Leaf Springs 4WD K10, K20, K30.
K10 is 52 inch springs. # of leafs and thickness of pack depends on RPO code.
K20 can be 52 inch or 56 inch springs. Depending on Heavy Duty RPO code or not. (Appears that 52 inch may be more common)
K30 is 56 inch springs. # of leafs and thickness of spring pack depends on RPO code.


Also, the K10 and K20 use the same master cylinder and have the same frame specifictions, so by simply swapping axles, it is possbile to convert a K10 to a K20. Might aslo need to add a leaf to the spring packs. But it is very possible that a K10 with Heavy Duty RPO code, could have the same amount of springs already, as a standard duty K20.

Hopefully someone besides me can use the info. Thanks for all the help.

[Irish_Alley]

sorry didn't get to read this before, but i was going to say it can be done we put 3/4 axles under a k5 no problem. even the frames on 3/4 and 1/2 are the same thickness like 5 or so inched unless i think if you go to hd 3/4 i know the one tons are about 8 inches and like you said i think the 52s are more common

[zieg85]

Less than 12 hours since you posted, I would expect an answer immediately.  It is always more satisfying finding the answer yourself.  Eventually someone will respond and this subject has come up before so you can always use the search function.  Thanks for posting what you found, good luck with your search.

[hotrodpc]

sorry didn't get to read this before, but i was going to say it can be done we put 3/4 axles under a k5 no problem. even the frames on 3/4 and 1/2 are the same thickness like 5 or so inched unless i think if you go to hd 3/4 i know the one tons are about 8 inches and like you said i think the 52s are more common

I just thought it was interesting that 2WD 1/2 ton, and 4WD 3/4 ton could use either 52 or 56 inch.

[Irish_Alley]

they are the same frame

[Captkaos]

I am not sure this is what you are asking, but the 2WD perches are not the same as 4x4 perches.
The difference in a the std vs HD springs is the rear hanger location.

[hotrodpc]

I am not sure this is what you are asking, but the 2WD perches are not the same as 4x4 perches.
The difference in a the std vs HD springs is the rear hanger location.

As far as the hangers go, yes on the C10 and the K20. Everything else, the hangers are in the same location. (According to what I read)

Do you by any chance know the differance in a 2wd perch and a 4wd perch? Its my understanding its not the spacing, so a 2wd rear end should bolt into a 4wd and vice versa.

[Captkaos]

The axles front and rear are the same as far as perch mounts. (minus the dually cab chassis for example)

[hotrodpc]

The axles front and rear are the same as far as perch mounts. (minus the dually cab chassis for example)

Are you saying the perches are the same between the K10 and K20???
You mentioned above the 2wd is differant than 4wd perches. Do know what the differance is between the 2wd and 4wd perches.

[Blazin]

The front rear spring hangers are taller on the 4x4's. In other words they hang down below the frame farther. Not sure if this is the answer you are looking for but now you know! 

[hotrodpc]

Thanks Blazin. That I did not know. But makes sense. So that is likely how the height differance in the front end is compensated for.in the rear end. Good to know hwere its done at. Do you know if the hangers are completely differant on 1/2 nad 3/4 or are they just rived on lower to add more height.

[VileZambonie]

I can make a measurement between the K10, K20 and K30 spring hangers since I have one of each if you want. The spring perches should be all the same.

[fitz]

 Do know what the differance is between the 2wd and 4wd perches.
[/quote]

  On some of the light duty 2WD trucks the rear spring hanger does not have the support bar that reinforces the hanger. You can see the arrow pointing to this bracket in the first pic, the second pic shows how it mounts.
  This set up is on my 81 4x4 stepside. I have a 82 2WD stepside that I assume is a light duty GVW because it does not have these brackets on it.

[hotrodpc]

Awesome guys !!! Some great info.
And sure measurements between the 3 would be great, at least for purpose of the thread and all the info in one place. Its my understanding the C10 and C20 frame are the same, and the C30 frame is taller rails, and same on K10 and K20 frame being the same the K30 frame is taller rails.

Thanks for all the input. The more the better.