Blitz Transfer Case Swap
 

Are C15A transfer cases interchangeable with C60L?
Or are there ratio, linkage, brake etc. differences?

Check the ratios here: http://www.mapleleafup.net/vehicles/.../chevspec.html

C15A case is single speed, C60 two speed.

Parking brake - C15A uses cable to the rear wheels, C60 (S and L are similar) uses a drum on the rear driveshaft actuated by a rod. It is possible to graft the parking brake setup from a C60 onto a C15A case. Early C30 had two speed cases with wheel mounted parking brakes.

Shift linkage - The single speed case uses a lever mounted to the floor to engage the front axle. the two speed case uses an entirely different linkage system to control range, front axle engagement and winch function (if fitted). Actually, there's more than one linkage setup for the 2 speed case. I'm not sure whether all C15A have the crossmember drilled to locate the bracket (both bolts and locating pins) for the shift setup used on the two speed case. The bracket has to be firmly and precisely located as there isn't a lot of adjustment in the 2 speed and PTO linkages (a bit better for the front axle engage). The cab flooor will also need modification as the levers for the cases need different size/shape holes, located differently. Single speed to the right of the case and somewhat slot shaped, two speed to the left and squarer.

In summary, I've seen a two speed case put into a C15A (Cab 11). It took a bit of work but was done. The benefit is that it is better for low speed work. The negative with respect to originality, you have to decide for your truck. I also believe a single speed case could be put into a C60, but why would you want to? I don't think the combination of a heavier truck without the lower gearing available would be good off road, parades, steep hills.

Unless the gears are terminally rusted, they are pretty durable. The bearings to do a rebuild are available (or were when I rebuilt mine). The cases are also pretty solid unless badly abused. Follow the manual and a rebuild isn't too bad. Just be careful on the adjustments of bearing preload and linkage setup (a bit fiddly but not terribly difficult, doesn't need a lot of specialized tooling).

From what I have seen with countless Farmer modifications doing this conversion, you have to cut some of the mounting crossmember to fit the larger transfer case into the smaller trucks.

No cutting on my cab 11......
 

The 2 speed T case was transplanted by a rural mechanics who had a surplus C60.... everything bolts to the rear for the fairleads...... NO modifications needed for fitting the Tcase itself.

Adjusting the linkage is finicky...... frame twist in hill/gulley climbs can shift the T case in neutral and leaves you stranded. The linkage is difficult to dismantle to adjust as the shifting requires the shifting rods to be screw in or out ...... a real headache.....but once it is working nicely it is a charm to drive in low range such as pulling the farm tractor out of a mud hole.........

I will need to fabricate and install pig tails for eventual use of the front fairleads.

But I love it.

Sorted.
 

Thankyou gentlemen ...
Have a seized one in the C60L - replacement supplied by seller, but was considering using one out of my C15A as it is a known functioner - and also one bolt is sheared off in t-case supplied (will drill and retap or swap with old case section).
Will stay with original - now that I'm aware of the 2-speed factor - will be no harm and a good learning curve for me to pull the old one apart once removed from truck - and shorty stays intact. :salute:

For removig the old bolt/stud, unless it broke off way down inside the case, give a try to the trick of centering a nut on the broken off bolt/stud, welding it on (nice and hot) and then wiggling back and forth to free up the offender before turning it out. There's no harm in soaking with your favourite penatrating oil/fluid for as long as you can spare before trying the weld trick. If the first nut shears off, do a second....

I have a 15cwt with a 3 ton two speed transfer. You must redrill one of the top crossmember mounting holes and exchange the lower mounting bracket with one from a c60 machine ss the bolt holes on a 3 ton case are further apart than on a 15cwt. Actually a useful conversion as it adds both a low range and a heavy duty pto drive...the opposit would also be correct if trying to put a single speed box in to replace a two speed.Finally ( Grant your thoughts) there are c60x transfers which are also two speed but I believe they are even wider and heavier than a c60 box..BP

I'm at work today (but had a USB stick with scanned manuals handy) but had always understood the major difference between the various 60cwt transfer cases was that the 60X had different internals to allow for the torque of the driven axle compared to the winch on the other models that was used less of the time. However - looking at the parts manuals, early 60S, 60L and 60X all had different part numbers for the case and cover assemblies but the last version of all 3 used a common part number. I don't have any idea at this point what the detail differences were but there must have been at least some small detail different to justify new numbers. They seem to have supplied the housing (case and cover assembly) only as assemblies, not the case or cover separately so I can't tell whether the cover might have been common to the C15A. The gasket between case and cover is listed as the same part number for all versions of C15A, C60S, C60L and C60X transfer case so the interface between the case halves must have been the same size, shape, assembly screw locations etc.


The frame cross member assemblies for each model are different with several numbers listed for each truck model. For the 60S and 60L, the part numbers are different for 1st and 2nd type cabs (11/12 and 13). For 15A, the numbers vary depending on whether the frame had reinforcements (later) or not (earlier) and a 3rd, later number for cases with "mounting bushing & cushion", but no mention of the cab types. For the 60X, the difference is tied to the thickness of a spacer (early 43/64", later 33/64"), (I'm not aware of 60X having ever been built in cab 11/12 configuration). At this point I don't know the differences between the crossmembers. Field observations will be needed - later in the week.

Great tip
 

Thanks for the tip Grant - will give that a go!
You can see the offender top right in this pic.
Attachment 114575