C60X Master Cylinder rebuild kit

[RHClarke]

Mike, What is the inner diameter of the of the cylinder? Jim Carter's in the states has rebuild kits.

Rob

[Grant Bowker]

I don't have a listing of a source for either the entire rebuilt master cylinder or rebuild kit but the manuals list the diameter as 1-3/4" (compared 1-1/4" for the Ford and Chev 15-60 cwt trucks).
I haven't done an exhaustive (or exhausting) search but www.steelsoldiers.com www.wheelsofvictory.com www.obschevy.com (Tim Tygart) www.oldchevytrucks.com (Jimmy Carter) www.chevsofthe40s.com all came blank so far. I haven't tried catalogue surfing at CarQuest or NAPA yet. Now that I have a C60X I need to start looking for sources for parts to decide about working on it.
Can anyone help with sources?

[Harry Moon]

Hi Grant
i have a little C60X project in the works too. I think I sorted out my bellhousing flywheel. i used a regular CMP bellhousing with a smaller diameter(than a CCKW) flywheel. Tryying to find out if it was a different clutch and disc than other CMP's
the tranny is different but would one of my CMP tranny' fit?
was I right that the bellhousing was the same?

[Grant Bowker]

I'm away from references until tonight, will check parts #s for the two bellhousings. From memory the clutch is 11-1/2 or 11-3/4 inch diameter for the C60X which seems larger than I remember for the C15-C60 series, this can also be checked. Do you have good sources for how close C60X is to CCKW or AxKW for engine (and transmission?) and brake system? There are two different brake booster systems listed in the parts manual (easiest to tell the version by length, early 13+ inches, late 21+ inches), but only the earlier one seems to be mentioned in the maintenance manual I have.
The next interesting puzzle will be to see what I can find out about the steering shock absorber.

[Grant Bowker]

Clutch facing diameter C60X 11-1/2"
Clutch facing diameter C60L 10-3/4"
Cluch "driven member" is same part# for CCKW, AFKWX and C60X, naturally C60L is different.

Bellhousing or clutch housing - C60X is different part# than C60L and CCKW and AFKWX, even the cover for rear of flywheel viewing is different #. The C60X bellhousing is more similar to CCKW part# series than C60L. But odd to note some CCKW minor parts in this area are common to C60L and not C60X.

Transmission - all ratios except direct (obviously) are different C60X to C60L, many specified clearances are different too. Shift pattern is different C60L to C60X. Case part# and internal parts are different C60L to C60X and also seem different to CCKW and AFKWX. The few internal parts I checked #s on were different too although the part #s suggest C60X is closer to the same series of parts as CCKW than C60L. The commercial use of the C60X transmission parts (if any) is unknown. The case and transmission assembly for the C60X unlike the C60L is marked * in the parts list, indicating CMP unique.

Master cylinder - The rebuild kit listed for the late C60X is also listed as fitting the CCW and CCKW. The rebuild kit for the early C60X doesn't appear in the Master Parts List for the CCW and CCKW. The illustration of the master cylinder for the C60X is virtually identical to the one in the GMC Master parts list for the AFWX-354, AFKWX-352 and -353 as well as CCKWX-353 and some CCKW-353 and -352. I don't know if this is a case of using an existing illustration to identify parts for a mirror image assembly due to RHD compared to LHD or if the cylinder assemblies were truly the same. Neither the complete assembly or bodies nor the input shaft for the C60X show in the GMC Master Parts List but many of the internal parts are the same. This suggests to me that the mirror image theory might be valid.

The steering shock absorber seems to share many component parts with the C60X front shock absorbers but has a separate assembly part #. This might reflect something as minor as the arm being set at a different angle for the different use...... One style of C60X front shock matches a C60L part#, but there are several other #s that don't match. The shock assembly #s are also different to CCKW and AFKWX and by the time I came to this I was not going to spend time checking individual part #s.

Sometimes, the more I look and learn, the more I realize I don't know. That's where this seems to be heading after an hour and a half in the manuals.

[Harry Moon]

Thanks for your efforts Grant they help a lot. So it is indeed a different bellhousing and mounting system for the C60X. I thought it might be as there is no crossmember at the transmission just boxed flanges out of each side.
So I'll go out tomorrow and take some measurements. I could just go with the bellhousing and CMP trans that I have. I think it being smaller won't create the same issues as the other way round. Now having read all about engine swaps I think this combo would also put the 270 in a C60L with the requisite modifications to the front mount and radiator support and shrouding. I wonder if the differences between early and late C60X' (never new that either) similar to early and late CCKW's? My trans and bellhousing from the CCKW I stripped are different than one of our members CCKW.