Hi there, I'm trying to ID the tranny in this C750, I know its a 5 speed, but the original tag on it has been replaced with one that says "Associated Truck Parts". Prob the name of the company that rebuilt it in the past, I'm assuming. not having trouble with it, just trying to research the exact oil the manufacturer wants in it, so i don't end up using the wrong stuff. I see mention on other threads of using SAE 90 in some, not sure if this is one of those. I have some 85-140 ready, it says acceptable for yellow metals, but I'm not sure if that is safe to use or not. thanks
[img alt="C750 codes
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C750 codes

 

I can’t get the picture to post, but if you quote the OP you can see it.

 

1977? If so, trans code 2* = Clark 282V Direct, which is spec'd for SAE 50 (approx. to a GL4 80W90 gear oil). As long as your oil isn't GL5, it's probably OK. ~4 quart capacity. More info here.

* = The 'R' is either "optional fan clutch" or "Calif. emissions".

 

C75 = C750 gas

F = 391 4V XD FT gas V8 (Also referred to as "HD" in the shop manual)

V = Kentucky Truck Plant

X89674 = 1977 numerical series, January 1977 production (Does your title say it's a '76?)

153 = 153 inch wheelbase

G = Chrome Yellow (is that a "G"?) If so, repainted....
EDIT: See post 13 & 14
3 = Dark Red Metallic, although this is shown as a model year '78 color.

C755 = C750 gas, 27,500 lbs GVWR

4A8
4A = Black Leather Grained HD Vinyl
8 = Standard Cab without sleeping compartment. Cab and chassis vehicle. Body type = 91A

R2
R = This is the auxiliary transmission code, also used to denote special equipment.
R = Fan clutch in sound package or engine with California emission. (supposedly model year '78 designations)
2 = Clark model 282V five speed direct transmission

HH5
HH = Eaton model 16221 two speed rear axle, 18,500 lbs capacity, 7.17 / 9.77 ratios (per shop manual) (Eaton 17221 also shows for this code, same specs)
5 = Ford 9,000 lb capacity front axle, without power steering.

27500 = 27,500 lbs GVWR

710915
71 = Los Angeles District Sales Office (thus possibly the CA emissions indication)
0915 = Special Order Number

As OEM 50W motor oil or 90W gear oil were mentioned. Apparently those two flow similarly.

Other info says to beware of corrosive additives in high pressure gear oil.

I think your 85-140, "safe for yellow metals" is a safe bet.

Note the discrepancies in the decode--anything seem off there? Does it look like a repaint? You say it's a '76 but the serial number is '77--any idea on that?

Air brakes?

 

CDL required then, unless farm use exemption or similar.


Engine oil and gear oil have different viscosity scales; from what I understand, SAE 50 engine oil and 80W90 gear oil have approximately the same viscosity (centistokes: "Centistokes (cSt) is a unit of kinematic viscosity").

 

thanks for the info! much appreciated, yes likely calif emissions, plenty of vacuum hoses on there, that's how they do it out here in the south west. I'll check the GL on this oil before filling her up. no clutch on the fan. Good to know the make on the tranny, no discernable markings on it, so your insight is very helpful. thanks again for your time.

 

thank you for the code read! The papers i have refer to it as a 76, but good to know the actual. It's definitely been repainted, but i don't see any signs of yellow, currently white but looks to be red originally, as for air brakes, the bendix compressor under the "hood" is for trailer brakes only, juice to the cylinders. The engine is a 389XD, as per the sticker on the air cleaner, is the block/heads the same for both? good to know about the oil, much appreciated. I also plan on changing the oil in the eaton, should be interesting, as I dont see a drain plug... what is the recommended flavor for that rear end? thanks again. the info on this site is priceless!

 

391 and 389 are the "same" engine. The 389 was the later version with some revisions, some say smog version. The 361 became the 359 also.

Factory info, including interchange info.

https://www.ford-trucks.com/forums/1...l#post21297703

 

A air brake trailer package added to a juice brake truck! That’s an oddity I’ve never seen before

 

For the main axle, MPC shows one.



Plug is listed as
C8TZ-4A309-A Trap (filler plug) - magnetic - 1" x 11 1/2"

From https://www.ebay.com/p/1835677941
Looks like it seals on a gasket.



From https://www.ebay.com/itm/256157477085
Seals on threads.




For the two-speed shifter motor, which uses SAE 10 oil, no it doesn't have a drain plug so you have to use a manual fluid vacuum extractor. I've had a for decades but everybody and their brother sells one these days, even HF, for a lot less than what I paid for mine. You can also round up the cover gasket and just remove the cover to drain the oil and spray out the housing. More info https://www.ford-trucks.com/forums/1508736-f-7-two-speed-rear-axle-eaton-16600-electric-shift-mechanism.html .

Link in my first post: here.

 

I'm going with 'J' for Rangoon Red.

 

Yeah, seeing the compressor had me confused when I first went to figure out the brakes, I was assuming there would be air brakes of some sort at the wheels, but upon further inspection it was obvious that there were only hydraulic lines and cylinders involved, and that all the air action went to the gladhand and air chuck on the rear bumper, also a control lever on the steering column. I'm assuming the trailer had some type of load/ momentum sensing setup at the tongue to apply the brakes? the compressor works, but missing the air filter, and since I'm not pulling a trailer, I deactivated it. If I install an air horn, I'll put the belt back on.

bendix compressor

 

hey I looked at the tag again, and for the color it shows a "3", not sure how many shades of red they offered, or why it's not a letter, but the original color is red from what I can tell

 

MPC doesn't list a '3' paint code until '78, go figure . . . but it's a red

 

That is super good information to know, I hadn't put any thought as to the servo, I would have assumed it was lubed by the diff oil, I'll dive into that one for sure, thanks. I also found the drain plug, the diagram is very useful, let the fun begin!