I was hoping to service my rear axle and see if seals were available. First step is identifying this single speed rear axle and locating the fill plug & level, and finding service documents.

 

I'm guessing it has to be one of the F6 single speed ones mentioned here, but haven't been able to connect the dots. Any help appreciated!

 

Comparing your photos with the descriptions in the service manual, it appears your axle is the one described starting on page 168 of your service manual, Split Housing Hypoid Rear Axle for F6 and F7 trucks. All of the 8TH axles would be the same except for the gear ratio. I can't read your stampings, but somewhere in those numbers may be the ring and pinion tooth count. The axle ratio may also be stamped on the glove box tag, if so equipped.

 

That axle will be one of the three listed for an F6; 8TH-4209-A, 8TH-4209-B, or 8TH-4209-C, depending on the ratio. It is a split housing Timken hypoid axle. The F5 and smaller trucks had Timken spiral bevel axles. The wheel seals are the same in the F4-F6 axles, single speed and two speed. I have the number for those in the shop and I can post that tomorrow. I don't have a number for the pinion seal, but I can cross reference it to a modern replacement if someone can post the Ford number.
Mark

 

Pinion grease seal, 50-55 F6 with single or 2 speed rear axles, 8T-4676-B

 

Thanks, Wayne. That is the same seal I just installed in my two speed, and I have the crossover for that. I will post them tomorrow.
Mark

 

Thanks all! I think I am in agreement that it is the Split Housing Hypoid Rear Axle. Unfortunately, I find the shop manual frustrating. The section starting on pg 168 mentions nothing about any gear oil (except to lubricate seals and bearings before installation). The exploded diagram dosen't even show a drain plug at the bottom.

 

These are the part numbers for the ring and pinion kits for the Timken model E155 single speed rear axle.

BB-1175-C .. Rear Wheel Grease Seal - 4.56" O.D. / Timken # A-1205-P-276 / Obsolete

1948/52 F4/F5/F6; F5/F6 COE; F5 Parcel Delivery.

CARPENTER NOS OBSOLETE PARTS in Concord NC has 5 = 800-476-9653.
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8T-4675-B (replaced 8T-4675) .. Pinion Seal - Timken E155 / Eaton # 12650 / Obsolete

No Ford dealer or obsolete parts vendor has any.

Pic: Rear Axle Application Chart .. JH = F5 Parcel Delivery; TL = F4; T = F5; TH = F6; W = F5 COE; WH = F6 COE

 

Here are the crossover numbers for the seals you need. The 8T-4676-B pinion seal crosses to National 410737 and C/R 22425. The hub seals BB-1175-C crosses to National 5751 and C/R 31288. I used both National seals, the 410737 pinion seal and 5751 hub seals, on my two speed axle. The 5751 National hub seal has the deep flange out the back of the seal and is leather like the original seals. The C/R hub seal is rubber, but if I remember correctly it doesn't have the flange. The flange is to help direct any oil that may leak past the seal into the cone on the backing plate and out the weep hole in the backing plate. These seals are available at most any parts store.
Mark
Also, in case you are not aware, there is a large snap ring retaining the seal in the hub. Usually they are covered in old oil and dirt and are not seen.

 

Thanks for the seal part numbers and such! I'll have to think about if I want to replace all the seals and such. I think first, I'd like to top off the gear oil and monitor how much it leaks. I presume 80W90 would work? I Still haven't located a fill location or an appropriate fill level. (On my F5, there was an obvious fill plug and you filled it on level ground until it started to leak out the fill plug.)

 

Isn't the big hex nut protruding from the side of the case by the pinion in your 1st photo the fill/level plug? Your axle would have had either 90W or 140W in it originally. I would top it off with one of those. If you were to do a flush and refill, you could use a multi weight gear oil, but you would want to make sure that it is yellow metals safe. There are bronze thrust washers on the differential side gears. If I understand correctly, if the oil has an MT-1 rating along with GL-5 or GL-6 rating, it is rated for manual transmissions, therefore yellow metals safe. I just flushed and refilled the Eaton two speed I installed in my F4. I used Mystic 85/140W gear oil that has the MT-1 and GL-6 ratings. The Eaton axle has bronze thrust washers in it also.
Mark

 

That big hex nut seems way to low...

 

It looks like it is at about the same level as the plug on my Eaton axle.

Mark

 

Well, I guess I'll try to find yellow safe gear oil and top her off through the hex nut.

Seems to be some contaversey if GL-5 is yellow metal safe.

 

140W gear oil is available at many parts stores. It is yellow metal safe. As far as I understand, GL-5 and GL-6 gear oils are yellow metal safe if they also have the MT-1 rating.
Mark