1968 f-250, 390, c6, dana 60. I put a rebuilt c6 in, slid the speedo drive gear on the tailshaft, used same 18 tooth driven gear into tailshaft, held it in with threaded adapter, screwed on cable. Speedo worked for 20 or so miles, then stopped working. Removed driven gear from tailshaft, and found teeth worn way down, slightly cupped in at the center of all teeth. No one has a clue what happened, trans rebuilders and speedo repairers can't figure it out. Anyone have an Idea? Also, where could I get another 18 tooth gear? (steel). Part # is C7SZ 17271- some letter (A, B, C, D,) that designates how many teeth. "D' seems to be 21 teeth, "C" might be 18 teeth.

 

I can't tell from your post, but was there a C6 in there before?

Might be that if there was a manual shift the thread twist was left hand and the auto requires a right hand twist on the gear.

Can you add additional info?


John

 

thanks for reply. yes there was a c-6 originally. mike

 

thanks for reply yes there was a c-6 originally mike

 

The C7SZ speedometer driven gears are ALL nylon, not steel.

These are the steel driven gears:

O1T17271A .. 18T Driven Gear / Obsolete

JST AUTOMOTIVE in Lebanon TN has TWO = 615-443-3086.

MILLER OBSOLETE PARTS in Binghamton NY has ONE = 800-546-7278.

No Ford Dealer or other obsolete parts vendor has any.
-----------------------------------------------------
O1T17271B .. 19T Driven Gear / Obsolete

O1T17271C .. 20T Driven Gear / Obsolete

O1T17271D .. 21T Driven Gear / Obsolete

I found a whole bunch of these three.
-------------------------------------
No one has a clue? No one? I find that rather odd.

Why did the driven gear strip? It may be because the drive gear is defective, or the drive gear may not be in the correct position on the output shaft.

Some early C6's have the drive made AS PART OF the output shaft, so if you have this type, and the drive gear is stripped, the output shaft must be replaced.

All of the 1968/69 F100/350's with C6's used steel gears. Some of the 1970/71's used steel gears, some used nylon gears. After 1972 = all nylon.

All the 1966 and later cars with C6's used nylon gears.

 

Mike, our guru can't help, so you might have to do what I did a while back. Spend a day yarding and you will be surprised how many gears are hanging out still on the speedo cables or laying on the ground. Most yard operators will give them to you if you purchase something else while there, or not charge much for them if you don't.


John

 

Thanks, Bill. The transmission rebuilder decided after taking another C-6 apart that there is a spacer shim that goes between the drive gear and the bolt on yoke, that immobilizes the gear when torquing the yoke nut. The old trans did not have this, he says some do, some don't. He is sending the shim. Without the shim, the gear just spins on the tailshaft, as it is not splined on, and slides back and forth while the output shaft is spinning, and supposedly was what caused the driven gear to wear down the teeth. We'll see when it is back together. Thanks for source on gears. Mike

 

Hi Again Bill I am wondering if you have a # and source for a DRIVE gear for the same application? (Slides on output shaft) Thanks, Mike

 

8J17288 .. Spacer-Speedometer Drive Gear / Obsolete

GREEN SALES CO. in Cincinnati OH has FIVE = 800-543-4959.
----------------------------------------------------------
If this is what the trans guy is refering to (I see nothing else in the pic), this actually fits between the drive gear and the output shaft bearing retainer.

Assembly sequence shown in the parts catalog:

Yoke, yoke splined flange, oil seal, output shaft bearing retainer, drive gear, drive gear spacer, output shaft bearing snap ring, output shaft bearing.

The drive gear fits into the front side of the bearing retainer, the spacer fits in FRONT of it. This keeps the gear from moving, because it's between the retainer and this spacer.

The DRIVEN gear fits thru a hole in the bearing retainer, where it comes into contact with the DRIVE gear.

Here is an example of why y'all should have the parts catalog! No more confusion about how things fit! ILLUSTRATION SECTION A76, PAGE 5.

This spacer was not used after 1971.

EDIT: I need the REAR AXLE RATIO to figure out the correct drive gear. There are THREE different ones. Do you know its tooth count?

 

What the are you talking about?

I told him the C7SZ DRIVEN gears he was looking for are incorrect, because they are nylon.

I found him three of the correct obsolete steel 18T DRIVEN gears.

I explained why I believed the DRIVE gear was causing the problem (which as it turned out, was spot on).

In my second post, I explained how the DRIVE gear spacer (why the DRIVE gear was moving around, because the spacer is missing) fits into the trans, even found him 5 extras.

What the hell else am I supposed to do?

 

Hi Bill The rear gears are 3:73 Dana 60. The spacer/bearing sequence was just paraphrased by me, thanks for getting the sequence right. I assume "FRONT" regarding the bearing retainer and the spacer means "front of car, towards the radiator". The driven gear has markings stamped "BJ 66 7" As the drive gear has diagonal teeth, it depends how you look at it as to count. It appears there are 7 teeth. It would be good to know that, since there are 3 drive gears, and at least 4 driven gears, which driven gears went with which drive gears. This parts book you refer to is a desirable item. The link "parts" send me to Rockauto .com, who has lots of parts, but no parts book online. I called them, and they said they do not have any diagrams or parts books that show breakdowns. If you know where I could get such a book, please let me know. Thanks, Mike

 

I will post the gear part number later, right now it's lunch time.

The 1964/72 FORD TRUCK PARTS CATALOG is available on a CD from hipoparts.com for $23.95 + shipping.

The catalog has 4,849 pages of text, 1,961 pages of illustrations.

 

8J17285 .. 7T Speedometer Drive Gear / Use with Drive Gear Spacer / Obsolete

KINSEL L/M in Beaumont TX has 4 = 800-816-2894.

GREEN SALES CO. in Cincinnati OH has 11 = 800-543-4959.

PARTS INTERNATIONAL in Farmers Branch TX has 4 = 888-727-0418.

WESLEY OBSOLETE PARTS in Liberty KY has 2 = 606-787-5293.

Kinsel will prolly be cheaper, they sell their obsolete parts at the original price.

 

Thanks Bill. I have ordered the CD from Hipoparts.com, it will ship today. Total cost w/ shipping $26.95. Way cheap for that kind of info. In the meantime, I could really use the illustration section A76, page 5 to give to my installer, as he is installing today. Also the chart page that shows drive/driven gear tooth count for a given rear end ratio. As the parts catalog CD is in Adobe Reader form, it would be easy to email. svemike@comcast.net, or fax to 707-996-5758. Thanks, Mike

 

Have a Ford dealer nearby?

Go there and ask to see this illustration, it's the SAME one that's in the 1964/72 parts catalog.

1980/89 FORD LIGHT TRUCK PARTS CATALOG / ILLUSTRATION SECTION A70.3, PAGE 3 / Lower pic.

I cannot scan and post, that's why I'm passing this info along. Most dealers will have this parts catalog.

You could also contact FTEpartsguy.com and ask him to send you a copy.

Uh...you want the charts that list all the drive/driven gears?

Boy oh boy, are you in for a surprise...just wait to you take a gander at those charts...there are literally PAGES of them...P-A-G-E-S!!

When you finally find the correct charts, you will see a little black dot next to the drive gear part numbers that when you go to the bottom of the pages to figure out what that black dot refers to....says use with spacer.