Toploader Driven Gear Replacement -Help

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Hi Guys:
After having fixed my SW Tachometer so that I now get stable and verified readings, and spending some time verifying that my Jag differential is indeed a 3.31 ratio rear end I deduced that my high engine RPMs in 4th at 60 MPH was being caused by:

1) clutch slippage (unlikely as none has ever been felt or observed)

or

2) wrong drive or driven gear in speedo cable (probable)

So my son and I took the Cobra and his car out for a drive at 60 MPH and sure enough, when he was cruising at 60 MPH my speedo registerd at 50-51 MPH! SO it seems that the current driven gear is not the correct one.....

I did the math for my rear wheels and tires and diff so it seems I need an 18 tooth driven gear.

So much for the background, now for the question. ..

I have not changed a driven gear before in a toploader. It appears easy, but then everything does before you get into it. However, there appears to be a "Clip" and perhaps a gasket or "O Ring" involved. To be on the safe side, should I have a spare of each of these on hand?

ALso, is the change out of the gear rather straight forward?

Will I have to drop the trannie? (Gosh I hope not)

What else should I have on hand to do the change? IE: gaskets, special tools, will I have to drain the trannie lube? Should I learn any special incantations, spells, etc.

Thanks in advance for you help and time.

[Ibr8k4vetts]

A jack, jack stands and a 7/16 wrench should do it. just make sure you have the right gear some are cut /// others are\\\ and thats it.
Mike

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Thanks Mike:
Got the jack and stands. Is the driven gear fitting above Toploader oil level? Is the clip that holds on the current gear reusable? Does it come off easy or can I butcher it up? (if that could happen, then it would happen with me )

Thanks

[Ibr8k4vetts]

It's above the oil.The clip can be pulled with you finger, but a small screwdriver works better. mike

[PatBuckley]

Does anyone have a part number for that clip? (or tell me where I can buy one?)

[steve meltzer]

I was about to undertake the same project, but didn’t need to. Your drive gear, with in the tailhousing, should be black. To replace it almost certainly will require an R&R of the tranny. Drain the gear box before pulling the driveshaft/yoke from the output shaft. If you need to replace the drive gear, you can do it with regular tools, but you will need the gasket between the tailhousing and the gear box itself. If you need the driven gear, it can be replaced in the cable without removing the gear box, but that 18 -tooth gear is a bear to find. I think your calculations for the gears are correct, but might check this website...http://www.boss302.com/speedo.htm
pretty good and well-written.

steve

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Thanks Guys. Ya, it is the 18 toothed driven gear I need for a SW speedo. I will give David Kee a jingle today. His website sadly does not list it as available. I wonder if this is going to be another interesting parts hunt. Mustangs Unlimited does show this part, availability unknown.

Does anyone know of other sources for Toploader Driven Gears for the speedo cable? I need an 18 toothed jobber for the SW 0-160 vs the Smiths 160 to 0 reverse speedo.

[steve meltzer]

Art, you might try Green Sales 800-543-4959 in Cinti Ohio. According to them, they sold me the last one. I'm thinking of making a bunch of these, so check with me in a week or two and I may have a better idea...they're tough to find, discontinued by Ford and neither Kee nor John's Mustangs had one two weeks ago. steve

[trularin]

I have a top loader. The gear is okay to service, if you have the tools.

I can give you an outline:

1. Secure the driven gear and gaskets before starting.
2. Get the car in the air.
3. Disconnet the present speedo and any other items attached to the tailstock like the shifter and linkage.
4. Remove the drive shaft.
5. Place pan under tail stock to catch fluids.
6. Undo and remove the four bolts that hold the tail stock to the tranmission. Remove the bottom right bolt last.
7. Place a jack stand or jack post under the transmission and take the pressure off the tail stock.
8. remove the center bar.
9. remove the tail stock.
10. Check the seal, copper bushing and gasket before you continue.
11. Push the retaining clip in and pull the driven gear.
12. Push the new driven gear into place and make sure the retaining clip is in place.
13. replace as necessary the seal, copper bushing and/or gaskets.
14. reassemble. Should take about an hour ( if you are clean ).

This may look inclusive, but I think I left out a step or three.

Hope this helps!

[trularin]

Crap!

I forgot the incantation!

You will most likely need to say sacred words as you go through this.

Fu%k
Sh&t

Are the most widely, accepted and used magic words for this proceedure. They also work on other tasks of simular nature.

To add strength to the incantation, add Mother and Holy to these words as adjectives.

Good luck!

[mr0077]

Don't forget the 12-pack of Bud...

[DAVID GAGNARD]

Red;

Just go down to your local Ford dealership for the gear,changed mine in my Tremec and went to the Ford dealership and they not only had plenty in stock,they even figured out for me which one I needed..... Seems these gears are color coded and very universal,they fit almost all trannys used by Ford (toploader,c-4,c-6,three speeds and even Tremecs).....

David

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Trularin, Dave and MR0077!

Thanks for the detailed information AND the procedure. I just cannot thank you enough for the time and effort to give that information. Much Grass Amigos!

Trularin:
Is the process you described for the DRIVE gear (ie the black or pink one on the tail shaft?) or the DRIVEN gear which is on the end of the speedometer cable?

I got a lead on some potential local sources for the driven gears. Seems there is a local old established trannie shop nearby that may have a small supply of these gears laying about in their massive parts bins. I just need to pull my old one and trot on down there to match it up with some new ones. Apparently there are two types: Type 3A and Type 3.

I think I may go with the 17 toothed model as it would be more optimistic and thus perhaps tell me I am doing 62 MPH vs the 18 which would tell me 59 or 58.

When I get some time, I will put "Half Full" back up on Jackstands and go at it.

As an aside... its friggin snow flurryin' outside right now. Gosh I Love Winter...

[Ibr8k4vetts]

OK I'm lost..... Ithought we were talking aout the one on the speedo cable, why can't you just change that one? Mine was off by about 8MPH so I just changed the one on the cable. Mike

[steve meltzer]

Art, as previously noted you need the black
drive gear (in the tailshaft) and the green-tipped
18-tooth driven gear. steve

[steve meltzer]

Oh yeah, and one more thing..if you have a tire
that is 26" in diameter and a 3.31 axle, the black
drive gear with a green tip 18-tooth driven gear
will give you a speedo that is virtually 100% accurate.
steve

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Hi Steve!
I talked to the previous owner and he recalls that the drive gear in the tailshaft is indeed colored black. So I will just be getting both an 18 and 17 toothed gear for the end of the cable. Thanks for your help OM.

[trularin]

Your are right, I was talking about the drive gear, my bad.

If you know the drive gear, and JUST need to fix the driven gear, just unbolt the hold-down-clamp and pull the assembly out of the tail stock.

Sorry about that, got carried away with the moment.

Cheers

[REDSC400]

No No, No Problem at All.

However, at first, I did want to brush up on my incantations and spells....

Shucks... ya had me goin' there amigo.

In any case, we have the procedure for changing the drive gear.

Just talked to the former owner of #375 and he has a set of driven gears somewhere in his garage so he is going to hunt them up and ship them down to me. He also has an original Stellings & Hellings 9" air cleaner and some other fuel system things (AN fittings and such) that he found when cleaning out the garage.

Ohhh. Im happy.

Bad news is that is SNOWED here last evening. Just a dusting but half the state was in a black ice situation this AM. Not Nice at ALL. Noo Sir Eeee.

[trularin]

Snowed and dropped to "very cold"

I got everything ready for the white stuff, but would rather have it later in the year.

Good to here you got the gears, those magic words work on just about everything, so you may want to write them down.

Good luck and have a great holiday.