Pinion gear

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Model T Ford Forum: Forum 2017: Pinion gear
Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 04:01 pm:

The ring/pinion in my '23 touring is something other than standard. I know this because the previous owner told me, and by how the car bogs down, especially in 2nd.

Question is ... if the ring gear ends up being a standard 40 tooth, can I just replace whatever pinion gear is in there with a standard 11 tooth and avoid the big overhaul job?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, July 03, 2017 - 04:07 pm:

You can, however, you need to set the clearances and be sure that it doesn't bind. It might be noisy because the existing gears are worn to mesh and the new gear will not exactly match the wear pattern on the old gear.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Monday, July 03, 2017 - 04:11 pm:

Unlikely. Assuming that you do have a 40 tooth ring gear, the larger pinion that is in there now may be too big to come out of the front hole of the axle housing. If it does come out, how will you ensure that you have the proper backlash and gear mesh with your standard 11 tooth replacement pinion?

If it won't come out, or if the gear mesh with the new gear isn't right, you'll have to split the housing, at which point you're "in for a penny, in for a pound" and might as well check everything. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 04:21 pm:

Is there a good how-to guide for Model T rear ends out there anywhere?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, July 03, 2017 - 04:22 pm:

I agree with Mark. Just bite the bullet and pull the read end out. Even if you have a 40 tooth ring gear, you have to get your lash set correctly, which means having everything apart.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, July 03, 2017 - 04:23 pm:

Erik there sure is!

https://www.modeltford.com/item/RM7.aspx

Get this and follow the instructions. It's an excellent manual, good pictures and good instructions.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Monday, July 03, 2017 - 04:28 pm:

Chances are very good that the gears in your car are "3 to 1". They could be either 13/39 or 13/40, both have been made over the many years. Either set requires a special ring gear with a "set-back" to allow for the larger 13 tooth pinion room to fit.
While it can be done (special spacer, special bolts, a lot of fitting issues), it is not recommended to try to use a 3 to 1 ring with a standard eleven tooth pinion, or a low ratio ten tooth pinion.
We can't know for certain what you will need until you take it apart and look. But likely a standard set of gears will top the list.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 04:30 pm:

Thanks Seth and all. I appreciate the input!

I was kind of hoping for the quick fix on this job because I'm deep into an engine rebuild project right now, too. Ugh. :-) Oh well. What's life without projects, huh?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 04:54 pm:

Wayne, if it is 3 to 1, what's your opinion of this gear ratio being used on a typical, flat road, short jaunt, weekend car? Do you think a solid, stock, rebuilt motor would pull this ratio, or is 4 to 1 the best way to go? I understand there is a matter of opinion here, but maybe my newly rebuilt motor will have more power.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, July 03, 2017 - 05:04 pm:

I have a 3-1 in one of my cars. It came that way when I bought it. It is a roadster so the car is light weight. If you live in flat country, you would probably have no problems, but here almost everything is on a hill. I have a Ruckstell and when I start out on even the slightest grade it is too high to start out in low so I need to go into Ruckstell. This works if you see the hill ahead and shift down before you come to a stop. It will go up a 6% grade in high as long as I can keep it moving, however, I need to go about 30 mph and when on a tour most of the cars go about 25 up the grade, so I have to shift down or lug the engine.

If you have a heavier car it would be even harder. I like the standard Ford ratio even with Ruckstell in this area.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, July 03, 2017 - 05:09 pm:

I know you're asking Wayne but on the 3:1s I recommend you swap them out for the standard 3.63s. I have GOBS more power and less weight with my speedster (45-50 horses, more than double stock output) and I only like the 3:1s because I have both an auxiliary transmission and a Ruckstell rear end.

If I leave the Chicago in direct and just drive low pedal to high pedal, I don't think it's a very pleasant way to drive. Even with all my power you have to wind it on out in low before shifting to high. Having said that, I think 4:1s are too far the other way. 3.63 really is a perfect gearing for a stock T.

I prefer to be in underdrive, or even underdrive plus in Ruckstell, then go from low pedal to high pedal and do the rest of my accelerating and driving in high pedal while just shifting the auxiliary and/or the Ruckstell.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 05:18 pm:

All makes sense. Thanks Norman, Seth and all. 3.63 sounds like the best call...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, July 03, 2017 - 05:41 pm:

If you have a std head on the engine and live in flat country, a Prus or Z head would be an alternative to pull the rear axle?
But if it's hilly, it may be best to go for std gears or a Ruckstell rear end first


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Monday, July 03, 2017 - 05:42 pm:

Forty years ago, a lot of T owners were putting 3 to 1 gears in mostly stock model Ts. The average stock bodied car could be driven at over 50 mph, and people wanted the engine to turn a little slower. While a Ruckstell was recommended with the higher gear ratio, I knew quite a few people that were running 3 to 1 gears in otherwise bone stock chassis with full bodies.

But, then, dirty politics got in the way. The books were cooked. And the liars sure did figure (some of that is an opinion statement, mostly it is a fact). Between 1990 and 2000, gasoline mileage dropped twenty five percent (I measured it myself, repeatedly). Basic laws of physics state clearly that when the mileage goes down in that way, the power/performance also must go down, by a similar percentage. Most model T owners today have never driven their car at near 50 mph. Most of them cannot get their car over 45 mph.
Most model Ts today, cannot easily pull the 3 to 1 ratio gears. They bog down on slight hills, and just don't have the power to push into and hold the higher speeds in even flat areas. A finely tuned T may be able to do it (like those that run the Montana 500 race, except if I remember correctly, 3 to 1 gears are not allowed there).
Standard model T ratio is 11/40, or 3.63 to 1. They seem to do fine at that. There are people that prefer the lower ratio of a ten tooth pinion, giving a 4 to 1 ratio. I had one T years ago with 4 to 1 in the rear end. It had a really tall overdrive, and needed the lower ratio to handle the overdrive at highway speeds. I did find that the 4 to 1 was fine for an around the town car and local driving. I could go 45 mph without using the overdrive. However, that WAS just before the gasoline went really bad.
For most basic model Ts? I think the 11/40 (3.63 to 1) is best all-around gearing, these days.
But that is just my opinion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, July 03, 2017 - 05:43 pm:

On the plus side, if they are in fact 3:1's inside and they're in good shape, you can sell them for $300 and use that to defray the cost of a new set of stock gears.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Monday, July 03, 2017 - 07:39 pm:

Or, Eric, If you discover 3:1 gears, that is 39:13 tooth, then you can buy just a 12 tooth pinion and set up a 3.25 ratio rear end. This is a good compromise between 3:1 and standard 3.64:1.

Hope this helps.
Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Larson on Monday, July 03, 2017 - 07:48 pm:

Now I'm even more curious what I have. Excellent information everyone! Thanks! Now I just need to carve out the time to dive in..,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, July 03, 2017 - 07:54 pm:

You can crank it on a level drive way with the lever forward and the ignition off - just start with the valve down on a wheel, count to three full cranks and check where the valve is - if the wheel has made a full turn, it's 3:1 in the axle.


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