Wobblybob
Elite Member
Joined: January 29th, 2009, 12:21 am

March 20th, 2011, 11:04 am #11

Thanks guys.

Neyrs, the only way I can imagine doing this on a loose transmission is if you had a couple axles or axle stubs that you could insert into the tranny and maybe some way to mark the input shaft and one axle (maybe magnetic pointers?). Then somehow figure out where 5th gear is, turn one axle (while holding the other!) until the input shaft makes exactly three turns, and see where your axle mark ends up. Sounds pretty unworkable to me, almost like trying to build a Metro on the guy's garage floor but I suppose it's better than buying the wrong transmission. Sounds like it would be easier to count teeth!



"The Flying Egg" 3/5 and "Otto" 4/auto
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Johnny Mullet
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Joined: September 8th, 2008, 1:49 am

March 20th, 2011, 1:45 pm #12

Pinned!
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pacapo
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Joined: September 15th, 2008, 9:11 pm

March 20th, 2011, 3:17 pm #13

:news
Nice write up and pictures, Wobblybob.
The 3.79 (3.78947368421052 etc. etc.)/72ring 19 pinion mark in the picture is perfect for three engine revolutions in 5th gear.
Thanks for taking the time to explain this technique.
:cheers
This gets my vote for 'thread of the year'.


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work car
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Joined: August 15th, 2010, 6:57 pm

March 20th, 2011, 7:39 pm #14

wobblybob..i also would vote for thread of the year for this also!!

muy bueno!!!!
many metro project's never enough time!

all this metro madness leads to a drained wallet, unhappy wife, full driveway, confused unhappy neighbors, and more motors and transmissions to trip over, than you can shake a stick at!! but i got 50 mpg!!!
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MR Bill
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Joined: August 20th, 2010, 3:10 am

March 21st, 2011, 2:32 am #15

Great job.

Bill
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Woodie
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Joined: February 13th, 2009, 12:29 pm

March 21st, 2011, 10:51 am #16

pacapo wrote: This gets my vote for 'thread of the year'.

You get an assist.
Alcohol, Tobacco, and Firearms
Should be the name of a convenience store, not a government agency.
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Wobblybob
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Joined: January 29th, 2009, 12:21 am

April 6th, 2011, 5:58 am #17

Thanks for the nice comments. Makes me glad I took the time to do it.

Just to let you know (especially you, nerys) I'm working on an equally simple method of determining final drive ratios of a trans on the bench (same basic procedure without wheels!) but have a couple details to work out before posting. It won't require the use of axle stubs or any special tools and will be just as easy and accurate as this method.




"The Flying Egg" 3/5 and "Otto" 4/auto
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Jittney
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Jittney
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Joined: January 9th, 2010, 5:54 pm

April 6th, 2011, 6:04 am #18

ahhhh.....that's awesome.
Iceman has a number of transmissions and was going to check for an XFi for me when the snow melts.
This will make it easier.
Melt, snow, melt!
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Wobblybob
Elite Member
Joined: January 29th, 2009, 12:21 am

April 7th, 2011, 3:28 pm #19

Here's how to determine the final drive ratio if the transmission is out of the car already. (See page 1 of this thread if it's still in the car).

Johnny Mullet had the transmission from Blue Jay laying on the garage floor so I went up to his place and he helped me run through this and take pictures. My thanks to him.

Also, pacapo deserves a lot of credit for this whole concept because it was his original post that put me onto the idea of turning the engine over so many turns and counting wheel revolutions. I neglected to mention him in my original post because I couldn't remember where I saw it in the first place. It was his post that started all this.

While working out this procedure I tried to make it generic enough that if you unexpectedly stumbled onto a transmission somewhere, you could, with a couple borrowed hand tools and about 10 minutes time, figure out what ratio it is.

First, the stuff you'll need to do this (assuming the trans is already out and on the bench).

- Something to rotate the input shaft. A clutch disk would be ideal, a pair of vise grips works fine, and an 18mm deepwell socket slides right onto the spline (ratchet & short extension too)
- An ordinary business card or a similar size piece of thin cardboard or thin plastic
- (Optional) A pair of scissors or a sharp knife. (you could actually tear the pointer material instead)
- (Optional) Something to make it easier to keep the left axle socket from turning - 7/8" dowel, piece of broomstick, rag on the handle of a ratchet, a pair of needle nose pliers, etc. (again, optional)

Here's the procedure:

Make a pointer from the business card (if you're going to do this often, I'd make one out of thin plastic)



Bend the 1" x 3" tongue slightly lengthways and insert it into the splines of the RIGHT (passenger's side) (must be in the right side) axle socket so the pointer almost touches the case






Now you have to put the transmission into 5th gear. This was much easier than I expected. On this transmission, which still had a big section of the shifter linkage attached, we were able to do this with no tools whatsoever just by grabbing the linkage shown in the photo and pulling and twisting by hand. For a transmission without the linkage you may have to use vise grips or a screwdriver slid through the holes.

First, slide the linkage in and out to find neutral (there are three distinct positions, just like 1st, neutral, 2nd in the car).

Then rotate the linkage clockwise (it will rotate easily in neutral). Once it hits the "stop", twist it hard clockwise (you'll feel the spring resisting just like when you go for 5th or reverse in the car) until you hit the second hard stop.

While holding it tight against that second stop, pull it towards you and you'll feel it click into 5th gear.

I really thought this was going to be the hardest part of this job and it was a piece of cake - really went smoothly.



Next, VERY, VERY IMPORTANT!. You have to keep the LEFT axle from turning when you rotate the input shaft. An axle stub would be ideal for this purpose but if you don't have one (I know I don't), you can use your finger. I really didn't think I could hold it in place without an axle or a dowel rod or something but, with some effort, it can be done. You DO have to be sure it doesn't turn because the results could be very misleading if it turns, even slightly. So if you have ANY doubts, use an axle, a broomstick, a dowel rod, a pair of needle nose pliers held wide open or some other object that will prevent rotation without damaging the splines or the seal.



Next, you have to attach something to the transmission input shaft to turn it (and to serve as an indicator so you can get exactly 3 revolutions).

- A clutch plate with a piece of tape on it would be ideal but not everyone has one laying around .
- Vise Grips clamped onto the shaft would work fine, with a rag to protect the pilot shaft or spline.
- An 18mm six point socket slides onto the input spline as if it was a bolt head. A deepwell is best because on a shallow socket the pilot shaft extends into the square drive hole. We had two shallow sockets between us and only one would work, but even then we couldn't get the extension all the way into the socket and had to hold it in place as we turned the ratchet. That would be pretty difficult if you were working by yourself and trying to hold the left axle socket at the same time. My advice? Use a deepwell. You'll also need a short extension and a ratchet (you can see the shallow socket installed on the shaft in photos 2 & 3 above).

The stud that sticks out of the case just above the right axle opening makes a convenient marker for counting revolutions.

You are now, finally, ready to do something! Get everything setup as shown in the picture below. Align your rotating tool with the stud as shown. Align the "pointer" so it's at BDC (6 o'clock). Hold the left axle socket to keep it from turning. Transmission in 5th gear. You're ready to go.



Now, rotate the input shaft exactly 3 revolutions CLOCKWISE and look at the position of the pointer. If you're working on a 4.39 transmission, like we were, you should see this:



Here's a summary view of where the pointer will be for the different final drive ratios.



If your results don't make sense compared to this last photo, one of four things probably went wrong:

1. You didn't get the transmission into 5th gear - you probably didn't keep it twisted when you pulled back on the shaft and ended up in 3rd gear instead of 5th. (don't ask how I know this!)

2. You allowed the left axle socket to rotate, or maybe bumped it when removing your finger or dowel.

3. The pointer wasn't tight enough in the spline and/or it didn't turn freely with the socket.

4. You inserted the pointer into the left spline instead of the right. This will produce backwards results: 3.52 will be 3 o'clock, 3.79 will be 5 o'clock, 4.10 will be 7 o'clock, etc.)

If the results don't make sense, start over. It's easier the second time and it really does work.

The only things that I can imagine that would cause this to not work would be internal transmission problems, like gears being bad or something binding up in the transmission. (You don't want that one anyways so who cares what ratio it is, right?)

So next time you go to the junkyard or on a "road trip", make sure you take a business card, a sharp knife and your Vise Grips!
Last edited by Wobblybob on May 4th, 2011, 1:43 am, edited 18 times in total.


"The Flying Egg" 3/5 and "Otto" 4/auto
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yiffzer
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Joined: December 30th, 2009, 10:11 pm

April 7th, 2011, 4:08 pm #20

Haha, I thought of doing this but feared it would've been "unscientific." Good job! =)
Is your willpower still stuck in your manpurse? -Dayle.
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