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Speedometer gear change this weekend- any advice?
https://www.slantsix.org/forum/viewtopic.php?t=10661
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Author:  northeast scamp [ Fri Oct 15, 2004 10:03 am ]
Post subject:  Speedometer gear change this weekend- any advice?

Since I swapped out my 2.76 for 3.23's last month my speedo is way off (or I really am going 95mph down the highway, not sure!).

So I bought what I belive is the correct gear and a 'seal kit' from year one but I have no idea where this actually goes. I do have the correct service manual but that is not accessable to me until tomorrow so I thought I'd ask the board for advise.

Any wisdom on this little job? I've done a search but didn't find much info.
Thanks

Author:  slantvaliant [ Fri Oct 15, 2004 10:29 am ]
Post subject: 

See if you have a buddy with a GPS. Many have a speed function, so you can verify your new setup.

Author:  DusterIdiot [ Fri Oct 15, 2004 11:08 am ]
Post subject:  It's off...

If you changed rear gears and you didn't pull the original gear out of the tranny body it'll be way off...

It's an easy swap:

Jack up front of car and put on jack stands.

You'll need a 1" box end wrench to loosen the speedo cable on the driver's side of the tranny body, just after the crossmember.

Next you'll need a 7/16" (or 1/2") socket and ratchet to remove the hold down "fork"bolt and fork.
pull the assembly out of the tranny (depending on model you may need a pan as it may "puke").

Clean the gear assembly, since it has an "orientation" for higher numerical speedo gears you'll need to read the numbers on the assembly.

Reassemble the cap/etc. with the new speedo gear (some models use a "hairpin" attached to the gear, if yours don't have this, don't worry about it), use new seal if needed. install back in tranny body with correct ratio pointing to the "bump" cast into the tranny case.

Install fork, install speedo cable. Top up fluid in driveway if needed. Jack it back down. Take a drive to check if you assembled it right, then have a buddy check a stop watch vs. a set of highway mile post markers. Try to pick a non-peak hour so you can drive 60 mph (if you pass the next marker in one minute at 60 on the speedo it is close enough).

due to tire variations and brands there's always a "fudge" factor when using these gears so use good judgement when on the street...

-D.Idiot

Author:  Slant6Ram [ Fri Oct 15, 2004 11:11 am ]
Post subject:  Speedo gear

The gear goes into the transmission. Follow the speedometer cable and you will find a round cover with a big 'C' shaped clamp holding it on to the transmission.

I recall someone saying that there should be marks or numbers on the cover which indicate the position to re-assemble it based on gear ratio being used.

I've never done it myself, but that is the procedure I've been told to expect. If the cover is not re-aligned properly to the new gear, the gear or transmission will quicky break, so pay close attention to what you are doing and check out a manual for more specifics.

The descriptions I've read make it sound very easy if you know what to look for.

Author:  Pierre [ Fri Oct 15, 2004 12:11 pm ]
Post subject: 

I recently did a gear change as well, also from 2.76 to 3.23. I bought a new speedo gear from the dealer and swapped it in.

The service manuals have good pictures I believe.

Also, I agree with everything that DusterIdiot said, except keep the front part of the car on the ground, and get the rear as high as you can. That way you won't loose any transmission fluid when you pull the gear out because it has all moved towards the front of the tranny.

Author:  northeast scamp [ Fri Oct 15, 2004 12:51 pm ]
Post subject: 

Excellent, I feel somewhat prepared now. Thanks everybody-

Author:  70valiant [ Fri Oct 15, 2004 2:33 pm ]
Post subject: 

I jacked mine up from just behind the driver front wheel and it puked all over me. I also went from 2.76's to 3.23's I put in a 34(it is dark green) I took out a black one IIRC it was a 29. You will likely have to clean the outside of the housing to find the numbersIt will look like this
Image

Author:  northeast scamp [ Mon Oct 18, 2004 6:28 am ]
Post subject: 

All finished with the swap, working perfectly now.

I jacked up front and rear subframes on the drivers side pretty high and it only leaked a couple of tablespoons of tranny fluid. The first time I put the new gear in and went for a test drive I had no speedo at all but the next time I did it it worked fine. I know I had the adaptor aligned correctly but it must have not been seated properly.

Anyway thanks for the advice, hopefully this will save me some speeding tickets in the future!
Todd

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