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Changing the speedometer gears in your WC T5 can be done with the transmission in or out of the car. The following write up was done with the transmission out of the car.
New speedometer gears
However if you do this swap with the transmission in the car here are a few quick reminders and starting tips.
In the car
If you choose to leave the transmission in the car you will have to remove the torque arm mount, driveshaft and transmission cross member. You will also have to remove the center console so that you can unbolt the shifter. Once these items are free the transmission will sag and hang only with the support of the motor mounts. I would leave a jack under the transmission at all times.
Step one: Remove shifter (The shifter will already be removed if the transmission is already out of the car)
The first thing you will have to do is remove the shifter. It is held down with four bolts. Remove the bolts and slightly pry on the shifter to break loose the seal.
Shifter removal (in pic console, and rubber boot have been removed)
Step Two:
The next step you will have to free the offset shift lever block from the input shaft. Locate the small hole on top of the block directly underneath where the shifter would be. You will need a roll pin punch at this time. Take the punch and place it on the hole. Give it a few smacks with a soft hammer until the pin is fully depressed into the offset shift level block.
Roll Pin Punch
Step Three: Extension housing removal
Locate the bolts that hold the extension housing to the rest of the transmission. Remove these bolts and slide off the extension housing. Have a catch pan ready because you will loose all your fluid (4 quarts or so).
NOTE: As you remove the extension housing pay attention to the offset shift lever block. Right before the extension housing is free you can grab and remove (slide rearward) the offset shifter block. Go slow and be sure to grab the roll pin, spring, and ball. They can be easily lost so go slow and catch them.
Offset shifter lever block components
Now that the extension housing is out of the way you can see the speedometer gears. The driven gear is in the housing located on the VSS unit and the drive gear is the round gear that surrounds the transmission input shaft.
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Before you remove the drive gear you will have to remove a c-clip. I use a 30mm open ended wrench and place it on the front face of the clip. I then strike the wrench with a soft mallet and slowly work the clip off of the input shaft. You will then have to slide the rubber seal off. You can now remove the gear. Take note of the clip that holds it to the input shaft. This clip will need to be depressed as you remove the gear. Removal of the gear is the same as the c-clip. Use a 30mm (1-1/4” or crescent wrench should work too) open ended wrench to tap the gear off. If you do not depress the clip you will break it. If you do (and I did) you can get a new one from your GM dealer for under $3.
Place wrench on gear and then tap on wrench to remove gear and c-clip.
Step Five: Drive gear installation
You can now install the new drive gear in the same manor that you removed the old one. Tap it on softly with a wrench and mallet. Be sure that you have the clip hole aligned with the gear slot. If you do not the retaining clip will not seat and you will have to slide the gear off and start over. After you have the new gear in place slide the seal back in place. You can now tap on the c-clip. My c-clip install tool was not adequate given the size of this clip so I used a 1-1/4” socket as a guide. I positioned the c-clip on the end of the tail shaft and tapped it on with a socket. I then used the 30mm wrench to guide it into its final position.
Allignment of gear slot with input shaft hole
Step Six: Driven gear removal and installation
Remove the VSS from the extension housing. It is located on the side and is held in with one ten mm bolt. When you pull it out you will see the gear on the end of the shaft. Pull the gear off of the shaft. If you push down on one end and pull at the same time it will slide right off. Pulling directly on it will not allow it to come off easy. Some people immediately put the new gear on but I wait until I have the area prepped for reinstallation. Take some brake cleaner and clean off the old RTV and oil from the VSS bung. Remove any large chunks of RTV that are lodged into the o-ring on the VSS. Drop the gear into the bung and place a small bead of fresh RTV around the opening. I drop the gear in first in order to prevent RTV from getting on the gear. You can now slide in the VSS and nest it with the new gear. When it sits into place reinstall the ten mm bolt.
VSS with gear removed
Drop gear in before RTV
RTV on VSS bung
If you look down the extension housing you can see the new driven gear.
Step Seven: Extension house reinstallation
At this time you can now install the extension house. As you feed the housing onto the input shaft you will want to slide on the offset shift lever block making sure to properly seat the spring and ball. When the offset block is in place, tap in the roll pin so that it is flush with the top of the block. You can now place a bead of RTV around the mating surface of the extension housing and the rest of the transmission (prepare the surface in the same manor you did for the driven gear). Slide the extension housing into place and reinstall all bolts.
You are now done and can reinstall your transmission in the reverse of removal.
This is a quick overview and I will be adding/editing this over the next few weeks when I can get back to my shop. More pictures to come. I hope this helps those who ponder this swap. It isn't that hard. Just messy.
Freaking awesome! Thanks for the post, your timing couldn't be better!!
BTW - What rear gears were you changing to?
__________________ Gina - 1969-2008
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I little tip I learned back when I replaced my speedometer gears was to heat up the drive gear to make it slide on easier. Just stick it in a bowl of water, heat it up for 1 or 2 minutes, and it should slide right on the output shaft without any tools. That also makes it a whole lot easier to align and get the clip in.
I'm doing the same thing in a few months and have already done it on a couple 700r4's. But I always worry about the offset block, spring, and ball not coming off right or not going on. Do you have more pictures of that or am I making an easy task harder than it needs to be?
I'm doing the same thing in a few months and have already done it on a couple 700r4's. But I always worry about the offset block, spring, and ball not coming off right or not going on. Do you have more pictures of that or am I making an easy task harder than it needs to be?
I will have some more pics soon. At the time my transmission was already aprt so I didn't get a good process picture. When you remove the shifter you will see the offset block. Place the punch on top of the hole that you see on the offset block. There is a roll pin in there. You must use a round punch. A screwdriver or any other round device will not work. A roll pin will twist if you do not push on it with equal pressure therefore making it impossible to remove. One good wack with a hammer and the punch will push it down. You won't lose it that way so push it all the way in. When you pull back on the extension housing and slide the block off that is when you need to catch it. It may have seated or rested onto other parts in there or it could fall out and leave you on your hands and knees looking to see where that ball rolled to.
i need help. my car broke its speedometor back in the winter.
1 dose the 0-145 work correctly if i install it even if mine is the 0-110
2 is there a cheaper way to fix it without another speedometer somewhere else
3 dose anyone know of any new or used speedometers for sale cheep.
Car info 1991 z28 camaro 350 700r4. i replaced the 700r4 with one from a differant camaro that the speedometer was cable driven so i replaced the cable drive with the sensor from my old tranny it worked for a while and broke.
Any suggestions are helpful. until i fix it mom will make me drive my 91 bonneville. such a boring transition.
I just want to add some critical info here guys. You MUST make sure the shifter is in neutral in the 3-4 position when you drive out the Offset Shift Lever. If you fail to do so, you'll be pounding the roll pin into the Detent Guide Plate!!
ok, so I had a tranny swap done on my 88 IROC. The T-5 is an 83 NWC. Is this the same as you're describing, and any suggestions on finding the speedo gear? Have searched far & wide...thanks!
Ok I need Help. Did this the other day, and now i cannot get the tail shaft housing back on. It fit when i test fitted it, but had a problem with the offset shift shaft spring and ball, so had to take it back off and now the houling will go on until it is about 3/4 of an inch away from complete and it wont go any further like it is hung up on something. Everything looks ok any ideas help please!!!!!
Ok I need Help. Did this the other day, and now i cannot get the tail shaft housing back on. It fit when i test fitted it, but had a problem with the offset shift shaft spring and ball, so had to take it back off and now the houling will go on until it is about 3/4 of an inch away from complete and it wont go any further like it is hung up on something. Everything looks ok any ideas help please!!!!!
I had the same problem 3 years ago, when the transmission was in the car. We took the transmission out of the car and it went back together easily.
Ok I need Help. Did this the other day, and now i cannot get the tail shaft housing back on. It fit when i test fitted it, but had a problem with the offset shift shaft spring and ball, so had to take it back off and now the houling will go on until it is about 3/4 of an inch away from complete and it wont go any further like it is hung up on something. Everything looks ok any ideas help please!!!!!
I had the same problem and I literally spent hours on it before I took a soft mallet and tapped firmly on the tailshaft. it "popped" into place. You will notice that as yours sits now the output shaft is notchy and will click hard when you turn it. After the "love tap" it will turn nice and smooth.
I have tried it now, but afraid to tap to hard, plus it feels as though something isn't lined up. I do remember when i took it apart a week ago the shorter shaft that has the fork off of it had some play, and now it won't move could it have gotten messed up, I know that in pulling the case on and off a few times the shift shaft has been cought and shifted into a geer. moved it back to neutral i thought? Did I mess some thing up? this prodject is beging to get bigger than me.
I have tried it now, but afraid to tap to hard, plus it feels as though something isn't lined up. I do remember when i took it apart a week ago the shorter shaft that has the fork off of it had some play, and now it won't move could it have gotten messed up, I know that in pulling the case on and off a few times the shift shaft has been cought and shifted into a geer. moved it back to neutral i thought? Did I mess some thing up? this prodject is beging to get bigger than me.
My brain is failing me but I think I tapped on the 5th gear assembly and not the tailshaft. I had this problem the first time I removed the tailhouse assembly. It came right off but no matter how hard I tried it was missalligned when re-assembly time came. I became so frusterated to the point I grabbed that mallet and gave it a solid tap (nothing to damage the gear teeth or anything else). If you are looking at the rear of the transmission (with it on front of you) I hit the 5th gear assembly towards the tailshaft (would be hitting from right to left, impact force towards the driver side of the tranny). I am pretty sure that is what I did. It didn't take much and it popped into place. You will notice that 5th gear assembly floats a little when the tailshaft cover is off.
