So my 91 trans has a connection for the digital dash and my 88 has mechanical so I needed to swap them. I got the digital connection out find but since the mechanical connection was plastic it broke as I was getting out. (Was a little pissed off about that) Once I had them both out I wanted to check with everyone to make sure I can or can not put the same one into the 91. Here is a picture of the two side by side, I need the 88 mechanical connection, in the 91.

The 91 digital connection is on the left and the 88 mechanical is on the right:


Am I able to put the mechanical one into the trans that the digital one came out of? Or how can I check to see if I can?

 

I don't recall ever seeing a thirdgen trans with anything but plastic gears, both drive and driven. Interesting.

JamesC

 

Well that's not very good haha.

Would you say it would be best to swap the whole trans instead?

 

Sean, sorry, I'm still unsure what you wish to do. The 91 speedo head is controlled electronically through the VSS which plugs in the the tail shaft of the trans. I'm unsure why you need the mechanical speedo gear and sleeve when that set-up won't function without a speedo cable, which your 91 doesn't have.

JamesC

 

The broken '88 speedo gear sleeve needs replaced. They're out there. Local trans. supply shoppe or eBay or whatever. There is one for lower tooth counts (39 and below??) and one for higher tooth counts (40 and higher I think) The new one must match the old one.

Because of the VSS style, the gear inside the '91 trans is probably not the same as the one in the '88 trans.

Once again:
You seem to be avoiding pulling the torque arm and tailhousing in order to get the '88 drive gear out.

Either go buy a new drive gear from the dealer (use a black marker on one of the teeth, put the trans. in neutral and spin it to count the teeth, it's more than likely 15 or 17 tooth) so you don't have to pull the '88 tailhousing. Part numbers are in the sticky threads on speedo gears. Or pull both tailhousings. Either way, you're going to need to pull one of them.

 

PS, your hockey puck VSS probably looks like the 4L60-E style here on page 3:

https://shell7.tdl.com/~jags/V8-chap...ed-Sensors.pdf

If your '91 trans. has straight horizontally cut teeth like that 40 tooth reluctor ring, you must pull the tailhousing to remove it and install the '88 drive gear.

If the '91 trans. has a later model 4L60 output shaft that does not have the hole drilled for the drive gear clip (this will make sense when you pull the tailhousing / drive gear from the '88 trans.,) you may want to consider part # 4L60-004 in that same link.

 

The only thing I am using from the 91 is the body, trans, and rear end. Everything else is out of my 88 so that includes my mechanical gauges and all my wiring. This is why I need to make the 91 mechanical and by the looks of it I might have to swap the whole trans or at least the tailhousing.

 

Yes, the one from my 91 looks exactly like the one on page three that you mentioned.

This means I will have to pull the tailhousing and drive gear out of my 88 and put it on the trans in my 91, correct?

 

Should I post it a 4th time?

 

Sorry, I am trying my best to understand everything you guys are saying.

I have decided since both the transmissions are in the cars I will just take them both out and I'll use the transmission from my 88 instead of pulling them both apart. I figured this would be much easier than pulling the end off both of them while they are still bolted up in the car and neither of the cars are very high off the ground, just enough for me to slide under haha.


Thank you guys so much for all your help! Time to go buy a new VSS to put back in the 88 transmission haha.




Sean

 

Which part specifically?

The torque arm and driveshaft can be pulled quickly without removing the trans. and at that point, the tailhousing comes right off with 4 bolts. I don't consider pulling the whole trans. easier. But, it sounds like you have a lot of work ahead of you anyway and it'll blend in.

You can still pull the tailhousings (they use a square cut seal that is able to be re-used) before dropping the trans. and if you go ahead and pull them, just bolt them back on before you drop the trans.

 

I have noticed the part you are talking about when I go under there but what all would I have to do? Would I have to take the housing itself and some gears from inside of it?

Sorry, I don't know anything about transmissions. (That is the problem here)

 

As far as everything else, it is all out of the cars and ready to go in, I just have to figure out this transmission issue.

 

It's pretty easy and it's all nuts and bolts. Not transmission internal shift-related stuff.
Pull 2 bolts holding a u-joint strap. 7/16" or 11mm wrench.
Loosen the other 2.
Pry the 2 u-joint cups out of the pinion yoke.
Slide the u-joint out to the side.
The driveshaft will pull out of the trans. at this point and some ATF will leak.

Loosen the nuts and bolts holding the torque arm bushing to the side of the tailhousing.
Shove the bushing and torque arm out of the way.

Remove 4 bolts holding the tailhousing on; probably 13mm or 15mm headed bolts.
Wiggle the tailhousing until it slides off.

You'll have to do the above, in or out of the car, no matter what in order to convert the '91 to speedo gear in place of the VSS.

Do the above on the other trans.

I think the 40t reluctor is pressed on with no clip:
Put a big open end wrench or pickle fork in front of the reluctor ring on the '91 trans output.
Tap it with a hammer to drive the reluctor ring off. You're trying to drive it straight off, not get it cockeyed.
If you have a nice long reach puller, that's the better way to take the reluctor off.

Look at the clip for the '88 drive gear that's on the output shaft. It indexes to a hole in the output.
Press down on the clip and slip/drive the gear off.

In neutral, spin and check the '91 output shaft to see if it has a hole drilled for the speedo clip.
If yes, install the clip and drive gear from the '88.
If no, get the 4L60-004 part I mentioned earlier.

You have the tools, now have the drive to do it.

 

Thanks for all the help, I'll take a look at doing that but I think just to be sure it'll work I'll just swap the transmissions. They both work I was just trying to avoid swapping them. I have to buy a new VSS anyways and I don't want to run the chance of pulling the transmission apart and having to buy the part you mentioned. Don't have time or money to be buying more parts. Thanks for all the help though, I know a little more about transmissions now!