Chevy Impala SS Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
192 Posts
Discussion Starter · #1 ·
1994 RMW, losing reverse, wanting to swap tranny's sometime soon to get everything back fully functional. I've been perusing craigslist and found a couple options. I know I need 94 trans due to the changes to the TCC in 95, but haven't found a whole lot of '94 only options locally.

One of the better options is a trans from a 1994 9c1 with a L99 4.3 liter. I read the stickies and know there are some minor differences (different servo, etc) for the L99 4l60e's. Just curious what I could expect if I tried to use the L99 trans in my LT1 car. Mainly, am I going to break it prematurely? How much difference would swapping my stock servo into the L99 trans make?

I also found a 1994 F-body trans which is supposedly a rebuilt/replaced unit with a 2800 converter which might be a good option, but it's more expensive and the stall is one I've never heard of and might be non-lockup.

Any advise?
 

·
Registered
Joined
·
50 Posts
I am unsure of when the practice began, or when (or if) it ever ended, but the 4L60 used in 262s used to have fewer clutch plates and steels with a thicker spacer ring than those transmissions built for larger V-8 applications. I suspect there may have been other areas where some robustness was sacrificed for lower internal friction for the smaller engine applications. While the valve body solenoid resistances and TCC application mode should match the PCM for a '94 model year, some areas may not otherwise be equal.
 

·
Super Moderator
Joined
·
4,543 Posts
If you don't beat on the car, the L99 trans will probably hold up fine.

The Z28 trans will be a better option; just sell the 2800-stall converter on CL and put your stock converter back on it or a new converter for $100 and keep going.
 

·
Super Moderator
Joined
·
4,543 Posts
I don't think the boost valve is the problem (though the Sonnax boost valve is good). How many miles on the car?

I just reread the original post. Probably the lo-reverse clutches are worn out due to the design defect in the '94-95 units. Reverse is independent from the rest of the gears in the 4L60E so one option is to install a '96 manual valve and drill a hole to fix the source of the problem, then replace the lo-reverse clutches and that problem will be fixed. You can do all of this without anything more than good snapring pliers, a small prybar, and some help. PM me for more info.
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #6 · (Edited)
If it's just reverse, try installing a new sonnax boost valve... Or is there something else re "everything back to fully functional"?
No it's just reverse. All the forward gears work as normal, no slipping or anything. When the car is in reverse though, it will only creep backward at idle (so only on level or downhill slopes), it will not engage further as you give it gas, it just revs as if it's in nuetral as it continues to slowly creep backward like its idling. It has gradually gotten to this point over time, not like it gave out randomly one day. Also doesn't make any grinding noises or anything either.

Trying to backup on any sort of uphill incline (or even flat if it's rough like gravel or something).... and forget about it, not going anywhere. Been selectively trying to not use reverse for like a month (pull through parking spots FTW).
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #7 ·
How many miles on the car?

I just reread the original post. Probably the lo-reverse clutches are worn out due to the design defect in the '94-95 units. Reverse is independent from the rest of the gears in the 4L60E so one option is to install a '96 manual valve and drill a hole to fix the source of the problem, then replace the lo-reverse clutches and that problem will be fixed. You can do all of this without anything more than good snapring pliers, a small prybar, and some help. PM me for more info.
256k miles on the old girl. I daily drive it and it runs like a champ. Original engine and trans with no major repairs to date beyond regular routine maintenance stuff. I figured reverse was just starting to get pretty worn out at this point.

I'm gonna shoot you a PM because I'm interested in this info. Automatic transmissions confuse me in their complexity, so I wouldn't normally think to start taking things apart, but if there is a chance I can fix it without having to do anything too crazy, that may be the way to go.
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #8 ·
Also, on another note, I might go check this z28 trans out on wednesday.

Is there a good way to tell if a converter is lock-up or non-lockup visually? I'm not really 100% sure how the TCC solenoid and all that stuff works, so am not really sure what to look for to try and figure out if this torque converter has lockup or not.
 

·
Registered
Joined
·
2,505 Posts
No real way to tell if a converter is lockup externally- need to cut it open to see if there's a lockup clutch in it.

I'd get a new converter bc you don't know if there's metal flakes in the used one your getting.

Nab
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #10 ·
No real way to tell if a converter is lockup externally- need to cut it open to see if there's a lockup clutch in it.

I'd get a new converter bc you don't know if there's metal flakes in the used one your getting.

Nab
That's too bad, was hoping I could find out one way or the other just by examining it. But, yeah, I've basically always been told that reusing converters is somewhat frowned upon.

Kind of a bummer though, sounds like it was all rebuilt and stall installed not long before engine problems caused him to park it and start parting out. Seems like he has it priced a little higher than other used ones nearby for that reason.
 

·
Super Moderator
Joined
·
4,543 Posts
Flip the converter face down and let it drain into a bucket overnight. See if there is any metal in the fluid. If the trans is clean, the converter will usually be good.

I've only gotten burned twice on low-mileage rebuilds I bought used on CL. One had been in an accident and had a bent output shaft that wobbled the driveshaft like crazy. You could tell that from the outside. The other one had very low miles but the pump housing was all scored up and I don't think it would have had much line rise as it sat. This was definitely a bad choice by the builder, and you'd only have known about it if you had removed and disassembled the pump, not something non-trans people normally do.

If the seller doesn't have any paperwork and you can't test it in a running car first before you buy it, then don't pay much for it.
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #12 ·
Yeah that's more or less what I had in mind to try and at least get a feel for if it's high mileage or been ragged on.

It's still in the car but the motor doesn't crank, so that's the unfortunate part. Definitely not willing to pay what he's asking without being able to verify anything, but I don't think its too far off, so might be able to find some middle ground.
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #13 ·
Well turns out that although the car is a 94, the guy said it was actually a 95 transmission that he had swapped into it, so not sure exactly what kinda issues that would cause. Isn't there an extra pin in the plug in a 95? I'm assuming I would lose lockup due to my 94 computer not being able to control the 95 TCC.
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top