1990 - automatic trans. question

[Rain]

What RPM should we be looking at while at Interstate cruising speeds of say 70 mph on a 1990, A4.

Believe Joe is on his return trip from Jacksonville, FL and reports nearly 4,000 rpm to maintain around 70 mph.
Sounds like he needs a transmission service -

 

[*89x2*]

although it might be helpful to know what gear ratio the car has, either way, even with the G92 perf. axle, 4,000 rpm's is too high in 4th. It sounds like it has not chifted out of 3rd.

The TV cable could be out of adjustment, preventing the upshift. Or of course, it could be more serious than that.

 

[Rain]

thats pretty much what I told him too -
knew that was too high and that it wasnt shifting on thru the gears for cruising.

Perhaps its never had a filter/fluid change

 

[*89x2*]

one school of thought on changing old fluid - the "thickness" of the fluid in some cases, is all that is shifting the transmission. I have seen transmissions "let go" soon after a flush and fill, go figure

 

[Rain]

true true -
When I did my 96 a couple years ago (first change she had ever had), I was nervous to say the least. Didn't think we'd ever get the metal ring out of the hole once we dropped the pan and pulled out the filter.
I hear some shops (that don't know about the metal ring on the filter) will just cram the new filter up in there - so its not unusual to find more than one in there..

 

[seajayiii]

YIKES!!! I have a completely stock '90 (L98 with a stock auto transmission). At highway speeds, I am only throwing about 2,000 RPM. Sounds like the tranny isn't upshifting into fourth gear and hence overdrive. I would get that bad boy looked at quickly.

 

[c4c5specialist]

HI there,
Before you throw up your hands, check your fluid level.
Then, if after that, you still dont have 4th the 2/4 servo should be checked.
Allthebest, c4c5

 

[Hrtbeat1]

Is the motor actually spinning at 4K or is the tach just reading 4K. On my old '90 the tach filter was bad and the RPM's were reading higher than the motor was actually spinning. I checked this by putting one of those small 2 1/2" tachs in temporarily. Hook up was easy one wire to each of the battery posts and one wire to the tach output off the distributor.

BTW the tach filter is a discontinued item and there is NO aftermarket replacement, or at least at the time there wasn't.



G

 

[Rain]

Thanks for the input guys -
CAC has not been notifying me of replies to this thread.
(sorry for the delayed reply)
Rain

 

[Rain]

He should chime in and give us a first hand experience.
But it sounds like sometimes the Tach doesnt respond at all sometimes.
Then other times it catches and starts displaying. Ive not had time to see the Vette yet.

 

[Hrtbeat1]

Sounds like the Tach filter to me. Its located on one of the upper bolts between the engine and transmission, on the drivers side. Its round, about 3/4" in dia, and about 3" long, it has one wire one either side of the canister.

Oh BTW Rain, in your first post you have his car listed as a M4, in '90 there was only the A4 and the six speed.



G

 

[Rain]

oops - i;ll see if I can correct it
LOL!
When are you in the Gport area again?

 

[Hrtbeat1]

Not till Christmas.

See ya around!



G