Zepher

iTrader: (1)

Does that seem kinda high?
Car is an 88 formula 305 TPI auto.
Car isn't showing any codes. I believe it has the 3.23 rear gears.
At 70mph in 3rd it reads at 3K.

I am not familiar with autos in a 3rd gen, my 86 was a 5 speed.

ctandc

I'll throw out some figures... NOTE : these do not take into account the RPM DROP when the torque converter clutch is engaged...


This also takes into account you're using stock 245/50/16 tires.

2.73 gears - 60MPH - 3rd GEAR ( D ) = 2100 RPM
70MPH= 2500 RPM

3.08 gears - 60MPH - 3rd GEAR ( D ) = 2400 RPM
70MPH= 2800 RPM

3.23 gears - 60MPH - 3rd GEAR ( D ) = 2500 RPM
70MPH= 3000 RPM


HTH

Zepher

iTrader: (1)

thanks,
Looks like I have 3.23's. I have stock 245/50/16 tires on the car.
Since my car is running at 2K in OD at 60mph, does that sound like my TCC is not engaging? I figure at 60 in OD, it should be maybe 1200 or 1500.

1986redbird

I doubt that your rpms will be that low at 60, I have 2.73 gears in my TA with the 700R4 and I run right at 1500 at 60 in OD. your should be around 1800 to 2000 I would think.

Zepher

iTrader: (1)

Ok, I was just making sure. I've only riden in a few auto 3rd gens.

Sitting Bull

I have 3.42s and my tach reads 2000 rpm at 100 km/h in OD, which is 62 mph.

I think you might have 3.42s, Zeph

Zepher

iTrader: (1)

That would be a plus.
I am changing the fluid tomorrow so I;ll check the ring gear to see if I can verify the gears.

Kingtal0n

80 MPH @ 2000 RPMS for me.

2.73 / 700R4 / -255/60/R15

jfreeman74

2400 RPM at 70 MPH... I have 3.42's

Zepher

iTrader: (1)

I tested it again tonight and
At 60mph in 3rd, I am at 2600
At 70mph in 3rd, I am at 3100

If it doesn't rain tomorrow, I'll change the diff fluid and check the gears.
It rained off and on today so all I was able to do was change my tranny fluid. I had 8 quarts of that B&M TrickShift tranny fluid and used about 5 quarts.

Sitting Bull

Well, I just got my new 700r4 back with TransGo shift kit in the Camaro and with the new stock torque converter, and my 3.42 gears, the tach reads 1800 rpm in Overdrive at 60 mph. That must be when it is locked up.

This tranny is like night and day over the stocker!

Zepher

iTrader: (1)

Mines at about 2100 at 60 in OD with the converter locked.
My friend said I may have 3.73 gears. I need to take his car out and check the rpms at 60 and 70 since he has 3.73 gears in his 86 Z28.

PHAT89TA

80mph @ 2000 rpms

700r4/3.08 /275 zr 17's

25thanniversZ

all I gotta say is..lucky you if your pulling that kinda rpm at that speed....I remember when I could back before I hulled my transmission...now I got 3:73 gears with a th350...its a blast on takeoff and at the strip but man it really hurts my feelings on the highway..lol

Zepher

iTrader: (1)

Mine accelerates quickly but I can't go full throttle from a stop, otherwise I don't go anywhere.
Car has some cheap all season 245/50/16 tires.

25THRSS

all indications say you have 3.23

Morley

You should be looking at around 2k at 60 mph (1750-2000 RPM) and remember, your stock tach isn't a precision instrument.
If you suspect the TCC isn't locking, try this simple test. With the car in OD hold a steady speed of 50 MPH and tap the brake with your left foot, the RPM should rise a couple hundred then go back down when you take your foot off the brake.

88Camaro350

I read about 2150rpm at 70mph in OD. This is without a locking TC and 2.73 gears. I have 245/50/16 tires also.

Id say I could get under 2k with locking TC.

Zepher

iTrader: (1)

When I am cruising at 60-70 and a press the gas to the floor, I feel 2 shifts. I guess this is the TC unlocking and then the tranny shifting to 3rd, right?

poorboy8

Yeah that sounds about right!

Your TQ con. should lock up at about 40mph with very light throttle....believe me you'll know when it locks up cause the rpms with drop a few hundred rpm and it will feel a little boggy until you pick those rpms back up w/ some speed!

88Camaro350

wouldnt RPM at speed also be affected by power output. Shouldnt say a l98 car run lower rpm at 60mph in OD than a lo3 t 60 in OD.

Ive never heard this mentioned but it has to be true.

25THRSS

no, it has nothing to do with power.

89cmrodriver

my 89 had 3.23 it ran about 2200-2300 at 60, my 94 camaro runs 1500 at 60, btw zepher, i saw your friend with the 86 z28 that looks like a 91-92 z28 on 264 yesterday, that is a very clean car..lol

Zepher

iTrader: (1)

Ya, that is one clean car, and it's fast. 355 TPI with Dart heads, 58mm TB, catback, and a cam. He doesn't have headers on it yet.

25THRSS

You can put a 500 hp car with the same exact gears and transmission as a 200 hp car and they would both turn the same rpm at any given speed. It has NOTHING to do with power.

tamu130

look at your rpo codes if you have them still. i think they would be on the inside of the console.

GU2: 2.73
GW6: 3.27

there is one other that was supposed to come on a stock 305 tpi/auto but i dont know what the code it. it is the 3.23. it will start with a G and if its not one of the ones above its probably the 3.23s.

Momar

GU5 is 3.23's. I know with my 3.45 gears in overdrive locked up I am at about 2000 at 60.

Ben

Zepher

iTrader: (1)

No codes in my car.
I'll probably change the diff fluid tomorrow since I ran out of time today. Finished swapping in my black interior. Looks pretty sweet,
The original,




Tha Black,