jweather73

My car does about 3500 RPM's at 60 MPH...is this normal for a stock '84 GSL? (NOT GSL-SE)

Seems kinda high... I don't remember my '82 running that high at that speed.... I guess if it's "normal" I can't do anything other than change the gearing, huh?

Thanks in advance!

-Jeff

bouis

In 4th, yeah.

jweather73

No, this is in 5th.... seems 5th gear is really "short"... I can floor it in 5th and go from 60-80 pretty damn quick.... of course, this means that my gas mileage really sucks too.... that's why I was wondering if it was normal and what I could do about it.

bouis

Well, here, I made this table for my car which has an '83 tranny with an '85 12a rear end: Should be the same for yours:

FIFTH 48.05x


Speed RPM

55 2643
60 2883
70 3364
75 3604
80 3844
120 5766
140 6727
145 6967

FOURTH 58.25

55 3204
60 3495
70 4078
75 4369
80 4660

THIRD 83.45

40 3338
70 5842
83.9 7000

bouis

Well, here, I made this table for my car which has an '83 tranny with an '85 12a rear end: Should be the same for yours:

FIFTH 48.05x


Speed RPM

55 2643
60 2883
70 3364
75 3604
80 3844
120 5766
140 6727
145 6967

FOURTH 58.25

55 3204
60 3495
70 4078
75 4369
80 4660

THIRD 83.45

40 3338
70 5842
83.9 7000

MicahMan

i know that in my 83 gsl tops out at 125 and it is about little less than 6k. my car needs to be a little bit more tuned though.

peejay

Your tach or speedo is probably off. Most likely the tach.

BTW - My car does 40mph at just under 2000, but it does 80mph at about 4200, according to the gauges. CLEARLY something is amiss. (I have an '80 tranny installed, this has a shorter and thus more useable 5th gear than the '85 junk)

Lotus00

Is it common for the stock gauges to be that inaccurate? I have always trusted mine without question... maybe I shouldnt?

peejay

The stock speedo is about 10% high even when new.

The stock tach varies.

jweather73

Yeah, well, my 5th gear sounds like what you show below with your 4th gear. I'm pretty certain the guages are pretty close to what they show, because again, when I'm in 5th, and I punch it while cruising about 60 mph, it takes about 10-15 seconds to get to 80.

Short of changing the gearing/rear end, is there anything else I can do to get the engine's RPM's lower at higher speeds? I assume not.

clashkpr28

I know the fb's have a really crappy 5th gear ratio, but I was wondering is the top speed of our cars limited by this? Can the 12a go all that much faster with a better ratio? Or are they so well engineered that top speed of a 12a= red line with our 5th gear ratio?

bouis

No, it's probably limited by engine power before you hit the redline in 5th. Redlining in 4th is only about 120 mph. Redline in 5th on my car would be about 146 mph and I don't think it has that much power [I haven't tried, of course].

Edit: the top speed is really limited by traction and aerodynamics. Don't try going that fast, please.

peejay

Redline in 4th is higher than the car's top speed, actually. In bone stock trim.

sweetege

yea i can only reach 110 and at that it feels incredibly stable paobably because there is so much drag.
And PeeJay how does that work cause if you redline 4th and then switch to fifth then I would guess that you would be going faster than in fourth because you have more RPM's to go? am i wrong???

peejay

IN stock trim, there isn't enough power to pull redline (TRUE redline not what the tach says) in 4th. Top speed is achieved in 5th but it's only a hair faster.

Nobody has a stock car anymore, though.

OtakuRX

iTrader: (1)

how can you tell if the tach is off?? What makes it go off?

peejay

General inaccuracy. That's just the way things are with mass-produced parts, with compromises against outright accuracy.