Here is my problem. I'm running 2.73 rear r235/60/15s tires and a 700R4 trans. At 50mph I am at 2500 RPM I think that's kind of high. Between the lock-up converter and a very smooth trans I'm not sure I am going into 4th. My weak 305 doesn't help matters (no pull ).
At 2500 RPM my Volvo is doing almost 70 mph.
Any Ideas? (short of pushing the Camaro with the Volvo)

Thanks Tom

 

How about 60 mph? I need a little help here.

 

I don't think your going into overdrive. I have a T-5, but with 3.73's I'm at about 2700-2800 rpm @ 70mph.

 

I agree, I don't think your getting 4th gear (overdrive).
I have 3.42's, 700R-4, 255/50/16 tires and I do 2,000 RPM @ 60 MPH (give or take)

 

Not to be cruel, but...

This has got to be a contenda for the most frequently asked inane question on this board, right up there with "how do I tell what gear I have" and "do I have posi". It comes up at least a couple of times a week. The answer is always the same:

The thing in your dash that moves according to engine speed is a trim package, not an instrument. Check it against a real piece of test equipment before getting all worked up about transmissions and gears. These tachs are never right, they fail by reading high, and they read higher as they age. Out of the 3 or 4 of these that I own, the most accurate one is only about 3% high. Numerous people on this board report that theirs reads double what it should, and a few read even higher than that.

So, verify your RPM indication first. Any tune-up place with a real tach should be able to do that for you.

 

60 mph, tranny selected in overdrive, 3.23 gears, 275/40/17 tires, 2k rpm's.

 

I am at 1500 in 4th at 45mph.
2700 or so at 80mph.
http://www.transamws6.com/video/accelerating.mpg

I've got 3.23 gears and a 700R4

 

Don't Flame me. I have a problem and I'm looking for ideas. So lighten up a little.
I never heard that the tachs we have do this with age. It is close at idle could it be off by 1,000 at midrange RPM? Is there a fix/ajustment for this? I know that they are not very good, I didn't know that they were that bad.
p.s. You did give me something to look into ,Thanks

 

last time i checked my engine with a strobe light, it was almost exactly equal to my tach, which was about 18 months ago.....

i am at 2500 rpm's at 75 mph, with a t5, 4.10 rear, and a 26 inch tire

 

1500 rpm shows me 94 km/h, about 58 mph.
T5 with a .62:1 fifth gear, 235/60R15's and a 3.42 rear gear in the Formula

Pete

 

I have the same setup as you, (2.73's, 235-60-15's, 700r4, and you are definetly not getting into 4th. At 45, im at about 2300 in 3rd gear. In forth at 50, im at about 1700 rpm.

 

I have the same setup as you, (2.73's, 235-60-15's, 700r4, and you are definetly not getting into 4th. At 45, im at about 2300 in 3rd gear. In forth at 50, im at about 1700 rpm.

 

Thank you all It's my tach going south. I'm now at 3500 at 50mph and getting worse!

 

Wow, that's quick!!!

But, typical for these things, they're pretty lame. Somebody could make some money recalibrating them, or even building a reliable replacement driver circuit for them (which is the problem, not the meter movement itself).... maybe someday whenever I get some spare time, since I have the technology for that.

 

65 mph, 3,000 rpm, 3.42 gears, TH400 though Speedometer says I'm going 70 mph but the GPS unit says 65.

 

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OD is just a lower (numerically) gear ratio the tranny goes into. Correct me if I'm wrong people but OD is only effective in 4th gear.

Now the original question:
At 80, I turn 1600RPM
50-1500 in 5th

245/50/16, 3.08's, 6spd

-Rippin

 

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I thought OD was 4th gear.
As a follow up I found a tach fix posted by Morley. I am now just waiting for a part I had to order online. I will let you all know how it goes.

 

OD IS 4th gear


1 makes it hold 1st gear. until you either WAAY over rev the motor, or you shift it. it also semi "locks" it in gear so you can kinda let off the gas and it will slow you (to a point) like a manual.

2 like "1" it makes you hold 2nd gear.. until you wayy over rev it.

D drive. aka 3rd gear. good for if you are going up a steep hill at light throttle and it keeps kicking in and out of OD.. it also doesnt let it lock the converter

OD overdrive... aka 4thgear. your crusing gear... leaving it in OD and it shifts "normal" thru all the gears.

the mystery "5th" gear: when the TQ converter locks up it brings down the tach a little... some people think thats it going into 5th... really, its still in 4th, the converter just locked

 

link to the fix?

 

I wanna say 1200 RPM with a T-5 and unknown rearend at 50 mph. Prolly doesn't help comparing a manual to an auto. I think a good clutch makes a big difference. 40 is barely within acclerating range. You can kinda weasel 35-45 in 5th gear, but it doesn't start to pull much until after 45. (35-45 in 5th = econo-i'm-gonna-lug-the motor-if-i'm-not-careful-mode)

 

3.73 gears, 700R4, 275/40/ZR17

2500rpm gets me ~72mph which is exactly what it should be.

 

with 2.73's and a 700r4, about 1600 and 60 mphin4th. you'redeffinatelyin 3rd

 

I don't know squat about Auto T's. Would it be better to drive in D or OD????

 

As i have read around, u should not use your over-drive whil you are driving round in town. It creates extra heat and lowers the transmissions life. there is a whole article on the message boards at www.chevytalk.com on the performance realated board. Now if you are not shifting into OD all the time, and are on the highway, you can use OD to your advantage. Just my .o2 cents

 

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