Why am i at 2500rpm at 70mph?

[y87inside]

This is in my y87 a4 with 3.42 gears. I have 255/50/16's and my mph is almost dead on accurate with my speedo. That rpm just seems kinda high to me.

[1998silverbird]

Are you in drive or overdrive?? Did you buy the car new?? if not put your car on a lift and check to see what gears you have..

[1998silverbird]

Acually that sounds right because I am at 2000rpm at 65mph with 3.23's.. at 70 its like 2250 rpm's

[99Camaro99]

3.42s here.

2,500 puts me at around 81mph.
3,000 puts me around 90.
2,000 puts me just under 70 so...hmm...

[Dominic]

2500 @ 70 is not right.

2500 = 80-82mph

70 @ 2500 isn't right for overdrive.

Here's an easy test... Put it in 3rd (non overdrive) and run the car @ 2,000RPM. With 3.42 rear gearing and stock height tires you should be turning 45mph. If you're not at 45mph something is wrong.

[Dominic]

2500RPM = 78mph for me now with the P245/50's and 3.23 rear M5.

So shifting @ 6K
1st = 38mph
2nd = 65mph
3rd = 101mph
4th = 143mph
5th @ 143 = 4500RPM

Just thought Id throw it in for fun. :D

[y87inside]

Well, i guess my tires are stock height..or pretty darn close. I bought them in that size after researching the boards to see what size i could get wider without affecting the speedo. Dominic...ill try your test on my way to work and ill post when i get there the result. But if i am at 2500 @ 70mph on stock height tires then what gear would that suggest i have? Might be pulling off the rear end cover this weekend.

[AMinor65]

If your car is y87, and you're positive that your speedo is correct, I wouldn't worry about pulling the cover off. I think that your issue will be tranny related. Almost sounds like a converter not locking up to me. Maybe a valve body going bad?

[y87inside]

Ok....had to go to the atm anyways so i did the test. At 2000 rpm's in 3rd im at 40 mph at 45mph my rpm's read at 2250 (give or take a few revs). I know the trannys in great shape. I know the converter locks up and i know the speedo is dead on. Tranny itself is in great shape because i just had it worked on when i installed my shift kit, servo and .500 boost valve. It shifts fine does not whine and my mechanic says everythings fine with it.

[RamAir95TA]

I have 3.73s, stock tire height, and I'm spinning exactly 2400 at 70mph.

Any chance you have 3.73s?

[Robafb]

same here, I run 3.73's and im right at 2500 at 70mph

[y87inside]

possibility i guess. I guess i'll just have to pull the cover off this weekend and count em. I know its posi though.... [img]smile.gif[/img]

[WickEdSix9838]

the tach in these cars arent dead on! by my tach my car idles at 1100 RPMs but on the autotap is 750-800...

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by WickEdSix9838:
the tach in these cars arent dead on! by my tach my car idles at 1100 RPMs but on the autotap is 750-800...<hr></blockquote>

That would be my first guess at why you are reading high.

[Dominic]

Well those tach #'s and speeds line up perfectly with 3.73 gears...

I'd say you have 3.73s and not 3.42s, or something is programmed funny, or something is not right... (TC not locking etc).

I had you do the 3rd gear test to eliminate overdrive problems... third is trully 1:1 and it will tell you what rear gear you have period if the speedo/tach is accurate and programmed right.

Thats so odd. Is the rear stock??