2.5 platinum gearing question

[benz-tech]

it seems that 2nd gear is abnormally tall for a car with 4.1 rear axle ratio. my car will do over 60mph in 2nd gear. also at 60mph it is turning approx 2800rpm. 3k yields about 65+. is that normal? i do have incorrect 205 55 15's on it but that would only change the distance traveled and overall speed, not the relationship of engine rpm to speedo ratio. the speedo feels accurate if not reading a little low- which makes sense w/ the tires.
is this how your cars are geared?

[Gubi]

Your tires are only 2% off from stock, which isn't bad. In 5th gear you should have 21.1 MPH per 1000 RPM. This works out to 9.6 MPH per 1000 RPM in 2nd.

At 60MPH in 2nd you should be at 6250 RPM, so it sure sounds like your tach is slow.

[Grant]

Maybe you have a verde differential for some reason? The gearing on those boxes are 3.55 final drive, same ratios for the rest of the gear set.

The tachometers on 2.5 liter Milanos always seem to read low. Hook up to a tachometer and see if that's the case.

That being said, Verde gears feel too tall for normal driving, 4.1 gearing feels too short for a V6 on the freeway. Come to think of it, when I had 3.55 gearing, I recall cruising around 3K when I was commuting to school...I was driving around 70 mph! Now to go 70mph, my tach reads 3400rpm after I switched to a platinum box, what you should have!

[benz-tech]

fuel cut is at 6500 right? is so my tach is just about right. 3k rpm in 5th is about 63-65 mph and the redlined shift out of 2nd is just over 60. i love how tight the ratios are from 2nd - 5th but that 1-2 shift has an huge gap.

[Gubi]

Yeah, but even with a 3.55 he should be at 5400 RPMs at 2nd in 60.

You're going to need to test your RPMs with a digital tachometer and your speedometer with a GPS unit to figure this one out.

[Grant]

hmm...3K = 63-65..

That sounds more like platinum gearing now, which is the most likely scenario. O well, hope you're enjoying the car!

[Craig]

Just not going to happen, 34mph @ 3000 rpm in second is the max with any standard gearset. You would have to be in fifth to get those speeds.

See the attached spreadsheet.

[benz-tech]

Quote:

Originally Posted by benz-tech 3k rpm in 5th is about 63-65 mph and the redlined shift out of 2nd is just over 60.

[Gubi]

What I was talking about is that in your original post you weren't clear about the gear, and Craig and I read it as you reporting your RPMs in 2nd. In re-reading that I'm guessing you meant that the 2800 and 3000 RPM speeds were in 5th, correct?

Anyway, my original post with the MPH per RPM is valid and that's what you should go with.

[Craig]

Quote:

Originally Posted by benz-tech it seems that 2nd gear is abnormally tall for a car with 4.1 rear axle ratio. my car will do over 60mph in 2nd gear. also at 60mph it is turning approx 2800rpm.

[benz-tech]

looks like i was already one martini into the evening with my original post. yeah, i meant 5th gear for the 2800 rpm thing.

[emerswf]

Quote:

Originally Posted by Craig Just not going to happen, 34mph @ 3000 rpm in second is the max with any standard gearset. You would have to be in fifth to get those speeds. See the attached spreadsheet.