What RPM is it running at 70 on the freeway with 4.56? I can't see having that in my car, it would defeat the purpose of having OD, and 1st gear would be like a granny gear.

 

well if its a z spec it has a .63 od I would guess 75 Mph would spin 2900....not a bad triad off for 4:56...in perspective with c4 that would be 4600 rpm at 1:1

-Gun

 

His highway rpm likely isn't all that bad (overall gearing in top = 2.87), but I bet he's one gear higher than most other folks just about everywhere else. Probably doesn't ever hit much more than 50 mph in 2nd, which is only a handful of mph more than what a tall 1st will give you with the same axle gears. Around 110 mph at redline-ish rpm in 4th sounds like it was built with the dragstrip in mind.


Norm

 

With 4.56, I doubt he is still in 2nd at 50 mph.

Also, I don't know anybody that has had their car going 50 in 1st gear.

 

I'll give you that he wouldn't be there very often - I think 7000 rpm gets him to 54 or so. But still do-able and very likely to occur at the dragstrip.


Really tall gearing will get you 50 in 1st. There are two ways to get it, one that I can demonstrate with the math and the other that I lived with for a number of years.

The close ratio 4-speeds in either the 1960's Mustangs (2.32:1) or the close-ratio Muncies (2.20:1) could run axle gears as deep as 4.10 with 25" tall tires (think 195/70-15) and still hit 50 in 1st without exceeding 6500 rpm.

The C-clip in the axle to my '79 Malibu decided to fall out and take the rest of it apart, 1986 I think. Long story short, I was on the road when it happened so I had to settle for 2.56's as the only thing available. 55 mph in 1st at only 5500 rpm with a 2.85:1 low gear iron-case Saginaw 4-speed. Yes, it was a lot like having a 5-speed that was missing 1st.


Norm

 

yes it was, but also sees a lot of street/freeway time. And the engine will turn 7800 and sees 120 mph in the quarter

 

In my opinion a 3.50:1 gear set is the perfect ratio for a T5 overdrive trans.

 

3:50 is WAY to light, you gotta go deeper than that. At least a 3:89, but you would like the 4:11's better. The 3:50 will just bog you off the line and kill your 60' times.

 

I daily dive 3:80s and could even do so with 4:11s and have very little overall change with the .63 od.

HEY....is the OP even paying attention anymore????...I think we lost him wayyyyyy back there.

 

Yeah, I don't know what happened to the OP.

I like my 3.50 gears for crusing, but would like 3.70 or 3.89. It would be more fun. I don't drag my car anyway though.