4.56's for the Strip and Street?

[Bob Eyres]

Many ZR-1 owners consider 4.10 gears an ideal compromise gear for street and strip, because with stock gears 6th is virtually useless unless you're going at least ten miles over the national limits. With stock tire sizes, 4.10's allow the car to use fourth gear in the qtr. mile. But, even so, fourth doesn't come near topping out in the quarter with 4.10's. So, how about 4.56's which allow you to go through the traps in the low 7K range, using the full range of RPM in the first four gears.
So, the theory with 4.56's is, not to use first gear except at the strip, and that still allows 6th gear for decent mileage.

Is there anyone out there that's using 4.56 gears now? If so, what's your opinion?

[mike100]

to add to the question- Do you need a different carrier beyond a certain ratio due to an ever decreasing pinion diameter? Or do the D44 vette applications just increase the ring gear thickness accordingly?


On that note, I will say that I have been told by a guy I met here locally that used to have a 95 that 3.73 was the most effective mod he did to his Z.

[Hib Halverson]

Obviously, for drag racing, as long as you have a tire under the back that can get the car to hook with such a short ratio, a 4.56 or even maybe a 4.88 gear makes more sense than 3.45, 3.73s or even 4.11s.

The downside is, if the car's driven regularly on the street, poor mileage and high rpm at cruise speeds. Another downside is if you went to 4.5s along with going to a big tire in back to get the car to hook, then the next thing to break are rear axles and axle shafts.

[Bob Eyres]

Originally Posted by mike100

to add to the question- Do you need a different carrier beyond a certain ratio due to an ever decreasing pinion diameter? Or do the D44 vette applications just increase the ring gear thickness accordingly?


On that note, I will say that I have been told by a guy I met here locally that used to have a 95 that 3.73 was the most effective mod he did to his Z.

I know that 4.56's will fit. Possibly 4.88's will too. Beyond that ?

A lot of people choose 3.73's. It's a good compromise. But that's the problem, any choice is a compromise depending on what you're doing with the car. I'm curious as to what is the best actual tire/gear combo for a stock, or stock block ZR-1 to have for the quarter mile.

255x50x16" BFG DR's are a good tire. Slightly larger, and with 1" more sidewall to create a bigger footprint at low pressure. Used with 88' 16" Corvette wheels, they fit on the ZR-1. Paired with the 4.56's they would be my pick for the strip. Along with a pair of those new radial skinnies up front.

[WARP TEN]

When I had my '93 one of my early mods in about 1995 was to add 4.10 rear gears. I loved them. Gas mileage dropped a bit, but the improvement in accelleration over the stock 3.45s was very noticeable. At one point afterwards I drove a ZR-1 with 3.73 gears but I did not think it was as good on acceleration and it cost the same to install. Gas mileage is arguably better. With 4.10s the car is much more responsive in sixth gear and still cruises nicely. I do have to use 4th gear to get through the 1/4 mile but I only do that once or twice a year vs driving regularly the rest of the time. When I got the '95 last summer 4.10s were one of the first mods I did. I have ridden in (non-ZR1) cars with both 4.56 and 5.13 gears and IMHO they are not for everyday driving. On the former you don't need 1st gear and on the latter you probably don't need 2nd either!--Bob

[Phil DeJohn]

I have a 92 with top end work with a 4.30 rear. At the finish line I'm at 6800 rpm in 4 th. which is where I shift at. It's great for the street and track. The car turns 11.70's all day at 118 to 121 mph.

[Bob Eyres]

So Phil, the 4.56's would put you right around 7,200 in the traps. Sounds good to me.
Do you still use 1st gear normally around town? or not?

[Phil DeJohn]

My car peaks at 6800 rpm,So anything higher than that does not do me any good. I went slower with the 4.56's in the same car, I was at 7400 at the traps, Way to much for this engine set up. I have a 415 car that does not like the 4.30 gear, Its very happy with a 4.10. With the 4.30 11.0's. With the 4.10's 10.85.I shift the car at 7400 end up at 7100 to 7200 rpm.
Yes I still use 1th gear, It's fun.

[Paul Workman]

Originally Posted by Bob Eyres

So Phil, the 4.56's would put you right around 7,200 in the traps. Sounds good to me.
Do you still use 1st gear normally around town? or not?

4.11s not zackly the same, but every 4.10/11 geared car I've driven I find myself doing a 1-3..shift in normal traffic driving. Would 4.56 result in a 2-4 habbit? I dunno....

4.10s I've heard it said is ideal for the ZR-1; "would have been standard if not for mileage consideration" (as the story goes).

I'm not so sure. A 4.30 has appeal too and would put me a little higher in 4th gear - more or less in the "wheel house" if I could reach 122-124 mph in the quarter. Pete doing 129.xx in 3rd on his stock bottom 350...still just blows me away. I've driven that car once, and I was in awe!

It seems (to me) the added shift might be the issue, aside from launching the Z. Looking at Pete's times comparing times with the 3.45s to his 4.10s, I think the edge is with the 4.10s, but not by as much as one might hope. Others have espressed similar comparisons between those two ratios. I'd like to know what people thought of the 4.30s vs. 4.10s compared to 3.45s. I've not driven a 4.56 car, but an associate of mine had them, and I didn't like the trade-off for a street driven car - a personal thing, I admit.

P.

[RyanChappel]

I had a '68 Chevelle, small block, headers, double-pumper, accel dual-point, mild hydraulic cam..and 4.56 posi with factory air shocks..first gear was unreal, but very, very brief.....I think the damn thing wouldn't run much faster than 110-115 flat out....I bought it new, and traded for a '70 when I came back from VN.....I have regretted that deal ever since...

The 4.56 was fun, but not the most user-friendly ratio...