ZL1 GEARS...LOOKING FOR 4.10 OR 4.30
 

What's the deal-ee-o? Can't seem to find any info on replacement gear sets for the ZL-1. Anybody got any ideas?:iono:

Not to sidestep but doesn't the ZL1 have 3.73 already? would 4.10 or 4.30 help much?

Yup. Car wants to shift into 4th about 100 ft from end of track. running out of rpm in third,and not enough room to rev out 4th. I guess the flip side would be to rev it to 7k, but that seems dangerous.

What other GM vehicle shares this rear diff with the larger ring and pinion gear? If you used DRs with a slightly lower height would that drop the effective ratio down enough to force earlier shifts and avoid a gear swap?

hmm. Maybe shorter tires would do it...

If there is another ring gear that would fit, it might be from the 9.5-inch truck axle. It's a semi-floating 14-bolt (I think it was semi-floating...). However - ZL1's ring gear is 9.9-inches (9.8XX").

How about a taller DR? Redline ran a slightly taller Mickey Thompson DR on their car if I remember correctly. That might be worth looking into. It's in the current GMHTP. I think it was a 305/40/18 or something. It would require you to go with a smaller wheel, but it sounded like the tire was taller, which might be a solution.

If you rev' higher, it'd probably be a good idea swapping valve springs/retainers for valve float. ZR1 features forged slugs, titanium rods, intake valves, hollow exhaust valves and better valvetrain, and it's limited to 6600. I'm not saying you couldn't take LSA to 7000, but it was my understanding blown motors don't like being over-rev'd...

JMVHO. I wish you luck :)

Depends on what end result you're looking for. You can go with a shorter tire which will give you a quicker ET or you go with a taller tire that will net a higher trap speed. I have a gear ratio, speed and tire size calc in an Excel spreadsheet if you would like to play around with the numbers to see what changing the tire size will do on your rpm's and speed. I've already plugged in the auto and manual gear ratios for the ZL1 as well as stock tire diameter. Shoot me a PM and I'll send it to ya.

What he said. Run a shorter tire on your DR's and it will cure your problem without swapping gears. Then back to stock tire diameter for fuel mileage and normal street driving.

I am already looking for wheels to use with drag radials, but so far can't find any for less than 350 a wheel which is a little steep for occaisional use.
I'm looking for 18" wheels that aren't too heavy.

tire is probabably the way to do this if you still want to be able to throttle out of coners hard on street rubber.

4.10's or 4.30's are nice at the drags but in turns on street rubber you might break grip to easy. I had this issue on a mustang. I think that is why the GT500 went 3.31's.

Anyone have an idea of what the smallest size would be that we could run? Any idea of what would be too small of a tire? And will an increase in horsepower affect what tire size we should choose?

They went with 3.31's so they could hit 60 mph in first, run 200mph and avoid the gg tax. Although I'm sure it does tame the power when coming out of a turn it wasnt the main reason.

No thanks...I like mine better.