4.10 gears. - ZR-1 Net Registry Forums

rhipsher · 11-30-2008

I was always worried that if I went with a 4.10 gear ratio that I would loose the ability to hit the 180mph mark. Then I went on Mark Haibeck site and read something that made total sense. He said with 4.10 gears 6th gear actually becomes a usefull gear. I've been at 175mph and shifted to 6th gear and the car started loosing speed and then shifted back down to 5th and the car started climbing again. Even Corey said don't ever use 6th gear at that speed. It will just create a drag on the transmission and it will get hot. Just stay in 5th gear. So it looks like 4.10 gear ratio may actually increase your top speed.

Locobob · 11-30-2008

I don't think Marc meant useful in relation to top speed. With 4.10's 180mph would be reached at just over 4800rpm in 6th - not many LT-5's are going to be making enough HP at that rpm to get there. Better to push the rev limit in 5th - a bit over 7200rpms in 5th = 180mph. I have heard there is an oiling issue when using 6th as a top speed gear - the ZF Doc can fix this but you're looking at a pretty expensive tranny teardown.

rhipsher · 11-30-2008

Quote:

Originally Posted by Locobob

I don't think Marc meant useful in relation to top speed. With 4.10's 180mph would be reached at just over 4800rpm in 6th - not many LT-5's are going to be making enough HP at that rpm to get there. Better to push the rev limit in 5th - a bit over 7200rpms in 5th = 180mph. I have heard there is an oiling issue when using 6th as a top speed gear - the ZF Doc can fix this but you're looking at a pretty expensive tranny teardown.

At the texas gathering I talked to a couple of guys that road race their Z's at Big bend. I believe curtis was one of them and he said he was hitting 201mph on the staight aways. And another gentlemen said he was hitting 210mph on the straights shots. Both cars were prepared by Corey. I should have asked how their cars were set up and what work was done to them. I do remember Corey telling me that in order to set the car up for road racing that he has to add another transmission cooler. I don't believe these ZR-1's were driven on the street anymore. Just strictly for road racing. The pictures I was shown they had racing #'s on each door and had racing slicks on them and full roll gages. I believe A26B knows who these guys are. So there's a good chance they were running stock 3.45 gears it they were hitting those speeds. Do any of you guys do any serious road racing in your ZR-1's and if so how has your car been prepared horse power wise and structurally?

Aurora40 · 12-01-2008

I wouldn't be surprised if open road race guys even went to lower gearsets than stock. Presumably you'd want your power peak to happen right around where your top speed is expected.

With 3.45:1's 7,000 rpm is like 202 mph in 5th I believe. If your power peaks at 6,200 that would be around 180mph. That actually seems like a good setup for stock top speed running (I'd think anyway). If you had more power and were gonna go faster, you might want a lower gearset than that, as I'm not sure one would want to run 7,000+ rpm for the extended period of time it takes to hit those higher speeds? A 3.33:1 would be easy enough to get as it was OEM on some L98's, and would push 7k up to about 210mph.

I'm talking out of my *** though, just speculating

11-30-2008	#1
rhipsher Join Date: Aug 2008 Location: Houston 90 Red ZR-1 Posts: 2,320	4.10 gears. I was always worried that if I went with a 4.10 gear ratio that I would loose the ability to hit the 180mph mark. Then I went on Mark Haibeck site and read something that made total sense. He said with 4.10 gears 6th gear actually becomes a usefull gear. I've been at 175mph and shifted to 6th gear and the car started loosing speed and then shifted back down to 5th and the car started climbing again. Even Corey said don't ever use 6th gear at that speed. It will just create a drag on the transmission and it will get hot. Just stay in 5th gear. So it looks like 4.10 gear ratio may actually increase your top speed.

11-30-2008	#2
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Re: 4.10 gears. I don't think Marc meant useful in relation to top speed. With 4.10's 180mph would be reached at just over 4800rpm in 6th - not many LT-5's are going to be making enough HP at that rpm to get there. Better to push the rev limit in 5th - a bit over 7200rpms in 5th = 180mph. I have heard there is an oiling issue when using 6th as a top speed gear - the ZF Doc can fix this but you're looking at a pretty expensive tranny teardown. __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368

12-01-2008	#4
Aurora40 Join Date: May 2005 Location: Leesburg, VA Posts: 2,713	Re: 4.10 gears. I wouldn't be surprised if open road race guys even went to lower gearsets than stock. Presumably you'd want your power peak to happen right around where your top speed is expected. With 3.45:1's 7,000 rpm is like 202 mph in 5th I believe. If your power peaks at 6,200 that would be around 180mph. That actually seems like a good setup for stock top speed running (I'd think anyway). If you had more power and were gonna go faster, you might want a lower gearset than that, as I'm not sure one would want to run 7,000+ rpm for the extended period of time it takes to hit those higher speeds? A 3.33:1 would be easy enough to get as it was OEM on some L98's, and would push 7k up to about 210mph. I'm talking out of my *** though, just speculating __________________ Bob Saveland Former owner of #2517 [IMG]http://a.random-image.net/aurora40/vette.jpg[/img]