4.10 gears...not what I expected.

[JFFerner]

I think everyone has about covered everything with the exceptions of up-hill vs. downhill and headwind vs. tailwind!
And so it goes....Jim

[ZZZZZR1]

Great discussion and explanations with different points of view!!!

I think this is one of the best upgrades for the ZR-1...

I know a few with 4:30 and 4:56 gears! Now that's tall!



David

[rhipsher]

True it is that a Fidanza flywheel is much harder to launch from a stand still than the stock DM due to loss of inertia. I launched at about 2500rpm's with the DM. But with the 13.5 lbs fidanza I found the best launches came at 4500rpm's. And even with Mickey Thompson drag radials on it was a fine line between lighting them up and bogging down at the Christmas tree. But with a line lock you can heat the drag radials up enough to grab and explode drive train parts lol! MT's heated up properly make for awesome launches though. You will jump out of the whole 20 feet. I mean look at the torque squat on that red SOB! It was Mickey Thompson awesome.


Hanging out after 11 runs down the dragstrip with my buddy Mike Johnson and his convertible C5. This was back when I was eating to many donuts. You know that the 90 ZR-1's are the worst seats for fat people to fit in lol. At 187 I fit fine now.

[Schrade]

Very well put.

Should be 'end of story'. Again...

Originally Posted by 5ABI VT

I believe many of you are just not understanding what gears do. Please re-read my post about final drive ratios of 3.45 vs 4.10. the ONLY advantage 4.10s gives you is 1st gear. When you go to 2nd the leverage advantage goes to the stock gears while still in first. and it passes back and forth. That is why there is a ET advantage with 4.10s but no MPH difference. IF the 4.10s were making you faster throughout the entire rpm range and through the gears there would be a mph difference but there is none. if you are gaining mph its possibly due to being at a better rpm through the traps where after the traps they would even out again.

Using 6th is not smart. its a .5 ratio. DESIGNED FOR FUEL ECONOMY ONLY. it shares a synchro with reverse so get ready to melt your synchro and destroy your zf if you are using it for acceleration.

I ran almost 118mph with stock gears. headers and a tune and emissions compliant. On 25 series tires pumped to 48 psi if I remember right on 450 lb springs. Set up for 1/4 mile it is not but right at home at high speed.


It is true the LT5 has more rpm but many of you are not realizing what the truth is. GM didn't want to alter rear gears or the zf SO Lotus was asked to build a dohc 32v motor that still had peak power at what.. 5800 ? I could bet something that Lotus was like WTF when gm asked them to do that. Basically they cammed and setup the potential screamer to act just like a wheezing pushrod sbc. if the motor truly needed 4.10 gears, the motor should peak power well higher than what an LT4 does. it would have pushed the hp and torque curver higher and 4.10 gears would have been justifiable because it would bring the torque back in the low end. As it is now on a stock motor I feel 4.10 gears just makes it too torque for a street tire and the increased rpm range isn't really used because of the way the cams are profiled etc.

If I ever have the chance and $$ to build a serious LT5 I would build a big bore LT5 to spin the maximum rpm possible (8000-8500?) then and only then would I drop a 4.10 in the back because the cams would be profiled to be efficient at a much higher rpm causing a noticeable reduction in low rpm torque.

Im babbling just bored at work. Gears are very misunderstood. In my opinion it was a trick first started by the drag cars to get off the line faster because that's all it really does.. have a shorter 1st gear.

[ZRXMAX]

I believe their is a thesis full of info here and I stopped reading at page 8!

My car has spent much of its life with 307s in it from the ORR I ran in 05. What is their to like about 307s besides running 180 mph in 5th at 5300 rpm ?
Less shifting is and a little bit better gas milage under the right conditions.
200 ft burnouts when your wanting to get rid of some rear tires aren't a problem either.

I remember years ago a couple guys in Texas with ZR-1s that were evenly matched commented on the difference between 3.45s and 4.10 gears. They said their was no noticeable difference in acceleration and were amazed by that fact. They both leaned towards thinking the 4.10s would help the LT5 accelerate quicker as I recall.

I do like the fact that 4.10 gears make the drop in rpm a little less between gears when shifting at 7000 rpm.

I tried a set of 4.30s for a while and didn't really like them especially when out a couple hundred mile cruise.

I have a new set of 4.10s ready to go and I am looking forward to it.

[Schrade]

Originally Posted by ZRXMAX

I believe their is a thesis full of info here and I stopped reading at page 8!

My car has spent much of its life with 307s in it from the ORR I ran in 05. What is their to like about 307s besides running 180 mph in 5th at 5300 rpm ?
Less shifting is and a little bit better gas milage under the right conditions.
200 ft burnouts when your wanting to get rid of some rear tires aren't a problem either.

I remember years ago a couple guys in Texas with ZR-1s that were evenly matched commented on the difference between 3.45s and 4.10 gears. They said their was no noticeable difference in acceleration and were amazed by that fact. They both leaned towards thinking the 4.10s would help the LT5 accelerate quicker as I recall.

I do like the fact that 4.10 gears make the drop in rpm a little less between gears when shifting at 7000 rpm.

I tried a set of 4.30s for a while and didn't really like them especially when out a couple hundred mile cruise.

I have a new set of 4.10s ready to go and I am looking forward to it.

How many miles on your 3.07? You selling the set?

[ZRXMAX]

Originally Posted by Schrade

How many miles on your 3.07? You selling the set?

This is my second set and they came out of a 47,000 mile car. I ran the 1st set out of oil when I let it sit to long with a slow leak a few years ago.

The set I have now probably have less than 60K on them. I will keep them for the next opportunity I get to run another ORR. Sorry...

Another thing about 307s is they are a little bit harder on your clutch overall. If you have to take off on a steep incline you will slip the clutch a bit more to get underway... or you can rev it a little and just pop the clutch.

You shouldn't have to look to long for a set. Both of mine came from early C4s that had 4 + 3 setups. My 89 6 speed coupe had 3.33s in it and you might be able to find a set of those if you can't find any 3.07s. I just look for the whole assembly including the batwing.

I do have an empty 44 housing here if your interested in starting with that.

[Bob Eyres]

I've been in love with the short gears since back in 1970, (when I was a kid). My first Corvette was a beat up $800.00 Split window with 340hp., a high winding solid lifter small block with 4.56 gears. Kind of like the ZR-1 of it's day.
I put some, new for the time, wide F60x15" Goodyears on 8" wide station wagon rally wheels on all 4 wheels.
That thing would squat down and launch like a demon. Two of my friends had big blocks, one a brand new 69' 427/435hp coupe, and the other guy had a 66' GTO with an L88 crate motor. But at launch, and in first gear, neither of them could beat the 63'. By the end of second gear though, I was toast.

[Dynomite]

Good information and great photos....thanks

Cliff

Originally Posted by rhipsher

True it is that a Fidanza flywheel is much harder to launch from a stand still than the stock DM due to loss of inertia. I launched at about 2500rpm's with the DM. But with the 13.5 lbs fidanza I found the best launches came at 4500rpm's. And even with Mickey Thompson drag radials on it was a fine line between lighting them up and bogging down at the Christmas tree. But with a line lock you can heat the drag radials up enough to grab and explode drive train parts lol! MT's heated up properly make for awesome launches though. You will jump out of the whole 20 feet. I mean look at the torque squat on that red SOB! It was Mickey Thompson awesome.


Hanging out after 11 runs down the dragstrip with my buddy Mike Johnson and his convertible C5. This was back when I was eating to many donuts. You know that the 90 ZR-1's are the worst seats for fat people to fit in lol. At 187 I fit fine now.

Originally Posted by 5ABI VT

I believe many of you are just not understanding what gears do. Please re-read my post about final drive ratios of 3.45 vs 4.10. the ONLY advantage 4.10s gives you is 1st gear. When you go to 2nd the leverage advantage goes to the stock gears while still in first. and it passes back and forth. That is why there is a ET advantage with 4.10s but no MPH difference. IF the 4.10s were making you faster throughout the entire rpm range and through the gears there would be a mph difference but there is none. if you are gaining mph its possibly due to being at a better rpm through the traps where after the traps they would even out again.

What I also suggested in post 87....thanks...I think you said it better
The issue then becomes the last shift into third or even fourth for those with 4:10s.

[A26B]

Originally Posted by Bob Eyres

I've found that the lightweight flywheel improves the performance of the LT5 everywhere but at the launch.
Once you're hooked up and moving though, the light weight unit gives you an advantage throughout the run, by using less horsepower that it takes to spin it.
Bottom line, shorter gears=advantage, lightweight flywheel=advantage, Marc's 510 package=big advantage.

You have the one performance "problem" that we all love to have, traction
If you don't want Drag Radials, check out the thread on the Toyo Proxes 888's. they look like a good alternative, if you don't put a lot of mileage on the car.

Now, with more choices of flywheel weight, combined with gear options, should allow for dialing in what works best with individual tire, engine combos.

Fidanza 13#
Jerrys Gaskets 18# (alum billet)
Jerrys Gaskets 22# (alum billet)
Stock D/M 33#
McLeod (unk)