Re: 4.10 gears...not what I expected.
 

According to Paul's gear charts the 4.10's give you 174.29@7,000 and 186.74@7,500. So you'd have to raise your rev limiter a bit, but you could get up there with 4.10's.

And as far as getting a better launch with more power, but stock gears, and the same tires....good luck.

Just what can you do on a ZR-1 for $1,500.00 that can give you the performance increase of 4.10 gears? Headers is the only thing I can think of, and that's only if you say good-bye to emissions compliance.

I bow down to Pete for his efforts to find the outer limits of the stock block ZR-1. Somebody's got to do it, and he's done a phenomenal job. The goal is to get into the tens with a stock block 350, and he's knocking on the door. But one look at his great 60ft. times with the 4.10's tells me that the right gear is the answer. My guess is that 4.30's or 4.56's and the right tire would get him there, because then he's using all the revs available. Running a three speed ZR-1 is like trying to do it with your hands tied.

Re: 4.10 gears...not what I expected.
 

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 :dancing
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.

Re: 4.10 gears...not what I expected.
 

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.
:cheers:

Re: 4.10 gears...not what I expected.
 

"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."

I'm not sure about a totally stock LT-5, but my ported top end w headers and stock cams(not degreed) peaked at ~6800rpm. Still does now.
I think there's more cam there than air available.

Re: 4.10 gears...not what I expected.
 

That is making use of what I feel is the LT5s greatest attribute. RPM =D>

Re: 4.10 gears...not what I expected.
 

With all due respect, I think you are defeating your argument in the first paragraph.

Let's establish that we're talking about performance in the quarter mile here, not overall performance in every situation.

You agree that 4.10's have an e.t. advantage in the quarter mile. In a drag race low e.t. wins, end of story.

Once again you mention "mph difference". The only thing that mph in the traps means is that it is an indirect indication of horsepower, of potential.
A car with a mediocre e.t. and a high mph reading in the time traps is a loser. Lots of power, but not set up for the drag strip.

As I see it, the goal in quarter mile gearing setup is to achieve the lowest short time possible (60ft.), then reach the end of the track at the top of the top gear, (4th in most cases).

In our ongoing example, Pete cut his lowest yet 60ft. time with 4.10 gears, but complained that by using fourth gear he reached the end of the track without reaching his desired peak rpm of 7,400. In my opinion, the way to fix that is an even higher gear, 4.30's or 4.56's depending on what tires are available to handle it. The lower the gear, the lower the potential 60ft. time. As long as you can use all of your available rpm at the other end of the track.

BTW, you mentioned that you trapped 118mph. with just headers and a tune. Is that a 375 or 405hp. ZR-1? And what was the actual tire size? thanks.

Re: 4.10 gears...not what I expected.
 

Not discussed so far.......what rpm do you drop the clutch and how fast can you shift (power shift?). If you are spinning your tires in first gear, does it matter what rear end ratio you have?

How does car acceleration vary with how fast you are spinning your tires?

Does traction vary with tire spin?

After you have spun your tires with 4:10s for a bit in first gear you are shifting into a range that is different in every gear with 4:10s as compared to 3:45s (but shifting into the maximum engine power curve zone "rpm vrs hp" each time) requiring you to shift into 4th at the end of the 1/4 mile. So the difference is at the start of the 1/4 mile and near the end of the 1/4 mile only.

Maybe I have it wrong but depends a lot on tires (traction) at least in 1st gear and second gear in a power shift :p

Re: 4.10 gears...not what I expected.
 

You are correct and i guess Ill clarify that IF you can take advantage of a short first gear with a suspension/tire setup for launch gears can make you 'quicker'. in Petes case i also agree that more gear can shave some more et assuming hes got the setup to launch hard and be at the right rpm to see some mph increase before the traps.

Im not a drag racer and make no secret to voice my opinion on why I don't like it but I think drag racing is about whos quicker not faster. Its just my preference and mph to me is everything. A car can run 10s and go 120 and I can be doing 13s and doing 130mph. ill be happy because if he rolled up beside me on the freeway where I do most my spirited driving I would walk away and ultimately be 'faster'.

I guess all im trying to say is for those who are considering gears.. if you are drag racing and have the suspension setup to hook first gear with an aggressive launch or are looking to optimize the gearing for the 1/4 mile. .. gears are easily justifiable.

I find most people tend to compare gear to gear ie. 3rd gear with stock rear vs 3rd gear with 4.10s. I think that most people fail to consider that the speed range in each gear has been reduced and it would be more fair to compare a 2nd gear with stock rear vs 4.10s in 3rd. That usually makes people think.

My z is a 94. Headers catted to corsa with haibeck chip. tires 315/25/19 on Invos which pretty much grip like all seasons lol.

Re: 4.10 gears...not what I expected.
 

Yup!

That and a relatively flat torque curve!

I've watched the result of the high rpm performance, and others* have noticed too that lots of cars may jump a ZR-1 at the light, but time after time the LT5s will run 'em down on the big end. As Bob G says, "Just about the time (pushrod motors) are getting interesting, you have to shift!" So many times, if the Z lost the 1/4 mile contest, it was gaining and just ran out of track.

Watch what happens at every shift the C5 makes... (I especially like the jubilant "Ha!" when the C5 lunges ahead...followed by the perplexed, "Huh???" as the Z is walking away. And then the reality sinks in: "Your not catchin' him!!")

http://www.youtube.com/watch?v=PzPPEK9Qf3M


And, the numbers seem to agree. Race results from the 1/2 mile shootout in Chicago last spring showed the LT5s - and their decades older technolgy - really took no guff from contemporary pushrod motors. The did really well!

Re: 4.10 gears...not what I expected.
 

I think most people understand the phenomenon of low gears vs high once you have driven a car with both, but have a hard time explaining it all in words. there are a lot of complex things going on and it isn't just a straight algebraic torque multiplication definition. Mathematically, you want to dwell in the fattest part of the hp curve and spend the least amount of time lugging off the line.

- You can integrate the function (hp curve) and gear the transmission accordingly to drop you back where the engine runs right (more gears or custom ratios in the ZF which don't exist).

-you can gear down the diff to reduce break-away tire spin (tall gears sometimes result in massive runaway burnout speed) and tires deal with wheel slip better if the slip speed isn't too much.

-you can figure out a way to shift faster (automatics and twin-clutch PDK types come to mind)

-or you can put a 400 cubic inch engine in to be able to accelerate harder regardless of gearing.

Obviously the transmission is probably the best place to see gains, but since that isn't available with the ZF, adding power makes sense (not to mention fun).

Re: 4.10 gears...not what I expected.
 

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

Re: 4.10 gears...not what I expected.
 

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!

:cheers:

David

Re: 4.10 gears...not what I expected.
 

:dancingTrue 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.
http://i301.photobucket.com/albums/n...0/DSC01537.jpg
http://i301.photobucket.com/albums/n...DSC01538-2.jpg
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.:-D At 187 I fit fine now.
http://i301.photobucket.com/albums/n...0/DSC01529.jpg

Re: 4.10 gears...not what I expected.
 

Very well put.

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

Re: 4.10 gears...not what I expected.
 

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

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. :cheers:

Re: 4.10 gears...not what I expected.
 

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

Re: 4.10 gears...not what I expected.
 

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.

Re: 4.10 gears...not what I expected.
 

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. :cheers:

Re: 4.10 gears...not what I expected.
 

Good information and great photos....thanks :handshak:

Cliff

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

Re: 4.10 gears...not what I expected.
 

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)

Re: 4.10 gears...not what I expected.
 

Right. Mine is an old Doug Rippie unit. A machined down stock Camaro single mass that weighs about 15lbs. It has worked well for 17 yrs.

BTW,What is the weight of the newest light weight flywheels?

Re: 4.10 gears...not what I expected.
 

Lower gearing like 4.10's or 4.56's wont affect on the eamount of rpm drop when upshifting. Transmission gearing is the only way to affect the rpm drop when shifting. This is where the terms, Close-Ratio and Wide ratio transmissions come into play, with the close ratio usually having less rpm drop during upshifts.

Re: 4.10 gears...not what I expected.
 

Yes, all else equal means that the cars are assumed to have identical variables, including having the exact same engine power output. The only variable being rear dif. gearing.

"Only way that would be lower is if the engine is running out of breath at the lights."
This makes 100% sense. I believe this to be the case in my setup, in going from a 3.08 to a 4.10 gear has had me trapping at an rpm that is beyond my power peak, where power is dropping off fast. Thanks for explaining.

xxxxxxxxxxxxxxxxxxxxxxxxx
Yes, ET is what matters in drag racing. If I cut a 2.0 60ft on pass #1 and trap a 12.0@100mph. Then on run #2 I lose traction off the line and run a 2.5 60ft time, I could theoretically run a considerably worse ET such as 13.0 seconds, yet still run the same MPH.

It could be argued that in drag racing, ET is as irrelevant as MPH because of the fact that having the quicker ET doesnt necessarily mean you will win the drag race.
ET is of course the most common method of comparing a cars acceleration. If all variables are the same, MPH is an accurate fashion in which to compare engine power.

Thank you !

Re: 4.10 gears...not what I expected.
 

If you look at the speed in each gear you will see that tallers gears add mph at the shift points as compared to shorter gears.

Here are the numbers for 3.07 compared to 4.10s
7000 rpm and 25.5 inch tall tire with ZF-6 ratios from Procrastination Racing's website.

http://www.angelfire.com/fl/procrastination/rear.html

3.07 1st 65.5 mph
4.10 1st 49.07 16.43 mph difference

3.07 2nd 97.17mph
4.10 2nd 72.76 24.91 mph difference

3.07 3rd 133.05
4.10 3rd 99.63 33.42 mph difference

3.07 4th 172.97
4.10 4th 129.05 43.92 mph difference

You are correct... the difference is "time" spent in each gear to gain those additional mph between shifts. The starting rpm at each shift is right around 4720 rpm.

However... It sure does seem like the rpm drop is increased with 3.07s :)

My speedometer calibration was off almost exactly 25% when switching from 4.10s to 3.07s. I made up a paper speedometer reference sheet for ORRing so I could look at the speedo and then look at my reference sheet.

I bought a Dakota Digital box years ago that was designed to allow me to calibrate my speedometer regardless of what gears I as using. I never could get it to alter the signal to the ECM to give me the correct speed. Has anybody here ever tried one of those boxes ?

Re: 4.10 gears...not what I expected.
 

I use that same rpm calculator as well, small world.

In this example, you are comparing how much MPH youwwill get out of each trans gear using a 4.10 or 3.07 gear. Not the amount of engine rpm drop that will occur when you shift from 1st gear to 2nd gear.

Using the exact same parameters you have used.
3.07 rear gear ratio
shiftpoint=7000rpm
tire height 25.5"
rear gearing 3.07
trans 1st rear ratio=2.64:1
=65.5mph @ 7000rpm in 1st gear

Now you shift to 2nd gear from a hypothetical shift rpm of 7000rpm, same variables except the 2nd gear trans ratio of 1.78:1.
Now you will be travelling at 65.5mph in 2nd gear, with your tach now registering 4725 rpm.
Shiftpoint rpm minus resultant rpm in 2nd gear, for 3.07 gears
=7000rpm - 4725rpm
=2275rpm
= For 3.07 rear gears the RPM drop of 2275rpm when shifting from 1st gear to 2nd gear

4.10 rear gear ratio
Now lets repeat for a 4.10 gearing scenario
Shiftpoint =7000rpm
tire height 25.5"
rear gearing=4.10
trans 1st rear ratio=2.64:1
=49.0mph @ 7000rpm in 1st gear

Now we shift to 2nd gear at our hypothetical 7000rpm shiftpoint, same variables except 2nd gear ratio of 1.78:1. Now we will be travelling at 49mph in 2nd gear, with the tach reading 4725rpm.

Shiftpoint rpm minus resultant rpm in 2nd gear, for 4.10 gears
7000rpm - 4725rpm
=2275RPM
=For 4.10 rear gears, the RPM drop of 2275rpm when shifting from 1st gear to 2nd gear.

As you can see, the rpm drop in both cases is exactly the same, therefore rear gear ratios have no effect on amount of engine RPM drop when upshifting. The only way to change the amount of rpm drop during an upshift is to change the gearing inside the transmission.

Re: 4.10 gears...not what I expected.
 

From what I am reading here, it would explain why I would be accelerating on Lgaff's car in the second 1/8. Just run out of real estate to catch up.

Re: 4.10 gears...not what I expected.
 

Little did I know how much money I wasted changing gearing in so many cars & bikes over the last 45 years..
Carry on,mates! :-D

Re: 4.10 gears...not what I expected.
 

I don't know about the wasted part you mentioned Clint. Back in the day I changed sprockets on my 750 Honda from 18-48 to 16-52. From that point on I could do wheelies from a dead stop! :-D

Re: 4.10 gears...not what I expected.
 

Except for one thing, E.T. is the only relevant factor.
Except for the factor of who leaves first, who gets the jump.
That's the essence of bracket racing, which programs the tree to hold back the the quicker car to make the race even. Then, whoever responds to the light quicker theoretically wins.
In a "heads up" race, both drivers respond to the same light sequence. If both cars run the same e.t., then whoever leaves first wins.

This puts driver skill into the equation. Shifting quicker also allows you to minimize the rpm drop between gears.

Re: 4.10 gears...not what I expected.
 

I had one installed in my automatic conversion. SGI-5 C

Worked properly at speed, but at '0' MPH, it gave an erratic reading, for which there was a troubleshoot symptom. Followed it to a 'T', and didn't solve the problem.

Ended up removing it, and using the Tranny Control Module for speed signal feed.

Solved it. Sold the DD on eBay, guy had no problems with it on his project wheels...

http://www.zr1.net/forum/showthread.php?t=19299

Re: 4.10 gears...not what I expected.
 

Using 19s and 3.55s, the stock trans speedo gear puts me at about 3mph low on the speedo when running 70mph. Something along the lines of 3-4% off which is acceptable to me.

Re: 4.10 gears...not what I expected.
 

They must've installed it wrong.
Have DD in the 441 auto Z for about 10 years works great no issues.

Pete

Re: 4.10 gears...not what I expected.
 

That was my point, there are ways for a slightly slower car to win a drag race against a quicker car.

Yes in bracket racing, if both cars run their dial in, the car that crosses the finish line first gets the win, so long as you dont "breakout" and run a lower ET than your "dial-in".
I remember being in a money class for eliminations. There were cars that sat on the line for many seconds before they got to launch. I see them launch wheels up in my rearview mirror and then charge by me at the finsh line. The guy was choked that he lost though.


Using the Pro tree in "heads up" drag racing whichever car gets to the finish line without "red-lighting" wins. The ET you run in this type of drag racing doesnt matter. ET is meaningless in heads up because the timers for your own lane dont start until your vehicle moves, and end when your car breaks the beams at the finish line.

On the quicker shifting. Having quick shifts on a manual trans increases the amount of time that the drive wheels are putting power to the ground. The only way rpm drop during an upshift would increase appreciably is if shifted VERY slowly. Slow enough that the car actually loses speed during the shift, otherwise rpm in a manual trans car is pretty constant. This is where an automatic has an advantage, power is always being transmitted to the rear drive wheels during upshifts. But thats a different discussion.

Re: 4.10 gears...not what I expected.
 

I see you mentioning 19" rims often, but what is your tire height? Curious.
Thanks.

Re: 4.10 gears...not what I expected.
 

OR, better yet, is what is the center wheel to pavement height - allowing for some "squish" factor?

Re: 4.10 gears...not what I expected.
 

Fronts are 275/35/19 (26.6")
Rears are 335/30/19 (26.8")

Re: 4.10 gears...not what I expected.
 

I know what you're saying, but I don't think e.t. is meaningless in a heads-up race. I think what you mean is that e.t. isn't the only factor, and that the quicker car can still lose if his reaction time is slower, giving the slower car an advantage.

On the quicker shifting issue, I think about it in terms of inertia. The difference between a power shift, and a granny shift, is that in a power shift the gas pedal is on the floor throughout the shift. When the clutch is disengaged, the rpms shoot up, the shift is made while this is happening, and when the clutch re-engages, the power is higher than before, therefore helping the engine rpm stay up higher in it's power band.
In the granny shifted car, shifted at the same rpm, as the clutch disengages the driver lets off the gas until the clutch is re-engaged. As it re-engages the rpms are lower than before, and pulled down further by the next gear. This loses inertia. The engine has to climb that rpm mountain again, three times during the race, (twice in a three speed car). It goes with out saying that when you are letting off the gas three times during the race, even for milliseconds, that is slowing you down.

Wear and tear on the gearbox is obviously the downside to power shifting. I've been through 3 transmissions doing this. So, now that I'm a Grandpa, I shift like Granny tells me to. :redface:

Re: 4.10 gears...not what I expected.
 

Semantics, quickest car, with the best reaction time wins.

I agree 100% with you during a proper "powershift". Including the factors that you describe, which are 100% correct, there is also the slight torque multiplication that occurs as the friction materials slip as they come together as the clutch is released. This multiplicarton is only apparent while the clutch disc and the flywheel are turing at different rates. Once the rates are equalized, only gearing supplies the multiplication.

I apologize for the "granny" shifting term. No matter anyones age, they deserve the same respect (perhaps more) that someone of another age.



USA ZR-1 thanks for the specs.

Re: 4.10 gears...not what I expected.
 

Semantics are important if you want your meaning to be clear.

I've never understood the semantics of the term "torque multiplication". I've seen it used, mostly, to describe the advantage the automatic transmission has, at launch, in the quarter mile. The torque converter allows enough slippage to let the engine come higher into it's power band before the car starts moving. So that you have more power available at launch. The automatic has other advantages, and disadvantages, but I don't see how torque is literally "multiplied" in any way. Semantics :confused:

Re: 4.10 gears...not what I expected.
 

I have 19s on the back. The fronts are 18s. Just measured the rears sitting there w ~ 35psi, they stand at 26.25". Size is 325/30/19. These are the Nitto Invos which I like quite a bit. Good wet, fairly quiet, and grab pretty well on hard shifts.