True Difference in 4.10 Gears ?

[Toronto]

hello all,


Purchased Motiv 4.10 gears from GPI.

i’m running h/c on my 6mt ls3.

How much of a difference will these make for roll racing on the street?

As for daily driving will these gears make my experience terrible?

[The_bald_eagle_machine]

following...

[SS_Dave]

Take a look at this. It gives you RPM, speed, and ratio differences with 3.91 and 4.10 along with differences at different tire sizes and some rather good explanations. Should be everything you need to make best decision.

https://gwatneyperformance.com/geari...1-manual-cars/

I will also say I recently did 3.91's with Eaton TruTrac, new clutch, and short throw shifter. For me, it's great. Pulls harder in every gear. 1st is still usable, though it goes quick. Cruising at 70-80+ is still pleasant. You can see from the charts the RPM differences aren't that much. I also had a conversation with Andrew Cammer on this. He encouraged me to not be afraid of the 4.10's. In the end, though, i just felt more comfortable with the idea of 3.91's I'm mostly cruising around and pounding on it for fun regularly. It's not purpose built racing. And if I do other power adders later, I think it will work nicely.

[rdavis]

I have 3.91s in mine & all I can say is that this is the gear that all manual ss's should have came with. Found an interesting video on the subject of 3.45's vs 3.91's . 4.10's should be a tad better.

[SS376]

I have 3.91's and I think it's just enough gear. I wouldn't be afraid of 4.10's at all, in fact they'd probably be perfect.

[CamaroCracka]

I have 3.91s with a cammed 416 and the car is so well behaved I call it the cream puff. I also run 30 series 305s all the way around, so if you have 28" tires, the difference would be negligible. I do find it in fifth a lot on local roads, but I can also run 6th at 65 without lugging, which it would not do stock.

[Danial]

Originally Posted by rdavis

I have 3.91s in mine & all I can say is that this is the gear that all manual ss's should have came with. Found an interesting video on the subject of 3.45's vs 3.91's . 4.10's should be a tad better.

Awesome video! It sure exemplifies the difference!

[Ashen L99]

Basically for all motor stuff, manual cars love more rear gear! The 1les got the 3.91s from the get go, with 1-3 being longer in the transmission but 4th is still 1 to 1. 4th will still get you to about 135 with the 3.91s. Winch for all motor stuff is more than sufficient.

You should be starting in 2nd with 4.10s from a 40 or 50 roll rather than 1st. Should wake the car up a good bit. 6th is still plenty deep, won’t affect your daily drivability.

6th gens got 3.73s with the 5th Gen 1le trans but they have more power from the factory, and they are a little lighter, but GM learned!

[acammer]

4.10's are awesome, whether it be a bolt on or a cammed car. Boosted cars have a little bit more of a balancing act to contend with, but even for some of those setups it could be right.

I ran 4.10s when the car was bolt on, and I would say it's one of the best mods you can do for the car. 1st gear is NOT too short, I don't know where people get that, but it actually improves the ability to launch the car substantially. When I went cammed the benefits of the 4.10 showed even more by helping lift the RPMs at critical phases of driving (ie. parking lot speeds, light throttle cruising).

MPG took a light hit for all out highway cruising - the car dropped from 26 to 24.5mpg (bolt on setup). Around town/city it would be fair to say it was no different.

All that to say, don't fear the gear. SS_Dave posted my gear article above, and it has some nice charts in it to show you how the gears lay out, and some more things to consider. I can tell you that now with the 9" in the car 4.63s ain't too much! I still pull 21-22mpg on the highway, and the car has never 60' better or been easier to launch.

[Joe.G]

I am very Happy with my 3.91 but if I was to do it again I would probably go with the 4.10 especially if staying NA.

[Oboy66]

A quick couple of questions for you guys that have gone from stock SS gears to the 3.91s.

If you have a shop/dealer do it what is the approximate cost? I know this can vary greatly depending on location etc. but I was wondering about a ballpark labor estimate.

Also if you do this are there any other supporting mods that should be done to get the best result?

Thanks in advance

[SummitWhite11]

Originally Posted by Oboy66

A quick couple of questions for you guys that have gone from stock SS gears to the 3.91s.

If you have a shop/dealer do it what is the approximate cost? I know this can vary greatly depending on location etc. but I was wondering about a ballpark labor estimate.

Also if you do this are there any other supporting mods that should be done to get the best result?

Thanks in advance

I was quoted $2500 to have the dealer install my 3.91 rear carrier along with SS rear axles, SS hubs and SS driveshaft in my 2LT/RS that I have on hand. That was including repairing the rear main seal that has a slight leak as well. Your cost will be much cheaper I can imagine.

[SS_Dave]

Originally Posted by Oboy66

A quick couple of questions for you guys that have gone from stock SS gears to the 3.91s.

If you have a shop/dealer do it what is the approximate cost? I know this can vary greatly depending on location etc. but I was wondering about a ballpark labor estimate.

Also if you do this are there any other supporting mods that should be done to get the best result?

Thanks in advance

Mine were part of a larger bill, but I think the labor on them was like $800, maybe? In my case, I did gears, Eaton Tru Trac, new bushings, Diamond Clutch (local builder) with billet flywheel, MGW short throw shifter.

[acammer]

Originally Posted by Oboy66

A quick couple of questions for you guys that have gone from stock SS gears to the 3.91s.

If you have a shop/dealer do it what is the approximate cost? I know this can vary greatly depending on location etc. but I was wondering about a ballpark labor estimate.

Also if you do this are there any other supporting mods that should be done to get the best result?

Thanks in advance

Anywhere in the $500-$1000 range is going to be pretty standard.

IMO, it's a fools errand to do the ring and pinion and not ditch the weak, failure prone OEM differential and clutch style limited slip with an Eaton TruTrac. Not only is is much stronger, it also works much better, and doesn't suffer from wearing out in a fairly short life-cycle as the factory clutch style LSD does. Other than that, an LPW diff cover adds some helpful rigidity to the soft aluminum case, and provides support over the main caps.

FWIW, if you plan to take one of these cars to the track and ask it to 60' hard routinely, there isn't a lot you can do to prevent eventually being let down by even a well build OEM 218mm diff. They are just too undersize and understrength for the application, especially when mixed with more power and traction.