Differential gears?

Im going to swicth my gears in the next 3 months and I've been a little confused about this subject for a while. So here are my questions:

Whats the difference between switching the whole differential and just the gears inside? Why would anyone switch the whole thing?

Does changing gears give you any hp?

What size would be best for my car if i want my top speed to be around 150 mph... and have a good take off?

Where to buy gears? and what are the best brands (if any)?

Im welcoming any opinions backed by some logic.

94 formy?

Well what many people do is switch the entire rear to avoid having to pay to get new gears set up / it's a cheaper route, that's what I've done twice now.

What you would want to do is get (I'd say 4.10s, I don't doubt you can hit 150 in a formula with them and you will freaking LOVE them off the line), a good Eaton or Torsen carrier (the two are debated over which is stronger... the eatons are rebuildable whereas if the torsen breaks you need a whole new differential), and get them installed.

Changing gears doesn't give you more HP but strictly affects rate of acceleration. it is one of the most noticable mods you can do to your car.

As for brand, it seems most people go with Motive or Richmond from what I've seen.

sounds good...where would i get an eaton with 4.10's already inside???

And can that be done by me? I know i can't change the gears on my own but can i change my differential on my own?

Come on guys i know there are a few people in here that changed their diff. Where can i get one of those suckers i really want to start looking for prices so i know how much i need to save. Also what is considered a good price?

sounds good...where would i get an eaton with 4.10's already inside???

And can that be done by me? I know i can't change the gears on my own but can i change my differential on my own?

My opinion

4.10's + V6 = Crappy Gas mileage and absolutely no top end

I would say go for 3.73's

But it's hard to say not knowing what you use your car for. (Long trips to work, crusing, racing, etc...)

Also a nice 3200 Torque converter for Auto's makes a great upgrade for almost perfect launches.

My car is not a v6... I have an LT1 5.7 liter V8... And right now it is my daily driver to work, but it wont be in a year.
But i just need to know were i can get one of these diffs with 4.10 inside

My car is not a v6... I have an LT1 5.7 liter V8... And right now it is my daily driver to work, but it wont be in a year.
But i just need to know were i can get one of these diffs with 4.10 inside

If you go for 4.10, expect a top end of like 90mph. A lot of highway miles will rag out the engine pretty fast.

If you really want all that top end get a 2.73. Thats what i have and with a 350/350 setup it has plenty of pedal left at 120mph. 70mph i can still grab second gear and off the line it still has a fairly decent launch. Im sure sombody with a 3.73-4.10 could launch a little harder, but with a gear like that expect anybody with a 2.73 to blow your doors off on the highway.

EDIT: i havent really pushed mine past 120 because my tires are shit right now, but i used one of those online deals that tells you what your top speed is, and i believe with my current setup it was like 167mph.

i have 4:10 gears and i like them. you'll have a great launch, little less top end, but ive had my car to 140 so...

kyle

My opinion

4.10's + V6 = Crappy Gas mileage and absolutely no top end

I would say go for 3.73's

But it's hard to say not knowing what you use your car for. (Long trips to work, crusing, racing, etc...)

Also a nice 3200 Torque converter for Auto's makes a great upgrade for almost perfect launches.

Your opinion?

So you've owned a 3.8 with 4.10s?

Gas milage is fine (25 mpg is fine with me), I've pegged out my speedometer with room to spare, and have been daily driving it for about 9 months now... city and highway, highway being cruising between 65 and 85.

And at for a torque converter, ye it is pretty much a must have for an auto, but the size stall that will work best is different car to car. It depends on things like powerband and gearing to correctly matcha stall size to a car. For instance, in the 3.8 performance world, 3200 is a tiny bit small, most people seeing the best gains have 3500-4000

Then *note* this...if you dont like the 3200 tq. converter...change the status of your current "Pending 3200 converter"

:popcorn:

Yall have fun with them 4.10 gears. Be sure to stay in the far right lane:evillol:

EDIT: really i need to think about gearing up mine. 273 is good top end but has crappy bottom end. I want somthing between 308 and 373.

yeah they wont give your engine any more horsepower but they will deliver more "umph" to the pavement. its just like downshifting on a bicycle, you dont go as fast but its a hell of a lot easier to pedal. this applies to rear ends in cars. you would probably be fast as hell with 4:10's off the line but youd be spinning a gazillion rpm in top gear on the highway

:popcorn:

Yall have fun with them 4.10 gears. Be sure to stay in the far right lane:evillol:

EDIT: really i need to think about gearing up mine. 273 is good top end but has crappy bottom end. I want somthing between 308 and 373.

you do not want 3.08s. 3.42s are not much to desire too... I should know, I had both.

Have YOU ever drven a 4.10 car?


And SLP guy, if you know me I was planning on getting a freak converter off a current 12.1 car... however that is taking too long so I'm getting a TCI 3500 instead

I wouldnt go with a 3200 stall if ur not heads and cam, LT1's make their power lower there for a higher stall doesnt really benefit u. Something like 2800 is better for u and coming from experience 3.73 is plenty of gear for an automatic, 4.10's are a little overkill for an A4 V8.

I have 4.11's.
75MPH in 6th gear is 2,000 RPM's.

A little much in an auto 4th gen though.

Have YOU ever drven a 4.10 car?

Yes i have. Not only have i driven one but a long time friend of mine has 4.10 in his 49 studebaker pickup. I couldnt help but notice the rpm @ mph difference between his v8/350 4.10 to my v8/350 2.73. The extra i see off the line with a 4.10 isnt worth the top end you lose IMO.

Thats with a 350 transmission. I wouldnt go past 3.73 on mine unless it had OD. Im sure some overdrive transmissions or 6 speed transmissions are better suited for 4.10.

as for the torque converter conversation going, i say why bother unless you have some serious HP mods.

Right. I agree with you on those counts.

But in a 4th gen, it isn't that bad.

OK, we're talking about two TOTALLY DIFFERENT THINGS... in this thread we were talking about 4th gen 3.8 cars with the 4L60E, I can prety much guarantee that a 49 studebaker with a 3spd auto is a world of a difference

And about your other statement... because having serious HP mods and launching hard do not necessarily go hand in hand. Big power has better potential for killer 60' times yes, but you can also work around that with things such as gears, weight reduction and suspension... and if you have none of those then your big HP car won't hook well either. As for a verter... well, good luck cutting good times launching at 1400 RPMs (the highest I can launch at on my stock converter, just using mine as my example)


With that aside, a high stall converter is one of the most noticeable mods according to most people who have them.

come on guys its not that big a deal. haha