OK, let's say I want to put 3.73's in a '94 (auto)...

What parts do I have to buy and how much should they cost?
Do I need to change out the whole thing or just the gears?

If I go to a shop and have them provide both the gears and the labor...what kind of price should I expect for quality work? Odds are that I should change a few other parts while I'm in there or no?

And last...what kind of 1/4 mile jump can you gain from going from 2.59's to 3.73's...?

Thanks guys.

 

You don't have to replace the whole differential. You CAN of course, buy an exchange unit, and consider swapping diffs yourself. Unless you buy a "thick" gear, the differential internal case (the case the ring gear bolts to) will have to be changed to a "3 series" case. While you're (or your mechanic) is in there, be sure to check the condition of the bearings and the posi clutch pack. Some people change these items as a matter of course. Other than that, you'll need a new pinion seal and grease. I think the cost can vary widely. I would guess between $600.00-$800.00. A word of caution. Discuss your aqusition of the parts before you walk through the door of a strange garage, parts in hand. Some outfits don't take kindly to installing "your" parts. You don't take your own eggs to the restaurant, do you?

 

When you say $600-800 does that include labor?

I've never had any gears changed on a car before so I'm clueless about this stuff. About the "egg" comment, I agree with that fully, that's why I was thinking of just having the shop I go to provide the parts for me.

Also, any of you auto guys, what does the 2.59-3.73 swap do for you in a 1/4?

Thanks again :cheers:

 

I hate to mention company names, but a company here called Pro Gear will change out your ring and pinion only I think if thats what you want. I think they can do it mail order to. But if your dif is in bad shape, you may want to have it redone at the same time. Gears are def the way to go to see a quick in the seat of the pants performance increase.

 

I haven't had it done, but yes, my GUESS of $600.00-$800.00 does include labor. I have seen a wide varience in the prices paid by forum members for gears. Now that you have a "general" idea of what's involved, make a few phone calls. Unless you plan to deal "mail order" what XYZ in California or Joe Blow in New York paid is moot.

2.59 to 3.73 is about a 44 % change in ratio. That is a HUGE difference. You won't believe it is the same car. 5000 rpms is about 103-104 mph in 3rd (direct w/auto trans) depending on your tire size. I have no idea how your engine or car are set up, but that could be ideal for the quarter.

 

Labor=580.00
parts= 300.00 includes rebuild kit

 

All right so basically if I find a good shop around town I can get it done for $800, including a rebuild kit, that sound about right?

Let's say the car is COMPLETELY stock except for this new change, how many tenths you think that would knock off? Of course I'd be doing other mods down the road, just couldn't afford to do anything, but this one at the time.

 

If the car only went from 2.59s to 3.54s........

How much less would it gain? Would it be easier for me to get traction from a launch by only going to 3.54s instead of 3.73s.......

Thanks again......

 

Going from 2.59 to 3.54 is about a 37 percent change. 37 is approx 85 % of 44. Therefore the 3.54's would represent 15 % less of a change. Is this what you are asking? Launch problems would likely be less with the 3.54's. Launch problems will be less still if you don't change ANYTHING.

 

Hah, I get your point. Would be pretty stupid to go for something with slightly less performance value just for better traction.

Was looking more for a comparison between the 2 though.... maybe if someone had 3.54s before and then switched to 3.73s, what kind of change did they see? Same with the converter issue which you also responded too.

I guess worded that VERY badly, odds are I would be doing 3.73s and the 2600.... but just thought I'd ask about the issues between the 2 in both cases also.

Thanks guys.

 

I think going from 2.59 to 3.73 should get about 3 to 6 tenths in the 1/4 depending on traction. I plan on going with 3.54 just to keep the rpms down a little. If I were going to the drag stripe a lot I would go with 3.73s :chevy

 

I hope I didn't insult you. Sometimes my tactfulness takes a vacation. To my way of thinking, go for all you can get. BUT, keep in mind what you want out of the car. The best quarter mile set up won't necessarily make the most pleasant cruiser. Your gear and converter questions only addressed traction and quarter mile times. I tried to address the questions you ASKED. I've played with my calculator and decided that 3.42 or 3.54 are the best gears for ME. My main criteria for this decision IS 1/4 mile preformance. I also considered cruise rpm levels, and what I thought I could live with. My choked up Crossfire doesn't have the rpm range or higher rpm power potential the your '94 has. Keep in mind what else you have planned for your combination. At least in the near future. My next step is going to be headers. My engine cries out for 1 & 5/8" tube size. I will only buy 1 & 3/4" headers, because of the plans I have for the rest of the engine. I don't want to buy headers twice. It would be better for performance if I did, but worse for the wallet. Personally, I think the 3.73 gears and the 2800 rpm stall would make a dinamite quarter burner. When traction suffers, solve THAT problem, and you'll be ready to move on to the next step. Take your time. Try to plan a package that will suit your needs. I'm here to help if you need or want it.

 

Anyone out there use 3.73s on a daily driver???

Mine WOULD be a daily driver, but it's not like I drive 20 miles even, each day. 3.54s be a little better for the everyday drive? And as for trips to the track, basically I'd probably go 3 times a year...and then of course when anyone pulls up next to a light late at night or something. (Ricers :U )

Also, how do gears affect things like 40 or 50 stomps???

 

I had 3.07 in mine and at the track with the STOCK converter it would leave the line without spinning.. it ran 13.38 BONE STOCK..

I now have 3.73 & love em... best move I ever made.. now here is the problem.. :(

If you go to a high stall converter as you said (2600 I think) you WILL NEVER hook up with ANY street tire. I have a Vigilante 2800 converter & with my GSCs it is like driving on a wet road... it spins em even if I hit it 1/4 so on the street or track I'm probably SLOWER with street tires..

Now the good news... NITTO DRAG RADIALS.. with them you CAN drive on the street & even in the rain "If you use your HEAD" and drive it EASY in wet weather..

I'll give you # to compare.. when I had the 3.07 & stock converter my 60' times were around 2.00

Now with the 3.73, Vigilante Converter, and DRAG Radials my 60' is 1.70 that is a .3 tenth GAIN in the first 60'

When I was completely stock I ran 13.3 now I have run 12.4s almost 1 FULL sec. quicker..

Yes I have done more than just gears, but I haven't gone into the motor at all... Also I have photos with BOTH of my front wheels OFF the ground at Englishtown...

 

Not to tread off of my original topic... :rolleyes: but, do any of you know how Pilot Sports would hold up to a 2600 stall tc and 3.73s or 3.54s...? :confused:

I've heard lots about Nittos and I was assuming that's what I'd have to get once I did some things...but haven't heard much about the sports, only thing I've heard is SOME guy told me that his friend with a turboed c5 runs sports and they work great as a daily driver... but on the track he suffers through 1st and part of 2nd... I would assume a TURBOED c5 would have as many issues as a c4 with a higher stall and gears.... am I wrong?

 

My car is a daily driver and is at 3.45 but with the way my 6 speed is setup I am doing like 2700 RPM at 75 MPH. So Maybe I am more like 4.11 final ratio, I am not sure. Its ok though, I still get at least 15 MPG or so :rolleyes: ....Of course I cant keep my foot out of the floor most of the time.