Ok guys...I need to know what is involved with a gear swap. I don't know a thing when it comes to gears. I think I want to go to 3.73s. Is this a good decision on a stock motor (guts). I have a list of mods below that i have bolted on etc. What I really want to know is what will I see in a change to my car. Will Gas mileage drop drastically? What other parts etc will I need to get along with the gears. My car is running very well right now. Let me know what you guys think. Thanks
Joe

 

Any help at all would be greatly appreciated....thanks

Another question I have is, How do I find out what gears are in it right now?...stock gears that is

 

With a TPI engine, I'd go with 3.42 gears. In the tech central section of this site, there is a equation you can use to find out what gears you currently have. You would also need to get new speedo gears from GM so the speedo would read right.

 

Thanks...any other imput from others.

How much would new speedo gears cost and is the install hard for them and rear gears? I have a buddy who has done gear swaps in other cars non f-body would he most likely be able to do this?

 

I got both speedo gears (drive gear and driven gear) for $15 from the dealer. They just fit right into the tranny tailshaft housing. And as for changing the rear gears, its no harder then any other car.

 

why do you say to get 3.42s instead of the 3.73s?

 

Because TPI engines start to run out of breath at upper RPMs, and with 3.42s, you'll help keep the engine more in its powerband.

 

With those gears, will I still se a big power increase, because I am looking for a good increase with gears.
I can't figure out how to use that equation to find my stock gear ratio...what mph and rpm does it want?

 

very basically you'd need to set the pinion depth, set the bearing preload on the pinion, set the ring gear back lash and preload, check the contact pattern. sounds simple and it is, to an extent. you'll need a few tools most people don't have, pinion depth gauge, or do as i do and use a home made tool to establish a datum surface on the bearing CL to measure from and use a depth mike, in/lbs dial type torque wrench, 0-1 mike or dial caliper, i use both, dial indicator and magnetic base, and finially you need something to keep the pinion yoke from spinning, i use a custom made tool for this. also you'd need to know how to read and use the tools.

 

any more imput you may have anyone please post...

if you have/had a TPI and did this...what did you go with

 

With TPI don't go with 3:73s like said they stop breathing past 4500 rpms. Get 3:42s you'll be much happier, I didn't match my gears to my cam and now I need to do a cam swap.
If you don't know much about gears don't even attempt to do it yourself, gears are among the trickiest things to do and have to be done almost perfectly.

 

to me 3.42 do not sound like they would be that big of an increase...but I will trust you guys in what you have said. What I really want to know is will my car be faster and have more torque? You guys are saying not to go any bigger than 3.42 on a 350 TPI L98 right? I just want to clarify this because I want the best to come out of this. Also the only other thing I will need to purchase along with my gears is the speedo gears...correct?

Thank you for all of your help and patience!!!!

-Joe-

 

Also will it increase my quarter mile times or speed...what will be the difference there?

 

Well, what would you consider a good improvement? With 3.42s, you will get a noticable improvement in acceleration. Prolly wont notice a lower MPG either. In my Motor Trend issue from 12 years ago, they did a test between 2.73 and 3.42 geared cars and it was about .5sec diff in 0-60.

 

I agree with the 3.42 gear in your application. As far as the change in performance that will depend on what you have now. Keep in mind that traction may become an issue on street tires.
If you know how to use the tools ede mentioned and have them or access to them you can do it yourself. Awhile back a friend of mine showed me a copy of his Mustangs and Fast Camaros magazine. It had a step by step article on a gear install. I decided to try it myself on my 89 IROC. It really isn't voodoo science by any means. Don't be intimidated by thousands of an inch or inch-pounds, just have the means to take these measurements.
I would add reference material to the list of things needed to do the install properly.

 

It won't give you more torque but I guess it will make it seem like you have more. You'll definately notice better acceleration, but your top speed will be decreased a bit, but unless you go over 100mph daily, I don't see that being an issue.

 

about finding out what gears u have jack ur car up and mark ur drive shaft with a peice of tape or somthing and have someone turn the wheel around one time. If ur drive shaft turns just under 3 rotations u have 2.73's or a little pass 3 rotations and u have 3.23's. only sure way to tell unless u tear ur rear end apart and count teeth

 

I think he should first find out what rear he has 10 bolt or 9 bolt then what code do you have? GU2=2.73,GU4=3.08,GU5=3.23,GU6=3.42, G80=POSI
These are what the manual lists I think if you have a 9 bolt they are the 9 bolt ratios in place of these. but, I could be wrong.