Like it said, I just swapped out from 2.73's to 3.73's.

Talking about waking the car up. It has a killer 1st gear.

I had been running the 1/4 in 1st and 2nd gear. I was changing to third right at the line at about 5800 rpm. lol.


I will be going to test and tune next friday to see how much it helped. I will also be installing LCA relocation brackets before going. I hope to cut down the 60 ft times.

To keep it tech, I did a test before changing the gears.


At 2500 rpm with 2.73's in drive, I was running 60 mph.
At 2500 rpm with 3.73's in drive, I was running 50 mph.

I hope this info helps answer a few questions about the 2.73 to 3.73 swap.

Keep in mind my mods. Im not running TPI anymore. Check out the sig.

 

im hoping going to 3.73 with a zexel torsen will wake my car up a considerable amount from the 3.08 and worn out posi

 

Quite a few years ago I went from an open/2.73 to an Auburn/3.73. Oh damn the difference it made. The Grey Car was a whole different beast after that.

 

I am right now going from an open 2.73 to a posi 3.23. Do you think that will wake the car up a whole bunch?? Also does anyone here know if a 96 S-10 yoke will work on a 90 camaro rear?

 

You will feel it, thats for sure. I did the same thing. Now I'm going to go to 3.73's though.

 

Awesome. Also does anybody have a yoke that they would like to sell me for my rear end? I need it like yesterday fast so if you have one speak up. Thanks-Joe

 

I drove the car ths weekend. Lets just say it was well worth the money. A definate seat of the pants difference.

Now to just get some more track times.

 

Should I migrate to 3.73 or 4.10s in the spring? I have a 700r4 with a shift kit. 88k miles on the current engine and trans.

P.S. POSI as well

 

I'm going from 3.42 to 4.56, think I'll feel a difference? Should have my rpm's at about 7100 to 7200 crossing the line

 

hey bluegrassz and you guys who had your gears upgraded: how much did you pay? i just got home from the shop and my estimate was $650 . im going from 2.77's -> 3.73's posi. the guy said about 200-210 for the gears and $80 for the gear kit then about 4 hours of labor. i was hoping for about 400-500 bucks.

 

Well, you should be able to get a richmond gear from jegs or summit for around $190 plus s&h. That would be about right for the gear kit, and most people around here quote $250 for install.

I managed to get a friend to do it for $70. Was a real good deal, and no noise from the rear as of yet. (crosses fingers)

 

anyone know of any shop in northern nj that are a bit cheaper?

 

If it is a daily driver, I would stick with the 3.73's. The 700R4 has a 3.06 first gear, which is lower than a th350. With the shift kit and 3.73's, you should be happy.

Right now, I have drivability. I think with the 4.10's, it would be pushing it on the street. You could drive it, but forget about saving gas. lol.

 

That's what I was leaning towards...

 

I'm looking to do the same swap, from 2.73 to 3.73, but reading the Jeg's cat I have some worries. I've already bought a really clean 3.73 gear set (41/11) that came out of an 86 camaro. Will this fit in my 2.73 carrier? Reading the Jeg's, it looks like the 2.73 and the 3.73 use different carriers- is this going to make the 3.73's I got not fit? They are GM take-outs, not aftermarket, and the posi 2.73 rear end I've got that I want to put them in came out of an 89 (I think) I've also found a 5/16 inch spacer for the ring gear in case I need to go bigger, but what if I need to go smaller? The local GM place said if I supplied all the parts, like an install kit and the lube, it's come to about$250. But I don't want to roll down there and pay them to laugh and point out I got the wrong parts. help?

Z

 

The carrier in the 89 with the stock 2.73's is a 2 series carrier.
The one from the 86 with the stock 3.73's would be a 3 series carrier. The spacer might work. Try calling richmond gears and ask if it will work. I know the aftermarket 3.73 gear for the 2 series carrier is thicker than one for a 3 series.

I would check with richmond to be sure.

 

The spacer will work. It should be the correct thickness to make up for the different pinion diameter.

http://www.drivetrainspecialists.com...=28&cat=GM+7.5 Search the page for "spacer", the one you want is about 2/3 of the way down the page.

I would not recommend the Richmond gear, if it's going to be street driven. Their racing gear is purpose-built for racing, and experiences noise and short life in street duty. It will of course last far longer in a drag-race-only application; but it gets that extra durability in that application at the expense of properties that make it last a long time on the street.

On that same page, look at the Superior, Dana, or GM Motive gears. Those are better suited to a street car.

 

Every Richmond gear set I have had or experienced was noisey. I now run Motive, they are quiet & reasonably priced, not to mention they are GM OE supplier.

 

i have an auburn posi w/ 373s and i love it but mine are noisy too cuz i have richmonds but i just crank the tunes louder haha. good choice for a swap

 

In my truck I went from a 3.73 12 bolt to a 4.56 14 bolt rear end. It made a huge difference and the 402 hit the 7k 10 feet before the 1/4 mark so I went to a 7200 which solved the problem, on a good run It would cut out right at the 1/4 mark. of course try to get a good run on a track thats cleaned once a month.

A little comment that goes along with the above posts.. Dont buy a richmond gear set, they do make noise even a street gear setup properly will whine. Motive and Polar seem to be real nice sets that are usually less expensive then richmond.

 

At 2500 rpm with 2.73's in drive, I was running 60 mph.
At 2500 rpm with 3.73's in drive, I was running 50 mph.

- how can the car have a lower cruise speed with bigger gears ?

 

RB83L69- I found a crapload of spacers for sale on that link, and a couple different ones made sense. What part number do you think is the right one? The GM shop quoted me $64 and hour for about 4 hours, but I think I'll help them out and save a little by taking the rear apart and cleaning it. There's a visible difference between the two sizes of ring gear, right? The pinions are about the same? I think I'll take it apart, and if the 2.73 ring and the 3.73 ring match up in height, I'm good. If they are different, I can measure to see what size spacer I need. Does this make sense?

Z

 

If I was running 60mph with the 3.73's, I would be cranking around 3000 rpm. Lower gears=higher Rpm

My speedo dosent work, so I wanted to see what the motor was doing at 2500 rpm for a baseline. Someone followed me, and when I got to 2500 in drive, I waved to them to check there speed.

I guess I could have got them to run 60 again and see what rpm I was running. I can still do that sometime. Sould be between 300 to 500 more rpm say around 3000.

 

right .. my bad

 

i went from 3.23 to 4.10 and they are sweet .

 

What trans are your running? and if its a 700R4, What kind of rpms are your turning in drive?

 

Doesn't richmond make a street gear? Are they still stronger than other brands such as motive and strange?

 

well , i was running a 700 but i just blew it up a few days ago. On the highway , using calcualtions since the speedo was way off , i would be goin 65 and the rpms were around 2700 to 2900 . But im going to do the t56 swap very very soon, so ill have some more gears .

 

anybody running 3.73s and a 5 speed. i cant find what speedometer gear part #s i need, my tires are 275/40/17

 

Ive seen no proof that Richmond street gears are stronger then any other gear out there.

 

anyone tahts swapped from 273 to 373,how did your times change... i jsut swapped from 273 to 373 and i ahve a 5 spd... so i wanna know what to expect at the track..
before i ran a 15.4 w/ a 2.4 60 ft.

 

Well, I just went to the track friday. My times before was 14.92

With the gear swap, carb tunning, finished exhaust, and going to mobile 1 synthethic I went to a 14.20

here is what my timeslip looks like.

reaction------------------.765 (I was asleep )
60 ft----------------------2.079
330ft---------------------5.944
1/8 et--------------------9.135
1/8 mph-----------------76.77
1/4 et--------------------14.203
1/4 mph-----------------97.57

I was happy. I still have LCA relocation brackets to install. I also need trans work.

 

I thought i read in a magazine that soemone makes a 3.73 gear for a 2 series carrier. Am i right on this ?....Anyone know who makes this??

 

yes, richmond (and im sure others) make them, check summit, jegs, and those kinda places

 

yeah richmond makes em. its what i got for my 2 series carrier. i got em from jegs. with 2nd day shipping the total was 120 somethin

 

strange makes them as well.

 

If you can post your time with the LCARBs installed, I want to see you 60fts before and after

 

Yeah, I will be sure to post them. I hope for some 1.90's.