Im looking for opinions for my set up. Its a 92 Z28 L98 with the usual boltons, 2k SLP conv., all stock internals and intake, some suspension stuff and is running 13.52 now on drag radials (1.77 60fts) with the stock 3:23 rear. When the time comes to repair/replace whats a good overall gear for my set up? Ive heard 3:73s are a good swap since my car will see a decent amount of street time still. Is higher numerically too much and if anyone has numbers before and after gear swaps, if you could please post the times Id appreciate it. Also at what point do you have to worry about the factory rear being too weak to withstand certain ETs? The car runs consistant mid 13s and hopefully low 13s by spring, is it better to start saving now and invest in a 12 bolt replacement?

 

I'd say you have a near perfect setup right now. Gears *may* net you something, assuming you can still hook up with them, but I'd wait until you went into the engine with more cam and better heads before wasting $$ on gears.

Mid 13's with a few bolt ons and a converter? Damn good.

 

Thanks!! Im real happy with what the cars doing as she sits Im looking to squeeze a lil more out if I can. I added SLP 1 3/4s and removed the AC since it blows luke warm and I hardly ever use it.(this is going to be my project/weekend/track car). I plan on adding glass hood, alum parts when the stockers die or I have $ to justify spending and then looking at intake manifold/porting plenum and I have SLP runners(not on) and fabricating a clean looking CAI. I heard that 373s might even hurt the performance and im not looking to take a step back but I hook great so i dont think traction would be a problem, Im more worried about running out of breath but my cousin went from 2:73s to 3:73s and he shaved off nearly .5 on his 91 TA 305 so I think Id be ok but I was hoping to see what some others thought, thanks for the reply!

 

I swapped my 3.23's for 3.73's and picked up about .4 with the same mph. My posi was shot so I replaced that at the same time so that might account for a little of that.
Its great on the street but I did notice a drop in gas mileage.
I cross the line at 99 mph and I'M about out of gear.
With your setup I'd switch to 3.42's once your posi needs to be replaced and then do them both.
From what I have heard, it takes repeated 11 second runs with slicks to blow up the rear. It should not have any problems with 13 or 12 second runs.

 

should I go back to my stock gears, within the next 2 weeks I will be runnign a 383, with ported everything, but stock cam for the time beiing until spring. . . I already have the slp short tube headers and 3 inche all the way back from there with a high flow cat. . . I have a 2400 stall converted with an otherwise stock tranny besides the shift kit. Do you think 3.73's are gunna be too tall for that set-up?? will I ever hook-up? especialy since the motor will be making huge torque numbers down low. Or should I just get really really fat tires and hope for the b est, the car will only eb driven in the summer, and prolly not even in the rain since I have a beater. any suggestions would be great

 

Well, I'll try and answer some of these questions with what happened to my car.

3.23 gears:

Street tire Bridgestone Potenza RE71
Best ET: 13.2XX at 105.4
60': 2.1xx

MT 29"x11.5 ET streets
Best ET: 13.02 at 101.XX
60': 1.92

3.73 gears:

No street tire passes

MT 26"x10.5 ET streets (closest I could get to actual street tire height)
Best ET: 13.12 at 105.5
60': 1.92x


Car specs are in the signature.

All the these runs are on the origional chip for an '89 2.77 geared car.

I think I was leaving a lot on the table using the stock chip in the first place, but making such a large change in gearing didn't help either. I'm now burning my own chips and think it'll will really wake up the car. With the 3.73 gears, the car is spending it's time in the higher rpms (not good for a TPI) and was running out breath in the traps.

I've an 3.27 rear out of an '89 TA I'm going to try running with the same ET streets next year when the track opens to make better comparisons and may end up switching to the higher gear(if I can't compensate for the 3.73 with the chip).

I guess what I'm saying is if you go 3.73, you should burn/have burned a chip modifying the fuel and spark curves.

Sparks a flyin'

PS: On the prom burning side: I just made a long highway trip with highway mode enabled in the chip, no TCC lockup(shorted wire), averaging 70 - 75mph and got 21 MPG. When I get the TCC lockup fixed, I'm figuring about 23 - 24 mpg. That's the same kind of mileage I got with the stock motor and 2.77 gears !

 

I'd stay with the 3.23's. If you were going to a mini-ram or super ram, then the gears would help. Like the others said TPI and high RPM's don't mix. Also keep in mind the 700R4 has a 3.06 1st gear. Combined with 3.73's, traction would be an issue.

 

Thanks for the replies. Ill be waiting until the rear gives me problems before I upgrade, Ill spend my $ elsewhere for now. Just need to see how much $ I have left after the holidays which should be none lol.

 

get the 3.73's if your going to get any gears now. With your car and your luck, with the headers and gears i could see you running a 13.0 or even a 12.9, and trust me gearing means alot, and with the 3.73's that I had(broke them after that day at the track when i ran the 13.5) i was at 4900-5000 rpms when i hit the traps at 100 mph. later

 

Itll be 3:42s or 3:73s when the time comes. For now the rear is fine but makes some groans here and there. When it quits on me is when Im gonna do the upgrade and since this motor wont be the only one to stay between the fenders I think Im gonna go with 3:73s, 3:42s wont give me much over the 3:23s and traction isnt a problem now so I think thatll be the way I go and maintain some streetability....

 

Right now my best run is a 14.12 w/ a 2.06 60' @ 97mph on a pretty much stock (well stock in my book, no internal work, and only bolt on is a MSD6A box, check sig) L98 w/ 3:23s. I have considered replacing them with 3:73, but I have herd good and bad.

The way I see it is that is will help you until you get to 3rd gear then your going to be real high in the rpm range and wont have as much pull if you were down in the rpm range a little bit, where the tq is on our cars. Right now I let the car shift itself and when I get throught the traps my baby is almost spent on power up near about 5000 grand.

On the flip side they say it all depends on them 60's.

I'll tell ya what though, now that you posted those times with those mods, I might have to find myself a set of drag radials or something and see if I can dip down into the mid 13s w/ a stock exhaust.

 

My car was running 14.1s when I 1st started and that was with Flowmaster muffler in stock pipes, airfoil, K&Ns, crank pulley and on street tires in good weather. My 60fts were 2.0s-2.1s usually. Since those times I added a converter(2k) w/ cooler & shift kit, MSD, MAT relocate, 8.8 wires, alum DS, LCAs,SFCs,STB and drag radials and in the same good weather my 60fts dropped down to 1.77s and my times hover around mid 13s with 13.52 being my best. If you are running those times now drag radials will get you high 13s guaranteed. I just added headers, remove the AC since it hardly ever gets used and needed a charge and now Im looking at more expensive stuff like manifolds, gears etc and like you, Ive read bad and good about gear swaps and shortness of breath on TPIs so I figured Id see what anyone had to say......

 

keep the 3.23 or if you really want a change get a set of 3.42's. The TPI doesnt breathe in the RPM range that the 3.73's will put you in and you wont be goin any faster(unless you go with taller tires like 28" d.r.)

on another note..i dont see how people go spend tons of $$ on 9" or 12 bolts for their ____ f body. Jim has a 91 Z28 with miniram,heads, cam, procharger,etc running 10.8X @131mph with a factory original 10 bolt rear with the only upgrades being and auburn posi and 3.73 gears( notice he has a miniram..not TPI)

 

Hey, its great to be back to the boards after a hiatus. I guess alot has changed since October. Well, anyway, I blew up the stock rear in my car when my car was basically stock. All that was different was that the 350 was in instead of the 305. All it takes is some miles and gas punching to blow up a stocker. And then again some people keep them for years, go figure. But to make a long story short. When I replaced the rear I upgraded to Richmond 3.73 gears too. It made a big difference off the line if I eased into the gas and the tires hooked up. I think out of all my mods, aside from the NOS, that made one of the biggest differences. I recommend them, especially if your going to do any street racing. There isn't a ***** out there that going to take a low geared F-Body off the line.

 

3.73's are the way to go! lots of off the line torq.

 

I dont have a 350, but when I had 3.73 put in the difference was amazing. Of course I went from 2.73 so any gears gonna kickass after those.

 

Does anyone have any times going from 3:23s to 3:73s? My cousin went from a one legger 2:73 to a built 3:73 rear and picked up .4-.5 tenths with his 91 305 TA. I know my gains if any wont be as dramatic, but it would be worth the $ if I could net atleast two tenths or there abouts...

 

4.11 posi trac out back, 750 holly double pumper, 10:1 pop up pistons edelbrock intake, scored .30 over, we're talkin' some serious horse par

 

hope you brought your wood screws cause I'm gonna blow the doors off that POS

 

Wood screws?? Do I even know you and are you talking to me??lol If you are, me and my POS will be at E-town come March. Either pack some more mods or pack a lunch, it'll be a long day

 

Easy there killer!!!

I guess you've never seen Dazed and Confused (movie)? If you havent check it out and then you'll know what I'm talking about.

Oh, as for being at E-town, why dont you come out on SLP day, I'll be there and we'll see if you can use some of them wood screws

By then I'll have packed up a few mods........full exhaust, some suspension goodies, and a little tuning, then we'll see how well the L98 rolls down the track

 

LOL my bad I never seen that movie and I dont take the car stuff serious, now if it were bowling maybe then lol. Anyways I was there for SLP day so Im sure Ill be there this year so Ill keep an eye out for ya, Im always quick to noticed other 3rdgens and Im always interested in what they run even if they make me carry around wood screws Ill be looking to see what the headers bought me and whatever mods I can get done from now til then so either way Im sure well both turn in some respectable times, see you there and good luck with the car....

 

I say can the idea of gears, and get a set of high flow runners for your TPI.... port the rest of the TPI while your at it (free) and the heads. Then you can change the cam and gears and then you'll really have a fast car.

 

I have SLP runners but when I had em on the car I was turning in miserable times but it was also the summer but the car was slower from start to finish. I replaced the stock pieces and the car woke up again and it was in the same weather. Im almost surely gonna pick up an Edelbrock base and port the plenum and see what that does after I see what the headers and stuff got me. Ill be holding off on a gear change until the rear gives me a reason to throw money at it. The reason for not wanting to mess with internals is I plan on swapping in a healthy motor by years end, the one I have now is nearing 100k miles and has had an annoying idle and rough revving problem for years now and no one can seem to figure it out. The car still performs well enough for me not to waste more time and money trying to solve whats wrong but thanks again for all the replies, the base and stuff comes next, gears later on and times to follow as soon as I have em...