speedo

iTrader: (15)

Ok it seems a sponsor finally has some gears in for 7.5 10-bolt rear end. I have been wanting to go with 3.73's for a series 2 carrier for six months now (just been on backorder). Well I did a search of the Gears and Axles section and I came across a ton of threads that the Colonel answered saying how "3.23's is the gear he has and isn't worth going any lower for a Tenth or so, just a waste of money and gas if you have a 3500+ TC. "

Now my question is with my 231/237 cam and factory 2.73's if I do go with a 3.23 or 3.42 is it going to hurt me big time in HP and Torque compared to the 3.73's. With this cam I am a bit light on Stall so I was told to go 3.73.
Should I stick with the 3.73 Idea??

I mean it does make sense, I spin the heck out of Nittos on the track now with my 2.73's, and my best 60' is 2.0!!! And the gas mileage issue on the street is a no brainer.... I went from 3.23's to 3.73's in my Iroc and almost felt no change also, that is why I could be a Colonel beliver.

My car isn't a daily driver, but I love to drive it daily...... I love to kick butt on the street, and don't really care if I loose a tenth on the track...just want to hook and run consistent. Those are my driving habits/goals with this car.

I hate to stick money into this 10 bolt, but I am hoping I am one of the A4 guys that have tons of passes and years on it and it still holds out.

Thanks for any and all info

Mooobunnny

iTrader: (1)

I just went from 2.73 to 3.73 and if I honestly had it to do over...I would go 3.23 or 3.42 probably....even though the air is a bit hotter, I did not pick up anything with the gear swap except some traction problems....no mph.....maybe my converter just like a little longers gear.....

speedo

iTrader: (15)

What converter and stall you running...?

I am way up in the air now what to do. I think I may just go down the middle with a 3.42.... Or think about it this winter and maybe go 12 bolt in the spring. Or wait until they perfect that 8.8 Ford Rear (suppose to be light and not rob HP) for F-bodies. Now that they have a group rate on gears for 163$ It doesn't bother me so much to stick 263$ (100$ install kit) into this rearend.. Could last 1 race could last 1000, who knows.

Thanks very much for the info!

Colonel

Ok, first things first. You're running a 150 shot I see, right? And you ALREADY have traction problems, right? And if you actually DID hook (you're nowhere close to doing that right now) then how do you think that flimsy stock rear is going to hold up with numerically higher gears?

Stay with the stock gears until you learn to hook. That may mean a better burnout, better tires, suspension, or practice and experimentation in timing the nitrous hit. I can tell you, you're certainly not doing something right if you're pulling 2.0s on drag radials. Heck, I can pull 1.8s on the stock Goodyear Runcraps on this C5s crappy independent rear suspension and I've been known to pull consistent low 1.5s on 17" Nittos.[/tootingmyownhorn] After you learn to hook, then consider going to a stronger rear. No sense wasting money on the stock rear. Do it right, do it once.

speedo

iTrader: (15)

I totally agree with the do it right do it once.

I hook like a freak on the street, almost NO wheel spin with this rearend. My concern is my cam for the gear ratio. I need the lower gears to get in the RPM power band quicker right? Or am I way out of line... I would rather be fast on the street than at the track. Well I want both....(hehe) if I had to choose I would choose street over track.

I live in MN, the night I raced the temps where around 60 degs or less. I put a thread on the racing section also about how I could hook better hoping to get some suspension tips and a member replied that when the temps are that low at night hooking up is going to be tuff. https://ls1tech.com/forums/drag-racing-tech/217397-my-60ft-suck-2-0-2-3-s-2-5-s-nitto-5555r.html

The racing started at 8pm my 2.0's where in the first 2 passes...then from there they started to climb 2.2-2.3-2.4 and finally I had a 2.5 @ 10pm. I quit racing realizing the track was so bad I could see the tread bite in the pavement from the car that had gone before me, almost looked like slush. It was a test and tune night with all street tires on a 1/8 mile track. No track prep all night.

My Nitrous I had on my Iroc and just finished up the switch to this car about a week before I raced. I was missing the 75hp and 100hp fuel jets for the LS1 setup (just got them in today) I ran the 50's since I want a forged bottom end before I run the 150's (I will change my sig). Realizing that I wasn't hooking I wouldn't hit the Nitrous until I was hooked up about halfway down the track, and I only did that maybe 4 times out of 28 runs because it was a waste of Nitrous if I couldnt use it for the whole run. I also have a Timing Tuner have the delay set high and the Nitrous doesn't engage until 3K. So I am not even considering that a factor in my 60's.

Now with all that information would you change you suggestion on the gear selection for me?

One more question... if I did go with a new reared what is your suggestion...9, 12, 8.8??? And what gear? Your totally right about the stock rearend and I want to do a new on in the future. Just wanted to skimp by for now and see what ratio works the best.

Thanks a bunch for taking the time to answer my question....

Colonel

Ok, sounds like you're bound and determined to do gears. Hope you're not expecting much for your trouble and money. But anyway, here goes....

Do you want to optimize for NA performance, for N2O (sounds like you don't too much care about N2O performance since you're not even spraying it out of the hole), or a compromise of each? Oh, and what kind of trap speeds are you looking to generate NA in the future?

BTW, it's not the gearing's job of getting your RPMs into the power...that's the converter's job. You have a great converter for nitrous. If you want to see REAL improvements in NA performance (at the expense of some N2O performance) then restall the converter to a 4000 and start looking for some more traction. Not only your launch but also your shift extension will be improved. If you care more about N2O performance then keep the 3500 stall and figure out how to spray it dead out of the hole without spinning. Now you're haulin' ***.

Me? I'd leave well enough alone until you're ready to get really serious (that means pulling 60 ft times at least in the 1.5 range.) Having said that, I like a 12-bolt rear and gearing to match my redline and trap speed. That depends on what your trap speed is, your tire height, and what RPM your feel comfortable crossing the line.

Colonel

Well, I might as well go ahead and throw this out there. With a 25.66" tire (stock height) and a 6500 redline, for example, you can pull out these trap speeds with the following gears....
3.42 = 136 MPH
3.73 = 125 MPH
4.10 = 114 MPH

Looks like 3.73s for NA or a mild shot of nitrous or 3.42s for a larger shot. For 4.10s you'll need taller tires even to run NA.

I calculated in 5% converter slippage, minimal tire growth, and a 1-2 MPH differential between trap speed and actual speed across the line (trap speed is always slightly higher than actual due to the measure method.)

speedo

iTrader: (15)

Ok I read everything over ten, fifteen times now. All this info is great. I really appreciate it.

Yes I had in mind to use the Nitrous as need only deal when racing on the street I want to run 100 shot to be as safe on my bottom end as I can. I am not sure where a 100 shot puts me on your scale mild-wild Nitrous?

Yes I am a bit light on stall, which was my fault when I ordered everything. My concern was drive ability on the street with the 3500 being the most stall I wanted to run when I decided to go Heads and Cam. I ordered the wrong cam for the 3500 stall (wanted the 231/231). I didn't realize this till I had the motor on the ground and the cam in going over some information for my tune. Just thought I would put a bandaid on with and go with a steeper gear. After having and driving the 3500 I realize that 4000 stall wouldn't be a big deal once the converter locks up. I use the car to race not to get to work.

Here is what I learned so far.
I will get a 4000 Stall. I have a friend that is looking for a 3500 soon, so I more than likely will give it up for the 4000. How much is a TCI re-stall offhand?
I then need to figure out what I have to do to hook up on the track, suspension or otherwise. 1.5 60’s is the goal. I will run some early races in 2005 on a 1/4 mile track to see if I can get that 1.5 with the 2.73's
A 12 bolt is in the near future with 3.73 gears (next spring). Just have to figure out what brand is the best? I have all winter to figure it out

How did I do?

Again thanks for all your help

Do it once do it right!