Questions about 3.73's in A4
 

Hello all,

I currently have a 2001 Z28 with factory 3.23 gears. I was thinking of switching to some 3.73 gears. I have considered getting a convertor in the past but I drive in alot of stop and go traffic and I just don't think I want to mess with the convertor and buying a tranny cooler, shift kit, etc. for the transmission right now. What can I expect from 3.73's going from my current setup? What kinda MPH gains and any ET gains with the swap? I would be getting some sticky tires along with the swap. Just looking to hear some thoughts on this and anyone who has done this swap please tell me how you like them. Thanks everyone for the help. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />

<small>[ March 30, 2003, 05:04 PM: Message edited by: Chris01Z ]</small>

Re: Questions about 3.73's in A4
 

You will get more bag and driving fun from the converter than from the 3.73s by themselves. There are plenty of nice 3200-3600 stall converters that will work nicely even in stop and go traffic.

I've run a Yank SY-3500 for two years after we put it in the car at the 1,500 mile mark. I use this car as a daily driver in a 45 mile round trip each day. Half the trip each way is on City streets in the Metro Detroit area.

Your right foot will get the feel for the converter in 2 or 3 days and after that it's all fun. The thing you're controlling in stop and go traffic is the noise level as you slip up the power band and the temptation to smoke the tires. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> You may notice a minor hit on city driving milage but it's not a killer and the highway mileage stays pretty much the same.

We added the 3.73s last year and it does tighten things up a bit that just leaves me wanting more stall. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

It sounds like the Yank SS-3600 maybe an interesting option for you. Either option will probably leave you wanting to run Nitto DRs are your standard tire if you like to play on the street. So those are some things to think about.

Rick

Re: Questions about 3.73's in A4
 

They'll help, but a mild converter will do more for you.

A 3000 - 3300 stall from TCS, a Yank SS3600 or Vig 2800 will do wonders for the car and still be very drivable. With a good converter and bolt-ons you can put a 3.23 car in the 11s. You don't need the shift kit, and a cooler is a good idea even with a stock converter too.

Changing your gears also increases your chance of gear whine and breakage. don't forget you need programming to correct your speedo too.

Re: Questions about 3.73's in A4
 

Thanks for the quick replies. I will have to think about the tourque converter
again.

What is your thoughts on the TCI 3500 TC.

Thanks again, Chris. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />

Re: Questions about 3.73's in A4
 

I had a 2001 Z28 A4 with 3.23's and swapped them out for a set of 3.73's about a year ago, let me give you another side to this.

Yes a TC change IS more dramatic from a dead stop, and with a 2.5 to 2.7 STR, you WILL have traction problems, however after 40 MPH, it is back to crappy 3.23 time.

With 3.73's, it is less dramatic off the line, however the car is more fun to drive accross the entire RPM range, I am now in the torque curve in O.D. around 82 MPH, instead of having to get to 100+.

Upon any kind of kick down into 3rd, the car is far more responsive with 3.73's, a TC is only good from a dead stop, and when it locks up, it's back to stock.

I used the SLP speedo recalibrater to correct the speedometer, I had the rearend shop install it when they did the gear change.

I am totally pleased with my 3.73's and overall the car is way more fun to drive.

JMHO

SteveC <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Re: Questions about 3.73's in A4
 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Upon any kind of kick down into 3rd, the car is far more responsive with 3.73's, a TC is only good from a dead stop, and when it locks up, it's back to stock.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">SOTP feel is impressive with 3.73s; My car felt so much faster from a roll on the street. But track mph indicates that the gears don't really provide much. Look at your 1/8 MPH and 1/4 mph before and after the gears. I doubt you gained more than 1 mph.

A good converter will eliminate the dead spots on the 1-2 and 2-3 upshifts. They will still be there with just gears. However, I agree that 3.73s will be more responsive on the highway at part throttle with the converter locked. Of course the trade-off is additional noise and slightly less mpg.

Or do the gears and then you can run an even higher stall and get the best of both mods. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Re: Questions about 3.73's in A4
 

What stall TC would you recommened if i would decide to go with a coverter? How much of
MPG would i lose if i went with TC?

Re: Questions about 3.73's in A4
 

I would recommend something in the 3200 - 3600 for a car that is an occassional weekend worrior at the track. You can quickly get comfortable with the noise, punch and slight city mpg drop in this range.

The impact of the converter on the highway is less than 1mpg because of lockup. I would say about 2-3 mpg with heads and cam on the city streets. Again this is somewhat manageable by how heavy your foot is and how much fun you're having pulling away from the lights. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Rick

Re: Questions about 3.73's in A4
 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SteveC:
<strong> a TC is only good from a dead stop</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I completely disagree. I went from a 12.8 to a 12.3 with the install of my Vigilante. My 60ft was the same for both runs. On every shift, my rpms immediately jump to 4000 now, whereas before, I was dropping to around 3000. You are always in your powerband with a good converter.

Re: Questions about 3.73's in A4
 

Gentlemen;

It is obvious most of you are pro TC, and I do not agree with all of you're analogies, and it is o.k. "to disagree" because that is what these formats are for, an exchange of ideas, and information.

Has anyone addressed the issue of the advanced torque management the 2001 & 2002(the year vehicle the origional poster has) have programed into the computer? Everyone is suggesting high stall converters, while it is my understanding (3rd Party info) that there are problems with stall speeds above 3000 in the 2001 & 2002 vehicles, to the point that you need "LS1" edit to delete the torque management all together, or at higher rpm's the tm system will cut the power to transmission in order to keep it from overpressurizing.

Just my .02

SteveC <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<small>[ April 03, 2003, 09:58 AM: Message edited by: SteveC ]</small>

Re: Questions about 3.73's in A4
 

LS1-Edit or Predator will delete torque
management for you. I don't think TM is meant
to prevent "overpressurization", pressure is
set by pump RPM (not input shaft torque) and
internal blowoff & PWM regulators. TM is to keep
shaft torque down during clutch apply so you
don't roast the dainty little things while the
computer is grandma-shifting.

3.23s to 3.73s only nets you a 15% pavement
thrust increase. It's across-the-board, at the
cost of a 15% across-the-board increase in RPM.
You are still bogged from a stop or an A/T
downshift.

A fairly mild converter with a 2.2 STR will
give you a 22% thrust increase in the lower RPM
and a negligible efficiency hit up top. You can
get outrageous STRs (2.5, 2.8, 3.0) at higher
stalls (3500, 3800, 4400, ...) but these incur
more efficiency loss. Seems like about 1% per
500RPM (ish) within a given converter "family".
The converter "automatically" slides you into
the power band (torque band). At higher RPM you
see no difference in RPM@speed, neither do you
see it with clutch locked up.

You do generate more heat during high-slip
operation. You shouldn't look at the tranny
cooler as a detriment; it's more like fluoride.
I put one on my car and the converter's still
in its shipping box. It's a cheap, easy, quick
install and it's good for you.

Nobody says you can't do both... beer -or- pizza?
I don't think so!

Re: Questions about 3.73's in A4
 

TM is present whether you have a high stall or not. You notice it more with a high stall

Re: Questions about 3.73's in A4
 

jimmyblue;

Thanks for all the in depth information concerning the TC, I too still mull in my mind about getting one, however it has turned into one hell of an internal battle.

It is funny you should mention a "trans-cooler", I am having a "B&M" 24K installed in a couple of weeks along with a 3 Qt.deeper aluminum "B&M" transmission pan.

So if I understand your above post correctly,"Chris01Z" WILL need to edit out his torque management with a higher stall converter.


SteveC <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Re: Questions about 3.73's in A4
 

TM or not, a good converter will kick the ever livin' shit out of a set of gears any day of the week. No comparison.