OK, so which of you guys has 4.08 gears and likes them for road courses?
 

I ask because last night I got jealous of DE's brake rotor post and went to Z1 to price rotors and ended up buying the friggin Quaiffe LSD. Not sure how that happened, but I got it for <$1000.00 bucks.

So if I am doing the diff I was considering the 4.08 gear option at the same time. I know the dragsters and street guys love it, but was looking for any road racers opinions. I can tell you this much, there is not one track that I go to currently that I even come close to reaching top speed. The highest speed I have gotten to is about 145 on the front straight and turn 1 of AAA speedway. Everything else I go to is well under 130, and rarely touch fifth gear on most of the courses I do.

On the same token, is there anything else I should consider doing while I have the diff installed?

Any thoughts?

Diff bushings and finned cover? Maybe some type of cooler?

Do the whiteline diff bushings.

I think SRM is worth more than gears, although EcuTek has claimed to fixed that.

Ive got a 7AT 7.08 gears conversion. If your running NA, IMO its one of the best upgrades. I also am running a Quaife LSD. The only thing i have ran into is that I was tracking the car at the hottest time of the year and with the extra RPM,s and no Diff cooler, I was cooking the fluid.

I also think that with me running no cats, I am getting some heat bleed over from the exhaust pipes. I need to address that issue as well.

If you are going to track the car, consider doing a diff cooler and at the very least a catch can so when the diff fluid starts getting hot, the fluid will have some place to go instead of pissing through the bleeder tube and getting blow back all over the car and the undercarriage. Its taken several pressure washings and long drives to finally burn off the smell.

I tried ordering the diff cooler kit that GTM has. It seems like they have great product but every time i called for one of the items, they never have it. Im sure GTM knows their stuff, but they never have it i stock. I also tried ordering their trick oil pan too ! They didnt have that in stock either.

Make sure you have a very good shop install the Quaife. I've taken mine back twice and I still have a little noise on acceleration..

I skipped the gears because on the tracks I frequent it would make me shift more, negating the gearing advantage. I also enjoy the SRM.

I had Specialty Z in Chatsworth do my installs. I know its a bit far from where your at . You could try corner3. Ive heard good things about them

Sorry...


How many miles are on your VSLD? And maybe we can swap pumpkins before you do the swap if you're changing gear ratios anyways

Will definitely be C3. Good friends with Mike and Steve is a Nissan Master technician. They are 10 mins from my house.

I am at 33K. How long do they last? I have been warned it will eventually burn out, but nobody ever says how long it takes.

do the whiteline bushings for SURE. My stock bushings ripped and are a pain so do them while your pumpkin is already out.

60k-ish, although I don't know how long they last if you track with it. I'm just saying that if you're going to do a gear ratio swap anyways. Please god let's swap pumpkins. I'll pay for the labor to swap it! :tup:

And PM!

I thought they had different stub axles and stuff?

Surely you can't do a 1:1 swap. Plus it'll hose your SRM Andrew (aren't you ATX? It'll mean you can't downshift worth a ****.)

That 4th to 5th shift will get old pretty quickly

I'll buy the stub axle, and you kinda lose cruise control, some people do, some don't. And as for SRM I'll just have joltier cuntier downshifts

i thought about it, but locally at the socal tracks, with my 18s im at the top of gears before brake zones, so i dont wanna start being in between gears with the 4.08s

And if your overall diameter is already smaller, you've geared up the car anyways.


If you want to gear up, maybe 3.9's?

Good point. Will think about that at Button Willow this weekend and see how often I am revved out before the end of a straight. I figured 4.08 would be good on tracks like Big Willow, and probably AAA, would force a shift on the long straight after the hairpin, but might be better coming back onto the main straight after the esses.

Does someone make a 3.9?

Tomei

Tomei 3.90 Final Drive Gear Set


$150 more than Nissan's

Hrrrrrrmmmmmm. That is interesting indeed.

For the track I go to the most any different gearing would hurt me but in some cases it would help. It's a toss up.

For the LSD you ordered the back lash needs to be set perfect or it will make some racket and end up having a shorter life.

for socal tracks new gears are not needed, the Z makes enough power

Go away, you're putting a supercharger on your car, lol



You should swap diffs with me :-)

I agree with DE, your argument holds no weight martin. Anyone removing stillen g3's is putting a Supa Chaza on. Whether they want to admit it on facebook or not. Pretty much the last person that should be arguing the Z has enough power. :P

I agree with your decision to do so though. Street is a dumb class for us. there is too much of a difference between entry street and the top of street. Since your suspension is still tuning in, why not tune it with more HP. That's why I am doing breather and drivetrain mods before suspension.

^I win :)

No idea where you guys get the idea to upgrade gears first lol.

Drag racing videos.

So Ru going to make it out Sunday?
DE Heading to Button Willow Sunday, but leaving Sat any interest in going up?

Saturday night there's a meet, and Sunday I'll be at work ;-(

You are running a 6MT and if you are a track junkie, then the answer to your question is based on whether you are likely run out of rev's in 6th at any track you currently visit.

I have attached copy of my gear ratio/speed sheet based on several tyre diameters so you can play with the options, BUT I reckon our Phillip Island circuit is going to match most of the high terminal speed circuits available in the US, and I don;t use 6th at PI and still don;t run out of revs heading into T1 which has a downhill approach, AND I am using 18" wheels with "little" 275/35R18 rear tyres (overall diameter about 650mm). I have a set of 265/35R18 to try next (I have gone square on this tyre recently, having used 265 on the front and 275 on the rear previously).

Now with 4.08 gears and my tyres, my Vmax with the OEM gear-box ratios and my own rev-limit of 7000rpm (as I do not trust the OEM oil-pump at sustained high revs) in 5th falls to 210kph and 6th is still 264kph, so I reckon that drag above 210kph is still going to affect the engines ability to continue accelerating the car a whole lot more. My car seems to be drag-limited at around 235-240kph as that is the best Vmax I have ever logged at PI (and that was with a 30kph following wind).

If I had more torque (SC or TT), then I would certainly go for it.

If you remain NA, then there will be some benefit for sure as in the lower gears the torque multiplication effect will be greater and for a given amount of torque, the engine will accelerate the car more quickly, so you WILL see gains, but I am not sure how significant.

Use the XLS to check your corner entry speeds with old and new diff ratio and establish whether your gear shift points will be radically out of phase with the way you currently drive your tracks, and make a decision based on that.

NOTE: The XLS is embedded in the DOC file attached as the forum would not let me upload an Excel sheet. Enter your tyre size in the boxes on the top row and it will re-calculate. I know that the rolling radius is a little less than that which the sheet calculates so you can adjust that if you like, and I also know that not all tyres respect the sizing but this will give you a reasonable idea at least).

RB

Thanks GB, I will definitely take a look at the spread sheet. On most of the courses I do, I never see even close to top of 5th. I know I will have the downside of an annoying shift here and there into 5th instead of topping 4th. But the door swings both ways- I will also get to the top of 4th faster. AS for anytime in the immediate future1-2 years the car will remain NA.

I have yet to go on a track in socal that needs 6th gear..........

But that is kind of my point, we can not even come close to getting to a speed that requires 6th gear, we hardly see any use of even 5th gear except at big willow and AAA. There is a whole gear that is basically doing us no good most of the time. Isn't it better to spread that usable range out over more gears? Sure it will cause some annoying changes in when and where you shift, but the net effect should be a more usable range of torque. And then if we did top out 5th gear, then 6th would still be available.

ur just rowing more gears, we are normally on 3rd or 4th gear, and straight away 5th gear, I think that's perfect....

i dont know about you, but if my gearing was any shorter id need 6th for ACS, which i dont wanna do cause it'll slow me down, since 6th is over drive

this is how i feel, i think the 370 gearing on socal tracks with 18s is pretty spot on

Pretty much the same at laguna and sonoma, you have to go to Vegas or thunderhill to get over 130 and the rovals

Another great shop for diff install is Unitrax in Anaheim (Unitrax • Differential and driveline parts and service. Ratio Changes & Overdrives. Axle Shafts. Using parts from the most reliable companies in the drivetrain industry: Dana Spicer, American Axle, US Gear, Timken, Gear Vendors, OS Giken, Autotech, F)

They work on a huge assortment of cars, from street to full blown race teams. They even apply a ID number plaque to the differential casing so that they can track the date of install, who the installer was, and any other special notes.

Speaking as someone that runs SoCal tracks and used to have stock MT gears, 4.08's are better gearing for the 4 SoCal tracks which are not pure power tracks (ACS) but only if you have uprev with higher redline. Without that you will top out early in 3 or 4 key places. With stock gears and uprev I used to leave some speed on the table.

Yeah I am even still considering the 3.9. It might be a good tradeoff with the tune. TY for the input. How did the 4.08 gear out at button willow vs big willow?

again, last time I will say it, if ur not maxing out ur car based on lap times, no sense in going gears.................

You do not need them ROFL /end