Final drive pondering

[curtis]

Ok this is an attempt to make tech more technical, Face it the old school guys are all JSB's and the new guys are slacking. For the new guys look back in the history around 03 and 04 there was some crazy tech articles back then. Not dogging anyone out but truth hurts so fix it.


from this thread look at the rearend buildup

NZ DRAG CAR THREAD, yes there's pictures
Owner used a 350Z final drive, diff, axles and ring and pinion with custom subframe.

This has had me thinking so I looked up and found this

350z tech page

Reason for all this thinking is the front gears. You have to have a really bad a** CNC mill (think 7 figures) to cut helical gear sets and a custom one off would be ridiculous in price. So maybe he found a stocked part for the rear that match a mitsubishi unit. Isn't 3.909 to 1 a JDM transmission final drive and can't remember the exact offset but the transfer case isn't a perfect 1 to 1 so maybe this works. I really don't think him being a drag car guy that he's using a 3.2 to one or even a stock 3.5 to 1 gear set. For you guys that didn't grow up driving V8's the old rule is the lowest final gear you can stand and the tallest tire that will fit the wheel well. Taller tires mph more and have a larger circumference so more traction. This helps also to bang through the gears faster to get to the 1 to 1 in high gear so you can use the rpms to move the car up top. Drag races are won in the first 300 feet, lower the 60 ft the lower the et.

Not that were all going to find a 350z in the junkyard but this is a larger ring gear and I'm sure a stronger piece and I believe are lsd's from the factory. People going after big numbers might find a new solution for there old trusted 4 bolt. I know there stronger than a 3 but their going to break because thats just the nature of metal its not if but when.


The flanges on the cups and also on the main driveshaft I'm sure are different but adapters can always be machined.

Anyway post up any insight you may have, I don't have any plans for this mod but I'm sure someone on here might. I already have a 4 bolt in the car with the 4ws pump installed as well and have an extra 4 bolt and GVR4 housing with pump waiting in reserve so if anything ever happens I'm not on jackstands.

 

[Andy_S]

FWIW, Sound Performance has gone low 9's on the stock rearend in there Z. And I may be wrong, but I think all 350'z except the very base model include an lsd.

 

[CarRacer]

You mentioned a Ford 8.8 rearend in the original thread. I think a 9" would be a better solution. We use to run one in a circle track car. There are a lot of options for those gearsets. We ran both a spool and a locker setups. We ran multiple tracks, and had separate hogs heads/third members for each track. I bet there would be a gearset that is compatible. Pop a new u joint on the driveshaft and fab up a subframe and you're in business. It kills the IRS, but the live axle might be better for racing. /ubbthreads/images/graemlins/dunno.gif Our 9 inch setups also used disc brakes with full floater axles.


If you wanted to get really really crazy, you could run a quick change rearend. They are mainly circle track stuff, but a trick part. The ring gear doesn't change, there are two additional gears in the back of the rear end. You pop off a cover and change those gears. It takes about 10 minutes if you're really taking your time. You can make really small changes to the final drive utilizing those two additional gears. The axle tubes are also really modular, so adapting to our track width would be painless. There might be clearance issues with the gas tank though. The additional gearset adds quite a bit to the back of the housing.

A 9 inch is a really small form factor, so might work out depending on the available gearsets. I'm not all that good at figuring that stuff out. I was the driver, I only had to worry about a steering wheel and two pedals. They didn't trust me to turn right either. /ubbthreads/images/graemlins/dunno.gif

 

[CarRacer]

Here's the picture of the quick change to show how much is added to the read housing.

Here's a link to the quick change gear set ratios offered.

 

[mrnvit]

the 3.9 ratio is the factory ratio fo the e123 and vr4 e zero and maybe the facelift rs's.
the car may well be running the 5 speed ppg gearset as the artical doesnt say if its a 4 or 5 speed.
most people racing the early evos and vr4s here change to the 3.5 diff ratio too avoid changing to 5th on the track.
ive found that close to the max speed acheived on the 3.9 in 4th gear is in the low 130's, my highest is 133mph thats using a 24.5x15 tyre.

 

[curtis]

9 inchers are h bomb proof but the 8.8 has a lower drag coefficient, can't remember from the mustang days. Sorry getting old.


I'm thinking that if you could get the Nissan diff fitted you could stock up on the jdm boxes because most people want the VR4 first but with the 3.5 rato to match the dsm rear. I'm sure there's importers with rooms full of these JDM boxes that can't move them.

 

[gtluke]

yeah 3.909 is evo/rs gearing, I have it in my galant.
8.8 is a better choice because it's smaller, lighter, robs less power and is almost as capable. pleanty of 7 second mustangs on em. plus they are dirt cheap and come out of mustangs which have the same exact bolt pattern as a 5 lug mitsu.
3.909 is also a gear ratio offered in the 8.8 (came out a few years ago)
most ring and pinion ratios are the same. there are only so many combinations you can do with the general size of the ring and pinion. stock our cars are 3.55, and that's a pretty common for rear ends.

 

[gtluke]

03 cobra rear would be trick if you wanted to stay IRS, but for drag go live axle, it's much better. but really at that point just turn the engine sideways, use a real trans and drop a full second off your times /ubbthreads/images/graemlins/smile.gif

 

[RedTwo]

Maybe I should reinstall Nissan FAST again. It's like CAPS... on crack!

What sort of rear end do those 9 second Evo IIX and IX run?

 

[spoulson]

Turbo coupe rears are 8.8 IRS, also.

 

[RedTwo]

From what I was reading last night you can get the following final drives/diff ratios on Nissans:
4.110 R32 & R33 GT-R
4.083 KA24DE S13 & S14, Z32 N/A
3.916 Automatic S14 and S15, R32 GTS4, R34 GT-R
3.692 Manual S14 & S15, Z32 Turbo
3.538 Manual G35, Manual Z33
3.357 Automatic G35

Are these diff ratios or final drives though? The VR4 has a 4.333 final drive but a 3.545 diff ratio.