Thoughts on a 4.36:1 VLSD in a Q45.

Post by **AZhitman** » Mon Sep 13, 2004 7:57 pm

Considering trying out a 4.36 in the Q, since my 4.08 whines and squalls like a damn Lexus owner (but I LOVE the acceleration).

I know this has been touched on before, and I'm intimately aware that I'll lose any semblance of a functional speedo / odometer...

Thoughts?

p.s. Does the speed sensor (mechanical geared unit on transmission) input to the ECU? In other words, could it be disabled by simply removing the shaft gear without consequence? Sorry for the doofus question....

Post by **maxnix** » Mon Sep 13, 2004 9:29 pm

Dennis posted a link to a device that will electronically adjust the number of pulses and fool the speedometer into the correct reading after it is calibrated.

I guess the fuel economy is of no concern?

Post by **Q45tech** » Mon Sep 13, 2004 10:52 pm

The correct speed signal needs to be supplied to steering, cruise, ecu, tcu, and ABS [a backup to the wheel sensors]........tcs[?]...........via correct gear or the black box convertor.

Remember the distribution box for above is integrated in speedometer asembly.

Takes a real craftsman genius to set up any gear swap........isn't the gears fault but the techs that they whine..........not spending the required 8 hours of work inside the diff unit.

Post by **AZhitman** » Tue Sep 14, 2004 5:05 am

Dennis, could you expound on the "black box" idea, which I'm assuming is an electronic "filter" to modify the voltage from the speed sensor?

Are you saying that would be a "behind the dash" modification?

Correct gear is almost out of the question, as I couldn't get the larger one for the 4.08 to fit (I KNOW I won't cram a 4.36-compatible speedo gear in there).

Dennis, could you also comment on the gearing itself, as regards performance, especially considering the 95 transmission ratios...

The guy that built my R200 needs a smack.

p.s. Fuel economy? What's THAT?

Post by **Q45tech** » Tue Sep 14, 2004 6:07 am

The black box is an [in line with speed sensor cable + 12 volts] frequency converter [divide by N counter with regenerator] that is adjustable by dip switches in 1/4% increments...........should handle a 5.5:1 diff gear..........or a 2.35:1 gear.

4.36/3.538= 1.2323346 cube root = 1.07 so a 7% increase in acceleration.

90-93= 2190 rpm per 10 mph in 1st vs 1333 rpm [2nd gear 912 vs 740 rpm] [3rd gear 592 vs 480 rpm] anyway in 3rd gear [with either 90-93 or 94-96] 5920 rpm at 100 mph seems ideal to me.

Decrease rpms in 1st and 2nd by ~~5% to correlate with a 94-96 transmission.

Quarter mile improvement depends on out of the 1 second acceleration improvement how much the EXTRA 2>3rd gear shift takes away.

I'm not sure I could stand 23% decrease in highway mpg ~~ 5 mpg nor a 2466 rpm 60 mph........about half what it would be in 3rd gear with a standard diff gear.

Post by **AZhitman** » Tue Sep 14, 2004 7:12 am

Thanks Dennis!

Are the stub axles difficult to remove/replace? I'd have to swap out the 5-lug 180sx ones for my 6-lug Q stubs.

Now, who wants to build a black box?

Post by **Q45tech** » Tue Sep 14, 2004 8:58 am

Buy the one I previously posted cheap under $200

Post by **AZhitman** » Tue Sep 14, 2004 9:28 am

Dennis - Where will than need to be wired? Behind the dash, or can I put it somewhere more accessible for calibration?

Post by **elwesso** » Tue Sep 14, 2004 11:07 am

Greg, why not just mate up a 92-93 transmission with your 4.08?

Post by **HeavyDuty** » Tue Sep 14, 2004 2:45 pm

Greg,

Buy Tech's, or get more info here. Like anything, there's good & better. Tech's one is probably better built than this one, judging by the price.

They're usually installed inside the car along the path from the sending unit to the ECU, or under the car at the sensor.

For the diff job, this time, find a good driveline shop (read: highest quote, whoever's been around for a while in PHX, or send it here if you like.

http://www.gaugeguys.com/ratioesa.htm

must......resist.....further..urge....to....comment

Post by **Q45tech** » Wed Sep 15, 2004 3:37 am

Each gear set ratio will require different ZEN and experience with that ratio to achieve exact grear mesh profile on acceleration and deceleration......Magic envolved.

Obviously the only place where the speed sensor signal is a varying frequency is pror to the speedometer [freq to analog convertor] speed sensor input.

The black box can allow the voltage to be set to withhin 0.15 mph [now if the analog volt meter [what we call the speedometer] could be set across the range to read so accurately but it varies with needle position due to gravity...........

Post by **AZhitman** » Wed Sep 15, 2004 6:02 am

Jason - This rearend is FACTORY. My concern now is the axle stubs, as they are 5-star as opposed to the Q45's 6-star...

Dennis, thanks for the input on that. I'm assuming this means removal of the gauge cluster regardless.

Post by **HeavyDuty** » Wed Sep 15, 2004 7:52 am

AZhitman wrote:Jason - This rearend is FACTORY. My concern now is the axle stubs, as they are 5-star as opposed to the Q45's 6-star....

Deja Vu. Aren't they different diameters?

AZhitman wrote:Dennis, thanks for the input on that. I'm assuming this means removal of the gauge cluster regardless.

If I may answer for him. No. Most of them instruct you to install inline at the sensor. If you mount it inside to protect it, that's a good idea, too. Just do so that you could adjust it easily if needed.

They have 1 million dipswitches on them, I'm sure you could get real close with the instructions provided.

Post by **AZhitman** » Wed Sep 15, 2004 8:12 am

Deja vu indeed. Same nonsense we ran into with the Z rearend.

Staying out of the dash is a plus for me. Ive never seen a car's dashboard and gauges removed that went back together QUITE right.

Post by **sijoko** » Wed Sep 15, 2004 9:14 am

If you want the Gear Swap done right, then contact UNITRAX at 1-800-622-4327. Talk with Devin or Scotty.

http://www.gounitrax.com/main.html

You cannot simply swap out the stub axles as they are of different diameters.

You have to rebuild the stock rearend with the higher gears.

-sijoko

Post by **AZhitman** » Wed Sep 15, 2004 10:01 am

Thanks Siju - That's what I was afraid of.

I'll buy it for my 240, and have UNITRAX do the Q diff.

Post by **rsiwicki** » Wed Sep 15, 2004 10:02 am

"If you want the Gear Swap done right, then contact UNITRAX at 1-800-622-4327. Talk with Devin or Scotty."

So true!!!

Post by **Rex** » Wed Sep 15, 2004 12:35 pm

AZ, can you temporarily put a smaller diameter wheel/tire on your car to feel the net effect of the 4.36 rearend, and wouldn't that be cheaper??

Post by **AZhitman** » Wed Sep 15, 2004 12:42 pm

Good question!

Can anyone help me with that math?

I REALLY need to find some 15" BBS's for CHEAP before October...

Post by **maxnix** » Wed Sep 15, 2004 12:44 pm

Rex wrote:AZ, can you temporarily put a smaller diameter wheel/tire on your car to feel the net effect of the 4.36 rearend, and wouldn't that be cheaper??

Hooptie wheels on Quella? The mind boggles!

Post by **Rex** » Wed Sep 15, 2004 1:33 pm

maxnix wrote:Hooptie wheels on Quella? The mind boggles!

I was more thinking the factory 15" BBS's with some serious LOW profile tires.

Post by **Jeff Williams** » Thu Sep 16, 2004 6:02 am

You would have to go to about a 20 to 22" tire diameter. The car would not accelerate any faster, it would just be going a lot slower than the speedo.

I think you should go to the 4.36, and get some BIG rear tires, like 305/60/18 (or whatever size would keep the speedo accurate, stock).

Then you could FLY on the interstate!

Post by **Q45tech** » Thu Sep 16, 2004 7:05 am

21" exact tire to simulate a 4.36 and such a thing probably doesn't exist in 15".

A 195/60/15 ~~ 24.2" so that might simulate a 3.80 diff

A 195/50/15 ~~ 22.7"....................................a 4.04 diff........

At least a [195/50/15] 1019 pound load index tire would probably be good enough to try drag time on the rear but we already know mathematically what the results will be!

A new nissan 5 speed AT with a 3.54 1st gear [with a 3.538 stock diff] would simulate a 4.49 diff gear with a 4 speed transmission.

Now that most G35 and all RWD have this 5AT transmission probably time to consider building adapter plates housing to fit this in a 90-01 Q........the junk yards will have them by now [2 years after first use].

The end result: cruise rpm will be 2300 rpm roughly what a 4.083 creates, assumming Nissan recreates the 5 AT gear set for 2005/2006 you might be able to future swap a better gear span [rartio spread] in another two years.

Current 90 span 4.0, 2004 span 4.4, guessed future span 5.1 unless they have a 6speed AT in the wings.

"Extra gears facilitate a broader ratio spread between launch and cruising ratios. The new ZF automatic has a 6.05 ratio spread between first and sixth compared to 4.0 for the typical four-speed, 5.0 for five-speed automatics, and 5.5 or so for wideratio five-speed manual transmissions. According to ZF's Executive Vice President for R&D Michael Paul, the 6.05 ratio spread is optimum for today's engines but direct-injection gas and diesel power-plants of the future may appreciate even broader spreads. When asked if that means ZF is investigating seven-speed automatics, Paul acknowledged that single-digit fuel efficiency gains are possible with them but refused to confirm that his engineers are actively pursuing that approach."

http://www.mathworks.com/acces....html

Website · Post by **diamond** » Sun Sep 19, 2004 5:56 am

where can one find this black box q45tech.im interested.

Post by **Q45tech** » Sun Sep 19, 2004 6:33 am

http://www.blackrobotics.com/yb_home.htm

Website · Post by **diamond** » Mon Sep 20, 2004 7:28 am

i think i will try one too hitman.thanks for the link q45tech.

Post by **sijoko** » Mon Sep 20, 2004 10:03 am

Since we are discussing gear ratios, what do you guys think about having an 8 speed transmission in your Q45?

It is not as far-fetched as it sounds.

What I am referring to is installing a Gear Vendors Overdrive Unit behind the stock trans.

-sijoko

Post by **HeavyDuty** » Mon Sep 20, 2004 10:23 am

sijoko wrote:Since we are discussing gear ratios, what do you guys think about having an 8 speed transmission in your Q45?

It is not as far-fetched as it sounds.

What I am referring to is installing a Gear Vendors Overdrive Unit behind the stock trans.

-sijoko

Oooohhhh Yeeeaahhhh,

They are awesome. Wanted one badly for my 4.10:1 equipped 1G Lightning, just finished installing one on a 72 Buick 455.

They can handle ungodly amounts of power.

Bring on the 5.10:1..........

GearVendors.com

Expensive, like $2500 or so.

Post by **rsiwicki** » Mon Sep 20, 2004 10:32 am

$2,500 is cheap compared to my $3,500 LevelTen transmission...I am ready.

Post by **sijoko** » Mon Sep 20, 2004 10:43 am

The Gear Vendors Overdrive bolts on at the rear of the factory trans.

You control it with a switch.

It allows you to split the gears. So you can have an overdrive for each of the gears.

The cost involved would be the actual unit plus: 1) making an adapter plate for the RE4R03A trans. 2) getting the speedo drive to work with our setup. 3) having a new shaft made.

I can't think of anything else that needs to be done, except maybe an additional trans. mount at the rear.

-sijoko

Thoughts on a 4.36:1 VLSD in a Q45.

Thoughts on a 4.36:1 VLSD in a Q45.

Re: Thoughts on a 4.36:1 VLSD in a Q45. (AZhitman)

Re: Thoughts on a 4.36:1 VLSD in a Q45. (maxnix)

Re: (AZhitman)

Re: (AZhitman)

Re: (AZhitman)

Re: (HeavyDuty)

Re: (AZhitman)

Re: (Rex)

Re: (maxnix)

Re: (Rex)

Re: (Jeff Williams)

Re: Thoughts on a 4.36:1 VLSD in a Q45. (AZhitman)

Re: (sijoko)

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums