4.08 gears for the Q45
4.08 gears for the Q45
Would anyone be interested in replacing the 3.62 gears with 4.08 gears? We are working on making a kit for this and are looking for feedback on how many folks might be interested in this swap.4.08 gears for a Q45?
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Why?
On a recent road trip, I was wondering why anyone would want to mess with the incredible highway passing performance this car offers with the standard engine/transmission/final gearing?
If stoplight drags are important, get a lighter car and Chevy motor you can blow-up cheaply. If you use your Q45 to travel, keep it like it is in top condition.
It's priceless to see the faces of SL500, 740i, 540i, LS400 and other owners amazed the Q can match or exceed their car's performance rather effortlessly. Even had a guy with a 850CSi remark to me how fast Q45s are, and his car is no slouch
If stoplight drags are important, get a lighter car and Chevy motor you can blow-up cheaply. If you use your Q45 to travel, keep it like it is in top condition.
It's priceless to see the faces of SL500, 740i, 540i, LS400 and other owners amazed the Q can match or exceed their car's performance rather effortlessly. Even had a guy with a 850CSi remark to me how fast Q45s are, and his car is no slouch
I have one in the Q I am buying.Before that I was actively looking for one dor the Q I wound up crashing.Many Q owners that get one get one from a wrecked 300ZX.An alterantive might be successful if the price is right.
It would be a price issue, but if you include the transmission sensor to keep the speedo accurate, it could be an incredible performance modifcation.
Right now, quite a few Q owners are looking for one and I have gotten a couple of emails/queries when it came out I was going to put one into my (now crashed 91Q).
Certainly the majority of us are convinved of the performance kick by a 4.08.
With as hi a redline as the VH45DE has, we can take good advantage of a 4.08.
I vote yes, towards conbsidering it an attractive mod, with the caveat that the car I am getting has one already.
Fred...
It would be a price issue, but if you include the transmission sensor to keep the speedo accurate, it could be an incredible performance modifcation.
Right now, quite a few Q owners are looking for one and I have gotten a couple of emails/queries when it came out I was going to put one into my (now crashed 91Q).
Certainly the majority of us are convinved of the performance kick by a 4.08.
With as hi a redline as the VH45DE has, we can take good advantage of a 4.08.
I vote yes, towards conbsidering it an attractive mod, with the caveat that the car I am getting has one already.
Fred...
kevin240 wrote:The price would be around $500-600 installed as an approximation.
Kevin
OHMYGOD!!
I think you'd get a lot of customers at this price.You'd need the old diff in exchange, I guess?
Would you inlcude for extra $ the new speed sensor part, that goes on it, to make the speedo read right?
Also would you make it so it fits the base Q as well?
The used 300ZX diffs are bolt on's <if> you have an "a" or "TCS" model, but if you have a base ( as most of us do) it wont fit.
Either way at that price you would be <very> competitive.
Do you plan to install locally?Or send w/ install intsuctrions and all parts?Or?
tell us more please.
Fred...:thumbup
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AZhitman
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Well, if you mean $500-$600 installed IN THE CAR, then that's a good deal. As fa as a "kit", there's really no need as it's a direct swap. I have access to two 4.08 rearends from sub-30K 300ZX's for $550 each, and could do the swap myself...
Where are you located?
Fred was DAYS away from buying one of these rearends when he decided to play Dorothy Hamill in his 91 on Christmas Day. Good thing I had the receipt!!!
Where are you located?
Fred was DAYS away from buying one of these rearends when he decided to play Dorothy Hamill in his 91 on Christmas Day. Good thing I had the receipt!!!
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maxnix
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- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
With a 5 speed, yes!
If I had another gear to use so I didn't take the 15% hit in mileage and range on the highway, I would consider it. Otherwise, the real world benefit doesn't compensate for the cruising performance losses. But the extra gear need s to be a shorter top gear, with 4th being a 1:1. So all the ratios in the transmission would have to be changed. Then there is reprogramming the ECU and TCU for the new ratios.
Remember, now 2500 rpm will be ~65 mph with the shorter rear end. What's a low et number to any speed worth compared to superb long term highway performance? For me, not much. I'd rather cruise the Autobahn (or Montana) for hours than win that stoplight lurch over an Impala with a rat motor in a few seconds.
I am sure Fred will have some interseting comments after he drives his 1994 on a couple of trips, although I think he mostly drives the East coast and Midwest.
Remember, now 2500 rpm will be ~65 mph with the shorter rear end. What's a low et number to any speed worth compared to superb long term highway performance? For me, not much. I'd rather cruise the Autobahn (or Montana) for hours than win that stoplight lurch over an Impala with a rat motor in a few seconds.
I am sure Fred will have some interseting comments after he drives his 1994 on a couple of trips, although I think he mostly drives the East coast and Midwest.
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Mayhem_J30
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
4.083/3.538= 15.4% higher rpm.................never heard of a 3.62 diff gear in a Q : 3.538 and 3.694.10.4% higher rpm for 97-01Q.
Never seen a gear set swap that didn't whine or fail soon [within a few years] unless 4-5 hours of fine adjustment was done to set the fine gear lash and mesh against the worn case. Remember the oem set lasted 12-15 years not 12months/12,000 miles as most aftermarket warranties are.
You must assemble with dye cream and disassemble. ressemble a few time LOOKING at the dye pattern on the gears............very tricky!
Never seen a gear set swap that didn't whine or fail soon [within a few years] unless 4-5 hours of fine adjustment was done to set the fine gear lash and mesh against the worn case. Remember the oem set lasted 12-15 years not 12months/12,000 miles as most aftermarket warranties are.
You must assemble with dye cream and disassemble. ressemble a few time LOOKING at the dye pattern on the gears............very tricky!
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Mayhem_J30
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Q45tech wrote:4.083/3.538= 15.4% higher rpm.................never heard of a 3.62 diff gear in a Q : 3.538 and 3.694.10.4% higher rpm for 97-01Q.
Never seen a gear set swap that didn't whine or fail soon [within a few years] unless 4-5 hours of fine adjustment was done to set the fine gear lash and mesh against the worn case. Remember the oem set lasted 12-15 years not 12months/12,000 miles as most aftermarket warranties are.
You must assemble with dye cream and disassemble. ressemble a few time LOOKING at the dye pattern on the gears............very tricky!
Oops! my bad. I read the opening post and just assuming he was correct. But at least I was using the right math..
Point was, there would be a noticealbe and immediate affect on MPG.-
Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
If everything is operating as new the 4 to 3 downshift occurs at an almost linear rate with throttle opening between 33 mph beginning at 2/8 [25%] throttle opening to 2.5/8 [32%] throttle opening at 42 mph.....then 3/8 [37%] at 47 mph to 5/8 [40%] at 65 mph 6/8 [75%] at 70 mph.
This is a function that requires the tcu software to be precise.
The tcu expects the engine power [at each rpm] to be as programmed for the system to work...........dirty intake/injectors will deliver less power and even 5% will throw the perfection out of whack..............as will changing the vehicle weight [above the ideal 2 - 160 pound occupants and a full tank of fuel and one very expensive set of titanium golf clubs in an Aligator bag......and one briefcase with planium pens..........allowances have been made for the bodyguard driver to carry a gun.
The point is there should be no lugging in overdrive as the system will downshift if the engine is operating properly.
Improper operation of a dirty or misset IAC [lack of range to compensate] can be another source of grief.
Whether the AC is operating or the headlights or other drain is compensated for by IAC [to add air] and adding injector time.......from signals sent to ecu...........even the battery voltage is monitored as even a 0.1 VDC difference will affect the injectors and require a new calculation of opening time!
Once you are at cruise speed [flat road] the IAC is the ecu's fine AIR tune as the road gets steeper the IAC adds more air to maintain the engine rpm BEFORE you mash the throttle more.........if the IAC is maxxed out [at best it can add 5-6% at 2000 rpm] you must mash the throttle more to maintain rpm/speed.
The cruise control actually opens the throttle since it is expected that the IAC [only fine tuning] will not be enough in hilly areas.
This is a function that requires the tcu software to be precise.
The tcu expects the engine power [at each rpm] to be as programmed for the system to work...........dirty intake/injectors will deliver less power and even 5% will throw the perfection out of whack..............as will changing the vehicle weight [above the ideal 2 - 160 pound occupants and a full tank of fuel and one very expensive set of titanium golf clubs in an Aligator bag......and one briefcase with planium pens..........allowances have been made for the bodyguard driver to carry a gun.
The point is there should be no lugging in overdrive as the system will downshift if the engine is operating properly.
Improper operation of a dirty or misset IAC [lack of range to compensate] can be another source of grief.
Whether the AC is operating or the headlights or other drain is compensated for by IAC [to add air] and adding injector time.......from signals sent to ecu...........even the battery voltage is monitored as even a 0.1 VDC difference will affect the injectors and require a new calculation of opening time!
Once you are at cruise speed [flat road] the IAC is the ecu's fine AIR tune as the road gets steeper the IAC adds more air to maintain the engine rpm BEFORE you mash the throttle more.........if the IAC is maxxed out [at best it can add 5-6% at 2000 rpm] you must mash the throttle more to maintain rpm/speed.
The cruise control actually opens the throttle since it is expected that the IAC [only fine tuning] will not be enough in hilly areas.
After reading this post I called a friend who has the gearset in his Q, he told me to come to his job and see for myself how the gearchange worked, our cars are set up almost exactly so I wasnt expecting anything dramatic. I must say that I was shocked as to how the change put new life in the Q, this thing pulled hard, it no longer was kinda doggy out the gate it just pulled out hard, on the highway its just as good, the downshift from overdrive to drive is awesome, I must say that you when the shift occurs to OD that you are not at 140, but the top end does not seem to be sacrafised at all, If anyone knows if the rear is a direct swap in to a 91 Tlet me know because im ready to do it.
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AZhitman
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Like Dennis said... No offense to our new "entrepreneur", but I'd trust a rearend built by little Japanese guys with thousands of hours experience before I'd buy ANY gear "swap". Rearends are WAY too difficult to get perfect, and every rebuild I've seen (or had) has been a disappointment.
Why not just unbolt the old punkin and replace with an unmolested one from a Z? Lots less work and the same $$$.
Why not just unbolt the old punkin and replace with an unmolested one from a Z? Lots less work and the same $$$.
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Getting it perfect
Reminds me of a friend who was an independent BMW mechanic, and rebuilt his 2002tii transmission (4 speed BW, I think). Even with all the factory tools and guages, he still did it twice more to get it just right and operating as new.
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diamondj30
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