transmission theory
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Q45ver
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transmission theory
My Q has the original transmission. I have installed a 93 TCU, cooler and am running mobil syn ATF. I have come to the conclusion the killer for this transmission is the overdrive. There is no way this thing should be lugged around at 12-1500 RPM in overdrive as it tends to do if you allow it. I have developed the habit of keeping it back in 3rd in town or until open road and at least 50 MPH. This may not be the answer for the best fuel economy, but I'm convinced I can prolong my transmission's life. What say ye experts?
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maxnix
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- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Transmission Operation
I thought every one did this. A senior tech whose dad has a 1994 Q45 told me to drive this way. I will hold it to 70 if the grade is steep.Q45ver wrote:I have developed the habit of keeping it back in 3rd in town or until open road and at least 50 MPH.
I have recommended this for some time now.
not only less lugging but it results in fewer shifts if in town.Actually I dont take it out of "D" until I go 65mph and know I will keep it for at least a couple minutes.Also a good idea on interstates if on a long steep hill.
Also you get better ATF flow and fewer heat pockets that way.
I have only stopped this habit now, that I have a 4.11 (4.08) rear end, as it is no longer as neccessary.
In summary :Your reasoning is both sound and correct.
Fred...
not only less lugging but it results in fewer shifts if in town.Actually I dont take it out of "D" until I go 65mph and know I will keep it for at least a couple minutes.Also a good idea on interstates if on a long steep hill.
Also you get better ATF flow and fewer heat pockets that way.
I have only stopped this habit now, that I have a 4.11 (4.08) rear end, as it is no longer as neccessary.
In summary :Your reasoning is both sound and correct.
Fred...
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Even the massive [in relative terms] 4.5 liter has a hard time making enough power below 2,048 rpm part throttle [60 mph] to not lug around town with AC on and a passenger load [too many twenkies]............it was great brand new but wear and tear and dirt and deposits have conspired to lower the power by at least 10% so there is no margin left.
Even mine pings and snorts at 40-45 mph on very light 4th gear acceleration [up an incline] with AC on [when it gets above 85F] and a 120 lb passenger.A can of BG 44k solves the problem until the next few tankfuls....for 1,500 miles or so...........probably raises the first tankful's octane by 0.2-0.3 points.
When the transmission monitors the TPS voltage it sees you asking for more power [how hard you push the throttle vs rpm].
Even mine pings and snorts at 40-45 mph on very light 4th gear acceleration [up an incline] with AC on [when it gets above 85F] and a 120 lb passenger.A can of BG 44k solves the problem until the next few tankfuls....for 1,500 miles or so...........probably raises the first tankful's octane by 0.2-0.3 points.
When the transmission monitors the TPS voltage it sees you asking for more power [how hard you push the throttle vs rpm].
It's a good call. You may see 12 MPG in the city.
A transmission installed is $3K - if the life of a transmission is 100K that's = 3 cents a mile.
At 16 MPG in the city at $2 a gallon is 12.5 cents a mile.At 12 MPG in the city at $2 a gallon is 16.7 cents a mile.
spending 4.2 extra cents a mile on transmission care. At first blush doesn't seem like a good investment, but in the last quarter of the 100K transmission lifespan this looks like a good way to delay the major outlay of cash. If your transmission is newer, start putting that 4 cents a mile away for a new transmission and keep it in D4.
A smart driver will always be squirreling away cash for their car - I figure a first gen Q needs 15 - 20 cents a mile to keep it in tip top shape.
The vast majority of wear in the transmission occurs during shifts as the clutch faces engage and if you can cut down the amount of shifting ...
Since the Q is a lux car the transmission shifts a little softly to make the car kick less. This actually increases the amount of wear that takes place. I'd be curious if anyone's ever pulled the transmission hydraulic circut and adjusted the springs insides so that it slaps into gear more quickly.
As far as the load across the surfaces of the clutch faces though: once the clutch is fully engaged it can handle a large amount of force (with the exception of the torque convertor cluch). So once the clutch packs are engaged for fourth gear, the torque (strain) applied the clutch at 40 MPH is less than at 75 MPH and it isn't intrinsiclly bad on the transmission to be in 4th at 40 MPH.
A transmission installed is $3K - if the life of a transmission is 100K that's = 3 cents a mile.
At 16 MPG in the city at $2 a gallon is 12.5 cents a mile.At 12 MPG in the city at $2 a gallon is 16.7 cents a mile.
spending 4.2 extra cents a mile on transmission care. At first blush doesn't seem like a good investment, but in the last quarter of the 100K transmission lifespan this looks like a good way to delay the major outlay of cash. If your transmission is newer, start putting that 4 cents a mile away for a new transmission and keep it in D4.
A smart driver will always be squirreling away cash for their car - I figure a first gen Q needs 15 - 20 cents a mile to keep it in tip top shape.
The vast majority of wear in the transmission occurs during shifts as the clutch faces engage and if you can cut down the amount of shifting ...
Since the Q is a lux car the transmission shifts a little softly to make the car kick less. This actually increases the amount of wear that takes place. I'd be curious if anyone's ever pulled the transmission hydraulic circut and adjusted the springs insides so that it slaps into gear more quickly.
As far as the load across the surfaces of the clutch faces though: once the clutch is fully engaged it can handle a large amount of force (with the exception of the torque convertor cluch). So once the clutch packs are engaged for fourth gear, the torque (strain) applied the clutch at 40 MPH is less than at 75 MPH and it isn't intrinsiclly bad on the transmission to be in 4th at 40 MPH.
forecast wrote:
1)Since the Q is a lux car the transmission shifts a little softly to make the car kick less. This actually increases the amount of wear that takes place. I'd be curious if anyone's ever pulled the transmission hydraulic circut and adjusted the springs insides so that it slaps into gear more quickly.
2)As far as the load across the surfaces of the clutch faces though: once the clutch is fully engaged it can handle a large amount of force (with the exception of the torque convertor cluch). So once the clutch packs are engaged for fourth gear, the torque (strain) applied the clutch at 40 MPH is less than at 75 MPH and it isn't intrinsiclly bad on the transmission to be in 4th at 40 MPH.
1)Yes,Level Ten has, spendy but works real well.
2)The reduced amount of ATF flow at low rpms/mph.Especially important on inclines in hot weather to not keep lugging it hence "3" vs "D" makes sens ein many situations even when travelling at 65mph.
Fred...
PS: With a first gen Q in "3" all day long in town I get about 13-15 mpg with normal driving style
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Q451990
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That sounds about right... the 13 MPH must assume a lot of WOT fun from light to light. I think my averages were around 16 when I did a substantial amount of in town driving. No after I leave my street it's basically 45-55MPH to the interstate (unless I get stuck behind grandma or have to stop for one stoplight).
Heath
Heath
I think the transmission theory is rather interesting, but my operating philosophy is different. I tend to dispose of cars after a year or two due to repairs or boredom, though I might keep this Q much longer.
I'd be willing to buy a new transmission instead driving an extended 50,000 miles of minimal joy and excitement. (I'm 21; I dont have kids to feed.)
I drive my cars hard, to their fullest, and maintain accordingly realizing the expense that follows. I just dont like the idea of babying a Q to the point of changing my enjoyable driving habits or parking it and driving it only on weekends. I want full use!
The odd feeling of driving around town in 3rd (slows down too fast when you let off the gas, jerky) doesn't allow me to fully enjoy the car. And on the highway at 55mph, 3rd gear is loud and fatiguing.
I paid to play, and so I will. Just another perspective...-J.
I'd be willing to buy a new transmission instead driving an extended 50,000 miles of minimal joy and excitement. (I'm 21; I dont have kids to feed.)
I drive my cars hard, to their fullest, and maintain accordingly realizing the expense that follows. I just dont like the idea of babying a Q to the point of changing my enjoyable driving habits or parking it and driving it only on weekends. I want full use!
The odd feeling of driving around town in 3rd (slows down too fast when you let off the gas, jerky) doesn't allow me to fully enjoy the car. And on the highway at 55mph, 3rd gear is loud and fatiguing.
I paid to play, and so I will. Just another perspective...
-J.-
Q451990
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I don't think anyone would suggest driving in 3rd at 55MPH. We're talking about at 40mph intown driving. I'll move into 4th above 45-50MPH. I think it also depends on the individual vehicle and the engine/transmission condition. Some cars seem to be more capable of lugging without it being noticeable.
Heath
Heath
anyone experienced transmission failure?
To evaluate Q45ver's essential theory - it's the overdrive that kills it, I need to get some data.
Anyone had a transmission failure and gotten either an autopsy or failure report?
Generally, when a transmission fails it's because a clutch pack has worn out. Anyone had experience with which is usually the first to go?
Even if you didn't get specific knowledge of what part failed, the details of your experienced failure could shed some light (what were the symptoms?)
My experience with other RWD trannies suggests the rear-most "LOW-REVERSE" clutch is the weakest link.
Anyone had a transmission failure and gotten either an autopsy or failure report?
Generally, when a transmission fails it's because a clutch pack has worn out. Anyone had experience with which is usually the first to go?
Even if you didn't get specific knowledge of what part failed, the details of your experienced failure could shed some light (what were the symptoms?)
My experience with other RWD trannies suggests the rear-most "LOW-REVERSE" clutch is the weakest link.
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Jerky Beef?
I have to say this is not my experience. Rather, I have to remind myself to check if I have shifted to OD at 70-80mph because it is so smooth and quiet. The VH45DE engine likes to run.Jesda wrote:The odd feeling of driving around town in 3rd (slows down too fast when you let off the gas, jerky) doesn't allow me to fully enjoy the car. And on the highway at 55mph, 3rd gear is loud and fatiguing.
Never jerky! Coast down is very slight increase over OD. I will occasionally shift into OD at less than 55mph on a long downgrade. __________________Brian1995 Q45 & Q45t
Discover the power of the button!
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szh
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Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
When my 1995Q transmission started to go, it was putting it into Reverse that was the initial problem. It just would not go into gear when warmed up - lever would move there, but the transmission was not "engaged". I had a flush and pan drop and flush done immediately, but it was too late. The ATF was brown and there metal particles in it. This happened at about 102k miles, by the way.
I had had a scheduled flush done at 90k miles (not a pan drop, just a regular flush only, unfortunately) and then at 98k, I had the local Infiniti dealer do the "hundred+ point inspection" that they do for "certification" of pre-owned vehicles. This was because I wanted to make sure that everything on the car was okay - the 100k extended warranty was due to end shortly.
Needless to say, at 102k miles, the transmission bought it. Either it went incredibly fast, or the dealer missed it at the 98k check up - so much for the "inspection" they do for pre-owned vehicles! The T3 checkout price of $140 is a bargain under the circumstances - everyone should move to Atlanta and give T3 their business!
Z
I had had a scheduled flush done at 90k miles (not a pan drop, just a regular flush only, unfortunately) and then at 98k, I had the local Infiniti dealer do the "hundred+ point inspection" that they do for "certification" of pre-owned vehicles. This was because I wanted to make sure that everything on the car was okay - the 100k extended warranty was due to end shortly.
Needless to say, at 102k miles, the transmission bought it. Either it went incredibly fast, or the dealer missed it at the 98k check up - so much for the "inspection" they do for pre-owned vehicles! The T3 checkout price of $140 is a bargain under the circumstances - everyone should move to Atlanta and give T3 their business!
Z
sounds like a worn reverse clutch. I can't put my hand on the Q shop manual at the momment, but if I remember correctly, there are just two clutches and a band involved in making reverse
Failure to engage cold points to a plugged filter and resultant low PSI in the system. Failure to engage hot points toward worn clutch faces or internal leaking (around piston seals or control valves).
!Transmissions really should have line level PSI warning lights!
Don't be to hard on the dealer, it's not easy to catch a transmission that's about to go.
Failure to engage cold points to a plugged filter and resultant low PSI in the system. Failure to engage hot points toward worn clutch faces or internal leaking (around piston seals or control valves).
!Transmissions really should have line level PSI warning lights!
Don't be to hard on the dealer, it's not easy to catch a transmission that's about to go.
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szh
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Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
The local Infiiniti dealer in San Jose (Frontier Infiniti) matched the transmission price from Scottsdale. I had them put in Mobile 1 ATF and install an external cooler (the B&M) - bypassed the radiator. They gave me a 12/12 warranty on the transmission - which just expired a few months back.
BTW, Frontier is willing to match parts prices from Scottsdale (sorry, Joe!) for NICO members if you have them do the actual work. Although I think they will not enforce the "do the work with them" too much.
Get your service rep to speak with the parts director Marty for this reduction in prices. Marty has been with Frontier since they started out - used to be my service rep when I bought my first Q from them in 1991 - and is a really good person to work with!
Z
BTW, Frontier is willing to match parts prices from Scottsdale (sorry, Joe!) for NICO members if you have them do the actual work. Although I think they will not enforce the "do the work with them" too much.
Get your service rep to speak with the parts director Marty for this reduction in prices. Marty has been with Frontier since they started out - used to be my service rep when I bought my first Q from them in 1991 - and is a really good person to work with!
Z
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szh
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Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
forecast wrote:sounds like a worn reverse clutch. I can't put my hand on the Q shop manual at the momment, but if I remember correctly, there are just two clutches and a band.
Failure to engage cold points to a plugged filter and resultant low PSI in the system.
!Transmissions really should have line level PSI warning lights!
Don't be to hard on the dealer, it's not easy to catch a transmission that's about to go.
Actually, it would not engage when warm.
I could not prove that they missed it, so I did not harass the dealer about it. It had been 4k miles since the inspection. Finally, they gave me good service and an excellent price to replace it, so it worked out well in the end.
Z
So far I have found it to be economical with my first Q45 exchange. I buy Q45 from older family, no mods, easy driving. I then drive the hell out of it, make it go fast, and little long-term care. While it is still good, sell it and buy another. The upgrade from a 93 w/107k to 95 touring w/58k cost only $4,700.
My 95 Q45 has recently lost use of R. Pretty much same symptoms as SZhosain describes in his case. Initially, R wouldn't engage when warm. Now R won't engage when cold either. This went from bad to worse in about 400mi. I'm not sure if my last ditch efforts to revive the transmission accelerated the decline ; I changed ATF when the R symptom first appeared. But, I think R was just dying a swift death because forward gears are still working Ok.
Anyhow, I'm now in the market for some sort of transmission rebuild/replacement.
The economical solution seems to be a rebuild at local transmission shop (Astro - http://www.yellowpages-ads.com/01257720) which has a good reputation and offers 12mo/12Kmi warranty (~$850 + any required hard parts).
A Level 10 (http://levelten.com) PTS transmission would be nice to have but requires considerably more $$$ than a standard rebuild.
Are there any 'moderate' cost transmission enhancements that I could opt for at this rebuild juncture ? I've already got an external ATF cooler on the list.
The one thing that I can think of that would be complement my driving style and might actually prolong the transmission life is a ShifTronic mod of some sort. It looks like Level 10 has such a kit (http://www.levelten.com/store/...c.htm) ... but again pricey for my pocketbook.
So, I'll have to afford the standard rebuild but could maybe do another $200 in mods for something that would pay back in day to day driving.
Anyhow, I'm now in the market for some sort of transmission rebuild/replacement.
The economical solution seems to be a rebuild at local transmission shop (Astro - http://www.yellowpages-ads.com/01257720) which has a good reputation and offers 12mo/12Kmi warranty (~$850 + any required hard parts).
A Level 10 (http://levelten.com) PTS transmission would be nice to have but requires considerably more $$$ than a standard rebuild.
Are there any 'moderate' cost transmission enhancements that I could opt for at this rebuild juncture ? I've already got an external ATF cooler on the list.
The one thing that I can think of that would be complement my driving style and might actually prolong the transmission life is a ShifTronic mod of some sort. It looks like Level 10 has such a kit (http://www.levelten.com/store/...c.htm) ... but again pricey for my pocketbook.
So, I'll have to afford the standard rebuild but could maybe do another $200 in mods for something that would pay back in day to day driving.
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Watch out for the $850 plus hard parts job as some cost almost $1,000 each [planetaries............the factory units are all inclusive [including a cleaned replacement valve body [remanned in Japan] for $1500 dealer cost.True the standard rebuilt kit [soft parts] only cost $150 at most but 90% is labor.
12/12 is pretty short even though they all are expected to last 36/36.
12/12 is pretty short even though they all are expected to last 36/36.
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szh
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Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
An alternative source
If you are considering not putting in an Infiniti remanned transmission, then you may want to consider these guys too:
http://www.phoenixhardparts.co...=IAT1
The price for a Q transmission from them is relatively low ($950 plus shipping) - then you just have to pay for installation. It may be easier than having to wait for a rebuild of your current one - albeit not necessarily a lot cheaper depending on what is broken and how much the "hard parts" cost.
Z
P.S. I have no experience dealing with the folks at the above site. Just saw them listing on eBay a while back and figured it might be a good source if my transmission goes again.
http://www.phoenixhardparts.co...=IAT1
The price for a Q transmission from them is relatively low ($950 plus shipping) - then you just have to pay for installation. It may be easier than having to wait for a rebuild of your current one - albeit not necessarily a lot cheaper depending on what is broken and how much the "hard parts" cost.
Z
P.S. I have no experience dealing with the folks at the above site. Just saw them listing on eBay a while back and figured it might be a good source if my transmission goes again.