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  #1  
Old 03-23-2010, 11:03 AM
elemgee elemgee is offline
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Quick Change Shift Kit Question

Am thinking about ordering a quick change shift kit, but am curious if there is any negative effect on the already weak transmission. The last thing I want to do is make it weaker. Anyone know? I've read some posts on it but nothing seemed to really address this question. Thanks.
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  #2  
Old 03-23-2010, 12:10 PM
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SoCal LS-L SoCal LS-L is offline
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Re: Quick Change Shift Kit Question

The quick change helps prolong the life of the transmission actually. Long smooth gear changes actually wear components out faster.
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Old 03-23-2010, 01:40 PM
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Re: Quick Change Shift Kit Question

Can anybody explain how disabling the engine torque reduction signal is good for the transmission? Because I would expect the exact opposite.

Presumably, the clutches slip during a gear shift, and the more torque you apply to them when they are slipping, the quicker they will wear out.
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  #4  
Old 03-23-2010, 01:54 PM
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Re: Quick Change Shift Kit Question

Duck and cover!
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  #5  
Old 03-23-2010, 03:09 PM
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Re: Quick Change Shift Kit Question

Here we go....
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  #6  
Old 03-23-2010, 03:23 PM
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Re: Quick Change Shift Kit Question

Have not had a problem with mine. I love it. Had it in since June 2008. I imagine if you abused the transmission by regularly hammering out full throttle shifts with no torque reduction you might break something.

Harvey specifically states not to put one on a failing tranny or without a good resistor in the quick change thread on the svxwf.

Quote:
The surge in the Torque peak is due to the torque converter, multiplying torque due to the difference in engine/transmission speed, it is not a shock loading, it is actually a very nice surge

I also recomend that it is only fitted to a working transmission, with a well adjusted brake band, and a working AWD.
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Old 03-23-2010, 03:29 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by b3lha View Post
Can anybody explain how disabling the engine torque reduction signal is good for the transmission? Because I would expect the exact opposite.

Presumably, the clutches slip during a gear shift, and the more torque you apply to them when they are slipping, the quicker they will wear out.
This is particularly the situation during down shifting for acceleration, after applying more than third throttle. The claim is that increased line pressure, the result of disabling control of solenoid "A", will prevent slip and damage to friction surfaces. However, it can not be denied that shock loads throughout the transmission train, will be much increased.

A quite drastic change is made in respect of the original design parameters. Were Subaru engineers stupid?
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Old 03-23-2010, 03:32 PM
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Re: Quick Change Shift Kit Question

How does a WRX or forester XT 4EAT deal with this shock load without using torque reduction?
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  #9  
Old 03-23-2010, 03:35 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by immortal_suby View Post
How does a WRX or forester XT 4EAT deal with this shock load without using torque reduction?
Change in transmission designs. Those use PhaseII transmissions that have had significant changes from the phaseI transmissions.

Not trying to argue for or against the quick change, just giving response to your question.
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  #10  
Old 03-23-2010, 05:55 PM
oab_au oab_au is offline
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by elemgee View Post
Am thinking about ordering a quick change shift kit, but am curious if there is any negative effect on the already weak transmission. The last thing I want to do is make it weaker. Anyone know? I've read some posts on it but nothing seemed to really address this question. Thanks.
Giday Elemgee, The Quick Change has been used on about 70 SVX so far, in 6 different countries.. There have been no reported problems, due to its use. I would not recommend its use on a transmission that is already experiencing problems. If it is fitted to a normally good box, it can help to extend the transmissions life, but it cannot prevent the driver from abusing the car.

Quote:
Quote:
Originally Posted by immortal_suby
How does a WRX or forester XT 4EAT deal with this shock load without using torque reduction?

Nate wrote: Change in transmission designs. Those use PhaseII transmissions that have had significant changes from the phaseI transmissions.
Nate the early WRX 94 to 97 and the 92 RS Turbo models here in Australia are fitted with the Phase 1 trans the same as the SVX . These did not use a torque cut, and have not had any problems that can be attributed to not having it.

Quote:
B3lha wote: Can anybody explain how disabling the engine torque reduction signal is good for the transmission? Because I would expect the exact opposite.

Presumably, the clutches slip during a gear shift, and the more torque you apply to them when they are slipping, the quicker they will wear out.
Phil to understand why this is so, you need to understand why Subaru did it in the first place.

When this transmission was used in the Sporty WRX and RS Turbo, the change was fast and solid, just what you would expect of a Sporty car. When the SVX was designed it was aimed at the higher end of the Luxury Grand Touring market. The same fast solid change did not suit this market, so they programmed the TCU to lower the line pressure during the change, to remove the solid engagement.

Because the reduced pressure would allow the clutch and band to do a lot of slipping to smooth the change, they turned the Engine torque down to prevent excessive wear. The result was that silky smooth gear change that suited the Luxury profile that they wanted, but at the expense of clutch and band wear.

As the Quick Change prevents the line pressure from being lowered during the change, there is no need to reduce the engine torque. So it converts the gear change to the same fast solid shift, as we had with the Sporty models.

Any fears of the transmission having shock loadings, is only in the minds of those that have not driven a car that is fitted with a Quick Change.

Harvey.
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Old 03-23-2010, 06:29 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by oab_au View Post
Phil to understand why this is so, you need to understand why Subaru did it in the first place.

When this transmission was used in the Sporty WRX and RS Turbo, the change was fast and solid, just what you would expect of a Sporty car. When the SVX was designed it was aimed at the higher end of the Luxury Grand Touring market. The same fast solid change did not suit this market, so they programmed the TCU to lower the line pressure during the change, to remove the solid engagement.

Because the reduced pressure would allow the clutch and band to do a lot of slipping to smooth the change, they turned the Engine torque down to prevent excessive wear. The result was that silky smooth gear change that suited the Luxury profile that they wanted, but at the expense of clutch and band wear.
Harvey.
The above statement constitutes no more than a personal opinion, unless additional published supporting evidence is quoted and is verified.
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Old 03-23-2010, 07:04 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by Trevor View Post
The above statement constitutes no more than a personal opinion, unless additional published supporting evidence is quoted and is verified.
Wouldn't the exclusion of torque reduction on turbo models equipped with a phase 1 4EAT serve as proof that subaru was not concerned with the longevity of the transmission?

I'll have to dig up my road and track guide to the svx to verify, but IIRC there was a section devoted to the pursuit of a seamless gear change on the svx to promote the luxury car ideal. Of course that is not fact as it is journalism, but the fact that concurrent subaru models of similar weight and torque did not use torque reduction while the svx did is evidence to validate the article.
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Old 03-23-2010, 07:14 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by immortal_suby View Post
Wouldn't the exclusion of torque reduction on turbo models equipped with a phase 1 4EAT serve as proof that subaru was not concerned with the longevity of the transmission?

I'll have to dig up my road and track guide to the svx to verify, but IIRC there was a section devoted to the pursuit of a seamless gear change on the svx to promote the luxury car ideal. Of course that is not fact as it is journalism, but the fact that concurrent subaru models of similar weight and torque did not use torque reduction while the svx did is evidence to validate the article.
edit: here is the page from the R&T guide
Quote:
"Gear changing was brought to luxury coupe levels of smoothness by instituting a torque management program which cuts fuel to half of the engine's cylinders on the 1-2 gearshift"
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92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles
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Last edited by immortal_suby; 03-23-2010 at 07:17 PM.
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Old 03-24-2010, 06:08 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by oab_au View Post
Phil to understand why this is so, you need to understand why Subaru did it in the first place.

When this transmission was used in the Sporty WRX and RS Turbo, the change was fast and solid, just what you would expect of a Sporty car. When the SVX was designed it was aimed at the higher end of the Luxury Grand Touring market. The same fast solid change did not suit this market, so they programmed the TCU to lower the line pressure during the change, to remove the solid engagement.

Because the reduced pressure would allow the clutch and band to do a lot of slipping to smooth the change, they turned the Engine torque down to prevent excessive wear. The result was that silky smooth gear change that suited the Luxury profile that they wanted, but at the expense of clutch and band wear.

As the Quick Change prevents the line pressure from being lowered during the change, there is no need to reduce the engine torque. So it converts the gear change to the same fast solid shift, as we had with the Sporty models.
Maybe that's true. I think that firming up the shifts by recalibration of the line pressure is probably a very good idea and might help to extend the life of the transmission.

But the less torque you apply to the clutches, the less they will slip and the longer they will last. It seems to me that reducing the torque during a shift must a good thing for gearbox longevity. Conversely, disabling the torque-cut signal must surely subject the clutches to more torque, more slip and more wear than leaving it alone.

I accept that the primary goal of the QS device is performance, rather than gearbox longevity. But it's stretching things a bit far to claim that it will definitely make the transmission last longer. Maybe in a few years time, when people have done 80000+ miles with a QC, we'll be able to look at the failure stats and say whether it is better or worse. But right now it's just speculation either way.
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Old 03-24-2010, 07:11 PM
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Re: Quick Change Shift Kit Question

Quote:
Originally Posted by b3lha View Post
Maybe that's true. I think that firming up the shifts by recalibration of the line pressure is probably a very good idea and might help to extend the life of the transmission.

But the less torque you apply to the clutches, the less they will slip and the longer they will last. It seems to me that reducing the torque during a shift must a good thing for gearbox longevity. Conversely, disabling the torque-cut signal must surely subject the clutches to more torque, more slip and more wear than leaving it alone.

I accept that the primary goal of the QS device is performance, rather than gearbox longevity. But it's stretching things a bit far to claim that it will definitely make the transmission last longer. Maybe in a few years time, when people have done 80000+ miles with a QC, we'll be able to look at the failure stats and say whether it is better or worse. But right now it's just speculation either way.
I do not have any experince with the quick shift product, and I do not personally believe it to be detrimental to any soft transmission parts, but it could be argued that the planetary gears or the lip seals could be damaged by it. I do not believe this is really relevant, because we don't see those kind of failures on these. What's more, what I have had done is surely more trying on those components than any electric mod, and I believe it to be within design limits.

MY OPINION, as a person who has extensive experience with this transmission (but again, absolutely zero with the QC product) is that the torque control signal was put in place to make the thing hold together AND to make it shift better, though I find it odd that it does not occur on the 1-2 shift which is where I think it is needed the most as far as feel goes. Further, I believe that a modification of the valve body to increase base line, apply pressure to the band, high clutch, drain from those areas to compensate for the added flow, and flow thru the cooler circuit could help with the longevity of the transmission, and that such modifications make the QC essentially unnecessary by achieving the same results. I believe a member here has made a product, which, like any modification, lacks the testing that an OEM part would, but that is a product to add to our lineup of impressive feats that we as a community have achieved together in these past 10 years that we have been together on the network. This is to be appreciated, and to be purchased and used by those who choose to use it. From what I have heard, the product does what it is supposed to.

Why, Nifty, did they not do this from the factory, you may ask, stating an excellent opinion that the pump in this trans is too weak, and I would answer "because it killed my fuel economy by an indeterminable amount that is somewhere between .2-.9 MPG.
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