Transmission Mods

[Huskymaniac]

Originally Posted by svxfiles

YES!
and what am I doing awake at this unGodly hour?

You were so anxious to get back to this discussion?

[Huskymaniac]

By the way, I have created an Excel spreadsheet to calculate the accumulated fluid age before and after a partial ATF drain and fill as well as the average accumulated fluid age over the most recent interval. You enter the total ATF capacity, the capacity that is changed out in a partial refill and the mileage between partial refills. You see that the accumulated age and the average age for an interval converges over time.

So what matters more, the maximum age of the fluid or the average age of the fluid over an interval? For example, if you did a full drain and refill and you did it every 30,000 miles. The maximum age would be 30,000 miles and the average age over the interval would be 15,000 miles since the fluid starts out at zero mileage after the change. So is it that we don't want the maximum age to exceed 30,000 miles or is it that we don't want the average age to exceed 15,000 miles. I ask because I can add a macro with a button to automatically calculate the OCI to achieve either target.

Does anyone have an accurate measure of the amount of fluid drained if the car is put up on a lift, level?

[oab_au]

Been done before. Have a look here.
http://www.subaru-svx.net/forum/show...37&postcount=8

Harvey.

[oab_au]

1.Transmission cooler
2. Transmission filter for post 1993 models
3. Upgrade valve bodies
4. Upgrade TCU with unit from ecutune.com
5. Harvey's quick change
6. Shift kit from smallcar.com
7. Remove the transmission resistor
8. Increase the resistance of the transmission resistor to 20-100 Ohms
9. Add switch to engage power mode
10. Switch to synthetic ATF

1. An extra cooler? I don’t have one on my car, it is used for the longer runs, doesn’t do any city traffic, stays cool.
2. No, that was only for those early ones that had flaky lock-up linings, not needed.
3. If the mods will improve the cooling flow.
4. If the ‘switched on’ Power shift map doesn’t suit you, that is an alternative.
5. I am too modest to say “it’s the best thing since sliced bread.”
6. No just supplies a pseudo effect of making the changes better.
7. No way.
8. A good ‘linger longer’ for an ailing trans, raises the line pressure more that the throttle position dictates.
9. Why haven’t you done it.
10. Your money. I drain and top up the transmission pan every other oil change, stays clean, smells lovely.

As everybody has said the problem with the trans is low line pressure and too much heat. The low line pressure is caused by the high gearing, and the ability of the engine to pull at such low rpms. The box will hold 4th down to 1500 rpm and pull away. This has the oil pump at 1500 rpm, trying to supply enough flow, to provide the pressure, to hold the High clutch and the band hard enough not to slip. Of course it does.

The box changes back to 3rd till the speed, and pressure comes up for the band to hold again. The high clutch suffers the same fate.
The majority of heat is produced during this type of driving. Because the transmission load is high, the torque converter will do it best to lower the ratio, this produces the heat.

The answer to this is drive in 3rd at speeds lower that 2000 rpm Pump runs faster line pressure is higher, converter heat is lower.

As Nifty has said the other source of heat and wear is when the clutches and band have to engage with a reduced line pressure to allow the ‘soft shift’, that Subaru programmed into the TCU. Because the engagement is a slow slip, they have to reduce the engine torque, to prevent the plates slipping away. The box was designed to engage the plates under the full line pressure that the throttle position dictates.

The Quick Change removes the ‘soft shift’ to allow the engagement pressure, to return to the pressure that the box was made to use, preventing the slow slip that causes the heat and wear.
Nothing makes the change as fast, and as sure, as the QC.

So if you want a stronger, longer lasting box, that will stand up to the power and torque that the eg33 produces, fit a lower final drive ratio, if you drive in traffic in a hot climate, fit an extra cooler, change the oil regular and fit a Quick Change.

Harvey.

[Huskymaniac]

Originally Posted by oab_au

Been done before. Have a look here.
http://www.subaru-svx.net/forum/show...37&postcount=8

Harvey.

No, this is different. I think you once told me that you do a partial change ever third oil change. Not sure if that is 9000 miles or 11250miles. Regardless, what my spreadsheet does is tell you the accumulated age of the fluid before and after each partial change. So say you swap out 60% of the ATF at each change and do a change ever 9000 miles. My spreadsheet will show you the effective age of the fluid before and after that 9000 OCI. What you linked to shows you how the percentage of new fluid increases if you do one partial drain and fill right after another without driving in between them.

Let's say you start out with 100% new fluid. Then at 9000 miles you do a 50% fluid change. When the OCI starts, your fluid age is zero miles. Before the first partial change your fluid age is 9000 miles. After the partial change your effective fluid age is 4500 miles. The average effective mileage of the fluid over the first OCI is (9000+0)/2=4500 miles. You drive another 9000 miles. At then end of that OCI your effective fluid age is now 9000+4500=13500miles. After the fluid change your effective fluid age is 6750miles. The average fluid age over this second OCI was (4500+13500)/2=9000miles. I take this out over N changes and OCIs. The effective fluid age before a partial change converges to one number and the average fluid age over the OCI also converges to another number. In this example (50% change every 9000 miles starting with fresh fluid at zero miles), the fluid age before the partial change converges to 18,000 miles and the average fluid age over an OCI converges to 13,500 miles. So what if we wanted the average fluid age to be 15,000 miles in this case? What would the OCI have to be? The answer is 10,000 miles.

If people are interested, I can provide this for posting in the how to section.

[Huskymaniac]

I'm glad you popped in Harvey. On the ecutune.com TCU upgrade, how does it differ from the standard TCU? When I looked at their website it looked like they slightly modified the shift maps at high throttle and it looks like they trigger the warning light (and TC lock up) at a lower temperature. But it looks like one would still need to do the power switch mod to get gear changes at higher revs for lower throttle positions. They still have normal and power mode shift maps. At low throttle, their maps are the same as the standard TCU, I think.

On the power switch mod, someone mentioned that the TC will not lock up when this is engaged. Won't that defeat some of the purpose since the TC will generate more heat when unlocked? The oil will pump faster since the revs will be kept higher but the TC will generate more heat. Has anyone proven that the faster pump has more impact than the unlocked TC so that the net effect is positive which is to say lower operating temperatures? It would be nice to get the higher RPM map while still allowing the TC to lock up. I haven't installed the switch because I hate re-wiring cars. I am not even a weekend mechanic. If there is an easy way to re-wire the manual button to be a power button, I will do it.

Am I correct that you said the higher resistance will increase line pressure? It sounds like your box does so too. What exactly is the difference and how does one install your box?

[kwren]

Dam...
Obviously, Trevor is back

Keith

[1986nate]

Originally Posted by Huskymaniac

No, this is different. I think you once told me that you do a partial change ever third oil change. Not sure if that is 9000 miles or 11250miles. Regardless, what my spreadsheet does is tell you the accumulated age of the fluid before and after each partial change. So say you swap out 60% of the ATF at each change and do a change ever 9000 miles. My spreadsheet will show you the effective age of the fluid before and after that 9000 OCI. What you linked to shows you how the percentage of new fluid increases if you do one partial drain and fill right after another without driving in between them.

Let's say you start out with 100% new fluid. Then at 9000 miles you do a 50% fluid change. When the OCI starts, your fluid age is zero miles. Before the first partial change your fluid age is 9000 miles. After the partial change your effective fluid age is 4500 miles. The average effective mileage of the fluid over the first OCI is (9000+0)/2=4500 miles. You drive another 9000 miles. At then end of that OCI your effective fluid age is now 9000+4500=13500miles. After the fluid change your effective fluid age is 6750miles. The average fluid age over this second OCI was (4500+13500)/2=9000miles. I take this out over N changes and OCIs. The effective fluid age before a partial change converges to one number and the average fluid age over the OCI also converges to another number. In this example (50% change every 9000 miles starting with fresh fluid at zero miles), the fluid age before the partial change converges to 18,000 miles and the average fluid age over an OCI converges to 13,500 miles. So what if we wanted the average fluid age to be 15,000 miles in this case? What would the OCI have to be? The answer is 10,000 miles.

If people are interested, I can provide this for posting in the how to section.

Don't worry about it... if you wanna go that far, go ahead, but what has been said has been proven to work by many different owners. Draining the pan and filling full every other oil change ends up more effective even without a trans fluid cooler than using a trans fluid cooler and changing it out every 30,000 miles.

The life of the fluid is purely affected by how hot it gets 1 time. I saw a graph somewhere but if the normal life is 100,000 miles. you get it past a certain temp once and its cut in half, a few more degrees, cut in half again, etc.

[Huskymaniac]

Originally Posted by 1986nate

Don't worry about it... if you wanna go that far, go ahead, but what has been said has been proven to work by many different owners. Draining the pan and filling full every other oil change ends up more effective even without a trans fluid cooler than using a trans fluid cooler and changing it out every 30,000 miles.

The life of the fluid is purely affected by how hot it gets 1 time. I saw a graph somewhere but if the normal life is 100,000 miles. you get it past a certain temp once and its cut in half, a few more degrees, cut in half again, etc.

Maybe I assume too much but I bet the people that had problems with otherwise solid trannys went way more than 30K between changes. It sounds like the basic problem, regardless of the exact mechanism, is that the tranny runs hotter than an average tranny. That ages the fluid which causes the tranny to run even hotter. The cycle continues until the temperature reaches a point where the clutch is damaged. So, you are right. If the fluid is changed frequently, the cycle is stopped before the damage point is reached. A cooler can slow down the process so that a more normal OCI will be soon enough to stop the cycle before the damage point is reached. Better valve bodies would essentially do the same thing but also improve the shifting feel and speed. If all these things are combined, versus people choosing their favorite, the tranny would last 500,000 miles!!! Well, maybe not.

Speaking of the cooler approach, anyone have a clue what the cooling capacity of the 12" single pass cooler in the radiator is? Maybe my little Flex-a-lite 10,000 GVW cooler is good enough and I can just go ahead and install that?

[1986nate]

Originally Posted by Huskymaniac

Speaking of the cooler approach, anyone have a clue what the cooling capacity of the 12" single pass cooler in the radiator is? Maybe my little Flex-a-lite 10,000 GVW cooler is good enough and I can just go ahead and install that?

Honestly, pretty much nothing.

[Huskymaniac]

Originally Posted by 1986nate

Honestly, pretty much nothing.

I'll bet the Subaru engineers thought it was at least 3580 GVW. But, if it really is only a single pass of 12" then it couldn't possibly be much more than that.

I'm still of the impression that any object placed in front of the radiator will cause SOME air flow restriction which will cause some loss of engine cooling. For that reason alone, I would think that one would want to go with the smallest area cooler. The other part of the argument is that a smaller cooler will have even less ATF flow resistance to help keep the fluid flowing through the tranny. At some point, however, that becomes less of a factor as the resistance through the ATF lines becomes the dominant resistance.

Now I am ready to flip a coin on my 10,000 GVW cooler I have in hand. Should be enough to keep the ATF of a 3580lb car cool. Cooler is better, however. Smaller is also better also though, from a air and fluid flow resistance standpoint. Maybe my 10,000 GVW cooler is a nice tradeoff.

[Wikedjuggalo]

Originally Posted by Huskymaniac

I'll bet the Subaru engineers thought it was at least 3580 GVW. But, if it really is only a single pass of 12" then it couldn't possibly be much more than that.

I'm still of the impression that any object placed in front of the radiator will cause SOME air flow restriction which will cause some loss of engine cooling. For that reason alone, I would think that one would want to go with the smallest area cooler. The other part of the argument is that a smaller cooler will have even less ATF flow resistance to help keep the fluid flowing through the tranny. At some point, however, that becomes less of a factor as the resistance through the ATF lines becomes the dominant resistance.

Now I am ready to flip a coin on my 10,000 GVW cooler I have in hand. Should be enough to keep the ATF of a 3580lb car cool. Cooler is better, however. Smaller is also better also though, from a air and fluid flow resistance standpoint. Maybe my 10,000 GVW cooler is a nice tradeoff.

Just get the PWR radiator and if you want (as I did) get a small cooler. The two should keep the ATF plenty cool.

[Huskymaniac]

Originally Posted by Wikedjuggalo

Just get the PWR radiator and if you want (as I did) get a small cooler. The two should keep the ATF plenty cool.

Yeah but you were in a warmer climate that I am. The PWR alone should be more than good enough for cooling the ATF in a 1996 model year car. If I added more cooling, I would probably have lock up issues. Until I need a new radiator, I don't want to spend that kind of money. With my luck, I will do all of this and the radiator will crack and I will end up getting the PWR anyways.

Has anyone estimated the capacity of the PWR radiator? If it truly is 5 pass, I would guess about 18,000 GVW.

[Huskymaniac]

A related link:

http://www.drwtransmission.com/subaru_svx.htm

Here is a tidbit I found interesting:

"A number of modifications have been made to the high clutch drum and related components. Some of the design changes were included in transmissions with I.D. # 463970 and after, with the rest showing up in transmissions with I.D. # 633658 and after. Some of the modifications were done to supply adequate oil flow to components for cooling purposes. Others to increase the friction surface area of the reverse clutch pack. The components are a newly designed high clutch drum, high clutch hub and bearings, reverse clutch fiber and steel plates and reverse clutch backing plate."

Any idea what time period would correspond to ID #633658?

[Sean486]

The part that piques my curiousity is the thing about the deteriorating gasket causing a delay going into reverse. Mine seems to take an extra second or two to go into reverse. (I'm such a hypochondriac)

Originally Posted by Huskymaniac

A related link:

http://www.drwtransmission.com/subaru_svx.htm

Here is a tidbit I found interesting:

"A number of modifications have been made to the high clutch drum and related components. Some of the design changes were included in transmissions with I.D. # 463970 and after, with the rest showing up in transmissions with I.D. # 633658 and after. Some of the modifications were done to supply adequate oil flow to components for cooling purposes. Others to increase the friction surface area of the reverse clutch pack. The components are a newly designed high clutch drum, high clutch hub and bearings, reverse clutch fiber and steel plates and reverse clutch backing plate."

Any idea what time period would correspond to ID #633658?