The failed transmission poll

[Huskymaniac]

Originally Posted by RSVX

My original tranny failed in the unmodified 93 that SomethingElse now owns.

But that was my fault. I was too poor/fiscally irresponsible to be able to afford more than two tires at a time.

I also had no idea of the consequences that decision would present to me, at that time.

As I said in an earlier response, I would lump this case in with those who modified the car for higher HP and put extra stress on the tranny.

[kcbsvx]

92 bought with Subaru Reman. Installed LAN's ecu chip and gutted stock muffler. No trans problems for 5-6 years as daily driver. Went to AWD LLC.

94 bought with original trans. Daily driver for several years. No trans problems.

96 bought with original trans. Part time driver for 4-5 years with no problems until a 2 1/2 hour fast (but not otherwise abusive) highway drive cooked the trans. It was not a hot day. Now is happy with 4.44 Outback trans, cooler, filter, and temp gauge.

[oab_au]

Mine is a 95 VTD model never had any problems, no power mods, has run the Quick Change for 3 years.

Harvey.

[Huskymaniac]

Anyone that never responded to this, here is your chance. As of right now, here are the statistics:

Tranny failure rate = 76.6%

Wow.

Failure rate by year:

1992 = 83.3%
1993 = 100%
1994 = 37.5%
1995 = 25%
1996 = 66.6%
1997 = 25%

1992 isn't a surprise but 1993 and 1996 seem like anomalies.

The failure rate for modified or hard driven cars is 66.6% so that doesn't seem to be a major factor.

Mike's new TCU code keeps the line pressure high at low throttle and Mike has said that he believes this is a major factor in tranny failure. Clearly, the modifications made by Subaru also reduced the failure rate. This implies the known flaws with ATF flow and clutch material were a factor. I think, together, TCU programming and original tranny flaws are a really bad combination. Here is a theory. When someone is stopped or cruising at light throttle, the line pressure is low due to the original TCU programming. If one then stomps on the gas, the engine soon delivers a ton of torque to the tranny. If that torque arrives before the line pressure rises in response to the TCU asking for more line pressure, the weak clutch material, high torque and low line pressure would result in a slip which would damage the tranny. If done many times, the tranny starts slipping worse and worse and the ATF heats up more and more and you have a downward spiral. The poor ATF flow may also cause the line pressure to rise more slowly when the TCU signals for higher pressure. This could be the main cause of or, at least, add to the delay. Just a theory. But, if true, Mike's TCU changes plus his valve body modifications would both be a big help in addition to what Subaru already did in the later models.

[lhopp77]

Originally Posted by Huskymaniac

Anyone that never responded to this, here is your chance. As of right now, here are the statistics:

Tranny failure rate = 76.6%

Wow.

Failure rate by year:

1992 = 83.3%
1993 = 100%
1994 = 37.5%
1995 = 25%
1996 = 66.6%
1997 = 25%

1992 isn't a surprise but 1993 and 1996 seem like anomalies.

The samples are so small in some years that just one entry will change the data percentages dramatically. I suspect 96 has changed with just my non-failure entry.

Lee

[icingdeath88]

I agree, way too few entries in the poll. Hopefully this will bump it up so that more people will answer.

[Huskymaniac]

Originally Posted by lhopp77

The samples are so small in some years that just one entry will change the data percentages dramatically. I suspect 96 has changed with just my non-failure entry.

Lee

That's why I called it an anomaly. The sample size is too small at this point. It looks like 1994-1997 have a failure rate of around 40%. It is probably even lower for 1995-1997 as, I believe, all of the Subaru changes were in place by around mid-1994. But you can see the issues with 1992-1993 models pretty clearly.

[Cam]

You also have to take into account the fact hat the 1992 is about 33 percent older than the 1997 models. Thats quite a large difference. Much more time for miles to add up and tranny parts to wear. I would take this poll with a grain of salt. I believe people should still post their personal experiences and vote on the poll but it is much too early to make any kind of conclusions outside of the obvious, already known facts.

[1986nate]

I need to add a few but I don't remember which ones I put in already... basically, with the SVXi that I've been in, and have, or have worked on, I'll list here in addition to the ones I listed earlier


92 silver- 2 dead transmissions by 103k miles
92 ebony parts car-pulled reman out of it, sold to fellow member and was told it was working but hasn't been driven much at all due to other circumstances, had 101k miles
94 fwd Laguna-trans was good but failed front diff, figures, it is a fwd, 93k when I got it, just turned 105k this week
92 Claret-2 transmission failures by 118k miles
94 FWD pearlie-original trans as far as I know, 160k miles(ish)
92 pearl parts car-paperwork of original trans dying around 76k, and as far as I know still was good (bought car without any drivetrain left
92 FL claret-143k, bad transfer clutch, had a rebuild in it
94 emerald-unknown, was wrecked badly, picked up with no drivetrain
97 ebony-110k miles, trans was replaced around 108k, unknown if trans was dead or just had transfer clutch binding
92 pearl-unknown, 142k miles, no trans in car so assumed old one was bad, hasn't been on the road since April of 02 as I found out
95 emerald-108k, has bad trans, I assume original
94 emerald fwd-130k miles, assume original trans
95 polo LSi-125k miles, bad trans and assume it is the original
92 pearl-111k, bad trans, haven't been able to find out if its original or rebuild, previous owner bought car around 93k miles
last 2 in my signature I have no clue

ones I've worked on
94 Emerald AWD-failed trans, original around 103k
92 pearl-front diff failed, 145k on body, had reman trans

Can't remember the others, so I'll add these newer ones to your poll...

can you tell I'm a little bored tonight?

[92snowmachine]

92 unmodified, original tranny failed at 70k during a trip up I70 to the mountains, was slipping a little when we bought it, stayed the same for over a year and then broke when driving up steep grades.
tranny had internal hard part failure, one drum crumbled to pieces inside the case

[oab_au]

Originally Posted by Huskymaniac

Mike's new TCU code keeps the line pressure high at low throttle and Mike has said that he believes this is a major factor in tranny failure. Clearly, the modifications made by Subaru also reduced the failure rate. This implies the known flaws with ATF flow and clutch material were a factor. I think, together, TCU programming and original tranny flaws are a really bad combination. Here is a theory. When someone is stopped or cruising at light throttle, the line pressure is low due to the original TCU programming. If one then stomps on the gas, the engine soon delivers a ton of torque to the tranny. If that torque arrives before the line pressure rises in response to the TCU asking for more line pressure, the weak clutch material, high torque and low line pressure would result in a slip which would damage the tranny. If done many times, the tranny starts slipping worse and worse and the ATF heats up more and more and you have a downward spiral. The poor ATF flow may also cause the line pressure to rise more slowly when the TCU signals for higher pressure. This could be the main cause of or, at least, add to the delay. Just a theory. But, if true, Mike's TCU changes plus his valve body modifications would both be a big help in addition to what Subaru already did in the later models.

For the engine to deliver a “ton of torque to the tranny”, you have to floor the throttle. Instantly the voltage through the dropping resistor to the A solenoid is reduced and the pressure regulator is set to full pressure. Next the engine rpms rise, to increase the pump’s ATF flow, along with the torque. The torque rise won’t beat the pressure rise.

The problem is the high final drive ratio is too high, for commuting at low speeds. The easy fix for this, is to shift back to 3rd reduce the load and increase the rpm of the pump, to increase the ATF flow, but lazy drivers will leave it in D while the engine is down to 1500 rpm, and eventually pay the price.

Harvey.

[oab_au]

To try to put the whole transmission saga into perspective, instead of the “hear say” tails that have given the gearbox a bad name. This is how I have seen it evolve over the 12 years that I have been following it.

The gear train is supplied by Jatco, the same as it supplies to other manufactures. It is a solid unit, improved over the years. When the car was first released in 92 the lock-up clutch facings/linings on the torque converter were faulty, in that they flaked pieces off. Other transmissions used the same type of facing and had the same problems. In Subaru’s case, because the torque converter produces 98% of the heat, the ATF is sent from the converter to the cooler, then to the mainshaft to cool and lubricate the gear train. The inevitable result was that the flacks lodged in the cooler, while the smaller pieces flowed to the mainshaft to block the lube and cooling of the epicycle gear set, which burnt up. As the 92 model was the largest number of cars sold, the problem was wide spread.

This should have been followed by a recall of the affected cars, to rectify the problem, but at that time Japanese car companies ‘did not do recalls’, they ‘did not have failures’, so they said nothing just fitting the filter, till the facings were replaced in 93 sometime. They also replaced the failed boxes with a remade box under warranty. Unfortunately a lot of the replacements were fitted, but the blocked cooler was not cleared, so that box also failed. They then removed the bronze mesh that was in the cooler, which reduced the efficiency of the cooler. Several updates were preformed on the box as Mike says to improve the cooling and lube of the ATF and to strengthen the clutch clamping. I believe the last mods were in the 95 model.

The rest of the troubles were confined to the US delivered model. In 92 the US did not have four-wheel dynos, as they only had rear or front wheel drive cars. This meant that they could not use the same VTD box that the car was developed to use, as it can’t be run on a two wheel dyno, so this car was fitted with the ACT-4 AWD that the Legacy used. The AWD relied on the action of the C solenoid/transfer valve to maintain the rear wheel drive. When this unit failed, and this was often, the rear drive was lost, to only have the front wheels driving. 240 HP to the front wheels through an open differential made wheel spin a problem. If both wheels spun together it was not too bad, but when one wheel looses traction to spin then grip, so the other wheel then spins, the grip changing sides, the differential planet/spider gears took most of the shock to break or the crown wheel/ring gear, was forced away from the pinion to break the teeth off, so front diff failures still continue to happen. This is not a problem that the VTD has due to it having all wheels gear driven.

Then there is the very high 3.45:1 gearing that this US model had, as if the 3.7:1 was not high enough to achieve the high cruising speed of over 200kph, it just meant that it was revving slower, and when it is used as a shopping trolley, the high gearing reduced the ATF flow and pressure to burn up the high clutch and brake band. Fitting a lower ratio box from a Legacy 4.11:1 or Outback 4.44:1 is the best move if the car is to be used as a city car. The lower ratio reduces the load on the box, and increases the ATF flow, but the C solenoid-transfer valve remains a problem for the front diff.

Harvey.

[NeedForSpeed]

Originally Posted by oab_au

To try to put the whole transmission saga into perspective, instead of the “hear say” tails that have given the gearbox a bad name. This is how I have seen it evolve over the 12 years that I have been following it.

The gear train is supplied by Jatco, the same as it supplies to other manufactures. It is a solid unit, improved over the years. When the car was first released in 92 the lock-up clutch facings/linings on the torque converter were faulty, in that they flaked pieces off. Other transmissions used the same type of facing and had the same problems. In Subaru’s case, because the torque converter produces 98% of the heat, the ATF is sent from the converter to the cooler, then to the mainshaft to cool and lubricate the gear train. The inevitable result was that the flacks lodged in the cooler, while the smaller pieces flowed to the mainshaft to block the lube and cooling of the epicycle gear set, which burnt up. As the 92 model was the largest number of cars sold, the problem was wide spread.

This should have been followed by a recall of the affected cars, to rectify the problem, but at that time Japanese car companies ‘did not do recalls’, they ‘did not have failures’, so they said nothing just fitting the filter, till the facings were replaced in 93 sometime. They also replaced the failed boxes with a remade box under warranty. Unfortunately a lot of the replacements were fitted, but the blocked cooler was not cleared, so that box also failed. They then removed the bronze mesh that was in the cooler, which reduced the efficiency of the cooler. Several updates were preformed on the box as Mike says to improve the cooling and lube of the ATF and to strengthen the clutch clamping. I believe the last mods were in the 95 model.

The rest of the troubles were confined to the US delivered model. In 92 the US did not have four-wheel dynos, as they only had rear or front wheel drive cars. This meant that they could not use the same VTD box that the car was developed to use, as it can’t be run on a two wheel dyno, so this car was fitted with the ACT-4 AWD that the Legacy used. The AWD relied on the action of the C solenoid/transfer valve to maintain the rear wheel drive. When this unit failed, and this was often, the rear drive was lost, to only have the front wheels driving. 240 HP to the front wheels through an open differential made wheel spin a problem. If both wheels spun together it was not too bad, but when one wheel looses traction to spin then grip, so the other wheel then spins, the grip changing sides, the differential planet/spider gears took most of the shock to break or the crown wheel/ring gear, was forced away from the pinion to break the teeth off, so front diff failures still continue to happen. This is not a problem that the VTD has due to it having all wheels gear driven.

Then there is the very high 3.45:1 gearing that this US model had, as if the 3.7:1 was not high enough to achieve the high cruising speed of over 200kph, it just meant that it was revving slower, and when it is used as a shopping trolley, the high gearing reduced the ATF flow and pressure to burn up the high clutch and brake band. Fitting a lower ratio box from a Legacy 4.11:1 or Outback 4.44:1 is the best move if the car is to be used as a city car. The lower ratio reduces the load on the box, and increases the ATF flow, but the C solenoid-transfer valve remains a problem for the front diff.

Harvey.

Edit:

That's a nice summary Harvey, much appreciated I have a few thoughts to add to discussion, based on personal experience.

Recently, I have changed my opinion on the reason the US, Germany, and other markets got the ACT-4 system. Today, in California, the SVX is except from the roller test. As an original owner of a 92 SVX, my first smog test was done registering in the State of Nevada. The car was exempt from the roller test. I'm not aware of any States, or any emission certification stations that incur the liability of installing the fwd fuse for the purpose of smog certification on rollers. That doesn't mean it has not happened, only that I am not aware of it. I've never been confronted with a 'mandatory' rolling smog dyno test with the ACT-4.

The smog certification theory always caused doubt for that reason. If Subaru installed the VTD system, which Subaru first sold here in the 2002 4EAT WRX, the car would have been exempt from roller testing, just as it is today. A manufacturer has no obligation to manufacture a car that can be tested in a certain way, rather, if technology doesn't exist to test cars without damaging the cars, the requirement is waved.

I recently purchased a '95 project. The car had issues, including installation of the fwd fuse. Comparing speed and rpm, I determined the car had been fitted with a 4.444 front diff or with a complete transmission, but hard to say, no numbers on the transmission. The stock 3.545 rear diff was still in the car. A 4.444 rear diff was then installed. A couple of 340 mile runs were made, before installing a 4.444 VTD transmission.

Both front and rear diffs were filled with Swepco Moly gear lube. Earlier, I in this post I reported a difference of 9% in fuel economy. Upon reviewing the calculations, the ACT was calculated at 355 miles, while the VTD was calculated at 326 miles, for the same trips A careful review of the receipts fuel used on ACT run and VTD run showed virtually no difference in fuel used on long, 70 mph, Cruise mode runs. CAFE Corporate Average Fuel Economy may not be a factor in the absence of VTD in America, even though all of our VTD cars seem to be slightly more thirsty. Maybe its me

So, we are back to two possible reasons for omitting VTD technology, maybe each reason enough to install the ACT-4 in its place. First, the dyno reason explained by Harvey, the reason we have always believed. Second, cost. That planetary center differential looks costly That said, the VTD was Subaru's crowning achievement in awd technology.

The dollar/yen exchange rate was strongly against the dollar in 1992. There was great concern about selling a $25,000 Subaru. After the 92s were sold at discount, and the small run of Barcelona Red 93s, Subaru introduced front wheel drive cars in 94 and 95 to contain the price. Not only was VTD not available, ACT-4, sunroofs, etc. was absent on the FWD models. Relatively few 94-97 models were sold in America, or anywhere else.

As for the gearing, the EPA test-cycle is a complicated driving cycle with stop and go driving, speed increases, etc., done on a dyno. Testing my 3.70-geared imports on a dyno was tricky. The car had to be driven very lightly to reach the top of the hill, imposed by increased resistance on the dyno. If the car shifted before the summit, emissions would far exceed limits, and the test would fail. This was an issue with 3.70 gears. I believe that installing 3.545 gears for US SVX had everything to do with the required driving cycle EPA-certification tests

[oab_au]

Originally Posted by NeedForSpeed

Edit:

That's a nice summary Harvey, much appreciated I have a few thoughts to add to discussion, based on personal experience.

Recently, I have changed my opinion on the reason the US, Germany, and other markets got the ACT-4 system. Today, in California, the SVX is except from the roller test. As an original owner of a 92 SVX, my first smog test was done registering in the State of Nevada. The car was exempt from the roller test. I'm not aware of any States, or any emission certification stations that incur the liability of installing the fwd fuse for the purpose of smog certification on rollers. That doesn't mean it has not happened, only that I am not aware of it. I've never been confronted with a 'mandatory' rolling smog dyno test with the ACT-4.

The smog certification theory always caused doubt for that reason. If Subaru installed the VTD system, which Subaru first sold here in the 2002 4EAT WRX, the car would have been exempt from roller testing, just as it is today. A manufacturer has no obligation to manufacture a car that can be tested in a certain way, rather, if technology doesn't exist to test cars without damaging the cars, the requirement is waved.

I recently purchased a '95 project. The car had issues, including installation of the fwd fuse. Comparing speed and rpm, I determined the car had been fitted with a 4.444 front diff or with a complete transmission, but hard to say, no numbers on the transmission. The stock 3.545 rear diff was still in the car. A 4.444 rear diff was then installed. A couple of 340 mile runs were made, before installing a 4.444 VTD transmission.

Both front and rear diffs were filled with Swepco Moly gear lube. Earlier, I in this post I reported a difference of 9% in fuel economy. Upon reviewing the calculations, the ACT was calculated at 355 miles, while the VTD was calculated at 326 miles, for the same trips A careful review of the receipts fuel used on ACT run and VTD run showed virtually no difference in fuel used on long, 70 mph, Cruise mode runs. CAFE Corporate Average Fuel Economy may not be a factor in the absence of VTD in America, even though all of our VTD cars seem to be slightly more thirsty. Maybe its me

So, we are back to two possible reasons for omitting VTD technology, maybe each reason enough to install the ACT-4 in its place. First, the dyno reason explained by Harvey, the reason we have always believed. Second, cost. That planetary center differential looks costly That said, the VTD was Subaru's crowning achievement in awd technology.

The dollar/yen exchange rate was strongly against the dollar in 1992. There was great concern about selling a $25,000 Subaru. After the 92s were sold at discount, and the small run of Barcelona Red 93s, Subaru introduced front wheel drive cars in 94 and 95 to contain the price. Not only was VTD not available, ACT-4, sunroofs, etc. was absent on the FWD models. Relatively few 94-97 models were sold in America, or anywhere else.

As for the gearing, the EPA test-cycle is a complicated driving cycle with stop and go driving, speed increases, etc., done on a dyno. Testing my 3.70-geared imports on a dyno was tricky. The car had to be driven very lightly to reach the top of the hill, imposed by increased resistance on the dyno. If the car shifted before the summit, emissions would far exceed limits, and the test would fail. This was an issue with 3.70 gears. I believe that installing 3.545 gears for US SVX had everything to do with the required driving cycle EPA-certification tests

Hi Ron, that could be a reason that the US got the ACT-4 trans instead of the VTD, but when you look at the countries that got the two different trans, it still is a mystery why it happened.

VTD markets; Japan, England, Australia, NZ, Belgium, Luxembourg, Austria and Brazil, Norway, Middle East.

ACT-4 markets; US, Canada, Germany, France, Switzerland, Israel.

There are other countries that we still don't know what trans was fitted.

Harvey.

[Huskymaniac]

Due to recent tranny failure discussions I went back and looked at this poll and noticed more people responded so here are the updated results. Anyone that never responded to this, here is your chance.

Tranny failure rate = 61.3%

Failure rate by year:

1992 = 77.6%
1993 = 57.1%
1994 = 46.2%
1995 = 33.3%
1996 = 55.6%
1997 = 22.2%

1996 still seems like an anomaly but the sample size is also still small.

The failure rate for modified or hard driven cars is 60% so that doesn't seem to be a major factor.

The failure rate generally trends down with the model years. Some will attribute that with age but there were modifications made by Subrau through the middle of the 1994 model year so those modifications were likely as much of a factor, if not moreso, than age and/or mileage.

I know that the flaky TC lining was a major problem but that was only an issue with the 1992 models and the failure RATE was still high in the 1993 and 1994 models which is probably why Subaru continue to modify other parts such as the high clutch drum, high clutch hub and bearings, reverse clutch fiber and steel plates and reverse clutch backing plate.

As such, I still stand behind my previous hypothesis and the recommendation of Mike's new TCU code and valve body modifications and especially for the early OBD1 models.

I still believe it is possible that torque, sufficient for damage, can arrive before the line pressure rises whenever the throttle is rapidly increased (pedal is stomped). The solenoid may respond fast enough to the signal that the throttle is higher and the tranny pump is tied to the engine RPMs so, yes, the pump will probably start pumping at or even before the torque hits the tranny. But the line pressure may still have a delay. In any enclosed system, the pressure will build over time once the flow of liquid into the system is increased. How fast this happens depends on the volume and flow rate. The flow rate depends on the pressure and flow resistance. The improved valve body should help decrease that flow resistance, increase the flow rate and increase the rate at which the line pressure builds. What the line pressure is at a given point in time should depend on that rate as well as the initial pressure at time t=0. Mike's new TCU code should result in that initial pressure being higher. Thoughts?

Finally, I am left wondering what happens during a shift. Doesn't the solenoid back off the line pressure during the shift? If so, and if the line pressure delay or buildup hypothesis is correct, then I would think that any stored energy built up in the TC during the shift could be a problem as the line pressure is ramped back up. That would make the signal to cut the engine throttle, and its timing, pretty important.