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az7000'
06-12-2019, 04:15 PM
The transmissions in the T1N have been reported to fail on a fairly regular basis here on the forums, and when people generally talk about the older sprinters. On this Forum I have been told my heaver Navion MH WILL fail at around 100K miles, not might but WILL citing the weight vs torque converter. Some here have towed boats for many many miles, some see sprinters on a daily basis. Trying to get numbers vs anecdotes.

I would like to get some information from the elders of the T1N cult on actual experience in 2 areas.

1. Have you had a trans failure, and if so were you able to determine if torque converter related?

2. If the numbers are as the grumbling suggests what would be the thoughts on a preventative TC replacement to save the trans?

Thanks all

DRTDEVL
06-13-2019, 12:13 AM
Your poll results are contrary to the anecdotal.

When you don't have a problem, you don't post to the forum about another trouble-free day. When you have a costly failure, you shout it from the rooftops. This is the likely source of the perception that the transmissions are weak.

I just towed an overweight trailer across the country for my cross-country move. My GCW on a scale at 1/4 tank of fuel came in at 15,900. That's about 2,000 over the maximum GCWR spec, and the transmission performed flawlessly. Two weeks prior, I pulled a Chevy truck on a car hauler. No weight scale ticket, but I estimate that I was sitting at about 14,000 GCW, right about the maximum rating. That trip didn't go off without a hitch, though... first, my tired engine spun a bearing, then a week later I toasted the rear u-join ton the shaft at the delivery end. The transmission, however, did not complain.

This experience is akin to 90's-2000's Dodge truck transmissions. If maintained according to mfg recommendations, they can go a LONG time. Most people skip the first service which includes a band adjustment at 30k, then they complain when the transmission fries at 60k, or when they stack power tuners on it and wonder why they suddenly gained a few more neutrals on the column shift the first time they launch from a stoplight. While they were all were experiencing failures on their second, third, or fourth transmission though, a former co-worker of mine finally killed his original transmission in his 2003... at somewhere around 640,000 miles, all of them towing a 8.5x24 or 8.5x26 enclosed trailer or a 32' 2-car trailer... but those transmissions are junk, right?

OrioN
06-13-2019, 01:08 AM
Your poll results are contrary to the anecdotal.

When you don't have a problem, you don't post to the forum about another trouble-free day. When you have a costly failure, you shout it from the rooftops. This is the likely source of the perception that the transmissions are weak.

I just towed an overweight trailer across the country for my cross-country move. My GCW on a scale at 1/4 tank of fuel came in at 15,900. That's about 2,000 over the maximum GCWR spec, and the transmission performed flawlessly. Two weeks prior, I pulled a Chevy truck on a car hauler. No weight scale ticket, but I estimate that I was sitting at about 14,000 GCW, right about the maximum rating. That trip didn't go off without a hitch, though... first, my tired engine spun a bearing, then a week later I toasted the rear u-join ton the shaft at the delivery end. The transmission, however, did not complain.

This experience is akin to 90's-2000's Dodge truck transmissions. If maintained according to mfg recommendations, they can go a LONG time. Most people skip the first service which includes a band adjustment at 30k, then they complain when the transmission fries at 60k, or when they stack power tuners on it and wonder why they suddenly gained a few more neutrals on the column shift the first time they launch from a stoplight. While they were all were experiencing failures on their second, third, or fourth transmission though, a former co-worker of mine finally killed his original transmission in his 2003... at somewhere around 640,000 miles, all of them towing a 8.5x24 or 8.5x26 enclosed trailer or a 32' 2-car trailer... but those transmissions are junk, right?

:wtf:

"My GCW on a scale at 1/4 tank of fuel came in at 15,900. That's about 2,000 over the maximum GCWR spec,"

:crazy:

DRTDEVL
06-13-2019, 02:08 AM
:wtf:

"My GCW on a scale at 1/4 tank of fuel came in at 15,900. That's about 2,000 over the maximum GCWR spec,"

:crazy:

It wasn't on purpose at all, I was moving and underestimated the weight of some of the furnishings and tools. My goal was to remain under GCWR and I used a weight distributing system, so it actually rode great (and got 17 mpg, too). I only weighed it out of curiosity to see at what weight the 17 mpg threshold was, and was like "oops!" It was too late by then, as I had already driven 1200 of the 1300 miles. Not a single axle was out of spec, either, as the front was 760 under GAWR, the rear was 280 under GAWR, and the trailer tandems were 320 under GAWR.

GaryJ
06-13-2019, 02:38 AM
AZ7000’ has a legit concern about the T1N transmissions in the early motorhomes. Possibly the cause for premature failure is that they constantly run at GVWR or often above. And some tow all the time. This is very different from hauling some large loads on occasion. Over on the Yahoo Winnebago group site a poll shows the average miles at failure was 89K.

Gary

DRTDEVL
06-13-2019, 03:36 AM
Over on the Yahoo Winnebago group site a pole shows the average miles at failure was 89K.

Gary

And how many of them changed the fluid (approved only), filter, electrical connector and cleaned the shift solenoids every 50,000 miles?

Mine started as a FedEx, getting abused for the first decade. It then spent about 5,000 miles as a hunting camp rig, then I put it in service as a hotshot van, usually running close to GVWR across country, and towing up to 5,000 lbs with a load inside within Texas. We're unclear on the actual miles, but it is assumed to be approaching 400k.

My point was its all about proper service.

Patrick of M
06-13-2019, 12:37 PM
Define “failed”. I’m pretty sure you mean spilled it guts, needs a new one, but when my transmission goes into LHM far from home (twice now) I consider that a failure (of foresight the first time as LHM was minor, and easily cleared with an appropriate scanner) but the 2nd time it was deep limp, eventually going to minimal forward motion. I had to pull the contact panel, clean the solenoids etc, with mosquitos chewing my backside, during a well deserved 2 weeks off from work (builder). That was a failure of the transmission from my point of view.

Midwestdrifter
06-13-2019, 01:39 PM
Heavy vehicle TC failures are a real problem with the T1N, (not NCV3). The TC is under sized internally for sustained operation with the engine over 60-70% load. The result is TC failure between 80-120k miles. Highly dependent on driving style, weight, and grades. If caught early, a rebuild TC can be installed, and the trans core is fine. If not, a rebuild is necessary.

vanski
06-13-2019, 03:43 PM
Heavy vehicle TC failures are a real problem with the T1N, (not NCV3). The TC is under sized internally for sustained operation with the engine over 60-70% load. The result is TC failure between 80-120k miles. Highly dependent on driving style, weight, and grades. If caught early, a rebuild TC can be installed, and the trans core is fine. If not, a rebuild is necessary.

What's the difference in the torque converter for a NAG1 NCV3 transmission and NAG1 T1N tran? Can a NCV3 TC be put into a T1N NAG1?

I run at 9k lbs and up into the Sierras at least 50 times a year, well this ski season probably closer to 60 times just this winter (we're talking 8.5k vertical feet in one run).

Although these poll results aren't reflecting this failure yet, I've also heard of these failures and may try to get ahead of it.

I do drive pretty slow, but at 9k lbs, I'm sure I'm not driving slow enough....

MillionMileSprinter
06-13-2019, 04:27 PM
So I see lots and lots of Sprinters on a weekly basis. Old and new.
My experience has been that heavily loaded vehicles that have NOT followed the forum recommended fluid and filter change every 60k (or even better a complete service) at 60k are at an almost 100% chance of failure. Properly maintained transmissions are almost always in excellent shape no matter what the miles.

az7000'
06-13-2019, 06:54 PM
What's the difference in the torque converter for a NAG1 NCV3 transmission and NAG1 T1N tran? Can a NCV3 TC be put into a T1N NAG1?

I run at 9k lbs and up into the Sierras at least 50 times a year, well this ski season probably closer to 60 times just this winter (we're talking 8.5k vertical feet in one run).

Although these poll results aren't reflecting this failure yet, I've also heard of these failures and may try to get ahead of it.

I do drive pretty slow, but at 9k lbs, I'm sure I'm not driving slow enough....

And I live at 7000' (obviously per screen name :laughing:) so every trip in pretty much any direction starts with a descent to 2000' and every return is a pretty good climb. Twice if we are on the 17 to Phx, goes up, down through Verde Valley, then up again. The ski hill here is at 9500', 2000' of that climb in 7 miles but I'm pretty winterized and as light as a Navion can be for those 10ish trips a season. We just ran through the Sierras from Tahoe to Yosemite Valley to Kings Canyon last week, seems like you are really high but then the signs are all 6-7K, solid climbs though.

@Calbiker, how often did you or your friend change/service your trans before your failures???

I did my first flush, filter, and connector at 41K.

az7000'
06-13-2019, 07:09 PM
So I see lots and lots of Sprinters on a weekly basis. Old and new.
My experience has been that heavily loaded vehicles that have NOT followed the forum recommended fluid and filter change every 60k (or even better a complete service) at 60k are at an almost 100% chance of failure. Properly maintained transmissions are almost always in excellent shape no matter what the miles.

Thanks, I'll be in touch for my next kits instead of my usual go to...
By complete service are you referencing this?
https://www.millionmilesprinter.com/product-page/van-life-transmission

vanski
06-13-2019, 07:16 PM
Nope.. 100’ and my home mountain is at 7.8k’ over 120 miles and there's ups and downs... so I figure 8.5k per trip. Still hoping my 4.11 diff ratio will help me a bit. Shifts smooth as any of the many many sprinters which I’ve driven, but when those TCs go there’s really not much warning.

I’m going to do a full tranny service (I have a few service kits in stock) pre July 4th weekend..

Midwestdrifter
06-13-2019, 08:34 PM
Most failures appear to be motorhomes. Most pushing 11k lbs 24/7, some towing a car, with gcwr over 14k lbs. What appears to happen is high absolute engine output puts part of the TC in the fatigue failure regime. around 75% of the steels yield strength. In this range a few million or 500k cycles causes crack formation. Thus part of the turbine or stator vane breaks. This causes ancillary damage. Quickly resulting in no drive, or a trans filled with debris.

Thus the cycles are cumulative. In aerospace these are called life limited parts. Parts that under a certain stress regime, will begin to fail within a certain cycle count. The solution is to avoid adding these cycles when possible. Avoid running continuously at throttle over 80%, and keep under 70% sustained. A higher gear isn't your enemy.

The ncv3 tc is physically larger. I don't think it will fit in the T1N bell housing.

Midwestdrifter
06-13-2019, 08:48 PM
Some quick math.
100,000 miles at 55mph is 1800 hours.

1% of those hours ay 100% throttle is 18 hours.

4000 rpm times about 50 stator vanes. Each vane gets a cycle, so 50x4000 is 200,000 cycles per minute.

Times 18 hours times 60 time 200000 equals 200,000,000 cycles.

Lots of room for failure. But only if you cross into the fatigue zone. Under the endurance limit, it doesn't happen.

GaryJ
06-14-2019, 01:50 AM
And how many of them changed the fluid (approved only), filter, electrical connector and cleaned the shift solenoids every 50,000 miles?

My point was its all about proper service.

The poll doesn’t have a service history for every failure unit, but a couple were serviced at 40K and 80K and still failed prematurely. There are too many variables to nail it down to one cause, but the common denominator in these failures that far exceeds T1N vans, is that these motorhomes are running at 10K lbs. to 15K lbs 100% of the time.

Gary

sailquik
06-14-2019, 02:04 AM
And, it depends quitre a bit on HOW the heavier than normal RV conversions and those towing heavy, high wind resistance, trailers are driven.
Are they manually downshifted to 4th gear to get out of 0.83: 1 Overdrive or do you leave the transmission in 5th gear overdrive and run very high % engine load (which wastes a ton of fuel).
If they aren't gearing down when the % engine load exceeds 80-85 % for longer periods of time (yes, time is a big factor here) they are needlessly stressing the torque convertor and transmission, plus over-fueling the engine significantly.
Do they understand that a T1N (OM-612 or OM-647) actually gets significantly better fuel mileage in the 2600-3100 RPM range in 4th gear than it will get running @ high % engine Load in 5th gear. at < 2500 RPM.
Many have tried this and most seem to agree, engine and trans run cooler, better performance, better fuel mileage at the lower % Load higher RPM. decreased GPM in 4th gear (or even 3rd gear if you need it and slow down to an appropriate speed.).
If you hammer your engine and transmission @ nearly 100% of their capacity.....how long do you think they will last?
Be proactive, manually downshift when needed and your rig will spend SO much less time @ or near 100%.
Hope this helps,
Roger

calbiker
06-14-2019, 04:35 AM
Gearing down could be part of the problem!

Failures increase with rpm squared.

The issue more than likely is metal fatigue. The T1N tc is undersized for heavy MHs. This comes from the company that rebuilds tc for Silverstar.

This failure has absolutely nothing to do with servicing. I change fluids (inc tc) every 40k.

BTW, the NCV3 tc contains clutch torsion springs. T1N does not. The springs will relieve some stress.

Midwestdrifter
06-14-2019, 10:06 AM
Yep. For all we know, full load downshifts may actually add fatigue cycles. That may be why the tcm refuses to downshift sometimes? Hard to say.

Aqua Puttana
06-14-2019, 02:52 PM
I find that if I downshift early for a known steep grade or other reason, the shifting will be much smoother. Looking ahead and anticipating/planning your moves has some benefit.

:2cents: vic

Midwestdrifter
06-14-2019, 02:54 PM
Its hard to say without more data. I would agree that using less pedal for sustained climbs is key. That last 10% is best served for emergency needs, and initial acceleration. I also do downshift to 4th or third in anticipation of a steep climb. Generally one in which I know I will be limited to 50mph or so. My van weighs about 8900lbs max.

az7000'
06-14-2019, 05:18 PM
So for those that maintained and still had a failure what is your plan moving forward? Just consider it a wear item and plan on a failure then replacement? It seems like the TC fatigues then fails scattering the shrapnel through the trans and then both need to be replaced. I’m not sure the shop charge to R&R just the TC, but they are way cheaper and would be a scheduled service. I’m in a smaller town and we just got a Benz dealer but no independent sprinter shops I know of, should a standard trans shop be able to swap the converter? I’m guessing getting the MH in the air would pose a challenge for a lot of shops.

Thanks for all the replies and information

Midwestdrifter
06-14-2019, 05:33 PM
The NAG1 is a common trans. Any competent shop can R&R the TC. I am not familiar with the fluid flow path on the NAG1. Does the fluid exit the TC, then flow through the cooler? If so, you could mount a quick check trans screen in this line. Check it every 10k miles for debris? Similar filters are used on racing vehicles to allow quick health checks on systems without a full fluid or filter change.

vanski
06-14-2019, 05:40 PM
thoughts on draining a little fluid and sending to Blackstone Labs?

Midwestdrifter
06-14-2019, 05:48 PM
thoughts on draining a little fluid and sending to Blackstone Labs?

I am not sure that would have much value. They don't get enough trans fluid samples to build a good database, and the failure is pretty rapid. So there isn't time for metal to build up in the oil.

In my opinion the best approach is a ~250 micron screen/mesh that can be checked easily.

calbiker
06-14-2019, 09:44 PM
The majority at the Winnebago Yahoo site believe this is a heat related issue. They added an additional tranny cooler, and a filter. My temperature measurements show no signs of overheating. Just lately had outside 100 F, while coolant and atf remains at 205 F. There’s no concerns there.

The day my tranny failed (in winter) I was driving more aggressive than normal, going up 3 passes in 3rd at 3200 - 3400 rpm. I now avoid higher rpm. Though I don’t know if that gains more than a few more miles before the tc explodes again.

DRTDEVL
06-14-2019, 10:28 PM
Yep. For all we know, full load downshifts may actually add fatigue cycles. That may be why the tcm refuses to downshift sometimes? Hard to say.

Why would you downshift at full load? I anticipate the need, then I shift at the start of the hill. If I find its not enough, I ease off the throttle until time to downshift another gear.

I crested San Augustine Pass on US 70 in southern New Mexico last month at 24 mph in second gear. The temp was the reason for the speed, as I was climbing steadily in third while watching the temp head towards 250*. I eased off further, dropped it into second for the duration, and made it another 1300 miles at 16,000 lbs combined without incident.

calbiker
06-14-2019, 10:59 PM
I go up hills at 3000 rpm and 100% load all the time. I would never consider down shifting. I call that my sweet spot.

nutterbutter
06-14-2019, 11:23 PM
Previous owner of my van had some transmission issues and took to a random local (non-sprinter) shop. They found the transmission fluid low, but no leaks, and simply topped off. It was all better after.

I've seen no signs of leaks, so it makes me question where did the fluid go? Also the little plastic breather covers--one was slightly melted. So it mush have gotten hot, presumably when it was low on fluid.

I'd imagine fluid burn off plus the increased heat does a lot of damage to the trannys over time

owner
06-15-2019, 01:34 AM
The ncv3 tc is physically larger. I don't think it will fit in the T1N bell housing.
I wonder if its possible to swap the entire trans/TC from the NCV3? possibly TCU as well. ROW NCV3's used the om646 and om651 with the 722.6 trans, so it should be possible here. but I think NAFTA only got the V6-722.6 which may not fit the 5cyl.

Midwestdrifter
06-15-2019, 01:56 AM
It would require modifying the flexplate I bet. You wouldn't need the whole trans or tcm. Just the bell housing and TC.

smiller
06-15-2019, 02:54 PM
I go up hills at 3000 rpm and 100% load all the time. I would never consider down shifting. I call that my sweet spot.

It really isn't, or at least not if you're constantly pegged at 100%.

A lot of confusion regarding the downshifting advice comes from a misunderstanding of what people really mean. It does not mean slam the transmission down into a lower gear, maintain your speed, and let it scream away. If that is one's conception then I can see why the practice would be questioned. What it does mean is anticipating the grade and using gearing to maintain an rpm within the powerband at perhaps 80-90% of full load, and the road speed just is what it is. This will in most cases greatly decrease stress on the drivetrain and likely save fuel as well.

.

Aqua Puttana
06-15-2019, 03:06 PM
I keep to lower speeds so we rarely run at 3000 rpm for longer periods of time.

My wife will tow our boat on interstates and major highways. She's not comfortable with towing in town and that is just fine.

My basic "training" for towing and grades has been to have her tap down to 4th when she sees a big hill coming up. With a 3.727 differential, setting the cruise at about 2500 RPM in 5th yields about 3000 RPM when dropped down to 4th gear keeping the same speed. That seems to work well.


I don't want to add too much pressure to wife's driving/towing experience. She may quit her position as co-driver. My K9 co-pilot is agreeable to most things, but so far he can't seem to grasp steering the Sprinter. :rolleyes:

:cheers: vic
Different methods will work for various driving habits/needs.

:cheers: vic

calbiker
06-16-2019, 04:40 PM
What do you do when “anticipating” or being “preemptive”? Are you slowing down before encountering the hill and then shifting down? Bear in mind, the vehicle will need to go into 3rd (standard hills out west). I doubt anybody is doing that. Shifting from 5 to 4 increases rpm by 400. Shifting from 5 to 3 increases rpm by 1400. It’s obvious you’re not going to maintain speed. I drop at least 10 mph.

The discussion then centers on how to reduce speed. Are you reducing throttle before shifting? Or slamming to higher rpm? I have no problems going to 100% load to slow tdown before downshifting. Shifting rpm will be lower and I believe less stress to the tc. As mentioned before, failure increases with rpm squared.



It really isn't, or at least not if you're constantly pegged at 100%.

A lot of confusion regarding the downshifting advice comes from a misunderstanding of what people really mean. It does not mean slam the transmission down into a lower gear, maintain your speed, and let it scream away. If that is one's conception then I can see why the practice would be questioned. What it does mean is anticipating the grade and using gearing to maintain an rpm within the powerband at perhaps 80-90% of full load, and the road speed just is what it is. This will in most cases greatly decrease stress on the drivetrain and likely save fuel as well.

.

smiller
06-16-2019, 06:47 PM
I can't say I've analyzed my specific actions microscopically but generally when I start climbing a grade and I see that 5th gear will not allow me to maintain desired speed within the desired rpm range without subjecting the engine to a continuous 100% load then I will downshift to permit operation at 80-90% load, and road speed then just is what it is. I don't recall if I consciously adjust throttle prior to the shift to minimize the rpm change but I guess I probably do so unconsciously at some level. I'm not saying anyone has to be crazy about it and of course it's of no concern if load peaks at 100% for short sub-minute periods of time, what I'm talking about is avoiding operating at maximum load (as indicated on a meter, or lack of any remaining throttle response, etc.) and subjecting the engine to unnecessary levels of thermal and mechanical stress for long periods of time for no reason (unless getting that extra 10 mph is so important to someone.) This just isn't advisable if it can be avoided and I'm not sure why it would be the subject of so much debate.

As to whether this has any negative effect on the transmission, I can't say for certain any more than anyone else but in general the NAG1 is a well-vetted unit and known more for being reliable (in most applications anyway) than the other way around. I don't see any evidence of common premature failure in the NCV3 and since that's what I have, not a concern to me. I do agree that there seems to be some kind of issue in the T1N applications and if anyone thinks that keeping the throttle mashed on hills will make it live longer then go ahead I guess, I'm just not sure that back-of-an-envelope calculations of TC stress are going to tell anyone very much.

Aqua Puttana
06-16-2019, 07:04 PM
What do you do when “anticipating” or being “preemptive”? Are you slowing down before encountering the hill and then shifting down? Bear in mind, the vehicle will need to go into 3rd (standard hills out west). I doubt anybody is doing that. Shifting from 5 to 4 increases rpm by 400. Shifting from 5 to 3 increases rpm by 1400. It’s obvious you’re not going to maintain speed. I drop at least 10 mph.

The discussion then centers on how to reduce speed. Are you reducing throttle before shifting? Or slamming to higher rpm? I have no problems going to 100% load to slow tdown before downshifting. Shifting rpm will be lower and I believe less stress to the tc. As mentioned before, failure increases with rpm squared.
I haven't anything scientific.

I will say that when I am prompted to shift down into 3rd gear, at that time maintaining speed is of little, or mostly no concern. If needed I pop the Emergency Flashers on and continue to do what I think is best for the drivetrain.

I hurt a 1994 Dodge B250 transmission while towing, downshifting and trying to maintain higher speeds for no real reason in the Pennsylvania mountains. The transmission got me home, but the burned smell told me it needed rebuilding. I recall my wife asking me why I was in such a rush. I shoulda listened. :bash:

Anyway, that expensive transmission rebuild taught me a lesson. Don't abuse the equipment.

FWIW.

calbiker
06-17-2019, 01:56 AM
If the tc impellers are exploding after some 90 k miles, then the failure is likely caused through shifting. The impeller sees greatest stress when clutch is not engaged. There is little stress to the tc when clutch is engaged. There is minimal clutch slip. Doesn’t matter if at 100 or 80% load. Makes no difference. There is however a difference in stress when preemptive down shifting at 2500 rpm as opposed to dropping speed by lugging or just letting up on the throttle and shifting at 2100 rpm. Again, rpm is the greatest stress factor.

smiller
06-17-2019, 11:31 AM
If the tc impellers are exploding after some 90 k miles, then the failure is likely caused through shifting. The impeller sees greatest stress when clutch is not engaged. There is little stress to the tc when clutch is engaged. There is minimal clutch slip. Doesn’t matter if at 100 or 80% load. Makes no difference. There is however a difference in stress when preemptive down shifting at 2500 rpm as opposed to dropping speed by lugging or just letting up on the throttle and shifting at 2100 rpm. Again, rpm is the greatest stress factor.

I'm not sure where you come by this certain knowledge, but if you say so. :idunno:

Midwestdrifter
06-17-2019, 12:50 PM
When the clutch is engaged, the slip rate is very low, less than 5% based on data logging. During shifts the TC clutch briefly unlocks to absorb the difference in energy as the engine matches speed. This has been logged by a couple users, and I have seen similar happen with my scan tool. Obviously I don't have enough data to be conclusive. Similarly climbing grades in first (possibly second) gear while in drive causes high slip rates (very low clutch application). Interestingly when manually selecting 1st or 2nd, the clutch actually engages, reducing TC loading.

smiller
06-17-2019, 01:09 PM
When the clutch is engaged, the slip rate is very low, less than 5% based on data logging. During shifts the TC clutch briefly unlocks to absorb the difference in energy as the engine matches speed.

That's how it works of course. What I'm questioning is some of the conclusions regarding relative levels of stress and what/where/when damage occurs, based on speculation but stated (more or less) as fact. All that is really known is that there seems to be a higher than expected incidence of failure, and not much more.

.

99sport
06-18-2019, 12:36 AM
I'm planning on pulling my engine and trans (2005 2500, 158" WB) to work on the engine. The van has 357k miles and I have no service history. Trans seems to work fine except for some rumble strip noise. If the failure mode on these transmissions is torque converter fatigue, any thoughts on preemptively replacing the torque converter while the trans is out? The Dodge part seems to be discontinued, but the MB part is $600 plus core. Aftermarket torque converters seem to be high stall speed and more expensive.

I plan on replacing the rear seal and torque converter seal while the trans is out. Will also replace the pan gasket, filter and connector.

smiller
06-18-2019, 02:47 AM
At 357k miles if I had the transmission out (and planned on keeping the vehicle a while) I think I'd probably refresh the entire unit with a quality rebuild (MB reman, Silverstar, etc.) Even under the best conditions at that kind of mileage it's probably due.

az7000'
06-18-2019, 06:44 PM
If the failure mode on these transmissions is torque converter fatigue, any thoughts on preemptively replacing the torque converter while the trans is out?

That is the question I have posed here a few times...

Midwestdrifter
06-18-2019, 06:46 PM
I don't see any downside assuming the replacement is a good quality reman. Other than cost of course.

calbiker
06-19-2019, 05:47 PM
I have not seen any difference in clutch slip whether in Drive (while in 1st), or 1st selected.

The turbine is under high stress when in gear, at stall (brake applied), and then accelerate forward. My tc failed right after exiting the freeway and stopping at the first red light. The tc failed within within a second of accelerating on green light.

The clutch has no impact in this scenario. It’s reasonable to assume the impeller or turbine is failing.


During shifts the TC clutch briefly unlocks to absorb the difference in energy as the engine matches speed. This has been logged by a couple users, and I have seen similar happen with my scan tool. Obviously I don't have enough data to be conclusive. Similarly climbing grades in first (possibly second) gear while in drive causes high slip rates (very low clutch application). Interestingly when manually selecting 1st or 2nd, the clutch actually engages, reducing TC loading.

Aqua Puttana
06-19-2019, 08:32 PM
At 357k miles if I had the transmission out (and planned on keeping the vehicle a while) I think I'd probably refresh the entire unit with a quality rebuild (MB reman, Silverstar, etc.) Even under the best conditions at that kind of mileage it's probably due.
It is better to replace the unit before any failure. After failure the system needs to be completely flushed out and parts like the radiator may need to be replaced.

It's a kinda high price to replace something that's still working, but as Smiller says, at 357k miles it's worthwhile to extend the overall service life and reliability. Especially when everything is apart already.

:2cents: vic

desertdog
07-19-2019, 01:37 AM
Our first t1n was an Itasca Navion. Even with proper service procedures, it let us down at around 80,000 miles.

The Grand Tour
07-19-2019, 01:51 AM
It is better to replace the unit before any failure. After failure the system needs to be completely flushed out and parts like the radiator may need to be replaced.

It's a kinda high price to replace something that's still working, but as Smiller says, at 357k miles it's worthwhile to extend the overall service life and reliability. Especially when everything is apart already.

:2cents: vic

I'm gonna respectfully disagree- it's no big deal to flush out a transmission cooler, to include transmission coolers that are built into the radiator.

You never know when an automatic transmission is gonna fail.

I bought an RPO B4C police pursuit Camaro new, and the transmission failed at something just shy of 100K miles, under normal use, with proper maintenance. When I disassembled it to rebuild it, I found a piston that had been cracked upon installation at the factory.

I built an absolutely ridiculous 9-second GMC (PAS) Typhoon that grenaded planetary gearsets spectacularly and with regularity, sometimes on the first full-boost 1-2 upshift at the drag strip, in spite of the transmission being hand-built out of the finest transmission parts money could buy.

We had an old Ford F150 that we bought dented up and caked in mud, from a contractor, with about 200,000 miles on it. He swore the maintenance was current and on file at a specific nearby Ford dealer when we bought it, but the dealer was closed at the time, so I wasn't able to call until the next day. When I did call, I found that the dealership had never even seen the vehicle, not even for an oil change. When I dropped the pan to do the service myself, I found the original "cherry" (that gets discarded at the first service) laying in the pan. It had seen 200,000 miles of abusive fleet service, with zero maintenance. It continued to serve us well, for about another 50,000 miles, until we sold it for a couple hundred bucks to a family from church.

You just never know...

locksmith72
07-22-2019, 03:05 AM
Mine went at 125000, 2 days before it was dues to go in for service , dead stopped on the interstate at 70 mph . When it got to the shop . not a drop of fluid , no leaks clean as can be . oh well

2004newbie
08-03-2019, 06:11 PM
I had major shifting hard and erratic behavior problems. After lots of research on here and talking with anyone i could, I replaced the conductor plate. I tried cleaning the old one but for only 145$ I got a new one. I was very focused and careful to reinstall plug and plate ect. During that repair I did the rumble strip fix, it shifts like butter now and no more rumble. I feel like the clutch softer now, but I dont know if that is from drivingstarting in 3rd gear or 2nd ln for a while and wearing down friction plates or from the rumble strip fix.
Any how, the conductor plate fix worked and rumble strip fix worked and I'm back on the road. When I reinstalled the cleaned conductor plate I miss aligned the little white valve actuator shifter selector and broke it. So after much trying to figure it out I found that broken piece, bought a new one for 7p?. Workin great now and just waiting for the nextchallenge, because as a T1n owner, its l about the preventative maintenance. No matter what, you can do the prevent things or learn the hard way. I didnt expect to be a damn near sprinter T1n Nag1 expert when I bought this thing but such is life. Cheers to all the forumcontributors. .