Has your transmission failed? When? Why?

Has your transmission failed?

  • No Failure. Standard weight.

    Votes: 24 44.4%
  • No Failure. MH, heavy build, or regular towing.

    Votes: 17 31.5%
  • Failed within 150k miles. Standard weight.

    Votes: 2 3.7%
  • Failed within 150k miles. MH, heavy build, or regular towing.

    Votes: 4 7.4%
  • Failed 150k-300K miles. Standard weight.

    Votes: 5 9.3%
  • Failed 150k-300k miles. MH, heavy build, or regular towing.

    Votes: 1 1.9%
  • Failed 300k+ miles. Standard weight.

    Votes: 1 1.9%
  • Failed 300k+ miles. MH, heavy build, or regular towing.

    Votes: 0 0.0%

  • Total voters
    54

az7000'

2007 Navion on a 2006 3500 chassis
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

Active member
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

2008 2500 170" EXT
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

Active member
: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

Here since 2006
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
 
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DRTDEVL

Active member
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

2005 T1N 2500 (NA spec)
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

Engineer In Residence
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

If it’s winter, I’m probably skiing..
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

Millionmilesprinter.com
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'

2007 Navion on a 2006 3500 chassis
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.
 
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az7000'

2007 Navion on a 2006 3500 chassis
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

If it’s winter, I’m probably skiing..
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

Engineer In Residence
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

Engineer In Residence
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.
 

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GaryJ

Here since 2006
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

Well-known member
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
 
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calbiker

Well-known member
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

Engineer In Residence
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.
 

220629

Well-known member
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
 

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