Toycrusher

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Thanks for shedding some real world informed light on the matter. I can't believe they didn't design it with a pilot bearing. If I worked for FCA I'd be firing a couple of engineers right about now...
Aisin has been building transmissions for many many many years. I can't find any other they've built without provision for a pilot bushing or bearing. Was this an experiment by Aisin and Jeep let them play with it, or did they build the transmission to Jeeps specifications? If the latter, then yes, some engineers should be sternly talked to

"Normal" input shaft, photo is AX15 5-speed that was in YJs, TJs and I believe some JKs



1619098242242.png
and here is my JL. Notice anything missing?

2021-03-07 13.50.29.jpg
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Kreepin1

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Aisin has been building transmissions for many many many years. I can't find any other they've built without provision for a pilot bushing or bearing. Was this an experiment by Aisin and Jeep let them play with it, or did they build the transmission to Jeeps specifications? If the latter, then yes, some engineers should be sternly talked to
You know, I'm a mechanical engineer. I recall chatting with a schoolmate that had recently graduated and taken a job at Bell Helicopter. I asked him about the mission critical aspect of his job, after all, when parts fail on a helicopter they have a tendency to drop like a rock. He told me they have a policy that the test pilots can ask the engineer that designed the new part to fly along, any time, no questions asked. He said "when a design leaves my desk, I am confident in it like my life depends on it."

I don't think a "stern talking to" covers it. How about five years in a dealership replacing transmissions?
 
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DanW

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I'll chime in again on this thread.

1st off, these issues have only seemed to affect some of us, I was (am) an affected JL. For most, the dual clutch works as designed and is quite enjoyable. Jeep should have given everyone 4.10 gears as the 3.45 ratio is inappropriate for any 4wd vehicle, much less a Jeep.

For those with issues...
I've had my transmission up and down multiple times myself and spent some time messing with it. The clutch hydraulics leave much to be desired. For some earlier questions, the slave cylinder is about $60 and the master cylinder $100. Easy to replace, difficult to bleed properly.

Now for the big issue. The powertrain was not designed with a pilot bearing, and in fact, the input shaft does not even have suitable length to engage a pilot bearing if you wanted to add one. Through my studies of the system, it seems some transmissions have or have developed slop in the input shaft bearing inside the transmission allowing the input shaft to wobble. That wobble means the clutch disc(s) are rarely perfectly centered and also remain in contact with flywheel components even when disengaged, building heat when they shouldn't be. I feel this has been the root cause of those who failed spectacularly.

For those who have not failed spectacularly, it manifests itself as the wonky dual-engagement points in pedal travel, making smooth starts for experienced drivers difficult and random. That drove me nuts personally. The touchy throttle control just made the off-center clutch engagement issue even more unpredictable.

I upgraded to a dual friction Centerforce clutch and it made a world of a difference in driveability. The heavier flywheel makes nuetral revs slower and controllable. It also transforms the motor, giving it a very torquey feel and allowing you to crawl up obstacles even in Hi without having to feed any throttle.

However, the clutch does not fix the design deficiency of not having a pilot bearing and therefore no way keep the clutch centered if the internal main bearing has or develops play. That has resulted in the clutch still rubbing on the flywheel even when disengaged, making entering into 1st or reverse difficult at times.

I feel the software update is an underhanded bandaid to cover over the real issue of an insufficiently designed transmission system that would be incredibly expensive for them to remediate
Thanks for sharing your insight. Maybe it is a deficiency, but I've never experienced any of the things you describe and mine goes into first as smooth as butter. I just don't know how that would make any sense if there is a fundamental design flaw. Maybe I got really lucky. But I don't think so. Hopefully it will continue to perform as it has so far, as I intend to keep it until the Jeep is no longer serviceable.

46k and climbing. I'll certainly post it up if I encounter a problem.

I doubt we can get one, but I'd bet if we had an Aisin engineer here we could get an explanation of the design. I'll check with a friend who was with FCA and still has some contacts to see if he can get any more info.

I'm also in a couple sizeable Jeep clubs and there are a few manuals in there. None have the miles I do, but all are extremely happy with theirs. That's anecdotal, but so is everything else posted here.
 

Toycrusher

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Thanks for sharing your insight. Maybe it is a deficiency, but I've never experienced any of the things you describe and mine goes into first as smooth as butter. I just don't know how that would make any sense if there is a fundamental design flaw. Maybe I got really lucky. But I don't think so. Hopefully it will continue to perform as it has so far, as I intend to keep it until the Jeep is no longer serviceable.

46k and climbing. I'll certainly post it up if I encounter a problem.

I doubt we can get one, but I'd bet if we had an Aisin engineer here we could get an explanation of the design. I'll check with a friend who was with FCA and still has some contacts to see if he can get any more info.

I'm also in a couple sizeable Jeep clubs and there are a few manuals in there. None have the miles I do, but all are extremely happy with theirs. That's anecdotal, but so is everything else posted here.
As I mentioned at the beginning, it seems most are just fine. Of the minority that are having these issues, it would seem to be a result of unwanted play in the front bearing. Whether that play was a result of unexpected wear, or perhaps just an occasional out-of-tolerance bearing that happens in production. If the transmission input shaft was supported on both ends, the slightly out-of-tolerance bearing would be nothing worse than noisy after many miles. But being unsupported, that .001" or whatever slop is (could be) causing driveability issues.
 

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Aisin has been building transmissions for many many many years. I can't find any other they've built without provision for a pilot bushing or bearing. Was this an experiment by Aisin and Jeep let them play with it, or did they build the transmission to Jeeps specifications? If the latter, then yes, some engineers should be sternly talked to

"Normal" input shaft, photo is AX15 5-speed that was in YJs, TJs and I believe some JKs



1619098242242.png
and here is my JL. Notice anything missing?

2021-03-07 13.50.29.jpg
Very interesting information. Much apppriciated. I have very little experience working with automotive transmissions but I have replaced a clutch and rebuilt a transmission including replacing the input shaft when I had my old 2002 BMW R1150RT motorcycle.

Those bikes used an "automotive style" dry clutch between the engine and transmission. It didn't have a pilot bearing either; however, the input shaft was much longer internal to the transmission and was supported in the rear on a second bearing:

20210422_073227.jpg


I haven't seen a parts diagram of the AL6/D478. Could have Aisin used a similar design with a front and rear support bearing on the input shaft internal to the transmission to keep alignment?

EDIT: It still wouldn't be engine referenced, but it would be better than a single bearing....
 

Toycrusher

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Very interesting information. Much apppriciated. I have very little experience working with automotive transmissions but I have replaced a clutch and rebuilt a transmission including replacing the input shaft when I had my old 2002 BMW R1150RT motorcycle.

Those bikes used an "automotive style" dry clutch between the engine and transmission. It didn't have a pilot bearing either; however, the input shaft was much longer internal to the transmission and was supported in the rear on a second bearing:

20210422_073227.jpg


I haven't seen a parts diagram of the AL6/D478. Could have Aisin used a similar design with a front and rear support bearing on the input shaft internal to the transmission to keep alignment?

EDIT: It still wouldn't be engine referenced, but it would be better than a single bearing....
I couldn't say for sure, but every automotive manual transmission, longitudinal or transverse I've ever seen has the input shaft spinning the layshaft only, it doesn't extend beyond the very front of the case.
 

Spaffy

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I couldn't say for sure, but every automotive manual transmission, longitudinal or transverse I've ever seen has the input shaft spinning the layshaft only, it doesn't extend beyond the very front of the case.
Aright, so I may have had too much time on my hands today. I did a little digging.

There were precisely ZERO technical diagrams or parts lists for the AL6/D478 that I could find to support my theory of a rear input shaft bearing.

What I did find, is that this isn't Aisin's first and only non-pilot bearing transmission.

The Aisin AY6 [also named RA60/RA61/RA62 in varying Toyotas, I believe] also has no pilot bearing. These were used in Tacomas, Tundras, the FJ cruiser, Camaros, Cadillac CTS's, ETC, primarily in the 2005-2015 model year range.

There are also a couple others I think are without a pilot bearing, but I'm stilling looking around at those.

Here are a couple of diagrams that show the input shaft of the AY6/RA62 with a rear bearing supporting the input shaft, within the output shaft:

RA62_cutaway.jpg


ra60-transmission-gear-ratios-2.jpg


Just more food for thought.... Info on all of these are hard to come by, but easier than the AL6/D478!
 

bwright1818

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That's what mine feels like. It drives me crazy. I just avoid driving it altogether. My ex would avoid driving the Jeep too. Along with the constant correction / drifting in the steering. I've only driven my Jeep 14k miles in 24 months. I'm blessed to have a few different cars to choose from. Most of those miles. I drive about 600-700+ miles a week. I've really only driven my Jeep when it rains or I drive offroad / fun. Out of all of the cars I owned / have owned. I've driven it the least. If I didn't have other cars. I would have pulled out my hair or traded it in.

I noticed yesterday, the clutch / transmission was being extra sloppy. I noticed when I pressed the clutch entirely. I can feel a grind / gritty feeling on the pedal. I grinded the transmission gears at least 3-4x as if I was missing shifts. When I shift, I can feel the engagement of every gear super notchy. So either I'm just a terrible driver after 13 years of consistently driving stick, theres something wrong with mine, or it was designed poorly.

My mom gets scared when I take her on long trips in my Jeep. I tried to explain to her that the steering was designed to wander the road and the clutch / trans sounds are also normal. All while I'm fighting down shifting two to three gears up the smallest hills. lol
Man, I can say is, I am glad I am not the only one. It is kind of mind boggling to imagine how all these little but significant things made it all the way from somebody's mind, into actual production. Maybe the people to fire first are those who test drove and approved them.
 

khramesh

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Hello Fellow Members:
I got the Y01 recall fix taken care of on my 2021 Wrangler Sport Unlimited on May 24th.
I like the way my jeep takes off and the way it drives now. I am also quite happy that the gear you are in shows on the dashboard.
Just my opinion!
Ramesh
 

yj93

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Hello Fellow Members:
I got the Y01 recall fix taken care of on my 2021 Wrangler Sport Unlimited on May 24th.
I like the way my jeep takes off and the way it drives now. I am also quite happy that the gear you are in shows on the dashboard.
Just my opinion!
Ramesh
My gear does not show on the dash. Does this mean they did not do the update?

2020 Jl Sport S Willys.

thanks
 

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What’s the fix? Had my Jeep in at the dealership about a month ago for another issue and asked them about that recall. They told me FCA has no current fix for the issue including the software flash. They said they had no such software update to give me…This was sort of confirmed by a notice I received in the mail essentially stating the same thing and that owners would be notified once a fix was in place.
 

IAJeepguy

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"Normal" input shaft, photo is AX15 5-speed that was in YJs, TJs and I believe some JKs
I agree with you completely about the engineering aspect. Just wanted to mention Jeep dropped the AX15 in ~2002 and went to the Mercedes derived NSG370. They continued to use that with the JK, but did make some upgrades after having Issues with the early versions.

The JL brought back the Aisin. My complaint of this change is that the new Aisin is not a typical top load manual, it is a cable shifted trans much like a front wheel drive application.
 

JohnT

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What’s the fix? Had my Jeep in at the dealership about a month ago for another issue and asked them about that recall. They told me FCA has no current fix for the issue including the software flash. They said they had no such software update to give me…This was sort of confirmed by a notice I received in the mail essentially stating the same thing and that owners would be notified once a fix was in place.
yep, and every few months the dealership calls me and tells me to come nad give them money for an oil change and oh by the way there's a recall but they don't have the "parts" lol. I usually ask them if I am driving a death trap, to which I get a lot of apology and oh no sir not at all...
 

DanW

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What’s the fix? Had my Jeep in at the dealership about a month ago for another issue and asked them about that recall. They told me FCA has no current fix for the issue including the software flash. They said they had no such software update to give me…This was sort of confirmed by a notice I received in the mail essentially stating the same thing and that owners would be notified once a fix was in place.
What year is your Jeep? If not a 2021, then you get Y07, which is coming in June.
 
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