Manual trans notchy with Dex 6/Mercon LV

[jaj]

My GT350 comes with a Tremec TR3160 and it's spec'd by Ford for Mercon LV. My problem is notchy shifting from 1 to 2. 2 to 3 can be notchy too, but it's not as bad. The notchy sensation comes when you try to shift straight through from 1 to 2. If I pull against the gate for 2 without pausing, it's hard to get the gear engaged and sometimes it will grind. And this isn't speed shifting - my datalogger says I'm spending about 2 seconds on each shift. However, if I pull against the gate, relax for a moment and pull again, it engages easily on the second try.

So far, Mercon LV is notchy and so is Dex 6, which is Tremec's spec for this gearbox. Now, before someone raises the "mechanical problem" point, it turns out that if I change the fluid, for about the first hour of use, all the way from cold to warm, it's brilliant - from gear to gear smoothly. Shifting with brand new ATF is perfect. It just doesn't stay that way. After a couple of days of driving, it's back to the old habits.

So, I'm thinking of trying a GL4 and I'm wondering which one is most likely to work best:

- Ford Motorcraft DCT fluid - XT-11-QDC which is about the same viscosity as Dex 6/Mercon LV
- Redline PSF - a hair more viscous at 7 cSt.
- RP Synchromax - I've tried it before and I haven't been impressed, but I'll try it again if it wins the bake-off
- a DCT fluid (thinking about BMW MTF-LT-5): Pentosin FFL3/Ravenol DCT/Redline DCT etc.

The key to success is going to be the right friction performance. ATF works for a short time, so I need something with the friction performance similar to brand new ATF that won't fade after an hour of use.

 

[SatinSilver]

Originally Posted By: jaj
The key to success is going to be the right friction performance. ATF works for a short time, so I need something with the friction performance similar to brand new ATF that won't fade after an hour of use.


Agreed, how about trying some AC Delco Friction Modified MTF. There was a TSB from Honda for the Accord V6 manual that had notchy shifting from 1-2. There solution was using the above which was much cheaper than a mechanical repair. The results seemed to last a good 30k or so. There's a few AC Delco MTFs so just be sure to get the FM version.

 

[Rand]

I would try the ford gl-4 fluid they spec'ed for focus transmissions.. or redline MTL

Notchy while hot seems like the fluid is abit thin.. for fuel economy or cold shifting performance.

 

[jaj]

I hadn't considered AC Delco FM MTF or the other usual suspects like MTL because they're higher viscosity than the OEM specs. The candidates I put up have about the same viscosity as LV ATF.

This transmission doesn't have a heat problem, it's more like a cold problem. It has a full-time cooler circuit and on a normal 70 degree day an hour on the highway gets you about 110F. In the city it gets a bit warmer, say 130F, because there's less airflow and the heat from the engine and exhaust warms it. Oh, and the shift feel improves as it warms up.

 

[69GTX]

Tremec 3160 specs

This is confusing (from 2013) that it specs Dexron II and Dex VI "AFT." Dex II is decades old. Wasn't that a similar viscosity to Dex III/Mercon? More confusing in that the Tremec 6060 with the same hybrid, sintered bronze synchronizer friction material specs Dex III ATF.

Tremec 6060

 

[RooflessVW]

Try Honda MTF.

 

[69GTX]

In looking at other tremecs, they only recommend 3 basic fluids: ATF/Dex 3, Synchromesh, and Pentosin FFL4 which is also in the Dex 3 ATF range. So I don't understand why they listed the TR-3160 recommended fluids as they did (ie Dex II and LV VI). I would call them as their own literature doesn't make sense to me....especially with very similar transmissions/synchro's using a different fluid. A quality synthetic Dex 3 is probably a better choice for the 3160. I'm actually surprised they listed a Dex VI / LV ATF for any of their transmissions. They didn't proof read the pages very well citing "AFT." Even a LV ATF will be too thick for shifting until it comes up to normal temps (100-130 deg F?)...and hence it should normally be notchy and slow when cold. Tremec made the transmission, not Ford. I'd be inclined to follow Tremec's inputs.

Tremecs transmissions

 

[slacktide_bitog]

You could try Amalie DCT fluid

 

[MrHorspwer]

For the Camaro, GM follows right along with the Tremec site in their recommendations:

2.0L and 3.6L with 3160 recommends Dex VI
6.2L with 6060 recommends Dex III

 

[jaj]

I have a 2013 Tremec TR3160 datasheet I downloaded in 2016 that doesn't list Dex II as an option, just Dex 6, but the 2013 datasheet that's posted now shows both, complete with spelling error.

Tremec really seems to like the Texaco Dex II ATF and that seems to be their baseline. They qualify everything else that OEM's ask them for, which is probably why we have Dex 6 for GM and Mercon LV for Ford. My TR6060 shifted way better with AC Delco Manual Transmission and Transfer Case fluid, which is supposed to be a GL4 version of Dex 3. But that fluid doesn't work in the 3160 - I've tried and it's about the same as LV and Dex 6 except its even stiffer when it's cold, which is most of the time.

In addition to Motorcraft Mercon LV and AC Delco Manual Transmission and Transfer Case fluid, I've also tried Mobil 1 ATF and AC Delco Dexron VI. As for Mercon LV work-alikes, I've used Castrol Transmax Full Synthetic Multi-Vehicle Automatic Transmission Fluid, which should have been brilliant because it's Mercon LV approved by Ford and licensed by GM as Dex VI. Well, it was brilliant for about 2 hours, then back to hard shifting.

When I go to the track (road course) with this car, the gearbox gets up to about 100C, so there are times when it runs hot. Shifts fine up there, or at least fine enough that it's not at the top of my list of things to think about. But when I'm out to pick up groceries, shifting requires too much attention to make a simple clean 1-2 transition.

 

[69GTX]

Originally Posted By: jaj
This transmission doesn't have a heat problem, it's more like a cold problem. It has a full-time cooler circuit and on a normal 70 degree day an hour on the highway gets you about 110F. In the city it gets a bit warmer, say 130F, because there's less airflow and the heat from the engine and exhaust warms it. Oh, and the shift feel improves as it warms up.


One would think with only 2.5 qts of trans fluid it would heat up easily. In any case, the "problem" seems like the cooling circuit which may be designed for track duty. It's probably not even needed when driving around town moderately with occasional spirited runs. Does it have a regulator of some sort or is it always at full cooling flow? If you had an accurate temp monitor you could block some of the cooling fins to raise operating temps to 135-165 deg. Though I'd consult with someone well versed in such things before attempting.

 

[jaj]

The car rolls out of the factory equipped for track time, and it works great in that situation. I'm just picky about shifting when it's not really hot. And the fact that I get great shifting at all temperatures for a few hours with new fluid says to me that there must be a fluid with the right friction characteristics and viscosity out there that will deliver great shifting all the time and I just haven't found it yet. ATF's are inexpensive, so I've tried a bunch. GL4's are a lot more expensive, so before I start rolling out $100 a crack for fluid changes, I'm seeing what the collective wisdom is regarding GL4's that might work.

 

[69GTX]

There's a lot of literature (and moaning) about the TR-6060 performance in GT350's and high end Camaro's, which use the same synchronizer material as the 3160. I don't understand why they recommend different fluids for what seem to be very similar applications. If you've been unhappy with cold weather peformance with both conventional/synthetic Dex 3's and the Dex 6's, it's unlikely you'll get any improvement with a GL-4 approved fluid.

Redline D4 ATF and Amsoil ATF ATD are 2 other synthetic ATF's you apparently haven't tried yet. One claims GL4 qualities. Both have pretty solid track records in most 2001-current Tremecs specifying ATF's. I don't think the GM MT and Transfer case Lube claims GL-4. It's just a conventional ATF with a slightly better add pack than cheap ATF's + friction modifiers. I would think a conventional ATF would produce easier cold shifts than a synthetic down to reasonable ambient temps.

It also makes no sense to me that your ATF could be brilliant in the first few hours of use when "new," then fades away after several hours of use. They just don't shear down that fast or use up their additive packages, oxidize, etc. That's a puzzler. But, it's what you have. The Max Life ATF is an LV fluid (5.8 cSt) with a strong add pack similar to M1 ATF, Amsoil, and Red Line. You could try that too considering it is a lower viscosity to boot...and inexpensive.

 

[Oro_O]

Originally Posted By: jaj
The car rolls out of the factory equipped for track time, and it works great in that situation. I'm just picky about shifting when it's not really hot. And the fact that I get great shifting at all temperatures for a few hours with new fluid says to me that there must be a fluid with the right friction characteristics and viscosity out there that will deliver great shifting all the time and I just haven't found it yet. ATF's are inexpensive, so I've tried a bunch. GL4's are a lot more expensive, so before I start rolling out $100 a crack for fluid changes, I'm seeing what the collective wisdom is regarding GL4's that might work.


Why not try Valv. Or Pennz. Syncromesh? Gl-4, atf viscosity like DexII/III, designed for synchronized transmissions. Not much more than plain atf in cost (~$7.50US/qt).

 

[Killer223]

on of the best shifting trans i ever had was full of swepco's 711 50wt oil,
next was my 93 Toyota with 40wt non-detergent motor oil in it.

 

[69GTX]

Originally Posted By: Or
Why not try Valv. Or Pennz. Syncromesh? Gl-4, atf viscosity like DexII/III, designed for synchronized transmissions. Not much more than plain atf in cost (~$7.50US/qt).


If I recall from Molakule's viscosity ranking of MTL's, the Pennz/GM synchromeshes come in at a considerably higher viscosity (9-10 cSt) than the Dex 3 ATF-type fluids (6.8-7.7 cSt). If they really were 7.5 cSt, I'd be using them in my Tremec T56.

 

[jaj]

Originally Posted By: 69GTX
If I recall from Molakule's viscosity ranking of MTL's, the Pennz/GM synchromeshes come in at a considerably higher viscosity (9-10 cSt) than the Dex 3 ATF-type fluids (6.8-7.7 cSt). If they really were 7.5 cSt, I'd be using them in my Tremec T56.


That's my understanding too. Good product, but on the thick side for a gearbox that spends most of its time at its 40C viscosity. The cooler pump runs off the input shaft, it turns all the time and there's no thermostat.

 

[jaj]

We'll see what the morning brings (it was 36F today). I just swapped to Motorcraft DCT fluid. It'll be interesting.

 

[jaj]

Well, it's 36F again today, light snow falling but not sticking.

The shifting with the Motorcraft DCT fluid is the best of all of the fluids I've tried so far. The shifting when ice cold is stiff, but it's not notchy. A strong pull is needed to get past the detent, but once past, there's no sense that things are crunching together. And, once the fluid picks up a few degrees, the "detent" gets easier and the shifting feels pretty good.

So, this is better, but I've only got an hour on it and I haven't gone very far, so who knows where it will go or how it will last. What I liked though was that the need to "pay attention to" the transmission is much reduced. That's what I was looking for. I don't like feeling that, every time I push the clutch pedal, I might have to nurse the gearbox into the next gear.

 

[Number_35]

Originally Posted By: Rand
I would try the ford gl-4 fluid they spec'ed for focus transmissions.. or redline MTL
Agreed, I would use a genuine manual-transmission fluid. Redline MT is great stuff - it's got the 'grabby' additives req'd to get the synchronizers up to speed.