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Magnum XL hard 2-3 shift when hot

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captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
Recently, I've had some difficulty with the 2-3 upshift on my MagXL - I just replaced a slave cylinder which I thought was the only issue I had (clutch in good shape). However, in the last race once the box gets hot, shifts up were very firm and very slow. No grinding, so I didn't initially suspect an issue with worn blocker rings on the synchronizer.

Anyone with some expertise in transmissions or experience around this sort of thing? I am going to swap the clutch master and the fluid in the trans (it has a fresh BG fill - but I am going to test some different weight fluids)

You can see the slow upshifts in this video:


Compared to this video where the shifts are quick and smooth:


Also, anyone tear into one of these? My usual rebuild vendor hasn't been answering their phones as of late, and I've had a few colleagues encourage me to just open it up myself (looks like a shop press and a long set of gear pullers are the only missing tools, though I can't find a service manual specific to the magnum variants)
 
1,171
2,152
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
If you’re swapping the master cylinder, order the one specific to the 13-14 GT500. Not 100% sure what the internal differences are between the two but it really seemed to clean up the shifts on my Magnum. We’re running the GT500 slaves, so it just made sense to match the whole system as Ford designed it. Could also be a stubborn air bubble down in the slave, which could explain the sensitivity to heat.

Working on these is pretty straightforward. I used the Ford Service manual for the TR-6060. Internally they are the same transmission, just the output shaft is longer on the Magnum which requires a different tail housing. The Rotunda puller they specify in the service manual has just enough reach to pull 5th gear from the output shaft. I found the individual pieces for the puller used on EBay, but I’ve seen several videos of guys modifying regular gear pullers to reach.

Here’s the link to the Ford Service Manual;
https://iihs.net/fsm/?d=949&f=Transmission.pdf&p=2
 
304
380
CA
Recently, I've had some difficulty with the 2-3 upshift on my MagXL - I just replaced a slave cylinder which I thought was the only issue I had (clutch in good shape). However, in the last race once the box gets hot, shifts up were very firm and very slow. No grinding, so I didn't initially suspect an issue with worn blocker rings on the synchronizer.

Anyone with some expertise in transmissions or experience around this sort of thing? I am going to swap the clutch master and the fluid in the trans (it has a fresh BG fill - but I am going to test some different weight fluids)

You can see the slow upshifts in this video:


Compared to this video where the shifts are quick and smooth:


Also, anyone tear into one of these? My usual rebuild vendor hasn't been answering their phones as of late, and I've had a few colleagues encourage me to just open it up myself (looks like a shop press and a long set of gear pullers are the only missing tools, though I can't find a service manual specific to the magnum variants)
What temperature are you seeing in the trans fluid?

It could be a matter of the viscosity of fluid getting too low. It took me a couple tries before finding a fluid which would still shift well in my car at hot and cold temps.
 
304
380
CA
ah, I have the 13-14 master in there now, I just bought a regular GT master to mess with - I was just concerned maybe it had some wear since my grenaded slave cylinder put a lot of trash in the hydraulics

On the temps- usually around 230 mid-race with the cooler running
230 huh? That isn't bad at all.

As you probably know....any good ATF will have the listed viscosity at 100°C in it's spec sheet. You may want to try and find one that is thicker than what you currently run at those temps.

For my TR-3650 I think amsoil ATF has been the best. I tried OEM motorcraft, redline, mobil and all of them were great when the fluid was cold/during street driving, but were not happy out on track. The amsoil was the opposite, not great cold, but fixed my shifting issues while out on track. If i remember correctly, the specs for the amsoil listed the highest viscosity at 100°C among the other fluids I listed. I'm in a low HP 3v though, so I'm likely not seeing much hotter than 250°F, which means we may be in a similar boat temperature wise.
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
I've seen it as high as 270, but the shifting issue was showing up as soon as 230 and maybe even sooner than that.

Oddly I had never had a problem before on BG fluid - it had shifted the best for me, but I also had used a MGC additive which currently is not in the fill. I'll try some fluid changes before I go opening up the box
 
Recently, I've had some difficulty with the 2-3 upshift on my MagXL - I just replaced a slave cylinder which I thought was the only issue I had (clutch in good shape). However, in the last race once the box gets hot, shifts up were very firm and very slow. No grinding, so I didn't initially suspect an issue with worn blocker rings on the synchronizer.

Anyone with some expertise in transmissions or experience around this sort of thing? I am going to swap the clutch master and the fluid in the trans (it has a fresh BG fill - but I am going to test some different weight fluids)

You can see the slow upshifts in this video:


Compared to this video where the shifts are quick and smooth:


Also, anyone tear into one of these? My usual rebuild vendor hasn't been answering their phones as of late, and I've had a few colleagues encourage me to just open it up myself (looks like a shop press and a long set of gear pullers are the only missing tools, though I can't find a service manual specific to the magnum variants)
Just a thought, its only on the up shift and not the down? That would be more RPM dependent? As in a clutch release issue? I suppose it could be just a blocker ring under load but just thinking it through, I will see myself out. Sent in a request to BG.
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
Just a thought, its only on the up shift and not the down? That would be more RPM dependent? As in a clutch release issue? I suppose it could be just a blocker ring under load but just thinking it through, I will see myself out. Sent in a request to BG.
I agree that I really should rule out any clutch disengagement issues before getting too crazy into the box.

In the video comparisons, both fills are BG ATF, just the fast shift video has MGC. Both have the same clutch unit, same style FTE-manufactured short slave cylinder and 13-14 GT500 master cylinder.

Though with the slave having grenaded and filling the lines with metal (Which I cleaned as best I could) I'm curious if there's wear inside the master. Usually they start to leak with problems like that, and I don't have any signs of leaking, but its the next possibility. There were some large master cylinders on the market that looked like a good potential fix but have since become unavailable.

Again on the blockers - I'd expect some degree of scratch going into gear. I did pull some broken fork pads out of the last rebuild, I don't think that's at play here but could also contribute to a difficult shift.
 
1,171
2,152
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
I agree that I really should rule out any clutch disengagement issues before getting too crazy into the box.

In the video comparisons, both fills are BG ATF, just the fast shift video has MGC. Both have the same clutch unit, same style FTE-manufactured short slave cylinder and 13-14 GT500 master cylinder.

Though with the slave having grenaded and filling the lines with metal (Which I cleaned as best I could) I'm curious if there's wear inside the master. Usually they start to leak with problems like that, and I don't have any signs of leaking, but its the next possibility. There were some large master cylinders on the market that looked like a good potential fix but have since become unavailable.

Again on the blockers - I'd expect some degree of scratch going into gear. I did pull some broken fork pads out of the last rebuild, I don't think that's at play here but could also contribute to a difficult shift.
Was everything smooth up until the point the slave let go? If so, that rules out the clutch or any internals of the gearbox and singles out the hydraulics. I keep coming back to air in the system. Are you pulling vacuum on the reservoir to bleed the system? The last time I was experiencing engagement issues, I couldn’t get it fully bled even with the vacuum. The fix was a PITA, but pulling the slave and redoing the bench bleed was the cure.
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
Was everything smooth up until the point the slave let go? If so, that rules out the clutch or any internals of the gearbox and singles out the hydraulics. I keep coming back to air in the system. Are you pulling vacuum on the reservoir to bleed the system? The last time I was experiencing engagement issues, I couldn’t get it fully bled even with the vacuum. The fix was a PITA, but pulling the slave and redoing the bench bleed was the cure.
That's a reasonable thought - though early in the race (and every session that weekend) the clutch was fine on upshifts - only 2->3 was affected, though that was the primary upshift for the tracks around here.

I did bench bleed the clutch slave before install, and I did both the pedal bleed and pull a small amount of vacuum on it to try and further refine.
 
1,171
2,152
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
That's a reasonable thought - though early in the race (and every session that weekend) the clutch was fine on upshifts - only 2->3 was affected, though that was the primary upshift for the tracks around here.

I did bench bleed the clutch slave before install, and I did both the pedal bleed and pull a small amount of vacuum on it to try and further refine.
Here’s the bleed procedure from the Ford service manual for reference - the key step I was missing initially is the quick release of vacuum after letting it sit for a minute or so.

https://iihs.net/fsm/?d=926&f=Clutch System Bleeding.pdf&p=2
 

Fabman

Dances with Racecars
6,549
8,196
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
230 huh? That isn't bad at all.

As you probably know....any good ATF will have the listed viscosity at 100°C in it's spec sheet. You may want to try and find one that is thicker than what you currently run at those temps.

For my TR-3650 I think amsoil ATF has been the best. I tried OEM motorcraft, redline, mobil and all of them were great when the fluid was cold/during street driving, but were not happy out on track. The amsoil was the opposite, not great cold, but fixed my shifting issues while out on track. If i remember correctly, the specs for the amsoil listed the highest viscosity at 100°C among the other fluids I listed. I'm in a low HP 3v though, so I'm likely not seeing much hotter than 250°F, which means we may be in a similar boat temperature wise.
X2 on the Amsoil ATF

Seems 3rd gear is the issue with these transmissions and RPM is the main thing kills them.
Shifted around 7200-7400 rpm my first one lasted years behind a 700/700 whp Blown stroked 3 valve but the mild mannered 476 whp Coyote quickly munched up 3rd gear shifting over 8K.
Amsoil was used with the 3v but I bought Tremec fluid for the Coyote and a few races into the season it started having problems.
I went back to the tried and true Amsoil and it seemed to heal its wounds but late into the second season of racing (and 2 years of excessive rpm abuse) shifting problems came back with a vengeance, literally coasting across the finish line at nationals because I could no longer get the car into gear.

My take:
Magnum= good
Amsoil = good
Shifting over the factory rpm limit = bad

I have a solution though....and if I can pull it off, I'll let you guys know what it is. ;)
 
We have been cautioned about running to high a viscosity fluid in any of these transmissions and Syncro Shift II is still the most recommended.
Any manual transmission that requires any version of ATF (Tremec Aftermarket transmissions all are spec'd for Dexron 3) can use SSII

The issue with heavier oils is they tend to not want to get out the way, which slows down the response of the blocker ring, in turn you end up with a non-synchronized transmission.
"Bro, just double clutch it"

When you look at the new DCT transmission in the GT500, it uses a similar viscosity fluid, and think about the load it is under.

It doesn't make anything much clearer when supposed shops are telling Customers not to run a certain fluid because it does not have enough viscosity.
I handle more calls than I would like about "my transmission guy said this..." What they are not saying is the recommended ATF fluid is slightly lower than the
BG fluid at full temp.
 

JDee

Ancient Racer
1,800
2,002
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
The issue with heavier oils is they tend to not want to get out the way, which slows down the response of the blocker ring, in turn you end up with a non-synchronized transmission.

Exactly what my trans guy told me when I had the MT82 rebuilt.
I've been using Motul DCT fluid since the rebuild. It meets Fords spec for this trans. At the time I had it rebuilt Ford was recommending their DCT fluid.
I also put a cooler on it and I think that has made the biggest difference of all.
 
1,171
2,152
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
Seems 3rd gear is the issue with these transmissions and RPM is the main thing kills them.
Shifted around 7200-7400 rpm my first one lasted years behind a 700/700 whp Blown stroked 3 valve but the mild mannered 476 whp Coyote quickly munched up 3rd gear shifting over 8K.
The 2.66 close ratio box has an advanced tooth synchro engagement on 3rd gear. These were a carry over from gears designed for the OE Tremec variants that needed better cold-fluid engagement and sacrificed the high RPM performance of the symmetrical design. Your original 2.97 box had a symmetrical 3rd gear, so a combination of lower RPMs and the symmetrical engagement kept it happy.

Carbon blocker rings are the final piece for high RPM capabilities. Both the 2.66 and 2.97 boxes have carbon blockers on 2nd gear only. 3rd and 4th are bronze, and again just aren’t up for 7500+ shifts. Swapping 3rd gear for a symmetrical tooth style and upgrading 3rd and 4th blocker rings to carbon are “the fix” for Coyote revs.
 
The 2.66 close ratio box has an advanced tooth synchro engagement on 3rd gear. These were a carry over from gears designed for the OE Tremec variants that needed better cold-fluid engagement and sacrificed the high RPM performance of the symmetrical design. Your original 2.97 box had a symmetrical 3rd gear, so a combination of lower RPMs and the symmetrical engagement kept it happy.

Carbon blocker rings are the final piece for high RPM capabilities. Both the 2.66 and 2.97 boxes have carbon blockers on 2nd gear only. 3rd and 4th are bronze, and again just aren’t up for 7500+ shifts. Swapping 3rd gear for a symmetrical tooth style and upgrading 3rd and 4th blocker rings to carbon are “the fix” for Coyote revs.
When I blue printed T5's in the early 90's carbon blocker rings were fairly common, that was an ancient Transmission designed in the late 70's.
 

Fabman

Dances with Racecars
6,549
8,196
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
The 2.66 close ratio box has an advanced tooth synchro engagement on 3rd gear. These were a carry over from gears designed for the OE Tremec variants that needed better cold-fluid engagement and sacrificed the high RPM performance of the symmetrical design. Your original 2.97 box had a symmetrical 3rd gear, so a combination of lower RPMs and the symmetrical engagement kept it happy.

Carbon blocker rings are the final piece for high RPM capabilities. Both the 2.66 and 2.97 boxes have carbon blockers on 2nd gear only. 3rd and 4th are bronze, and again just aren’t up for 7500+ shifts. Swapping 3rd gear for a symmetrical tooth style and upgrading 3rd and 4th blocker rings to carbon are “the fix” for Coyote revs.
3rd gear Fix? How fixed is that exactly? I’m looking at converting mine to a dog box but libertys build time is 20 weeks….would this fix be good enough or am I still doomed?
 

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