Magnum XL hard 2-3 shift when hot

[captdistraction]

Correct me if wrong, but that involves swapping the third gear, the synchronizer assembly (from advanced to symmetric) - then just the blocker rings while in there.

Next time I go in, I'll definitely do all this, but hopefully I'm at least a little ways away from needing it.

 

[67GTA]

Correct me if wrong, but that involves swapping the third gear, the synchronizer assembly (from advanced to symmetric) - then just the blocker rings while in there.

Next time I go in, I'll definitely do all this, but hopefully I'm at least a little ways away from needing it.

That’s exactly right. Texas Drivetrain Performance sells just the synchronizer outer ring for the synchro 3-4 assembly (link below). They also sell the replacement 3rd gear with non-advanced design.

The carbon blocker rings are a Tremec part number TUES10357. You’ll have to search a bit to see who has them in stock - Tick Performance had them when I upgraded a couple years ago.

https://txdrivetrain.com/product/tr6060-3-4-slider-advanced/

 

[67GTA]

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?

Carbon blockers on 3-4, symmetrical tooth 3rd gear and replacing the plastic shift fork pads with bronze pads would have you in business - worlds better than it was stock. About $500 in parts and the R&R is something you could tackle in a weekend.

 

[Fabman]

Carbon blockers on 3-4, symmetrical tooth 3rd gear and replacing the plastic shift fork pads with bronze pads would have you in business - worlds better than it was stock. About $500 in parts and the R&R is something you could tackle in a weekend.

It’d sure be cool if somebody made up an upgrade kit with all the correct pieces…..probably would be a popular product…. vendor’s?

 

[67GTA]

Correct me if wrong, but that involves swapping the third gear, the synchronizer assembly (from advanced to symmetric) - then just the blocker rings while in there.

Next time I go in, I'll definitely do all this, but hopefully I'm at least a little ways away from needing it.

The carbon blocker rings are a Tremec part number TUES10357. You’ll have to search a bit to see who has them in stock - Tick Performance had them when I upgraded a couple years ago.

One other note on using this Tremec part # for 3rd & 4th; you won’t find anyone list this as a replacement for 3-4. That’s because you reuse the inner cone from your existing blocker ring. There’s no friction material on the inner cone of 3-4, so I just scuffed the surface up with a very light Emory cloth. This was the only way I could get a true full-carbon setup for 3-4 back in 2020.

Synchrotech transmissions has since started making a full-carbon 1-6 kit that comes with bronze pads, or you can source the individual pieces if you don’t need all of the blocker rings. With all of theirs, you reuse the outer ring and the inner ring from the OE Tremec bits. The friction material is what wears out or glazes, so reusing these OE pieces is perfectly acceptable - just comes down to preference on using Tremec brand friction material or going with Synchrotech.


https://sync-trans.com/products/copy-of-syn-t56-12-carbon-synchro-center-friction-ring-1-2-t56-t45

 

[67GTA]

Here’s some pics comparing the 2 different friction materials - carbon on the left, bronze on the right. This is the bronze rings that I removed after 2,000 miles - they glazed after using the wrong fluid and crazy gear clash ensued on 4-3 downshifts.

 

[captdistraction]

Torn mine down since I don't have a working powertrain - It was pretty easy to do, was able to get all the blocker rings out without needing a press (just two puller kits combined into one long puller system). Gears looked great, and even most of the blocker rings. I was surprised to see every gear with a hybrid ring set (as I thought typically these featured a double carbon blocker on 2nd). Ordered 4 of the synchrotech rings and some replacement brass fork pads. I also have a new 3-4 fork as I was told my previous one had to be welded up, but I can't find any signs of where or how they did it. Either way, will get her freshened up. At the point where its scary to think of how all this goes back together. That said, its dirty now but everything will get washed and put together cleanly.

 

[Fabman]

Torn mine down since I don't have a working powertrain - It was pretty easy to do, was able to get all the blocker rings out without needing a press (just two puller kits combined into one long puller system). Gears looked great, and even most of the blocker rings. I was surprised to see every gear with a hybrid ring set (as I thought typically these featured a double carbon blocker on 2nd). Ordered 4 of the synchrotech rings and some replacement brass fork pads. I also have a new 3-4 fork as I was told my previous one had to be welded up, but I can't find any signs of where or how they did it. Either way, will get her freshened up. At the point where its scary to think of how all this goes back together. That said, its dirty now but everything will get washed and put together cleanly.

View attachment 84638

View attachment 84639

View attachment 84640

View attachment 84641

View attachment 84642

View attachment 84643

View attachment 84644

View attachment 84645

View attachment 84646

You are a braver man than I……I ordered a fresh gearbox and the recommended upgrade parts as per @67GTA and need to find someone local that will understand what we are trying to do….stay tuned.

 

[captdistraction]

At this point I have literally nothing to lose

 

[captdistraction]

An update on findings now that I've had it apart:

• The blocker rings looked reasonably OK, but were all hybrid rings. The double carbon blocker which is typically used on 2nd gear was also just a hybrid brass
• Third gear blocker ring showed some signs of wear with a darkened ring, but really didn't look that bad. Reverse gear also had a similar ring, oddly enough (as I never use it)
• The brass fork pads looked pretty rough, and 6th and reverse had plastic pads still
• 3rd gear (non-symmetrical/advanced) had some wear on the engagement teeth - nothing critical yet but definitely something that would contribute to hard shifting
• 3/4 synchronizer had some odd wear as well - 4th gear (symmetric side - teeth peeling back), 3rd gear looked mostly ok
• 3/4 synchro center section - it had signs of significant wear on the mating face, sharp edges worn into it, darkened oil and hot spots
• This transmission had some rem polishing back when I bought it - but I can't find much signs of that

Synchro observations:

TUES11858 (1/2 synchronizer hybrid)​

Looks ok - replace​

​

TUES11858 (1/2 synchronizer hybrid)​

Looks ok - should be carbon/carbon -replace​

​

TUES11859 (3/4 synchronizer hybrid)​

Moderate Wear ring down center of brass side - replace​

​

TUES11861 (5/6/R synchronizer hybrid)​

Looks ok (out of focus picture above) -reuse​

​

TUES11861 (5/6/R synchronizer hybrid)​

Light Wear Ring down center of brass side - reuse​

​

TUES11861 (5/6/R synchronizer hybrid)​

Light Wear ring down center of brass side - reuse​

​

TUES11859 (3/4 synchronizer hybrid)​

Looks ok - replace​

Now comes the fun part of remembering how all this stuff went back together. I picked up the following parts to rebuild it:

• New center Carbon/carbon friction rings for positions 1-4 blockers
• New synchronizer for 3/4 (non-advanced/symmetric) - I had only intended to buy the outer hub, but was fortuitous to have bought the whole assembly since I needed a spare inner hub to replace the bad one.
• New 3rd gear (non-advanced, symmetric) - seen in black phosphate below.
• New shift fork for 3/4 (I had been told in the past my 3/4 fork needed welding, and figured I should replace it - but I can't find the signs of welding. Either way, new one going in)
• New brass pads for all positions (1-4, 5-6-R)
• new temperature sender as I broke the original's retaining tab on the connector - they're way too frail for motorsports use, looking for an alternative for future
• I had some new seals, but I'm leaving the existing ones in there as they look great

 

[Fabman]

An update on findings now that I've had it apart:

• The blocker rings looked reasonably OK, but were all hybrid rings. The double carbon blocker which is typically used on 2nd gear was also just a hybrid brass
• Third gear blocker ring showed some signs of wear with a darkened ring, but really didn't look that bad. Reverse gear also had a similar ring, oddly enough (as I never use it)
• The brass fork pads looked pretty rough, and 6th and reverse had plastic pads still
• 3rd gear (non-symmetrical/advanced) had some wear on the engagement teeth - nothing critical yet but definitely something that would contribute to hard shifting
• 3/4 synchronizer had some odd wear as well - 4th gear (symmetric side - teeth peeling back), 3rd gear looked mostly ok
• 3/4 synchro center section - it had signs of significant wear on the mating face, sharp edges worn into it, darkened oil and hot spots
• This transmission had some rem polishing back when I bought it - but I can't find much signs of that

Synchro observations:

TUES11858 (1/2 synchronizer hybrid)​

Looks ok - replace​

​

TUES11858 (1/2 synchronizer hybrid)​

Looks ok - should be carbon/carbon -replace​

​

TUES11859 (3/4 synchronizer hybrid)​

Moderate Wear ring down center of brass side - replace​

​

TUES11861 (5/6/R synchronizer hybrid)​

Looks ok (out of focus picture above) -reuse​

​

TUES11861 (5/6/R synchronizer hybrid)​

Light Wear Ring down center of brass side - reuse​

​

TUES11861 (5/6/R synchronizer hybrid)​

Light Wear ring down center of brass side - reuse​

​

TUES11859 (3/4 synchronizer hybrid)​

Looks ok - replace​

Now comes the fun part of remembering how all this stuff went back together. I picked up the following parts to rebuild it:

• New center Carbon/carbon friction rings for positions 1-4 blockers
• New synchronizer for 3/4 (non-advanced/symmetric) - I had only intended to buy the outer hub, but was fortuitous to have bought the whole assembly since I needed a spare inner hub to replace the bad one.
• New 3rd gear (non-advanced, symmetric) - seen in black phosphate below.
• New shift fork for 3/4 (I had been told in the past my 3/4 fork needed welding, and figured I should replace it - but I can't find the signs of welding. Either way, new one going in)
• New brass pads for all positions (1-4, 5-6-R)
• new temperature sender as I broke the original's retaining tab on the connector - they're way too frail for motorsports use, looking for an alternative for future
• I had some new seals, but I'm leaving the existing ones in there as they look great

View attachment 84873View attachment 84874View attachment 84875View attachment 84876

Jesus.