I have recently discovered some interesting information regarding the Magnum XL synchros during my transmission rebuild. I had issues shifting into second gear last year so I decided to drop the transmission and see what was wrong. Checked clutch and it was good so I decided to tear into the transmission. I discovered that I had two broken fork pads and the synchros for 2nd and 3rd did not look great either. I decided to upgrade all of the internals. Replaced the stock plastic fork pads with bronze, replaced the 2nd gear blocker ring with a new CF one, replaced the 3,4,5,6,R blocker rings with hybrid CF/Bronze, and replaced the synchro assembly for 1-2 and 3-4. I didn't want to get into this thing again and figured doing all this now was cheap insurance.
After I received the new 1-2 and 3-4 synchronizer assemblies they looked different than the ones I was replacing so I decided to call Tremec and see why. They told me I had the wrong part numbers. After calling all over the country to Elite Tremec distributors I found out that none of them knew why the part numbers were different than the other Magnums and TR6060s. One shop even said they had installed the exact part numbers I was using in one of their Magnum XL rebuilds. I kept researching and ended up talking to Don at DDPerformance. He was very helpful.
Don was also stumped, but ended up calling an engineering contact he had at Tremec to find out why the synchronizers were different in my transmission. Come to find out it has to do specifically with the 2.66 first gear transmission that I have and the fact that these gear ratios are also used in the OEM TR6060 transmissions used on the GT500s and 2012+ Camaros.
Apparently the Camaro guys were complaining about hard shifting in cold weather so Tremec changed the synchro designs for only the 2.66 Magnum XL transmissions. The change allows for better shifting in cold temps, but it is not the best synchro design from a performance standpoint.
There are two types of synchronizers that Tremec uses in these transmissions. The first type is the symmetrical and the other they call advanced tooth. The original Magnum came with all gears using the symmetrical synchronizer, but there were complaints by the GT500 guys about shifting into second gear. They ended up going to the advanced tooth design for second gear and adding CF blocker rings. According to Tremec, the real advantage was moving to the CF blocker rings and not the advanced tooth design. This is the design that is used for the 2.97 Magnum XLs and most TR6060 transmissions except the ones using the 2.66 first gear. Those transmissions also have an advanced tooth design for 3rd gear.
I do not give a crap about cold weather so I have decided to change out my 2nd and 3rd gear (which were shot anyway) and change them to the symmetrical design like the 1st generation of Magnums. I was assured that this was the best way to go and that I would have one of the best 2.66 Magnum XLs out there with this setup. We shall see.
To summarize (Synchronizer type, blocker ring material):
First Gen Magnum:
1- Symmetrical, Bronze
2- Symmetrical, Bronze
3- Symmetrical, Bronze
4- Symmetrical, Bronze
Second Gen Magnum:
1- Symmetrical, Bronze
2- Advanced, CF
3- Symmetrical, Bronze
4- Symmetrical, Bronze
Magnum XL (2.97 first):
1- Symmetrical, Bronze
2- Advanced, CF
3- Symmetrical, Bronze
4- Symmetrical, Bronze
Magnum XL (2.66 first):
1- Symmetrical, Bronze
2- Advanced, CF
3- Advanced, Bronze
4- Symmetrical, Bronze
My new setup with Magnum XL (2.66 first):
1- Symmetrical, Bronze
2- Symmetrical, CF
3- Symmetrical, Hybrid (CF/Bronze)
4- Symmetrical, Hybrid (CF/Bronze)
