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Tremec Magnum XL swap

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Norm Peterson

Corner Barstool Sitter
939
712
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HPDE
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5-10 Years
a few miles east of Philly
I wasn't really thrilled with either of the magnum gear sets and definitely not thrilled with the magnum price tag. So I went with a used 09 GT500 trans. In my opinion, this is the best gearset for a mostly street / part time track car. You still get a decently low 1st gear for the street with farily close and evenly spaced 2-3-4-5.
Where did you source yours?

What supporting conversion items did it require? I know that the shifter is semi-remote without being the same as the shifter for a 3650, and I think it uses the same sort of attachment for the driveshaft on the output shaft (not at all sure about driveshaft length). I'm sure I'm missing a number of details.


Norm
 

racer47

Still winning after 30+ years
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Where did you source yours

I'm a patient guy. I knew what trans I wanted and just looked for one occasionally. Eventually I found one local out of wrecked gt500.

As far as parts, you need the trans mount, shifter and 26 spline clutch. The driveshaft needs to be 3/4 inch shorter. Many aftermarket gt shafts have to enough travel to work with the tr6060.
 
Okay Drivers, I finally got in two real good track days at Laguna Seca with my new Tremec Magnum XL swap. Here's the general parts list:

Tremec Magnum XL
MGW short throw shifter
Driveshaft Shop one piece lightweight driveshaft
Ford Performance Torsen T-2R differential
Ford Performance 4:10 rear gears
JPC driveshaft loop
Braided clutch line
Trans cooler from parts

I sourced the parts as follows:
Got the Tremec, driveshaft and Tremec oil from Joe Dederichs at Dederichs Motorsports, Texas -- (682)-231-3510, and (682)-365-5555 mobile. I dealt with Joe directly. He's a Mustang guy, Ford guy and racer, and Elite Tremec Dealer. He knows this stuff and is very easy to work with. He had in stock a 2.66/1.78/1.3/1.0/.80/.63 box. The overdrives are a swap from the 2.97 box. My mechanic (see below) and I debated over which box to get.... the 2.66 (above) or the 2.97/2.1/1.46/1.0/.80/.63; since I only run road course HPDE, and gears 3 and 4 are the most important. Joe pitched in his opinion as well. And, doing some research I found that:

2008 FR550S car uses Tremec 2.97/1.78/1.3/1.0/.80/.63 (the same as mine, except 1st gear)
2013 Boss S car uses Tremec 2.66/1.82/1.3/1.0/.77/.50

Both of the above have 3:73 rear gears. We liked the progression of gearing in the Tremec XL 2.66 box, even though the gearing is taller than the 2.97 box. To compensate for this, and doing some math on various turns at the tracks I run (Laguna, Sonoma, Thunderhill), we opted for the 4:10 rear gear. This would keep the car in the power band/speed realms I was used to and keep end of straights/corner entry/shifting in a reasonable realm.

As mentioned above, I sourced the parts. MGW shifter directly from MGW website, and the other stuff from either Summit Racing or American Muscle. The car already had a McLeod RXT clutch, so the discs had to be sent back to Mcleod to be resplined to match the Tremec. My mechanic and his shop did the swap -

Michael Thompson at McGee Motorsports, located at Sonoma Raceway. (707) 996-1112. All his shop does is race cars and track cars, and some vintage race cars too. Michael himself races, and Matt his lead mechanic, is superb. They are easy to work with, and Michael and Matt give 120%.

Okay, the on track experience. As expected, first gear is uncomfortable in the paddock (would never work on the street). It takes a lot of clutch work to get the car rolling, but who cares: it's the paddock. (By the way, this is a track car, sees no street time and runs maybe 25 track days/year. Dyno'd 424hp to the wheels, and is not stripped out but no A/C, 4pt roll bar, seats, 6pt harness, Cortex/JRI Track suspension, Apex 18x10 wheels).

The shifting is flawless. A far cry from the OE junk. A good, solid mechanical feel, short and quick. No guessing anymore. Reverse takes some getting used to and is a hard-slow push to the right and up. There's no chance to blow it. The progression 2-3-4 is excellent, although, as expected, the car feels a bit sluggish due to the Tremec gearing. Thank gawd I went for the 4:10 rear. The FR500S and BOSS S are lighter cars; the Boss S with more HP, which is why they get away with the 3:73, I assume. Sluggish noted, the car is very driveable; gear progression right where you'd expect it and **important**, I am shifting less, at least at Laguna. Laguna is all 3-4, except for T11 where I go to 2nd gear now. And the 2-3-4 on the main straight around T1 is a joy. Downshift (DS) to 3 for T2 is smooth (whereas the OE was troublesome, and I had to do a 5-4-3 DS). Exiting T2 in 3rd is a little slow, but 2nd would be a poor choice I think. Then 3rd gear all the way through T4, which also is a joy as I had to 3-4 shift between T3 and T4 with the OE then roll through T4. Exiting T4, shift 3 to 4, then DS to 3 for T5, up the hill in 3rd (pedal to the floor - no sound violation), shift to 4, then back to 3 to enter T6. I can pull through T6 in fourth fine, but get better oompf going uphill to T7 in 3rd. Upshift to 4 after T6, then DS to 3 for the corkscrew. Then downhill through T9, T10 all in 3rd. Being in 3rd here is great because it makes passing a snap (I had to be in 4th with the OE). T10 to T11 in 3rd, then DS to 2nd for T11, and then exit T11 for the straight as mentioned above.

I'm still getting used to it, and it will take some time. I need to improve corner exit because I can't just depend on power to catch me up. Honestly, I think this is a good thing. My driving will improve, and therefore be faster and smoother. My buddy with his FR500S was there for the second day and we ran together some. When we were exiting T11 together and shifting on the front straight, he pulled away from me. Even though his car has about 325hp and 3:73 rear, it's lighter and he's a better driver, and the 3-valve motor has different power. I'll work on getting weight out of the car next, and always am working on my driving.

Bottom line: The Tremec is a great change. After blowing up two OE's, I'd had enough. It's an expensive swap, and there is more inherent vibration. But hey, it's a track car. I'm running two days at Thunderhill soon, and excited about the change for that track.

If you can spend money, get one.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Okay Drivers, I finally got in two real good track days at Laguna Seca with my new Tremec Magnum XL swap.

Bottom line: The Tremec is a great change. After blowing up two OE's, I'd had enough. It's an expensive swap, and there is more inherent vibration. But hey, it's a track car. I'm running two days at Thunderhill soon, and excited about the change for that track.

If you can spend money, get one.
I can spend the $, but I only want to do this one once, so I'm still in research mode.

Pretty sure you've got a 2012 with the 5.0, which is probably a hundred or so lbs heavier than my '08 . . . what size tires are you running and what rpm are you shifting at?

I'm not writing off the idea of a lighter steel flywheel quite yet either.


Norm
 
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Norm, you are correct. 2012 GT with CAI and a tune. Tires are Nitto NT01 275/40-18. I need to look at my in car video to see my rpms, but casual glances at the tach at Laguna and one rev limiter hit, looks like I'm shifting at about 6400. I did feel like I wanted to wind it out more than with the OE trans - quilty as charged - but I was happy to see that my CH temp was staying reasonable. I'm going to try 275/35-18's to reduce the gearing a tad. It was a few years ago that the McLeod RXT was installed, but I'm sure I also got a new lighter flywheel at the time, packaged from McLeod.

I knew the money question after I killed the first OE tranny, and wimped out and tried it again. Bad idea, it lasted a year. I think the Tremec is a good option for converting our street cars to track cars, but if I could do it all over again....uh, huh..... I'd just buy a Boss S, if I could find one.

BTW - you have a full cage, don't you? Who did it ??

TS
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
No cage, as it still sees significant street duty (sometimes with a passenger) and runs on true street tires (currently MPSS). Maybe you're thinking of somebody else?

For me, it's beginning to feel like a close-ratio Magnum XL will be worth the upgrade just to get rid of the huge gear-spacing gaps in the 3650 (2-3 and 4-5 are both about 1.5:1). Even in street driving.


Norm
 

racer47

Still winning after 30+ years
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SE WI
Norm,
I looked at my video. At Laguna, exiting T11 in 2nd gear, 2-3-4 upshifting on the straight, I shift at about 6300 and the rpms drop back to about 4900-5000 at each shift. The progression/splits are very good.

I also looked a bit at my data, and I am a bit slower in most areas of the track, especially T6 - T8 up the hill. Lots of variables: tires, track conditions, psi etc.. I drove near the front of the pack both days, so it may have been just the conditions. There were vettes, a Mclaren and a Ferrari; Bimmers as usual. I do need to re-learn how to drive this tranny, but it's not a bad thing. Just will take some time.

If you drive your car on the street, and go with the 2:66 box, remember, first gear is a challenge. But, enjoy.

TS
 

racer47

Still winning after 30+ years
392
497
Exp. Type
W2W Racing
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SE WI
It always comes down to cost. I've worked at 3 big oems and see this all the time. We see how good stuff could be for just a few dollars more. But sometimes decisions are made based on nickles
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Norm,
I looked at my video. At Laguna, exiting T11 in 2nd gear, 2-3-4 upshifting on the straight, I shift at about 6300 and the rpms drop back to about 4900-5000 at each shift. The progression/splits are very good.

I also looked a bit at my data, and I am a bit slower in most areas of the track, especially T6 - T8 up the hill. Lots of variables: tires, track conditions, psi etc.. I drove near the front of the pack both days, so it may have been just the conditions. There were vettes, a Mclaren and a Ferrari; Bimmers as usual. I do need to re-learn how to drive this tranny, but it's not a bad thing. Just will take some time.

If you drive your car on the street, and go with the 2:66 box, remember, first gear is a challenge. But, enjoy.

TS
Thanks for the above information; it's all valuable because it helps clarify what I should expect.

I'm already anticipating at least a brief learning period, since I went through a learning period when the shorter tires I went to (285/35-18's from 255/45-18's) caused shifts to happen at different points on the track - and actually added an extra upshift/downshift pair on each of NJMP's courses.

One thing I intend to do (but haven't gotten around to yet) is run a comparison of your setup against various options for my own. I'm still thinking in terms of 3.73's, because I do want 4th to be good for a bit more than 110 mph @ 6000 rpm, and there are more times on the street where I'd rather have a few more mph available in 1st than have stronger acceleration in that gear. Maybe I really don't have a single drag-racing bone in my body.


Norm
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
The car already had a McLeod RXT clutch
That's a dual-disc unit, correct? If so, don't they tend to be a bit abrupt in their engagement? With only a NA 4.6L, a 6000-ish redline, and anywhere from about 70% up to 95% street driving, I'm not looking for a dual-disc any time soon. Maybe never. Basically, I'm guessing that this has a lot to do with your warnings about 1st gear with the 2.66 1st on the street.

I did run your numbers against one set of mine, and it turns out that we'd be shifting at very similar speeds, just that you'd be running 400 - 500 rpms more than I and shifting sooner after track out even if we passed the apex at the same speed.


Norm
 
Just got back from 2 days at Thunderhill 3 mile. Must say, the gearing is almost darn perfect for that track. To your point about stretching out 4th gear around 110mph.... I captured data from yesterday that shows I'm at 120 just past the S/F tower at about 6200 rpm. I'm still in the throttle there. THIS is the ONLY place that I'm even a tad nervous about the gearing. For now, I'm stretching 4th out there and not going to 5th. That was the plan all along with my gearing choice. I really don't want to short shift into 5, then back to 4th like the OE tranny. It's on the edge... If I change tires from 275/40-18 to 275/35's, the shift may be required. The slightly lower gearing resulting from the 35's would help at Laguna a tad. Will be running Sonoma at the end of October, so we'll see how she does out there.
FWIW - I have two buddies that track FR500S cars; the 4.6L motor, and their gearbox 2-3-4 is the same as mine, but with 3.73 rear. They both stay in 4th thru the front straight and T1. We all run similar shifting habits.

Regarding the McLeod RXT, yes it is dual disc. It also takes some rpm run-up and clutch slipping for engagement, and is a bit ubrupt, now that you mentioned it. The OE clutch got swapped out years ago, and that was the first thing I noticed. That aspect, combined with Tremec's tall first gear, would make stoplight driving a PITA, IMHO.

BTW - I mentioned in a post earlier about a little more vibration. I didn't even notice it that last two days, so it obviously isn't bad at all...
 
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Update: Ran Thunderhill 3 mile again yesterday. It was hot, so to keep the motor running a bit cooler I experimented upshifting to 5th on the front straight. Initially, I fumbled with this until I got better at the shift points exiting Turn 15. Bit of a short shift out of 3rd exiting T5, a short stretch in 4th and then 5th. At one point along the straight I saw the tach at 5000 and speed at 115. The .80 overdrive 5th gear works here - can't imagine anything taller.

This is a case of splitting hairs and driver skill/adjustment. Shifting 3-4-5 on Thunderhill front straight is not faster, but keeps my car cooler, which on hot days is critical. I'm sure as I improve navigating T14-15 and exiting T15 better, the 3-4-5 shifting will work. On cooler days I can stay in 4th, well, until I get so fast exiting T15 that I have to get into 5th.

All of that said, the Tremec shifts precisely. A real treat over the OE MT-82, where I had to be in 5th on the straight and the 5-4 shift was always problematic - always.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Here's the general parts list:

Ford Performance Torsen T-2R differential
Ford Performance 4:10 rear gears
I still have a couple of questions. Is your Torsen the 2.7 bias unit as used in the Laguna Seca, and did you have any difficulty with the 4.10 gear teeth getting in the way of reassembling the diff after installing the axles?

Still only want to do this once.


Norm
 
Yes, it is the Laguna Seca Torsen unit and it installed fine, at least I didn't hear about any issues. My shop did the install. Good luck! I'm running Sonoma Raceway soon for he first time with the Tremec, and I'm sure I'll be a happy camper.
 
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@ tetstang, previously you wrote:
the 3-valve motor has different power
I know it has alot less, but could you please elaborate on how you feel this compares to your Boss Coyote motor and what effect it has on the tranny gearing and the rear end gearing?
 
@ tetstang, previously you wrote:

I know it has alot less, but could you please elaborate on how you feel this compares to your Boss Coyote motor and what effect it has on the tranny gearing and the rear end gearing?

Well, I can't elaborate a whole lot because I've never driven a 4.6L car. Only my 5.0 GT (not a Boss). But, I have been a passenger in a FR500s car, which is the 4.6L motor and a stripped factory built race car. I don't know if the ECU programming is different from a street 4.6L car (most likley), but the Spec Mustang class cars are just that: stripped 2005-08 street cars.

My car drives very similar to my buddy's FR500S car, from the rides I've taken. We virtually use the same gears and shift points except for a few minor driver preference differences. His car moves out well, but it winds out at a lower rpm than my car, but he has the 3:73 rear which allows him to stretch it out. He has good torque, and it may be a little broader power band than my car. My car's best power is above 4500 and up to 6200. He says his is a momentum car.... he means it's not like a 550 hp Corvette, but it's spunkier than a Miata. Mind you, it is no slow poke at all. Having gobs of power isn't really that useful on road courses, and can get you in trouble fast. Riding with him I could find no fault with the power/gearing setup of his car.

He and I have yet to be side by side on track and compare, but I suspect our two cars run very close. I think weight is a big component here, and mine needs a diet.
 

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