TREMEC T56 Magnum S197 Transmission

fdjizm

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No; the McLeod clutch friction disc surfaces do NOT line up with an OEM flywheel's surface...whereas the McLeod flywheel is a PERFECT match to their clutch. If the Surfaces do not mate perfectly, the flywheel will cut a groove into the friction material on the clutch surface and then as the clutch gets hot, the clutch will hang up and fail to release. (Clutch material will swell and lock into the worn groove in the flywheel)

The bottom line is a use a McLeod flywheel with a McLeod clutch if you don't want to think about it - or if using another brand flywheel, make SURE the surfaces mate correctly or you will be tearing the tranny out to replace the clutch again very soon.
Thanks man, I didn't know that. Sucks that McCleod doesn't just copy the stock flywheel dimensions though like other manufacturers.


You mean the McLeod friction material diameter is smaller than the OEM flywheel or larger?
I am going to double check tonight to see where it lines up, never thought to slap them together and check yet.
 

Norm Peterson

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No; the McLeod clutch friction disc surfaces do NOT line up with an OEM flywheel's surface...whereas the McLeod flywheel is a PERFECT match to their clutch. If the Surfaces do not mate perfectly, the flywheel will cut a groove into the friction material on the clutch surface and then as the clutch gets hot, the clutch will hang up and fail to release. (Clutch material will swell and lock into the worn groove in the flywheel).
Is this a case of the McLeod disc having a smaller inside diameter than that of the OEM flywheel's machined surface?


Norm
 

DiMora

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Is this a case of the McLeod disc having a smaller inside diameter than that of the OEM flywheel's machined surface?


Norm

The inner ring of the clutch friction material does not mate with the OEM flywheel. Not only is 1/3 of the clutch friction disc not being used, but as the clutch heats up, the ridge on the friction disc binds with the inner edge of the OEM clutch flywheel.

A McLeod flywheel has more mating surface on the inner circle and mates correctly with the entire friction disc.

2v23eEBsoxUQZjg.jpg


2v23udv1DxUQZjg.jpg
 
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Norm Peterson

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Wow . . . that's a whole lot of mis-match.

Do you have any suggestions either for discs that are compatible with the factory flywheel or flywheel & clutch sets where the flywheel is the same weight/rotational inertia as stock?

The reason I want to keep flywheel the same as stock (or very close) is because I'm planning on running a 2.66-low Magnum XL with 3.73's for road course duty and mild to moderate street driving. No drag racing or hard street launching.


Norm
 

1950StangJump$

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Makes sense.

I'm assuming that the computer is comparing engine rpms against transmission output shaft rpms (speedometer connection), and comparing that against a gear ratio table. I wouldn't be too surprised if 2nd gear with the 2.66 1st Magnum caused the same problem. I'm only guessing here, don't ever use CC myself.


Norm

For what it's worth, I tried 2nd gear with my 2.97 Magnum . . . no joy. Didn't try 1st gear, but I don't think I could get to the minimum cruise control speed for that.

Only 4th and 6th for me. I know someone else on here said 3rd worked, but not mine.
 

1950StangJump$

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There is a transmission gear ratio table somewhere in the tune file that needs to be updated for the 6 speed. Cruise control in 4th gear works because both the 5 spd and 6 spd are 1:1 in 4th.

6th gear works because its close enough to the original stock 5th gear, 0.63 vs 0.68. The computer thinks the car is in 5th.

5th gear on the 6 spd won't work because the computer does not recognize it as a valid gear ratio.

This sounds logical. But, I will say, when I upgraded from the 6-speed MT-82 to the Magnum a few years back on a 2011, cruise didn't work in 5th there either. Still could have been a confused computer because of different drive ratios, I suppose.
 

Norm Peterson

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This sounds logical. But, I will say, when I upgraded from the 6-speed MT-82 to the Magnum a few years back on a 2011, cruise didn't work in 5th there either. Still could have been a confused computer because of different drive ratios, I suppose.
Could be a similar story where 5th in the Magnum is too far away from the 1.00:1 that the computer is expecting to find . . . on the "too tall" side rather than "too short".


Norm
 

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Wow . . . that's a whole lot of mis-match.

Do you have any suggestions either for discs that are compatible with the factory flywheel or flywheel & clutch sets where the flywheel is the same weight/rotational inertia as stock?

The reason I want to keep flywheel the same as stock (or very close) is because I'm planning on running a 2.66-low Magnum XL with 3.73's for road course duty and mild to moderate street driving. No drag racing or hard street launching.


Norm

McLeod makes a lightened steel flywheel that is perfect. That will be perfect for road-course work. They also make an aluminum one, but I’d go lightened steel so the car performs well on the street if revving and launching.
 

fdjizm

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The inner ring of the clutch friction material does not mate with the OEM flywheel. Not only is 1/3 of the clutch friction disc not being used, but as the clutch heats up, the ridge on the friction disc binds with the inner edge of the OEM clutch flywheel.

A McLeod flywheel has more mating surface on the inner circle and mates correctly with the entire friction disc.

2v23eEBsoxUQZjg.jpg


2v23udv1DxUQZjg.jpg


I am happy to say that I found totally different results.

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Seems like the pressure plate has the same exact blank space that the clutch disc has on the exedy lightweight flywheel anyway... looks like a fit to me. The OEM flywheel would have that outer space blank too. maybe they switched up or maybe the twin disc is different yours looks like a twin disc? This is the McCleod super street pro clutch (single disc) with an 11" disc and the exedy lightweight flywheel is for an 11" disc.
 

DiMora

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I am happy to say that I found totally different results.

20190801-203807.jpg

20190801-203825.jpg

20190801-203938.jpg

20190801-204007.jpg

20190801-204102.jpg

20190801-204123.jpg

20190801-204324.jpg


Seems like the pressure plate has the same exact blank space that the clutch disc has on the exedy lightweight flywheel anyway... looks like a fit to me. The OEM flywheel would have that outer space blank too. maybe they switched up or maybe the twin disc is different yours looks like a twin disc? This is the McCleod super street pro clutch (single disc) with an 11" disc and the exedy lightweight flywheel is for an 11" disc.
Awesome!

Mine was an RST; I now run an RXT. Both are twin disc.
 

fdjizm

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Yea you got the big boy clutch, I got the little baby :roflmao:
No way to justify an 800hp clutch on a 300hp car!
But it holds 550 so should last a while on the strip.
 

Norm Peterson

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McLeod makes a lightened steel flywheel that is perfect. That will be perfect for road-course work. They also make an aluminum one, but I’d go lightened steel so the car performs well on the street if revving and launching.
I probably understand the physics behind this better than most.

I also know that my axle gearing and transmission choices are relatively tall for the street driving that still constitutes anywhere from 80% to 95+% of the miles this car gets driven. Overall reduction in 1st is only going to be 2.66 x 3.73, for 9.9, which corresponds to about 7.5 mph/1000 rpm. That's about 20% taller than 3.55's with the TR3650's 3.38 low gear ratio. The 2.97 low version of the Magnum is not an option (gear spacings between intermediate gears 2 through 4 are too wide).

I suspect most non-road course people choosing the 2.66-low Magnum with street duty in mind would want at least 4.30's in the axle, or even 4.56's. 4.10's even with the 2.97-low box.

It's a bit trickier trying to find "best overall solutions" for both street and road course driving than when you're only having to satisfy one or the other. With the best chances of getting it right the first time (being retired does have a way of discouraging the "try it and change it again if you still don't like it" approach to car modification).


Norm
 
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Saleen304

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I run the 2.66 Magnum with 3.55 gears and 28” tall tires. I run a twin disc ACT clutch with lightened steel flywheel as well. No issues for me. I have also run 3.73 and 4.10 gears with this combination and I prefer the 3.55 at my horsepower (650 whp). I also have no issues with cruise control in any gear. Tuned by Lito.
 

Norm Peterson

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I run the 2.66 Magnum with 3.55 gears and 28” tall tires. I run a twin disc ACT clutch with lightened steel flywheel as well. No issues for me. I have also run 3.73 and 4.10 gears with this combination and I prefer the 3.55 at my horsepower (650 whp). I also have no issues with cruise control in any gear. Tuned by Lito.
Thanks.

My engine isn't making anywhere near that much (it's a 4.6 with only the FRPP cold air & tune). I'm looking at the Magnum specifically for its ratios and the all-internal shift linkage instead of torque capacity (yeah, I know it's massive overkill strength-wise).

With respect to cruise control, what year is your car? I've heard of CC issues (5th?) with some transmission swaps where some computer is looking for the gear ratios to fall within certain ranges and gets a bit stupid when they don't. It's really an academic question, given that I don't ever use CC myself (haven't tried it out on the new WRX to see if it even works).


Norm
 

Saleen304

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Thanks.

My engine isn't making anywhere near that much (it's a 4.6 with only the FRPP cold air & tune). I'm looking at the Magnum specifically for its ratios and the all-internal shift linkage instead of torque capacity (yeah, I know it's massive overkill strength-wise).

With respect to cruise control, what year is your car? I've heard of CC issues (5th?) with some transmission swaps where some computer is looking for the gear ratios to fall within certain ranges and gets a bit stupid when they don't. It's really an academic question, given that I don't ever use CC myself (haven't tried it out on the new WRX to see if it even works).


Norm

My car is a 2005.
 

1950StangJump$

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OK. I think the CC problems I've heard of mostly involved MT82 swaps where 5th is 1.00.


Norm

I've had swaps with both, and it's the opposite of what you state . . . more folks having CC issues when going from the 3650 to the Magnum than when coming from the MT82
 

fdjizm

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I've used cruise control twice in 6th gear and been fine.
But rarely use it at all.
 

Norm Peterson

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I've had swaps with both, and it's the opposite of what you state . . . more folks having CC issues when going from the 3650 to the Magnum than when coming from the MT82
All of the 3650 to Magnum swap information I've read to date either didn't mention the CC issue at all, or I skipped completely over it because I don't ever use CC anyway. If/when I get this swap done, I might try CC once to see if it even works . . . and never touch it again.


Norm
 

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Tried CC in 5th for the first time today and it worked just fine. I do have issues of CC canceling itself for no apparent reason when cruising, though. I think I made a post a long time ago in this thread about it. Not too concerning, but it is a peculiar problem.
 

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