Installed a Tremec Magnum XL in my S550

Red65

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I am not. The tune I have in the car for the magnum disables that. My understanding is leaving that enabled causing strange rev hang issues between shifts.
I figured as much. I'm still on the stock MT82 with plans to go to a magnum eventually. Even with the stock MT82, I am getting some REALLY obnoxious rev hang issues. I am suspecting it has to do with the upshift rev match specifically since I am Lund tuned and it was my understanding that aftermarket tunes tend to get rid of some of the EPA-based rev hang that's built in from the factory. I basically have to rev it up past 2200 rpm to keep the engine from taking 5 seconds or so to wind down between gears.

 

aleccolin

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Back from the dead as I wanted to give an update on my situation and help out the next guy so they don't have to go through what I am. As mentioned, I blew the hydraulic slave on the second WOT shift after breaking in the magnum and new McLeod RXT clutch. When everything was initially installed, I always thought the trans was really notchy and the clutch engagement was way too close to the floor and felt weird....

I finally got some motivation to work on the car a month ago and removed the trans to inspect things. McLeod had me take a number of measurements and it was determined I was over extending the slave...by a lot. I'm running the sprung hub RXT twin disc with matching flywheel with the correct shorter Ford slave cylinder (from a GT500). This is supposed to be a plug and play setup with the magnum, but it sure wasn't. This is the setup: CLICK ME

It was determined that I need a .450" shim behind the slave to put it in the right place and have the correct air gap. To me that is a huge number! My setup wasn't even close... I will say McLeod was great to work with and really wanted to help get my setup correct. They said there are a handful of guys they are working with right now with this exact problem.

As mentioned, McLeod had me take a bunch of measurements, but this video shows the mose critical: A and B measurement video

I'm not sure if Tremec changed something with the gearbox or my setup is just goofy. But no matter the clutch you are going to put in your car, do those measurements to ensure the air gap is correct!!
Setting the correct gap between the face of the throwout bearing and the fingers of the clutch is a typical part of the process. As the clutch wears the fingers will extend outward, which is why they typically recommend a 1/8" (0.125") gap. For aftermarket "race" type HRBs this distance is set with the throwout bearing fully compressed. I'm using a twin disc Tilton with a Tilton adjustable throwout bearing and needed a .400" spacer behind the mounting plate to ensure I had plenty of thread engagement on the adjustment sleeve when the bearing was set to the right location.

I'm working from memory, but I believe the OE S550 clutch master cylinder bore is 3/4". You shouldn't over-stroke the GT500 release bearing with a stock clutch master, because the 2013/2014 GT500 had a 13/16" clutch master bore diameter with the same master piston travel, so the available throw on that release bearing should accommodate more fluid volume not less. This is assuming the clutch pedal ratio/master cylinder stroke is the same, which I haven't found anything to suggest the GT500 had a different clutch pedal stroke, just a larger bore MC and a shorter HRB to accommodate the factory twin disc clutch.

So your clutch wasn't disengaging adequately for two reasons, throwout bearing height, and available throw length with the GT500 release bearing and your 3/4" bore CMC. Since aftermarket dual disc clutches tend not to need a ton of throw to disengage, you'd probably be fine with the GT500 throwout bearing so long as it's set to the correct height.

The reason the OE S550 throwout can and has been used successfully with the Tremec swap and a dual disc clutch is because it's taller to begin with. The OE slave also has an extension spring and is designed as a constant-contact throwout bearing, so once bled it'll press up against the fingers of the clutch just slightly without being enough to disengage it.

I'm curious how you came to the 0.450" spacer thickness, with an OE style (GT500) slave. Did you measure the bellhousing depth, minus the clutch height, then subtract the compressed HRB height?
 
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J17GT

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Thanks for the additional insight @aleccolin. So if I wasn't over extending the HRB, then why did it fail so quickly? McLeod was certain I over extended it which is why it failed on the second WOT shift.
 

aleccolin

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Yeah guessing it was nearly fully extended when in place, so that would make sense. If that's true, the .450" spacer would compress the throwout into somewhere in the middle of its range when installed. Where that actually puts your engagement point in the throw of the clutch lever is the question.

Edit: I take back that last statement, so long as it operates between it's min and max through the full pedal travel, once bled it should have the same engagement character regardless.
 
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aleccolin

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Random unnecessary info. I run the Ram pedal adjuster and a dry break fitting to allow me to dial in pedal engagement and allow for easy trans removal without having to bleed it all the time. Ran this setup for 3 years ~50k miles with minor issues.
Okay so this Ram (78300) doohickey is new to me, but apparently has been around for a while. Cool concept, kind of a hydraulic blowoff valve, and given that I've got a good bit more throw than needed to actuate my clutch (as do most people with a twin disk and stock CMC), this could be a good option to both shorten that throw and make it more comfortable to drive.
 

Ruiner46

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@J17GT I finished up my car today and got it out of the garage for the first time in 6 months. For what it's worth, my car with the same setup doesn't seem to have an issue. I didn't measure or anything, but I can easily get into any gear and downshift to 2nd, etc without notchiness. My clutch pedal also grabs about mid-travel, maybe a slight amount closer to the floor, but not right at the floor or anything like that. Maybe I got lucky? I was curious which model of T56 you have. I have the model with 2.66 first gear, but with the 0.80/0.63 5th/6th. Seems weird that there would be different slave mounting depths for different models...

Thinking about this some more, the kit we bought is for the GT500. GT500 has a TR6060 trans, and I assume the engine block/crank side is all the same. So any difference would have to be in the bellhousing and transmission between TR6060 and Magnum. I'm curious if GT500 guys ever swap to a Magnum and use the factory slave.

Anyway, we'll see if I blow mine up at some point. If so, I will take measurements and post results, but I think I'm going to leave it alone for now.
 

J17GT

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@Ruiner46 Great news your car is back on the road! It sounds like your setup is just fine with the clutch engagement.

I was able to find one guy on SVTPerformance forum that put a Magnum in his GT500 car with a McLeod RST and needed a shim of just over half an inch. But it does seem most just install and go without any issues.

My Magnum is the wide ratio 2.97 first gear setup. Maybe there is a different with the close vs wide ratio? I’d be curious to know the measurement of the slave mounting point to the face of the bell housing on a 2.66 trans. I did measure from the tip of the input shaft to the face of the bell housing on my Magnum and broken MT82. That measurement was the same, so I’m confident the bell housing is correct.

My shim arrived from McLeod yesterday along with my clutch that was cleaned up and balanced. My plan is to install the flywheel, clutch and bell housing on the car and take my ‘A’ measurement again. Then take the ‘B’ measurement on the trans with the shim installed. Just wanting to validate my numbers one more time and report back to McLeod to get the green light before I wrestle the trans back into the car. It’s freezing cold here in Chicagoland, so I need some decent weather too!

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biminiLX

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I have installed a Magnum in my ‘14 GT500 and the 2.66/2.97 is identical except for internal gear ratio.
I used a stock slave with minor shimming.
To those installing without those critical measurements, big caution.
I’d definitely consider it an absolute requirement.
The Tremec is so much better than an MT82, it’s worth the effort!
-J
 

illtal

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I have installed a Magnum in my ‘14 GT500 and the 2.66/2.97 is identical except for internal gear ratio.
I used a stock slave with minor shimming.
To those installing without those critical measurements, big caution.
I’d definitely consider it an absolute requirement.
The Tremec is so much better than an MT82, it’s worth the effort!
-J
Dunno, Calimer has the MT82-D4 has a rating of 2000 HP that's the way I'm going, seems like these swaps have a lot to manage.
 

biminiLX

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Dunno, Calimer has the MT82-D4 has a rating of 2000 HP that's the way I'm going, seems like these swaps have a lot to manage.
Sure you can make it work but when 99% of fast manual guys run Tremec that should tell you something.
I do respect Ben and his products. I almost bought a stage 2 Mt82 for my dads Boss LS but we sold it.
Only reason to stay MT82 is for convenience or originality.
-J
 

J17GT

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No SFI approved bellhousing for the MT82 so it will not work for serious racers. I also can't stand the MT82 gear ratios personally, including the Stage 3 with the g-force gearsets.
 

aleccolin

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Setting up a trans with an integral bellhousing like the MT82 with an aftermarket dual disc or similar clutch still requires you to take measurements to ensure the hydraulic release bearing is located correctly. Just one of the things that comes with the design. Generally I prefer an external slave with a fork and TO bearing, but that has disadvantages too.
 

 
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