RXT clutch with Spec flywheel?

[Champale]

Hey guys,

Looks like I am going with an RXT to try to solve my high rpm lockout issues which the Spec Stg 1 clutch and Spec alloy flywheel didn't fix at all. Does anyone know if the RXT will work with a Spec flywheel? I spoke to McLeod today and they weren't sure.

This is the flywheel I have:
https://lmr.com/item/SPC-SF50A-9/Spec-Mustang-Aluminum-Flywheel-11-14-50-SF50A-9

Thank you in advance.

John

 

[VoodooBoss]

I'm not sure. If your car is driven on the street a fair amount I'd go with the RST. I had the RXT and while it got better after breaking in after a couple of thousand miles it still sucked driving in on the street. I've driven a Boss with the RST and it engages much smoother. How many track days a year are you doing in your Boss?

 

[2012-Boss]

If it is not to late, I would recommend the Exedy Hyper Single if this is a track car. There are a few members on the board who have had problems with the McLeod pressure plates. The Exedy, on the other hand has been run in PWC for years. I have run both the RXT and currently the Exedy. I prefer the Exedy, it is quiet and has a much smoother engagement than the RXT, but higher pedal effort.

 

[Flyboygsxr]

I have the RST and so far I love it. It shifts just as easy at 7500RPM as it does at 2000RPM. It chatters a little bit and is almost like an on off switch so you have to get used to it. Getting the clutch to engage slowly isn't easy but it's slowly getting better. I would definitely recommend it still.

 

[Champale]

Oh man you guys are making my head spin with alternatives! No trackdays, just me beating on it a few times/month when I have a chance to pull it out of the garage. Rev limit currently set at 7900 with AED tune.

[email protected] recommended the RXT despite me telling them that car will remain naturally aspirated (more profit in an RXT?). This is part of his email reply and then I actually called him this afternoon to follow up.

"The RXT is a great street clutch in that it has very smooth engagement without a hard pedal feel.

The floater plate is strapped so it is not a noisy clutch either.

The discs are line with a Miba lining which is excellent for occasional track use.

The RXT is rated to 1000 HP.

If you are looking for a full race clutch, we also have those available."

Chatter doesn't bother me too much since it's not a DD and the Spec has some chatter anyway (and I have owned several dry clutch Ducatis so I know chatter!). The Exedy is crazy expensive, right??

Thank you for the input guys. Still leaning toward an RXT or RST but just need to see if I need yet another flywheel.

 

[BigTaco]

The Hypersingle works out to be about the same if not cheaper. It also has a sprung clutch disc which makes it easier on the trans and nicer to live with.

 

[VoodooBoss]

My friend, neighbor and member YoPauly put the RST in his Boss and beats on it pretty good at the track and no issues. It solved his high RPM lock out issues. McLeod told me the same thing and I went with the RXT. I'm telling you it ruined driving my car on the street. You've been warned!

 

[Champale]

Hah got it, Rick! This whole high rpm shifting issue will be on my gravestone. "He Lived a Full Life, But Never Did Get to Bang 7800RPM Shifts".

Does anyone have a part number for the Exedy so I can cross-shop it?

 

[BigTaco]

EH06SD1 Is the Exedy part number. That's the full kit with flywheel sans throw out bearing.
It includes flywheel bolts and hardware. Just no throw out bearing.
Call:

Matt Korczyk
Parts Sales
KohR Motorsports
Phone: 734-895-1543
Fax: 734-895-1587
[email protected]


The are the only vendor that I know of that stocks this part number for 23 spline Boss 302s

 

[Sydewaysix]

EH06SD1 Is the Exedy part number. That's the full kit with flywheel sans throw out bearing.
It includes flywheel bolts and hardware. Just no throw out bearing.
Call:

Matt Korczyk
Parts Sales
KohR Motorsports
Phone: 734-895-1543
Fax: 734-895-1587
[email protected]


The are the only vendor that I know of that stocks this part number for 23 spline Boss 302s

@BigTaco - How does this Exedy setup compare to the ACE clutch that you were talking about the other day? I see that you prefer the Exedy over the RST/RXT setup, but from your research, is the Exedy equivalent to ACE?

 

[TMSBOSS]

I run the RST on the street and the track. Smith shifts at 7500.

The RST has a softer engagement than the RXT with the fiber discs. One disc also have a spring hub.

 

[Champale]

BigTaco - thank you very much! I will check in with them. Now I just need to go sell some blood to pay for it.

TMSBoss and FlyboyGSXR - did you have shift lockout issues with your stock clutch? I have all of the usual mods - WL bushing, MGW (1st gen), stainless clutch line, Blowfish bracket - and even with the Spec clutch and alloy flywheel, I simply cannot get it to shift into gear above 7k rpm without waiting a second or two. It doesn't grind, just locks me out.

 

[Mad Hatter]

It could be that your tranny already is compromised. I had the same problem as you until I changed to a Ben Calimer stage one gearbox. I also switched at the same time to a spec setup and since then I can shift at 7500 rpm as fast as I can with no lockout issues at all.

But that was after killing three trannys...... Its been a while now with over track 15 events with zero problems on the Calimer box. Having a fast shifting transmission brought down my track times.

Removing the helper spring, better mt82, better clutch and better shifter are all good moves. Hopefully all together

 

[TMSBOSS]

Yes. Mid had lockout from day one. First fix was the MGW shifter. This did help immensely but did not solve lockout issues.
In order of install:
MGW
Stainless braided clutch line
Upgrade to 1st gen MGW
RST clutch

Once the RST went in all shifting issues were gone.

The MGW eliminated about 70% of the issues. The clutch line....none. Only buy if heat from long tubes are in your future.

After the RST was installed the overall effort needed to shift decreased greatly. I assume the RST allowed the syncros to do their job more efficiently by decreasing inertia/weight.

Yes, I am very pleased with the RST. You will need to adjust to the decrease in pedal effort.

 

[2012-Boss]

Hey guys,

Looks like I am going with an RXT to try to solve my high rpm lockout issues which the Spec Stg 1 clutch and Spec alloy flywheel didn't fix at all. Does anyone know if the RXT will work with a Spec flywheel? I spoke to McLeod today and they weren't sure.

This is the flywheel I have:
https://lmr.com/item/SPC-SF50A-9/Spec-Mustang-Aluminum-Flywheel-11-14-50-SF50A-9

Thank you in advance.

John

I did not directly answer your question. No, you need to pair the RXT / RST with a McLeod flywheel. Most of the aftermarket clutches for our car are designed for a specific flywheel offered by the clutch manufacturer.

 

[2012-Boss]

Oh man you guys are making my head spin with alternatives! No trackdays, just me beating on it a few times/month when I have a chance to pull it out of the garage. Rev limit currently set at 7900 with AED tune.

[email protected] recommended the RXT despite me telling them that car will remain naturally aspirated (more profit in an RXT?). This is part of his email reply and then I actually called him this afternoon to follow up.

"The RXT is a great street clutch in that it has very smooth engagement without a hard pedal feel.

The floater plate is strapped so it is not a noisy clutch either.

The discs are line with a Miba lining which is excellent for occasional track use.

The RXT is rated to 1000 HP.

If you are looking for a full race clutch, we also have those available."

Chatter doesn't bother me too much since it's not a DD and the Spec has some chatter anyway (and I have owned several dry clutch Ducatis so I know chatter!). The Exedy is crazy expensive, right??

Thank you for the input guys. Still leaning toward an RXT or RST but just need to see if I need yet another flywheel.

The Exedy Hyper Single is not anymore expensive than a complete RXT with the correct flywheel if you look for a deal / sale.

You can buy the Exedy from Kohr for $1,329.00. The Exedy kit contains the clutch, pressure plate, and lightened steel flywheel. I got lucky and purchased my Exedy on sale for around $1,100 shipped.

The RXT clutch and pressure plate is $899.95 from JPC plus another $279.99 for the steel flywheel, so around $1,179.94 total.

Having said that and understanding your intended use better, I have to change my recommendation to either the RXT or RST. The RXT / RST chatter, but for a street car the pedal effort is a lot lighter than the Exedy. I would not want to be stuck in traffic with my current clutch. The McLeod clutches will hold up fine for street, drag strip, and occasional road coarse use. For a dedicated track day or race car, then the Exedy.

 

[BigTaco]

@BigTaco - How does this Exedy setup compare to the ACE clutch that you were talking about the other day? I see that you prefer the Exedy over the RST/RXT setup, but from your research, is the Exedy equivalent to ACE?

Not to be cryptic, but I wouldn't say at this point that I prefer one over the other. I need to do my homework with regards to the ACE clutches to find out how they are to live with on the street every day. I plan on talking ACE about this clutch when I'm out at SEMA in about a month.I'm not a track rat (at this point anyway ) so I am looking for the most durable/street able option.

The Hypersingle is a really cool unit that has a forged aluminum cover/pressure plate that is lighter and stiffer than a OEM style pressure plate. The stiffer cover does not flex and has a really great engagement feel that is very consistent. It's also a little lighter that the stock unit so that would free up some power and help the engine rev faster (higher RPM sooner) without giving up street manners. These clutches have been proven in WC racing where they are beat to death. In truth, I would probably be very happy with this clutch.

The McLeod offerings (RST/RXT) are proven to have great durability and holding power. The pedal pressure is soft (I really dig that) A RST/RXT with an aluminum flywheel is 37LBS so you get a lower MOI (Moment of inertia). There are some hardcore racers that have had great success with this clutch. One person raced it hard for 2 seasons before it gave up the ghost. I kind of complained about the clutch failing but 2 complete seasons is really nothing to sneeze at. My problem with McLeod is that they don't have sprung hubs. This will transfer more noise and wear down your transmission faster. The springs actually absorb and dampen driveline vibration/shock. I know someone who had the RXT installed and with the graby/aggressive compound, he felt it actually ruined the car for him (with regards to street manners). In addition, I spoke to McLeod about their Street Extreme clutch that was installed on a car that was featured on this site. This clutch is a single disc, sprung hub unit that apparently has great street manners. They advised against using this clutch. I was baffled by this. It strikes me as strange when a MFG makes a product for specific applications and then advises against purchasing them. To be honest, this turned me off. It raises more questions that it answers for me.

Another clutch that looked promising to me is made by Quarter Master. It's the Optimum SR single disc unit. It has a rigid aluminum cover, lower MOI, and is completely rebuild able. I have not been able to find anyone how has this installed. The price is +$2500.00 for the unit. It's complete with hardware and flywheel but is a grand more than anything else on the market. It may be a great clutch but at that price, I don't want to be the first one to give it a try.

The ACE Powerforce clutches are new to the street market. The company is not. They have specialized in drag racing clutches (Pro stock for example). The ACE company has been making heavy duty clutches for over the road tractor trailer rigs since the 60s. They have in house CNC manufacturing and a very comprehensive R&D strategy.

The Powerforce clutch is really unique in the way it uses levers to take advantage of centrifugal force that swing out as RPM increases and presses the pressure plate harder against the clutch disc. This is done completely different way the Centerforce does it with weights on the fingers of the pressure plate spring. The unit is made entirely of aluminum and is completely rebuild able. The clutch discs are sprung and the friction material is their own "blend" made in house. It is claimed to be smooth on the street, aggressive enough for the track, and does not require break in. These clutches are available re-branded through Shelby and Hays. I'm really intrigued by this clutch.

My whole reason for even looking at clutches is due to the fact that at high RPM, the pedal stays low to the floor and the trans locks me out of gear. It's not every time and I have never ever forced the trans into gear. It just ruins the whole experience for me during spirited driving. Ford has offered to replace my clutch but they will just install the same POS. Lather, Rinse, Repeat.......

The next clutch going into this car needs to address all of my concerns so that I can just install, forget about it, and enjoy driving my car.

If you don't have any of these symptoms (high rpm lockout, pedal on the floor), then the clutch is a non-issue.

That being said, it comes down to what the end user is looking for.

At this point I'm leaning towards ACE........

 

[Mad Hatter]

The other day at the track I fell in Love with my Spec 2+ clutch. I was coming out of a a fast corner in third at 7500rpm and I made a quick shift to fourth, I spun the wheels and the car took off like a bat out of hell. Its a little bit jerky on the street when new but the price is very nice compared to the other twin disc options. I only have 403 rwhp but I can keep up with ZL1's now.

I think the spec2+ is a excellent, very affordable street/track option.

 

[Champale]

Wow excellent posts and information, guys! This is exactly the kind of information I am looking for.

I spoke to the Mustang shop that installed my Spec (Maximum Velocity in San Antonio) and he thinks the RST is probably the best option. He says most guys jump straight to the RXT (he mainly does GT500s these days) because they are going for big power but the RSTs are a really good option for my needs and should not have any high rpm issues.

He was unfamiliar with the Exedy Hypersingle but he said that they typically make excellent products.

My fear, of course, is that I spend all of this money on whatever clutch setup and I still have the high rpm lockout. The idea of spending $1400 on a clutch plus labor and it still not work right is keeping me researching. The Hypersingle is intriguing because it is such a proven product. A slightly stiff clutch pedal doesn't bother me since my Spec is comically heavy - most people get in and say "you have got to be kidding me!". This is after two new Exedy slaves and two bleedings.

Thank you guys. Anyone else have any comments?

 

[Flyboygsxr]

I am more than please with my RST. It is the single best modification I have done to the car. Zero RPM lockout issues since being installed and I do track my car. It's been tried and proven and so far no regrets with my decision. One thing I would do differently is leave the stock clutch line. It's formed to fit properly in the car and it will outlast any aftermarket line. The after market braided line I got leaked a few months after install eating away some of the paint in the engine compartment. Unless you have headers I would stick with the stock unit. It's not a rubber line like some said, it's actually a hard line and it has nothing to do with the high RPM lockout. Good luck in your choice