Spec Clutch

After trying to pick up with Gripforce where Robstah left off, I was getting nowhere fast. I was cruising the net looking for options when I came across Spec Clutch. On thier website they note a bunch of conversion clutch options. Unfortunitly none of the options were populated with data. I contacted them directly to find out what they could do for the 944 conversion. It turns out that one of the guys there is doing a 1987 951 conversion of his own!

In his email he writes:
"We already make a complete setup. I have an ’87 951 with a 402ci LS2. I have been providing this for many conversion builders." "All of our LS1 stages are available. If you will let me know where you will drive the car and what mods you plan to make to the engine (and transaxle if any) , I will make a recommendation as to which setup will best suit your build. I offer 7 single disc options and 6 multidisc options."

The person I have been trading email with is David Norton [You must be registered and logged in to see this link.] .

The reason I chose Gripforce was to hopefully retain the C5 stock clutch engagement feel and wear. Plus, does Spec provide a flywheel and pressure plate to match all around the price I mentioned?

I've had a few friends try to run Spec clutches but so far, it has yet to be worthwhile.

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Check out that thread. Most of the guys who have used Spec clutches have around the same power as we will have (300ft/lbs to 450ft/lbs) and most of them did not have any luck with them. Not that I am saying that a Spec clutch setup will not work, I just prefer to not have to deal with a pain of a clutch while driving.

I have never used them myself. And personally dont know anyone that has so the info from the other forum is interesting to read. FWIW, that thread is 2 years old. I cant believe that these guys could still be in biz if thier stuff is all grabage. Anyone on this forum have direct experience with them?

Here is a little more from David @ Spec:
"I like the stage 2 regardless of how stock your engine may remain. The st2 is very smooth/easy to drive, wears very well and will take the abuses of 550+ engine tq should you ever change your mind. I recommend lighter parts regardless of power level, as you will benefit from ‘free’ hp gains, throttle response and the lighter parts are easier on the driveline components and engine internals. Most 944/LS1 simply use the billet aluminum flywheel and stage 2 clutch. We also offer a stock appearing aluminum pressure plate option that makes the pressure plate rebuildable like the flywheel and drops 8lbs from the assembly. Or, if you need this to be a budget build, simply use our billet steel flywheel and standard st2 clutch."

BTW, when I pulled the transmission apart from my engine, There was a spec clutch, stage 3, set up in there. It looks like it was well used, almost down to the rivets.

Sooooo, I Dont Know???

Gripforce was offering a _very_ reasonable price, but they're not really setup for custom jobs and seem "out to lunch" on the subject. Spec's prices compared to Gripforce are much higher for the same components.

Just for comparison:
- Gripforce C5 kit, PP, FW, DISC - $313 on ebay.com.
- Spec C5 "kit", PP, FW, DISC - $558 on specclutch.com.
- Renegade Hybrids, kevlar disc - $355.
- Old 944 clutch disc - Free or $100 used on ebay.

One could buy the gripforce C5 kit on ebay throw the disc in the trash and have several hundred to spend before you reach their stock application C5 pricing for their most basic kit.

Two options jump out at me:

1) Gripforce C5 kit for $313 + RH disc for $355 - total $668
2) Gripforce C5 kit for $313 + Mopar disc for ~$100 - total ~$413

I just called gripforce again, Gregory is in a meeting. I started mentioning multiple clutch sales, and we're going to their competition because we can't get ahold of him, and they may lose opportunities here... The lady I spoke with seemed concerned when I started talking about Spec Clutches and multiple sales. ...took my number (again) and said she'd try to get him to call me back today.

We shall see. A matched kit from Gripforce for $405 with correct splines (which is what was discussed with them) would rock, and I could stop thinking about it!

Those with high HP numbers or LS3 engines might want a high end clutch, but I just need some bread and butter here.

Likewise. I called today also. It was looking promissing last week but no followup from them this week.

Endernet: FYI the price I shared with you was for a stage 2 set up with steel billet flywheel (as discussed in my earlier email in this thread). I would assume that a standard stage 1 woudl be less? Probably in your sweet spot?

Spec has a good reputation as far as i know. In fact, that's what i assumed RH was selling me... (Could that be what "we've been selling a lot for conversions" means?)

Those with high HP numbers or LS3 engines

You talkin' to me? .......You must be talkin' to me!

I just went with factory stock parts. The flywheel is the stock unit and the clutch disc is the factory LuK piece. Would love to find a 11-7/16 23 spline disc oh boy would I.

Bluemach1 wrote:Likewise. I called today also. It was looking promissing last week but no followup from them this week.

Endernet: FYI the price I shared with you was for a stage 2 set up with steel billet flywheel (as discussed in my earlier email in this thread). I would assume that a standard stage 1 woudl be less? Probably in your sweet spot?

I'd be happy with $405 for a complete kit, especially if the splines are correct and the plate is designed for our use.

I've also wondered how much a machine shop would charge to modify a C5 disc, or maybe make a machine-fit adapter we could put in a stock plate, possibly even re-use. I don't know the dimensions involved or if machining a disc hub is doable.

Clutches are expensive, but....get a cheap one and you'll be ssssooooorrrrrrrrrrrryyyyy.......

944-LT1 wrote:

Those with high HP numbers or LS3 engines

You talkin' to me? .......You must be talkin' to me!

I just went with factory stock parts. The flywheel is the stock unit and the clutch disc is the factory LuK piece. Would love to find a 11-7/16 23 spline disc oh boy would I.

The flywheel and pressure plate should be stock from Gripforce. Outside of that, I am pretty sure the clutch is a correct spline 11-7/16 if not 11-5/8 (basically proper spec for the flywheel and pressure plate). You can't argue with $405 especially when it comes with the proper clutch disk with the correct porsche spline.

As for my involvement in the matter, Gripforce maybe waiting for me to talk to them, since I did set up the group buy for these things. I'll try to get a hold of them as well here soon. I've been pretty swamped with a couple of things and will have the money coming in next week for my clutch kit at least. I'll see if I can push them into it. So far, it looks like we have at least 3-4 people interested in this and we need 5 for the 375 group buy discount. If anything, I may order two just to finish the group buy and then try and sell the 2nd one off to someone. We will see.

Just got this note from David @ Spec: (his o.t.l. statement is referring to spec)

I see. Wow.. 'out to lunch ' on the subject...that's not good. Let me elaborate a bit further on our options. The statement 'Spec's prices compared to Gripforce are much higher for the same components.' can't be further from the truth. They are not the same components. SPEC manufactures in house and our LS1 components are purpose built from scratch, not modified or stock OE components. Changing the clutch on a converison 944 is not easy, so I would warn against installing inexpensive products. That does not mean everyone needs a precision machined kit like the one I quoted you. But you will experience superior drivability, wear life, performance and manufacturer support, which is worth something.

I have disc only options, for those who have already purchased pressure plates and flywheels. Any of our top line custom performance disc stages can be purchased a la carte, most under $299.

I also have more stock-like options. We have a sister company that manufactures higher end OE replacement components. I can offer one of their kits, which is still stronger than OE, for high 200's.

There are a couple of issues with LS1 conversions that must be considered. We have been building units for LSX's since 1997. Do NOT mix original equipment LS pressure plate and flywheel components without having the set balanced. LSX clutch and flywheels were balanced ONLY AS AN ASSEMBLY. The individual components are not balanced. Separating them creates an imbalance. Also, LS1/6 flywheels are deemed throw-away units by GM and Luk. They are not meant to be machined. If a used oe setup is used, 2 issues must be addressed. Due to lack of throw in the LS hydraulics, dropping the stackup by more than .015 can cause initial release issues. Secondly, the OE LS flywheel castings are porous. We have seen pitting just .010 under the surface. They also come new with a slight dish, so clutch seating , particularly with a performance clutch, takes longer if at all. In review, if a used factory flywheel setup is utlized , be sure the surface is like new , or it is worth purchasing a nice billet aftermarket. You'll spend that money fixing the OE unit or replacing it in the near future. Our billet steel flywheels are actually manufactured slightly thicker, so they can be machined multiple times without worrying about release. And our billet aluminum units are infinitely rebuildable, having replaceable steel friciton surfaces.

I would be happy to talk with everyone on the board about their builds. Please feel free to forward my emial address and extension (110). We have so many options and experience with these cars, it would be a pity not to take advantage of that, regardless of where they buy their clutch. Maybe tomorrow I can sign on.

I'm sorry but I find most of that hard to believe. He goes from talking about precision machined parts to talking about adjustments on a used flywheel, which is not the case with Gripforce at all. When has a clutch ever been precision machined? All a clutch is is just a certain material riveted onto a base properly setup for the flywheel and pressure plate for the car. All Gripforce is doing is spec'ing out the LSx clutch but with a different, proper hub. They deal with OE/OEM manufactures directly and push a lot of product, which explains the fairly low price. Don't let the price look inferior because it's 'cheap'. I've seen new clutch discs at Autozone go for 20 dollars. Saying a custom clutch at 150 dollars is cheap is saying a lot about a company that wants to charge you basically double that to 'insure quality'. So far I have heard mixed reviews on Spec and all I am looking for is a simple clutch kit (pressure plate/flywheel/custom clutch disc) that will work and is fairly priced. Knowing Spec, they will probably upsale you into a 1000-1500 dollar flywheel/pressure plate/clutch combo kit. I just don't have the money or the patience to have to worry about the clutch not working or lasting long in my car.

I know my little 5.3L should not have problems with a stock rated clutch disc, along with any stock rated motor, but if you are planning on pushing more power, I may actually recommend leaving the stock clutch in there, unless you plan to build up or replace transaxles all the time. If you do build up the transaxle and torque tube, then by all means start looking into Spec clutches for higher ft/lb ratings, but once again, you pay to play. To my understanding though, Gripforce has connections to build higher rated discs as well, so who knows.

I agree with robstah, when I first put my motor(LT1) in I used a stock 70's Camaro pressure plate and a stock Road Runner clutch disk, both were ordered from Autozone. My motor is, what I consider to be "Built", about 500hp at the crank, I never had a problem with the stock components. I did DESTROY two trans axles in a matter of about three weeks. Upon pulling the clutch and other parts out of my car, I found no damage to the clutch disk or pressure plate. If you plan to race your car all the time I say go for the expensive stuff, but if your going to make it a daily driver do just that.

What "expensive" stuff? If i'm not mistaken:

SPEC: We have a sister company that manufactures higher end OE replacement components. I can offer one of their kits, which is still stronger than OE, for high 200's.

I did a quick google on gripforce and came up with a LOT of bad reviews on Honda's, Subaru's, and others. It's an ebay brand...and if it craps out on you, you'll have to remove the entire motor to replace it! The salesman won't even call you back to sell 10 units, that should be your indicator right there.

I'm already set for a clutch, but i'm just sayin...

Spec got back to me with a reasonable offer. I'll likely be ordering a kit from them forthwith. I'll post a follow-up when I know more, or pm me for details if you can't wait.

EDIT: Good find Bluemach1.

did you end up with the stage 2 set up?

12" billet flywheel and stage2 disc

Placed my order today. It's a 12" upgrade from stock, supposed to fit in C5 BH, and it was 1/2k chickens before shipping (weight 52#). Billet fw, 12" disc and pplate, rated to carry 600hp. Should ship monday. Pictures and results of install to follow in the next couple weeks.

Well I got Spec's kit today. The disc is 11-7/8". The billet flywheel looks 100% better than what you'd find in a stock kit. I will be putting it shortly - have to pull the motor and fix the steering column clearance issue.

I know, pictures man, pictures, here they are:

What you get out of the box:

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What the kit contains:
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The splines are where the Porsche/GM magic happens:
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Cool. I like what I see!

I meant to get mine on order last week but I didnt get around to it.

I like it, I hope it holds up....

Has anyone installed one of these, yet? I just got one and it came with a spacer. Is it necessary to use it or do you have to measure first to see if it is needed?

Anthropraxis: you should check the post right below (mine)--someone just posted a good link to ls1tech on how to know when it's necessary.

I have one of these also. I recall that when I spoke with David Norton at Spec, that they recommend that you use the spacer because the 944 master cylinder may not have enough travel to release the hydraulic slave enough. Give them a call if you are questioning it. My experience has been very positive with these guys. very helpful.