Tilton Clutch

Real tech discussion on design, fabrication, testing, development of custom or adapted parts for Pontiac Fieros. Not questions about the power a CAI will give.

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Kohburn
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Post by Kohburn »

fabbing a slave by welding stainless together, machining a plunger (piston) with grooves for O-rings, and you'll eb set - super easy.. GM is th only company I know of that uses the umbrella seal
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Post by The Dark Side of Will »

Took some more measurements today.

The max clearance inside the transmission from the crank flange to the part of the case covering the output shaft is ~2.425".

According to http://www.tiltonracing.com/pdfs/82.pdf the distance from the button flywheel friction surface to the tips of the bolts on top of the clutch is 1.98". Making the button 0.400" thick leaves 0.045 clearance between the clutch and the transmission case. The bolts can be cut down to be flush with their nuts, freeing up an extra ~0.060 and allowing up to 0.450" button thickness. The bolts *may* be reversible so that the nuts would stay on the inside, but I'll have to get one in my hands to figure that out.

In order to fit a button this thin, I will have to bore a N* or V6 flexplate to the OD of the button and weld the remaining outer ring of the flexplate to the OD of the button. Oh well... the finished product will have lower MOI than it would by stacking a button on top of the flexplate.

The flywheel bolts can protrude above the friction surface by about 0.050 so long as they stay within the 5" ID of the friction material on the disks. ARP makes flywheel/flexplate bolts with thin heads. I'll have to see what they have in the way of 8x1.25 bolts. The N* crank flange is 0.575 thick and I know from experience that I want as little protrusion as possible beyond it. The factory bolts have a head thickness of 0.175, which means that the counterbores would have to be 0.125 deep. With a 0.450 thick button, this leaves 0.325 after the counterbore. 0.325 + 0.575 = 0.900 or about 23mm would be the best bolt length in that case.

I ordered a 62-002-5 Tilton TOB from Summit. I disassembled a stock Fiero TOB and may be able to use the housing with a small custom sleeve to fit the Tilton unit where it has to go... which is about 5/8" closer to the crank flange than the stock TOB sits.
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Post by The Dark Side of Will »

Kohburn wrote:fabbing a slave by welding stainless together, machining a plunger (piston) with grooves for O-rings, and you'll eb set - super easy.. GM is th only company I know of that uses the umbrella seal
I'm probably just going to machine it. I can turn something from bar stock for the cylinder and similarly for the piston, then drop into a counterbore in a new slave bracket and retain with snap ring on opposite side. Fitting & bleeder will tap directly into the cylinder. The new bracket would be lasered out on should only require machining the counterbore, and maybe drilling the bolt holes that are smaller than the thickness of the plate. The only welding necessary will be to weld the shift cable bracket from Rodney Dickman's ultimate shift linkage onto the new slave bracket.
Last edited by The Dark Side of Will on Thu Jun 08, 2006 8:07 am, edited 1 time in total.
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Post by The Dark Side of Will »

Oh yeah... the mounting surface for the pressure plate is NOT flush with the friction surface. The mounting surface needs to be 0.100 below the friction surface, which means that the material into which the 5/16 clutch bolts are threaded is 0.100 thinner than the button. For a 0.450 button, this section is 0.350, which is thick enough for a 5/16" bolt... barely.

Overall, this project is going to be as much of a miracle of automotive packaging as getting the engine into the car in the first place...
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Post by The Dark Side of Will »

Got the Tilton TOB to look at. Pics when I find my dam camera. It's a bit different than I thought.
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Post by coinball »

obviously i'm a little late on this topic, but Will I ran the QM setup on a 4spd in my fiero before I wrecked it. roughly 1500miles and the fingers on the TOB fork were fine. my brother put another 3-4k miles on the clutch before he roasted the copper disks. no noticeable wear on the fingers.

I have 1 of the 3 remaining QM TOB's in existence...if you need pics or anything.
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Post by The Dark Side of Will »

Pics of that would be nice. Is that the same round faced Fiero style TOB that Cali Kid has?
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Post by coinball »

yea i believe they are similar. is cali kid using a 4spd? i know this TOB is 4spd specific, but it has the radiused face and is about 3/4" longer than a stock TOB (to make up for the shorter stacked height, obviously).

i should have pics sometime tomorrow for you.
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Post by Series8217 »

coinball wrote:yea i believe they are similar. is cali kid using a 4spd? i know this TOB is 4spd specific, but it has the radiused face and is about 3/4" longer than a stock TOB (to make up for the shorter stacked height, obviously).

i should have pics sometime tomorrow for you.
Will and Cali Kid are both running the 5-speed Getrag.. different throwout bearing..
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Post by The Dark Side of Will »

Yeah... CK found some strange oddity of NSK manufacturing to use in his transmission. I tracked down an example of that P/N and it looked just like every other TOB I've ever seen come out of a 282.
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Post by The Dark Side of Will »

Got a trans case into the shop and put it on a surface plate today... 2.422 instead of 2.425... dam, my eyeball is calibrated well. 2.420 should probably be the design dimension.
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Post by The Dark Side of Will »

Quartermaster clutches:
http://www.racingclutches.com/~rclutch/ ... _Guide.pdf

506630 is listed as "FLYWHEEL PONTIAC FIERO 7.25". I guess that's what coinage has.

296626 and 296630 are listed in his application list as 2 disk clutches for 1 x 14 spline.

236626 is listed as "RELEASE BEARING FIERO L-4" (probably just means for the Muncie 4 speed).

296626 is still listed in the current application guide under "2 Disc 7.25 Pro-series clutch and flywheel" as "Clutch Pontiac L-4 7.25 1x14".

296630 isn't listed in the current app guide.

I wonder if any of these parts are actually still available.

Anybody know how the crank bolt patterns and flywheel pilot diameters compare from the Iron Duck to the 2.8?
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Post by The Dark Side of Will »

I was looking around the QM website and found these:

http://www.racingclutches.com/product.p ... cat_key=52

Tilton only lists 153 and 168 tooth Chevy flywheels, but it looks like, judging by this listing and Coinage's post on Old Europe that I can buy a bolt-on 142 tooth ring gear from QM. Holy cow, that makes building this clutch setup a LOT easier. I need to get the mounting bolt circle for that piece...
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Post by Indy »

You'll have to be a little careful here. The QM ring gear in that listing mount on the outbd side of the clutch cover. They're almost invariably used with QM's bellhousings with trans-side starter mount. For the 7.25" clutches, this is a 7.875" x 6 BC.

Oh yeah...From what I just measured, the Duke pilot diameter on the FW is 1.500". Crank BC looks like 2.325+-.010, six bolt.

I'm planning on using either a Fiero ring gear shrunk onto a billet center section, or the stock Fiero 2.5 FW with almost all of the structure milled away, and expanded out to the 6.080" BC needed for the 5.5 clutch. Unless you want to help me figure out where to mount the starter on the trans :thumbleft: The motive is there. If you want a REAL reduction in MOI, move that heavy ring gear further in.
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Post by The Dark Side of Will »

I stole this from a post Coinage made on the "other forum":

Image

The flywheel is still listed in the QM applications list, so it at least formerly was available. I was going to make a setup like that by boring a V6 flexplate, but if that QM part is cheap enough (yeah right) I might be able to use it instead, if I can get everything to stack up inside a 282 bellhousing. There might not be enough room for thread engagement with everything in the stack.

The Tilton also uses a 6 x 7.875 bolt circle, so that matches.

Getting rid of the flywheel mass at the large radius is the lion's share of the reduction in MOI. In his LS4 thread on Pfiffle, Jon Lagler says that he's got a fixture for machining Fiero transmission cases for welding on a starter mounting plate. I don't doubt that the space can be found, but it would definitely be snug.
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Post by The Dark Side of Will »

Really good info on MOI and some testing to demonstrate how huge the effect of MOI is on dynamic power output:

http://www.popularhotrodding.com/featur ... index.html

http://www.stockcarracing.com/techartic ... index.html

http://www.superstang.com/horsepower.htm

The Mustang in David Vizard's longer article put down 85 fewer HP and 140 fewer ftlbs in 1st than in 4th. This 85 HP difference is ALL due to MOI. I think that 50 HP of that is accessible through the installation of a very light clutch & flywheel.
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Re: Tilton Clutch

Post by The Dark Side of Will »

A little more info: The ID of the clutch friction material on a Tilton is 5.12 (130mm).
The Northstar crank bolt circle appears to be 8 x 78mm.
Assuming 15mm bolt heads for a worst case, the worst case dimension across the extrema of the heads would be ~95 mm, which is well within the 130 mm limit imposed by the friction material. The bolt heads can be up to .100 proud of the flywheel's friction surface.
The overall OD of the clutch is 8.5 inches.
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Re: Tilton Clutch

Post by Series8217 »

Chris West is running a Tilton 7.5" or 8.5" (I think it's the former, but I'm not sure) clutch on his Aurora V8 (same as a Northstar). It is a twin disk setup with a specially modified pressure plate so he can use it with the NSX transmission. I have no idea if the setup would fit in a Getrag bellhousing, but it certainly fits on the motor!

The throttle response is fantastic (I've driven the car), and it's not quite as touchy as I expected, but it's definitely not for traffic.
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Re: Tilton Clutch

Post by Datsun1973 »

Will did you ever finish this clutch setup?
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Re: Tilton Clutch

Post by The Dark Side of Will »

Not yet. I have the engine running at last, but had to go to Iraq. I'm in Ali Al Salem, Kuwait right now waiting for a flight back to Baghdad. Dust storms are causing flights to be cancelled, so I'm stuck in purgatory for a few days.
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