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The GM HTOB

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260mgb Jim Nichols
Sequim,WA, USA   USA
Jim, Specs are different. The 10.4 for the 305 with T5 is shorter. I know about the older high finger issue. The high finger was meant for high performance, high RPM applications.



Edited 1 time(s). Last edit at 2017-06-18 04:05 PM by 260mgb.

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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
Yes, I agree, but the part number on RockAuto is the same for the '84 and '92 Camaro 305. I checked. It's the PP that I just unbolted from the flywheel, and the fingers stick out pretty much the same as the Hayes PP. See photo.

Jim


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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
This is definitely a bent-finger PP. In fact it looks like it may have more bend than the Hayes.

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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
I remember the old low-finger PP's. No bend in the diaphragm spring fingers at all, just a straight cone. They went nearly flat when it released, and could over-center. At the moment I'd love to find one of those. I have no problem using a pedal stop.

Jim

260mgb Jim Nichols
Sequim,WA, USA   USA
Ok, The parts houses want to simplify their stocking and use a shorter TOB, Another idea, 66 malibu straight six? Or redrill flywheel for the newer V6 pressure plate meant for the HTOB.

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
Rock auto shows yet again the 361675.

Jim

260mgb Jim Nichols
Sequim,WA, USA   USA
Jim, You may want to check your local auto parts store. I remember originally the bent diaphram was only used in Corvette and high performance applications.

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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
Yeah, the flat finger PP was the standard part up into the mid 60's, then everything changed over to the new design by the simple expedient of installing a 1/2" shorter TOB. I can remember doing just that myself. The old TOB had a rounded edge and the new one was flat.

Here's what I can't quite get my head around though: Why doesn't it work with the OEM HTOB???? I'm quite sure the 9-1/2" clutch was not the only thing used in front of all those T5's. But then again, I've not seen any applications for 10-1/2" clutches. I did see one 11", maybe it used the old flat finger PP? The bearing on these things DOES have a curved outer edge.

This is seriously weird. Maybe I'll have to look for a PP to fit a 55 Bel-Air with a 265? And hope it isn't a retrofit.

Bought two new ones already... 3rd time's the charm?

Jim

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
This just keeps getting better and better. Not.

So, as it turns out, the old flat finger pressure plate should work.... if they were available any more which apparently they are not. Makes sense though, everyone switched to the newer better part by just using a shorter TOB and the old setup gradually went away. Out of sight, out of mind. Even Dayton Clutch and U-joint doesn't have any of those old cores.

So maybe I could use the 9-1/2" PP and drill the flywheel? Well not quite. The clutch disc I got from Mike is 9-3/4" and the PP is too small. Good grief.

I did get some useful information. Bolted to the flywheel with no clutch disc (Fully worn out position) the stock 10-1/2" PP fingers sit 2-1/4" forward of the tranny flange of the bellhousing. (The Hayes is 2", fully clamped new disc measurement should be the same for both). The OEM HTOB measures 3" from the T5 bellhousing mounting flange so that right there is a bit of a problem.

So now what? I'm really beginning to think the old mechanical TOB is the best way, and deeply regretting ever attempting to consider the OEM HTOB. I know some of you use it and are happy with it. But for all practical purposes it seems to be limited to a 9-1/2" clutch.

But wait, didn't LS engines use this? So how? Probably a $pecial 11" clutch I imagine.

Anybody got a Buick cable operated bellhousing and clutch fork they'd like to sell? I'm about done here.

Jim

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V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
In reply to # 3535659 by Jim Blackwood

So maybe I could use the 9-1/2" PP and drill the flywheel? Well not quite. The clutch disc I got from Mike is 9-3/4" and the PP is too small.

So, slap that clutch disk on your lathe & cut it down. That is exactly what the local clutch & brake shop did for me many years ago. Cut down a Mercedes clutch to fit my S10 pressure plate.

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
That's a thought. So, take the flywheel back off, drill it for a smaller pressure plate, cut down the clutch disc to fit, slap it together, hope it works, and then go out and smoke the whole works. Yep, one heck of a plan there. I can see this will be totally worry free.

And this was supposed to be the simple solution.

Jim

DIPPY Avatar
DIPPY Bob Davis
La Mirada Cal, USA   USA
1975 MG MGB
1975 MG MGB
I HAVE A 2.8 LATE 80 WITH A STK CAMARO EARLY 80 v8 TRANNY

Works like a champ I do have a pedal stop easy squeeze and use dot 3

drilled and tapped the bleed port to a npt and used 90 elbows as the pic shows

and replaced the bearing retainer from Anaheim gear

ALL STK GM PARTS

LuK® 04-155 - RepSet™ Clutch Kit
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more details on - https://www.carid.com/luk/repset-clutch-kit-mpn-04-155.html

Stk camaro slave Dorman® CS360058 - Chevy Camaro 1998-2002 Clutch Slave Cylinder
stk skinny flywheel s10?

PEP BOYS

Rhino Pac New Clutch Flywheel

Part #: 167513

PRESSURE PLATE BOLT CIRCLE(IN.)10.551
RING GEAR OD (IN.)12.45
NUMBER OF TEETH 148
NUMBER OF CRANK HOLES 7
CRANK SURFACE TO PP SURFACE 0.811
CRANK CENTER HOLE DIA. (IN.)1.265
FLAT OR STEP Flat
DUAL MASS FLYWHEEL OR SOLID Solid
FLYWHEEL STEP (IN.)0
PP BOLT HOLE THREAD SIZE M8 X 1.25
PRESSURE PLATE BOLT PATTERN 6 Holes equally spaced
DOWEL PIN LOCATION No dowel pin



MAY ALL YOUR FUTURE ENDEAVORS BE PROSPEROUS

Bob Davis



Edited 1 time(s). Last edit at 2017-06-19 03:14 PM by DIPPY.


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DIPPY Avatar
DIPPY Bob Davis
La Mirada Cal, USA   USA
1975 MG MGB
1975 MG MGB
I dont think you can measure these unless they are bolted up to get right compression on springs



MAY ALL YOUR FUTURE ENDEAVORS BE PROSPEROUS

Bob Davis

scott68B Avatar
scott68B Scott Costanzo
Central, Ohio, USA   USA
1968 MG MGB "GM 5.3 LS4 V8"
Here's the details for the Howe 82876 - GM T5 HYDRAULIC THROW OUT BEARING:

Quote: Our T-5 throw out bearing has all of the same features and is based on the same design as our model number 82870. The base of the T-5 bearing is machined to fit the bearing retainer of the T-5 transmission. The compressed thickness is 1.513” and 2.048” fully extended for .536” of travel. The inner diameter of the throw out bearing is 1.379”. Does not fit Ford with 1.441 O.D. bearing retainer.

Would that work? $165 and you can use the stock master.

What did Mike Moor use? His has worked perfectly for about 80K and still going strong.

DIPPY Avatar
DIPPY Bob Davis
La Mirada Cal, USA   USA
1975 MG MGB
1975 MG MGB
i have 2 here you can have for all most nothing but the both need to be rebuilt plus a ram htob



MAY ALL YOUR FUTURE ENDEAVORS BE PROSPEROUS

Bob Davis


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