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HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

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Slipping Clutch
Posted by: HealeyRick
Date: August 15, 2018 02:31PM

My clutch has begun to slip in 3rd and 4th gear when I punch it. Ford 5.0 with T5Z transmission, Fidanza aluminum flywheel, Howe HTOB. 345 hp at the crank. Has always been fine with about 2000 miles on it. No abusive starts. Only thing I can think of is a HTOB problem. The clutch reservoir is full and no signs of leaks. Clutch engages and disengages fine, no problem shifting. All I can think of doing without disassembly is bleed the clutch. Maybe I can get a peek at what's going on through the clutch fork hole. Anyone got any good ideas before I pull the tranny?


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1032 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

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Re: Slipping Clutch
Posted by: ex-tyke
Date: August 15, 2018 06:34PM

If the HTOB has crapped out, surely there must be some fluid evidence somewhere in the vicinity of the braided supply line.
My only experience with HTOB leakage was caused by a bad O'ring at the banjo fitting..
If you have to remove the xsmn, do yourself a favour and replace that HTOB with an external slave - you'll thank me later!


kstevusa
kelly stevenson
Southern Middle Tennessee
(872 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

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Re: Slipping Clutch
Posted by: kstevusa
Date: August 15, 2018 07:49PM

Correct me if wrong, but a clutch slipping in top gears indicates the clutch is worn or pressure plate is not exerting adequate pressure. Unless the HTOB has failed to retract, seems the disc or plate is problem??


IaTR6
Dennis Costello
Central Iowa
(134 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6 '97 Explorer 5.0

Re: Slipping Clutch
Posted by: IaTR6
Date: August 15, 2018 08:00PM

Rick, I'm only theorizing here, but relating my experience. I have a HTOB, on a T5, and measured several times to get the correct
spacing on the HTOB to the clutch fingers. Regardless, when I removed my trans to correct an oil leak, I found the HTOB to be fully retracted. The clutch worked fine, but as the driven disc wears, the fingers move back slightly toward the trans. If the HTOB
doesn't have any retracing room, it will hold the fingers slightly depressed, and eventually you would have a slipping clutch.
Perhaps a test to get an idea is where does the pedal engage the clutch and the car start to move? I THINK if the HTOB is against the fingers, the clutch will engage high on the stroke. I think there is supposed to be about .150 minimum extension on the HTOB when the clutch is released. Keep us in the loop!
Best wishes.
Dennis


HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Slipping Clutch
Posted by: HealeyRick
Date: August 16, 2018 09:25PM

Thanks, Dennis. I'm not seeing any signs of leakage so there is probably something wrong with the adjustment of the HTOB, I set it up using the Speedway tool, but it seems like the only way to solve the mystery is pulling the tranny.


IaTR6
Dennis Costello
Central Iowa
(134 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6 '97 Explorer 5.0

Re: Slipping Clutch
Posted by: IaTR6
Date: August 16, 2018 11:18PM

I think you are right Rick, as much as you would like an easier solution. If the HTOB is fully retracted when the trans is moved back, that would be what I found. I know I used a dial caliper depth gauge, and measured several times and was still wrong!
Unfortunately, that wasn't my only mistake!
Dennis


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5648 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Slipping Clutch
Posted by: BlownMGB-V8
Date: August 16, 2018 11:58PM

When you set up your HTOB did you do it with the PP fully pulled down with the mounting bolts?

A good idea is to check it with the PP bolts finger tight. If you have clearance then it will be able to accommodate full wear of the clutch disc. There should be enough throw in the HTOB to set it there and still get full clutch release with the PP tightened down properly.

Jim



HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

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Re: Slipping Clutch
Posted by: HealeyRick
Date: August 17, 2018 01:50PM

Jim,

Of course I set it up with the PP fully cinched down. Only wish I knew of your advice sooner. If I decide to continue using the HTOB, will I be looking at adding or subtracting spacer washers?

https://vgy.me/t10UpM.jpg

I went with the HTOB originally for concerns about room for the clutch fork. While I'm in there, I'll check the spacing. Mike Forte has a very nice hydraulic slave for the T5 and I don't want to have to go through this BS again.


MGBV8
Carl Floyd
Kingsport, TN
(3498 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

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Re: Slipping Clutch
Posted by: MGBV8
Date: August 17, 2018 04:30PM

Subtracting one or two.


IaTR6
Dennis Costello
Central Iowa
(134 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6 '97 Explorer 5.0

Re: Slipping Clutch
Posted by: IaTR6
Date: August 17, 2018 08:38PM

Rick, I'm chiming in here uninvited, but this HTOB looks like the one I have. It looks like it has the ring on the end which is
there to prevent overextending the cylinder. Carl is correct from what I see, as you want the throwout bearing to move back toward the trans. As it is now, the throwout bearing is partially depressing the clutch fingers. Now the question is, is removing two spacers enough? I suggest doing what I did, and although it is extra work, I suspect you would rather drive the car than do this again. Remove perhaps 4 or 5 spacers, extend the throwout bearing to the end of the stroke of the HTOB, and with the HTOB In place, seat the trans in place. Insert and snug up two trans to bellhousing bolts diagonal from each other. Remove the trans, and measure how far the throwout bearing is extended. I think you want .100 or so. So, add or subtract spacers to get near this figure.
Dennis


HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Slipping Clutch
Posted by: HealeyRick
Date: August 18, 2018 09:28AM

Thanks, guys. All this info is helpful. Going back to a slave setup is starting to look better and better but don't know until I check out how much room I have. As Dennis said, I really don't want to do this again.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5648 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Slipping Clutch
Posted by: BlownMGB-V8
Date: August 18, 2018 10:50AM

You'll want to subtract maybe as much as 1/4-1/2".

If your HTOB fully releases the clutch before hitting the stop that's all you need. The rest of the travel should be back into the body. I'm not sure how much travel your HTOB has, some of them don't have much. All of the excess travel should be used to allow for wear.

Jim


IaTR6
Dennis Costello
Central Iowa
(134 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6 '97 Explorer 5.0

Re: Slipping Clutch
Posted by: IaTR6
Date: August 18, 2018 01:04PM

I looked at what I thought was a treasure trove of notes I took when readjusting my HTOB, and voile' I didn't take as many as I thought, or put them somewhere only my kids will discover as they load my "stuff" into a dumpster after my passing. Anyway, my HTOB kit came from BMC (NFI), and his printed instructions state the HTOB has .688 total travel. With my 3/4" master cylinder, I got 13/32" movement per stroke of the pedal. So, I don't have the info on the required stroke for clutch release, but it must be something less than 13/32". So, to prevent hitting the end stop, it would be wise to have a little less than 13/32" extension on the HTOB when the throwout bearing is in contact with the clutch fingers.
Dennis


HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Slipping Clutch
Posted by: HealeyRick
Date: September 08, 2018 01:17PM

The guilty parties:

https://vgy.me/TfJ0fn.jpg

Bit the bullet and pulled the transmission. Remeasured the clearance using a carpenter's square and HF micrometer instead of my fancy dan Speedway gauge and found out, as predicted by Dennis, that the HTOB was way too close to the pressure plate fingers. Removed three shims, bolted everything back together and no more clutch slip! I think a couple of the starts at my last autox might have just worn the clutch enough to cause the slippage.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5648 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Slipping Clutch
Posted by: BlownMGB-V8
Date: September 09, 2018 12:05PM

Sure, give Dennis all the credit. ;-)

Jim



HealeyRick
Rick Neville

(460 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Slipping Clutch
Posted by: HealeyRick
Date: September 09, 2018 02:06PM

Your ego's already big enough, Jim. Don't want to encourage you. :-). At least you can tell from the picture, I turn my own wrenches.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5648 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Slipping Clutch
Posted by: BlownMGB-V8
Date: September 10, 2018 01:04PM

Good point.


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