[V8Vairs] hyd clutch info wanted

[Tim Barrie]

The difference in pedal pressure was substantial. At 3/4 it was a chore to
hold the clutch pedal down. At 5/8 it is very similar to my 70's Vette for
clutch effort.

I chased my tail for a while having installed a new clutch and not getting
it to disengage enough. I started with the original truck clutch slave
cylinder as designed by Kelmark. I graduated to a Tilton cylinder that was
matched to the master. Still no success. I pulled the engine to make sure
that the clutch was OK and decided to put the Howe in while apart. Still not
enough travel. 

Turns out there was just enough slop in the clutch pedal to shaft, shaft to
hanger bearing, swing lever to clutch push rod, and cowl movement. Although
the clutch pedal was traveling the full distance the cumulative slop allowed
only about 1/2 inch of travel to the clutch master. I pulled the steering
column support and built the structure tying in the master cylinder. I also
put a pillow bearing in to support the passenger side end of the clutch
pivot shaft. That bearing block was tied in better to the body structure as
well.

With that in place I had a working clutch but at considerable leg effort.
Those on this group suggested going to 5/8 master and that seems to be
working fine. 

My clutch shaft pivot arm is adjustable so I was able to start out with the
max stoke suggested by Tilton. I then backed that stroke off as far as I
could to make sure that I would not be blowing the Howe apart.

Bleeding the Howe is a chore. I have the remote bleeder and ran it as high
as I could. It still took a long time to get the air out. I wouldn't think
that you could create enough vacuum to over ride the seals when the seals
are made to withstand a couple of hundred psi of hydraulic pressure.  I
would take some pictures but my car is at the body shop. 

Hope this helps. Tim

-----Original Message-----
From: v8vairs-bounces at corvair.org [mailto:v8vairs-bounces at corvair.org] On
Behalf Of Test User
Sent: Wednesday, January 21, 2009 6:01 PM
To: discussion of non-stock engines in Corvairs
Subject: Re: [V8Vairs] hyd clutch info wanted

tim-what differences did you see in going to the 5/8 bore master cylinder.
i'm using a wilwood slave with 7/8 bore and 1-3/8 stroke and a 3/4 bore
master cylinder. clutch doesn't engage until the end of the pedal movement.
could i have screwed up by using a mighty vac to bleed with and might have
gotton fluid on both sides of the seal. thanks-mike mann

On Wed, Jan 21, 2009 at 8:49 AM, Tim Barrie
<tbarrie at meritprecision.com>wrote:

> Tom,
> I just went through this with a Kelmark that I am building. Bryan
Blackwell
> asked me what I ended up with and this is the summary that I sent him.
>
> "I used the Howe Racing throw out bearing from Summit Racing. The Summit
> part number is HRE-82870. I added the remote bleeder kit which was part
> number HRE-8287 as well.
> I used the Tilton master cylinder from Summit which was TIL-74-625U. I
> started with the 3/4" and went to the 5/8"; the result of our V8Vair
> discussion.
> I used 1/4" hard line from the master to the flex line from the Howe.
> The hardest part was making the clutch pedal pivot point robust enough to
> take the forces. I ended up making a 1" tube structure from the Corvair
> steering column bracket to the kick plate where the clutch master cylinder
> bolted up. I replaced the cross shaft with solid bar stock and a pillow
> bearing at the end; also supported by the structure. Without the structure
> there was just too much flexing of the sheet metal and I couldn't get the
> stroke I needed through the master."
>
> Tim
>
> -----Original Message-----
> From: v8vairs-bounces at corvair.org [mailto:v8vairs-bounces at corvair.org] On
> Behalf Of tom zimmermann
> Sent: Wednesday, January 21, 2009 10:22 AM
> To: v8vairs at corvair.org
> Subject: [V8Vairs] hyd clutch info wanted
>
> ..I'd like to find more detailed info on what master+ slave setups are
> being
> used,pics and measurements of the mods to the pedal shaft,piston bores and
> what clutch fork is used..any problems running the Howe slave bearing?
> Ron's
> 327 is in the shop,and now's the time to correct the pedal effort/travel
> issues (Ansen bell,Vette fork,new 1 1/6" slave,1 1/8" and 1 1/4" pistons
on
> the '60 truck combo master;11" flywhl w/10 1/2" disc-PP is getting all
> stock
> 11" parts..)..I've got a couple options for mine, either use the OLD
> Lakewood on the '92 4.3 stock 11" clutch/hyd system,or modify the 4L60
bell
> with the Howe bearing...TIA, Tom Z,   s10birdman1966 at yahoo.com
>
>
>
>
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