[V8Vairs] hyd clutch info wanted

Thu Jan 22 17:38:55 EST 2009

tim-thanks for the info on the vacuum bleeder. don't know why i didn't think
of that. one less thing to worry about. this is on my kit car project with a
custom frame and i don't have any flex nor pressure problems like you
described. using the 3/4" bore master cylinder i can push the clutch in with
my arm and i'm 70 so it's easy for my leg. engine is a modified 140 and at
15#'s of boost hp should be around 250(clutch) and with 18/1900# (me and 16
gallons of gas) should be interesting. engine has handled 20+# of boost if i
want to get brave(VBG). thanks again-mike mann

On Thu, Jan 22, 2009 at 7:10 AM, Tim Barrie <tbarrie at meritprecision.com>wrote:

> 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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