Carbon Release ( Throw Out ) Bearing Information

[John Friese]

CARBON RELEASE ( THROW OUT ) BEARING INFORMATION

I've done a lot of research and testing on the release bearings used
on the Amphicar clutch. It turns out that using the ball bearing type
of release bearing is not a good idea because it cannot compensate for
off the center positioning that is inherent in the Amphicar clutch
design.

1. The clutch release bearing for the Amphicar swings on an arc as it
goes in and out and actually moves from side to side against the
clutch. The ball bearing system must scuff against the clutch when
off center while the carbon bearing has no center and can handle this
sideways movement. The ball bearing type of release bearing will
often make noise and shows wear after a short time. Another benifit
of the carbon type is that it won't be damaged if it gets wet.

2. I found a posting that recommends soaking the carbon bearing in
oil before installation and my tests suggest this is a good idea
since whatever oil that may have been in them has long since dried out.

Later designs for clutch release bearings added a tube around the
transmission input shaft and the release bearing was centered by the
tube and any sideways motion was taken up at the end of the clutch arm
(fork). Amphicar never did change to this type of release bearing
arrangement.

Allan Woodcock has located a source for NOS carbon bearings and he can
provide them to Amphicar owners. See his listing in the Amphicar
classifieds for bumpers etc.

John Friese

White 67
Red 67

 

[Brian Crombie]

John,
I just put my engine and tranny in the hull last Saturday. I replaced the
carbon style throw out due to a large crack with a Gordon's ball bearing style.
What your saying is the Gordon approved throw out is no good. I would like to
think that Gordon's too has researched this item before offering it to their
customers.
It seems to me that the arc swinging action caused by the fork will leave an
oval shape footprint using both styles. At this point, I'd be hard pressed to
pull that tranny out and replace it. It looks so good inside the hull!
Are your conclusions on this subject due to using both styles for extended
periods?

Brian Crombie


[Non-text portions of this message have been removed]

 

[John Friese]

Brian,

One of my cars has it's original carbon throw out bearing and it runs
perfectly without any weird noise or drag on the engine. My other car
has been a test vehicle for different engines and clutch units. I did
a lot of switching of clutches and throw out bearings to figure out
what I have learned. One incarnation was the original spring clutch
and a ball bearing throw out and I noticed a slight grinding noise
when pressing the pedal. When I pulled the engine I found a red
powder substance on the pressure plate housing and swirl marks on the
collar of the original clutch and the throw out bearing. The red
powder is finely ground metal from the misaligned metal parts that has
rusted. Hugh knows about the swirl marks and I recently told him what
I've found about the cause and fix. Hugh was not aware that these
carbon bearings were desirable for this application and thought that
the ball bearing type would work and wouldn't have the cracking and
wear issues that people seem to fear with the carbon bearings, though
I've never had a problem with the old style bearing. The bearing he
sells is simply not a good substitute for the original throw out
bearing because it wants to turn around a center and the carbon type
simply doesn't care about a center since it can slide in any
direction. Since the bearing is sliding around, it does develope an
oval wear pattern on the carbon but it's no problem since that's the
way it's supposed to work. I think, after my discussion with him,
Hugh's going to locate some carbon bearings and make them available
too. My latest incarnation uses a Triumph 1500 flywheel and diaphram
pressure plate, a larger driven plate and a custom made throw out
bearing that works on diaphram clutches. The system works very well
and I've run it for about 1000 miles so far. I'ts also better able to
handle the additional torque of larger engines like the 1300 and 1500.

John Friese

White 57
Red 67



--- In amphicar-lovers@yahoogroups.com, Brian Crombie <baddogg@d...>
wrote:
> John,
> I just put my engine and tranny in the hull last Saturday. I
replaced the carbon style throw out due to a large crack with a
Gordon's ball bearing style. What your saying is the Gordon approved
throw out is no good. I would like to think that Gordon's too has
researched this item before offering it to their customers.
> It seems to me that the arc swinging action caused by the fork will
leave an oval shape footprint using both styles. At this point, I'd
be hard pressed to pull that tranny out and replace it. It looks so
good inside the hull!
> Are your conclusions on this subject due to using both styles for
extended periods?
>
> Brian Crombie
>
>
> [Non-text portions of this message have been removed]

 

[David Chapman]

Re: Re: Carbon Release ( Throw Out ) Bearing Information

> I've never had a problem with the old style bearing. The bearing he
> sells is simply not a good substitute for the original throw out
> bearing because it wants to turn around a center and the carbon type
> simply doesn't care about a center since it can slide in any

John, I haven't bought this bearing from Hugh for a few years (as I stocked
up when I was over there a lot in the early 90s) but the ones I have are
ball bearing but with a carbon face which I've thought of as best of both. I
drove about 10,000 miles on the first one I fitted but did change it as part
of another job last year as the carbon face had started to crack.

>My latest
>incarnation uses a Triumph 1500 flywheel and diaphram pressure plate,
>a larger driven plate and a custom made throw out bearing that works
>on diaphram clutches. The system works very well and I've run it for
>about 1000 miles so far. I'ts also better abile to handle the
>additional torque of larger engines like the 1300 and 1500.
>John Friese

That is a much better solution, by 1964 Triumph were using the diaphram
clutch even on 1147cc cars, it has a nicer action, is lighter but also is
much longer lasting, the problem has always been the release bearing on the
Amphicar transmission (the Triumph bearing will not fit on the Amphicar
release fork). I've seen a few solutions but none I'm completly happy with
as it's such a pain if it goes wrong. Please share you experiences with it
and the parts you used !

David Chapman in the UK.

 

[John Friese]

Hello David,

A ball bearing with a carbon facing would also reduce the scuffing
problem but from what I've been told that type of bearing is no longer
available and the metal on metal type that's sold now is not a good
replacement. What I use on the 1500 clutch (and it also works on the
1300 diaphram clutch) is a ball bearing with a hardened, rounded face,
that's designed to ride on the forks of a diaphram clutch, mounted on
a custom turned holder that adjusts for the spacing differences and
fits the Amphicar throw out bearing arm. It was expensive to have it
machined (especially since I went through 3 variations before I was
happy with it) but I'm looking into getting some sort of price break
for a small run of them. I've put about a 1000 miles on this system so
far and plan to switch engines again next week so I'll be able to
check for any wear at that time. I'll be surprised if anything
unusual shows up since it works so smoothly and quietly. I'll drop
you a photo of the bearing.

John Friese


--- In amphicar-lovers@yahoogroups.com, "David Chapman" <david@m...>
wrote:
> > I've never had a problem with the old style bearing. The bearing he
> > sells is simply not a good substitute for the original throw out
> > bearing because it wants to turn around a center and the carbon type
> > simply doesn't care about a center since it can slide in any
>
> John, I haven't bought this bearing from Hugh for a few years (as I
stocked
> up when I was over there a lot in the early 90s) but the ones I have are
> ball bearing but with a carbon face which I've thought of as best of
both. I
> drove about 10,000 miles on the first one I fitted but did change it
as part
> of another job last year as the carbon face had started to crack.
>
> >My latest
> >incarnation uses a Triumph 1500 flywheel and diaphram pressure plate,
> >a larger driven plate and a custom made throw out bearing that works
> >on diaphram clutches. The system works very well and I've run it for
> >about 1000 miles so far. I'ts also better abile to handle the
> >additional torque of larger engines like the 1300 and 1500.
> >John Friese
>
> That is a much better solution, by 1964 Triumph were using the diaphram
> clutch even on 1147cc cars, it has a nicer action, is lighter but
also is
> much longer lasting, the problem has always been the release bearing
on the
> Amphicar transmission (the Triumph bearing will not fit on the Amphicar
> release fork). I've seen a few solutions but none I'm completly
happy with
> as it's such a pain if it goes wrong. Please share you experiences
with it
> and the parts you used !
>
> David Chapman in the UK.