Subject: [TR] Adding a VSS pulse generator inline with speedometer cable

From: Brad Kahler <[email-masked]>
Date: Tue, 14 Aug 2012 15:50:57 -0400

The subject line pretty much describes what I need to do.  I've checked
with some speedometer shops and either I get someone I can't understand or
they don't understand what I'm looking for.

What I need is to add one of the VSS signal generators in line with my
speedometer cable so I can finish the installation of the cruise control on
my TR4.  The only signal generator I can find has the typical GM style 7/8
male thread at one end with a 5/8" (I think) male thread on the other end.

I don't mind sending the speedometer cable and adapter some place to have
it fitted.

Any suggestions?

Thanks,

Brad
1963 TR4

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From: Wbeech <[email-masked]>
Date: Tue, 14 Aug 2012 15:18:30 -0500

Or, as an alternative I remember adding cruise to an old truck, they sent me
two magnets and roll of tape.  Strap one to the driveshaft and the other
mounted on a bracket in close proximity.  Voila! Le pulse generator.  Drove
that old truck for 20 years.

Have you tried West Valley Instruments in SoCal or ZepCo in Dallas?

Sent from mobile Bill

On Aug 14, 2012, at 2:50 PM, Brad Kahler <[email-masked]> wrote:

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From: "Randall" <[email-masked]>
Date: Tue, 14 Aug 2012 19:03:35 -0700

> my TR4. 

Have you considered using ignition pulses instead?  You'd want to be sure
the cruise control drops out when the clutch is pressed, but you'll need
that anyway.

-- Randall

---

From: Brad Kahler <[email-masked]>
Date: Tue, 14 Aug 2012 22:18:11 -0400

The first version of the SCS/Frigette cruise control (circa 1998) had coil
sense capability and I used it with great success on my Spitfire.  The next
SCS/Frigette cruise control I bought in 2001 had that feature removed and
it only works with VSS type signals.   Connecting it to the coil actually
fries the cruise module as I found out recently.  I've been looking at
other brands but so far the only ones I've found all require some sort of
VSS and don't allow connecting to the coil.

Quite frustrating.

---

From: Geo Hahn <[email-masked]>
Date: Wed, 15 Aug 2012 06:50:09 -0700

On Tue, Aug 14, 2012 at 7:18 PM, Brad Kahler <[email-masked]> wrote:

> ...I've been looking at

I know some who are using this unit (on VWs):

http://www.murphskits.com/catalog/product_info.php?products_id=422

Basically a clone of the old (low-tech) Audiovox CC which I have used on my
VW for 20+ years and 2 other cars before that (same unit moved from
car-to-car).

Never put it on a TR but see no reason why it wouldn't suit.
Geo

---

From: Brad Kahler <[email-masked]>
Date: Wed, 15 Aug 2012 09:59:42 -0400

Geo,

This one doesn't allow connecting to the ignition coil as a speed source
either.  It seems that all of them on the market now require a VSS signal,
pulse generator in the speedo cable or else magnets on the drive shaft.

Also the one you've listed is a vacuum unit and I prefer the electric servo
type.

I installed an SCS/Frigette cruise control with electric servo unit on my
Spitfire back in 1998 and it worked great.  Bud Rolofson then installed one
on his TR6 and it's been working great all these years.  Now that I want to
install one in my TR4 they don't make the style that will sense speed from
the ignition coil.

The two simplest options are a VSS in the speedometer cable or the magnets
on the drive shaft.  I haven't given up on the speedometer cable option
just yet, still a few more places to check with.  Barring that I'll
probably end up with the magnets on the drive shaft.

Thanks,

Brad

On Wed, Aug 15, 2012 at 9:50 AM, Geo Hahn <[email-masked]> wrote:

> Basically a clone of the old (low-tech) Audiovox CC which I have used on
> my VW for 20+ years and 2 other cars before that (same unit moved from
> car-to-car).
>

---

From: John Innis <[email-masked]>
Date: Wed, 15 Aug 2012 09:02:12 -0500

You could also get (or build) a converter that will take ignition pulses
and give you a VSS signal.  Do you know what the Specs are for the VSS that
your unit wants?

On Wed, Aug 15, 2012 at 8:59 AM, Brad Kahler <[email-masked]> wrote:

> http://autox.team.net/mailman/options/triumphs/[email-masked]
>

-- 
=================================
= Never offend people with style when you   =
= can offend with substance --- Sam Brown  =
=================================

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From: Brad Kahler <[email-masked]>
Date: Wed, 15 Aug 2012 10:04:01 -0400

No, I don't.

Since the new cruise units are designed to work with modern cars I would
imagine whatever is typical for a modern VSS would be appropriate.

Just shows you how little I know about modern cars :)

If it was made after about 1973 I don't know much about them!

Brad

---

From: John Innis <[email-masked]>
Date: Wed, 15 Aug 2012 09:20:19 -0500

Ok, so a little googleing shows that most of the GM VSS output a 0-5vdc
square wave at 4000 pulses per mile.  So at 60mph, you are going to get a
square wave with a 66.6hz frequency.  Assuming you are running about 3000
rpm on a 4cyl engine at the same speed, your tach pulse will be a 0-12v
irregular spike at about 200hz.  The two frequencies are close enough that
you might just have to reduce the voltage down to get the tach signal to
work.  I'd use a Schmidt trigger to reduce the signal to 5v and try it.
Once you get down to 5v, there should be no risk of damage to your cc
module.  If it doesn't work, then you will need to add a frequency devider
to requce it to a point that it operates.  Should only take 3 or for
components to build the circuit.  You could probably do the same thing with
just a transistor but you might not get a clean enough square wave to make
the CC module happy.

---

From: Frank Fisher <[email-masked]>
Date: Wed, 15 Aug 2012 08:45:59 -0700 (PDT)

why not have 2 custom speedo cables made.
there are lots of little shops
around that will do this.
if you need a place i have a lead in fallbrook
California
Frank

From: Brad Kahler <[email-masked]>
To: Triumphs
<[email-masked]> 
Sent: Tuesday, August 14, 2012 12:50 PM
Subject:
[TR] Adding a VSS pulse generator inline with speedometer cable

The subject
line pretty much describes what I need to do.  I've checked
with some
speedometer shops and either I get someone I can't understand or
they don't
understand what I'm looking for.

What I need is to add one of the VSS signal
generators in line with my
speedometer cable so I can finish the installation
of the cruise control on
my TR4.  The only signal generator I can find has the
typical GM style 7/8
male thread at one end with a 5/8" (I think) male thread
on the other end.

I don't mind sending the speedometer cable and adapter some
place to have
it fitted.

Any suggestions?

Thanks,

Brad
1963 TR4

**
[email-masked] **

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Archive:
http://www.team.net/archive
Forums: http://www.team.net/forums
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http://autox.team.net/mailman/options/triumphs/[email-masked]

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From: Brad Kahler <[email-masked]>
Date: Wed, 15 Aug 2012 12:10:13 -0400

Frank,

That's what I've been trying to find is a decent speedo shop that can
rework cables.  I've called several and I'm not sure we were speaking the
same language and I've tried emailing/calling others and they don't respond.

If you wouldn't mind sending me the info on the place in Fallbrook I would
appreciate it.

I just got a lead on a shop in Denver that I'm going to check on right now
so who knows, maybe that will pan out.

Brad

On Wed, Aug 15, 2012 at 11:45 AM, Frank Fisher <[email-masked]> wrote:

> there are lots of little shops around that will do this.
> if you need a place i have a lead in fallbrook California
> Frank
>
>   *From:* Brad Kahler <[email-masked]>
> *To:* Triumphs <[email-masked]>
> *Sent:* Tuesday, August 14, 2012 12:50 PM
> *Subject:* [TR] Adding a VSS pulse generator inline with speedometer cable
>