Alpines List Archive

This read-only message was archived from a public mail list.
Mail From: Brent Kasl <(email redacted)>

I need help from the list. My S2 has a S5 rear axle of 4.22. I installed
an OD unit earlier this year which is electrically disconnected due to a
malfunction. My speedometer is an OD rated speedo. It has always
fluttered when registering so I replaced my original with an OD cable.
Now the fluttering is gone, but the reading is way off, much like it was
after the OD install. I mean 65-70 mph at 3000 rpm! Is it the
combination of the OD unit and the axle causing the problem, or should I
install a non-od cable in it? It was off before the cable was renewed
but I thought this would help both problems. Thanks Brent

This read-only message was archived from a public mail list.
Mail From: Victor Hughes <(email redacted)>

Brent

I wouldn't have thought a cable would make any difference, because all it
does is transfer revolutions from the OD speedo offtake to the back of the
speedo - there is no gearing up or down effect. The problem could either be
the OD pinion or the speedo. What was the donor car for the OD unit? The
reason I ask is because ODs from Series 3s have a different number of teeth
on the speedo drive pinion to all other series - because S3s have 3.89 rear
ends. If you have an S3 OD your S2 speedo would read wrong. I'm fairly
sure it would read fast (as you have described). However even that would
not account for all the discrepancy and I suspect you speedo and possibly
your tach is also out.

Hope this helps

Vic Hughes

Brent Kasl wrote:

> I need help from the list. My S2 has a S5 rear axle of 4.22. I installed
> an OD unit earlier this year which is electrically disconnected due to a
> malfunction. My speedometer is an OD rated speedo. It has always
> fluttered when registering so I replaced my original with an OD cable.
> Now the fluttering is gone, but the reading is way off, much like it was
> after the OD install. I mean 65-70 mph at 3000 rpm! Is it the
> combination of the OD unit and the axle causing the problem, or should I
> install a non-od cable in it? It was off before the cable was renewed
> but I thought this would help both problems. Thanks Brent

This read-only message was archived from a public mail list.
Mail From: Brent Kasl <(email redacted)>

I think I have it figured out. My original speedo is a factory OD calibrated one
for a 3.89 gearing. When I installed the 4.22 rear it will be off and has
nothing to do with the cable. So the choices are to either swap the speedo head
for a 4.22 or find an original 3.89 rear for a S2. Sound correct? Brent

Victor Hughes wrote:

> Brent
>
> I wouldn't have thought a cable would make any difference, because all it
> does is transfer revolutions from the OD speedo offtake to the back of the
> speedo - there is no gearing up or down effect. The problem could either be
> the OD pinion or the speedo. What was the donor car for the OD unit? The
> reason I ask is because ODs from Series 3s have a different number of teeth
> on the speedo drive pinion to all other series - because S3s have 3.89 rear
> ends. If you have an S3 OD your S2 speedo would read wrong. I'm fairly
> sure it would read fast (as you have described). However even that would
> not account for all the discrepancy and I suspect you speedo and possibly
> your tach is also out.
>
> Hope this helps
>
> Vic Hughes
>
> Brent Kasl wrote:
>
> > I need help from the list. My S2 has a S5 rear axle of 4.22. I installed
> > an OD unit earlier this year which is electrically disconnected due to a
> > malfunction. My speedometer is an OD rated speedo. It has always
> > fluttered when registering so I replaced my original with an OD cable.
> > Now the fluttering is gone, but the reading is way off, much like it was
> > after the OD install. I mean 65-70 mph at 3000 rpm! Is it the
> > combination of the OD unit and the axle causing the problem, or should I
> > install a non-od cable in it? It was off before the cable was renewed
> > but I thought this would help both problems. Thanks Brent

This read-only message was archived from a public mail list.
Mail From: (email redacted)


>I think I have it figured out. My original speedo is a
>factory OD calibrated one for a 3.89 gearing. When I
>installed the 4.22 rear it will be off and has
>nothing to do with the cable. So the choices are to
>either swap the speedo head for a 4.22 or find an
>original 3.89 rear for a S2. Sound correct? Brent

Yes, regrettably, the Rootes method (and possibly most English cars) for
getting the speedo to match the tranny and rear end was to have a different
speedo for each application. Other cars, like our Ford running breatheren,
do it by having interchangeable gearing at the tranny where the cable comes
out.

There is a chart in the SAOC Guide that lists all Alpines and lists the
exact speedo for that application. The problem is that they simply are not
readily available anywhere.

The second problem is that tire diameter also plays a part in the accuracy.
So, the only real way to get this done right is to take out the speedo and
count exactly how many times the cable goes around (with your tranny, your
rear end and your tires) over 1/100th of a mile (52.80 feet) and send the
speedo to a speedo repair shop with that information.

Note that there are two parts of the speedo that are inaccurate, the speed
needle and the odometer. If you don't care about the odometer, they can
recalibrate the needle only based upon the magnetism needed. If you want
both accurate, they will have to find different gears for the inside, or
hange a converter box off the end. If you have the stock set up, and your
speed needle is off, your odometer should not be off and the magnetism
reset is probably all you would need - unless you want the exact speed
because your tires have changed the odometer too.

Good luck. I'm still running my stock speedo with my OD and 3.89 and
Michelin XZX's, just knowing that a read of 65 is about 45 and a read of 95
is about 65 - and hoping that "about" is good enough not to get a ticket.
One of these days I'll get it fixed.

Jay