Which model overdrive unit is appropriate for a series V

[Jay Laifman]

I just went back and looked at Mike's link. That talks about everything above. Also adds the different speedo. I had mine recalibrated at West Valley Speedo to be exact with the tires and rear end I run.

That's one crazy thing about Sunbeams (probably most Rootes of the period). Rather than change a gear in the transmission to match the speedo, they supplied a different speedo for each configuration, including transmission and rear end. So unless your car is 100% stock, and you are using 1960 ratio tires (pretty unlikely), your speedo is already off. So plan on getting it recalibrated anyway.

 

[alpine_64]

Here is another difference not listed here.

The S1-IV OD switch clicked on and clicked off, and there was a light on the dash if it was clicked on. The SV had a self cancelling switch. The stalk was always in the middle you could push it up and down, but it would spring back to the middle. The OD unit has switches on the box that allows the OD to turn on if you are in 3rd or 4th, and otherwise turns off the OD. With the S1-IV OD, if you leave the switch in the "on" position, the OD always comes on when you go in 3 or 4. But with the SV box, once you drop out of 3rd, the OD goes off and never comes back on unless you spring up the OD stalk again.

At least when I did the installation, the relay necessary for the SV version was close to impossible to get - though I found one..

Jay,

Have to correct you. The self cancelling OD came in on the series 3 alpine.. And ironically so did the warning light.

The SI/II had a the on/off toggled column switch and no wanring light. Cant recall if it had the cancelling switch on the trans when moved across the 3/4 plane to 1/2.

The S3 introduced the momentary self centering switch and the warning light...fun sunbeam fact.. The S3 also had a uinque lighting switch with resistors on the top that if you had the headlights on it would auto dim the OD warning light to not be a distraction. The S3 is also the only series that standardised the 3.889 rear with or without OD so it had a uniquely gear speedo for OD and special close ratio trans with a taller first.

These details were gone by SIV.

Late SIV they get the all syncro trans and still have OD warning light.

SV the warning light is deleted

 

[alpine_64]

oh and the lucas 6RA special self latching relay was used on s3-V. .... And a bunch of rare ferraris...

 

[Tom H]

There's a better solution to the relay. Just any single standard 5 pin relay, including a Lucas 6RA can he made to work by adding a diode and a resistor:

http://mhartman.net/files/sunbeam/Overdrive Relay Replacement V1-0.pdf

You can also buy, from Alpine Innovations, a 6RA relay with these added parts built inside the relay

Tom

 

[alpine_64]

There's a better solution to the relay. Just any single standard 5 pin relay, including a Lucas 6RA can he made to work by adding a diode and a resistor:

http://mhartman.net/files/sunbeam/Overdrive Relay Replacement V1-0.pdf

You can also buy, from Alpine Innovations, a 6RA relay with these added parts built inside the relay

Tom

Tom everytime you post your solution.. I like it.. I was lucky enough to get an original...but if it fails... Ill be going the aftermarket path

 

[Tom H]

Michael, thanks. I have an original relay as well, but when it started acting up, I kept it installed, but simply moved one end of the white jumper to connect C1 to C4 and installing the diode across W2 to C1 (or C4) . That way the two contacts are in parallel, acting like a single contact but with a redundant action, such that if one fails the other still carries the load. This then uses the original built-in resistor. Seems like a great way to keep the original relay working with just one little added device, the diode. I think 90% of the failures of this special relay are simply one of the contacts. The original design is a bit of a tricky design as it tries to maintain enough contact pressure on BOTH contacts with just the pull-in power of the one coil. With this jumper swap and added diode, as long as either contact stays closed the OD stays on. The more I think about this the more I think this is the best solution in most cases and might be worth doing even in advance of any failure.

Also note that if you have an OD indicator lamp on the dash this arrangement provides more information about your OD situation than the original arrangement, as the lamp will light up whenever power is on the wire leading to the solenoid. With the original design, the lamp being lit only tells you that the relay is ON, but it does not tell you if the solenoid is actually getting power.

Tom

 

[SierraNev]

Novice question for sure,

How and what does the overdrive do on a 1966 Series V?

Thanks

Emmett

 

[Hillman]

Novice question for sure,

How and what does the overdrive do on a 1966 Series V?

Thanks

Emmett

The OD changes the final drive ratio, when in third or forth gear, lowering the RPM needed to maintain the same speed.

 

[Alpine 1789]

The OD changes the final drive ratio, when in third or forth gear, lowering the RPM needed to maintain the same speed.

That is a good technical answer. I'll put it differently: It turns it into an entirely different car when it comes to driving on the highway. After adding one to my S5 and seeing how much it transformed the car, I don't think I will ever want to own a stock-ish Alpine without an OD.

 

[alpine_64]

The stock OD in the alpine is a 0.82 ratio iirc? So drops the effective rpm by 18% .. There are different od ratio in units.. Iirc some volvos had a 0.73.

All Alpines ( bar series 3) with OD had a 4.22 ratio instead of the 3.89. This allowed faster acceleration and the OD still gave a taller final drive than the stock 3.889.

For series 3 they standardised the 3.889 with OD giving a great cruising gear in top and 3rd OD almost being the same as a stock 4th.. So a very flexible gear change on the run using the od like a paddle shift.

The s3 also had a cr trans so taller first.. Thr later all sync gearbox has a very similar gearset.

An OD with the 3.889 is a great combo.. ( or with the later arrow cars 3.7 even better) add some larger wheels and appropriate profile tyres and you have a very effective freeway car...

My SII has od 3.89 and 195/65/14 rears and cruises at 60mph at 2700rpm

 

[SierraNev]

Ok,

So how do I know if I have one and how do I engage it?

And I don' think I will ever be brave enough to take this on the highway.

I got it to 62 mph over Colima in Whittier and said prayers I have not used in years

Thanks again

Emmett

 

[alpine_64]

Emmett,

The Od will be bolted onto the back of the gearbox, you will see it under the car.

Od trans:




Its activates by a switch on the column opposite the indicator switch.

If your car scares you at 62mph i suspect you have serious suspension issues or your wheels are terribly out of balance. An alpine will cruise easily at 60+ mph.. Especially in OD.

 

[Mike O'D]

I believe the D Type overdrives use in the Alpines were 26% reduction. I agree - on modern highways, I can't imagine driving a non-OD car very far. 70 mph is about 3300 rpm in my car (S3 with 3.89 rear). Smooth and stable - the only thing that makes me a little uncomfortable is when a semi passes me doing 75 - 80.

 

[alpine_64]

on modern highways, I can't imagine driving a non-OD car very far.

For my first decade i had no OD.
My fathers SIVGT was a factory OD car with 4.22 and the extra gear.. It was so much better than mine on long runs and you would arrive much fresher on a long run.
Being younger i used to sit on the highway at 60mph spinning at 3700rpm in my car (also was running 165/70/13s so slightly under geared) i would run roof down as it was less wearing than constant rpm.. That said . the alpine at 60mph without od was very good at out accelerating othrr cars on the freeway as it was sitting at about peak torque

When i finally got the OD i kept the 3.889 and added 14" wheels and running taller tyres ( intially 205/65/14 on the rear) with 195/60/14 front and 195/65/14 rear.. With this combo and a hardtop the car is great on long runs

 

[Alpine 1789]

And I don' think I will ever be brave enough to take this on the highway.

I got it to 62 mph over Colima in Whittier and said prayers I have not used in years

If your car scares you at 62mph i suspect you have serious suspension issues or your wheels are terribly out of balance.

Emmett: I had my Alpine out on the highway yesterday and found myself thinking about what you said and I just want to strongly reinforce what Michael wrote. While the car is far more comfortable on the highway with an overdrive, it definitely should not make you say your prayers. I used to worry about the engine - 4000+ RPMs at 62 mph can make it feel like it is going to self-destruct - but not about my life. If your car scares you that much at highway speeds, something else is wrong.

 

[hartmandm]

Emmett hasn't indicated why he has that feeling.

My Alpine scares me at every speed, including sitting still. That has nothing to do with how it rides or handles. If some idiot in almost any vehicle hits me in the Alpine, I'm either seriously injured or killed. I don't have that feeling in any of my other cars, because they have been designed to handle collisions.

Mike

 

[Alpine 1789]

My Alpine scares me at every speed, including sitting still. That has nothing to do with how it rides or handles. If some idiot in almost any vehicle hits me in the Alpine, I'm either seriously injured or killed. I don't have that feeling in any of my other cars, because they have been designed to handle collisions.

Yeah, there is that. It is funny, I didn't feel that way when I first bought my SV in 1978, but there were a lot fewer SUVs on the road back then. I generally drive very defensively in it now.

 

[Clark]

Just finished installing a rebuilt Laycock all synchro overdrive in my series 5. It is like a new car! Easy cruise up to 70 (my max) I find lots of new ways to travel off the freeway and a lot more fun too. Installation took 2 of about 6 hours and was pretty straightforward.

 

[RootesRacer]

The stock OD in the alpine is a 0.82 ratio iirc? So drops the effective rpm by 18% .. There are different od ratio in units.. Iirc some volvos had a 0.73.

All Alpines ( bar series 3) with OD had a 4.22 ratio instead of the 3.89. This allowed faster acceleration and the OD still gave a taller final drive than the stock 3.889.

For series 3 they standardised the 3.889 with OD giving a great cruising gear in top and 3rd OD almost being the same as a stock 4th.. So a very flexible gear change on the run using the od like a paddle shift.

The s3 also had a cr trans so taller first.. Thr later all sync gearbox has a very similar gearset.

An OD with the 3.889 is a great combo.. ( or with the later arrow cars 3.7 even better) add some larger wheels and appropriate profile tyres and you have a very effective freeway car...

My SII has od 3.89 and 195/65/14 rears and cruises at 60mph at 2700rpm

Actually the OD ratio of a Rootes D Type OD is .80/1 or a 25% decrease in revs.
Math is funny.

 

[Tom H]

Actually the OD ratio of a Rootes D Type OD is .80/1 or a 25% decrease in revs.
Math is funny.

Yeah, Math IS funny. But I am 95% sure you got it wrong. If you were cruising along at 60 MPH with no OD, turning 3000 RPM, and you turned on your .80/1 OD, you would only be turning 2400 RPM, a drop of 600 RPM, 20 % of the original 3000 . On the other hand if you were turning 3000 RPM going 60 MPH, then turned on the OD but maintained 3000 RPM, you'd now be going 75 MPH, a 25% Increase in speed!

As I said, I'm only 95% sure of this due to thinking about it at this late hour. But am I not correct?

Tom