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Overdrive
- Thread starter roger
- Start date
RootesRacer
Donation Time
all you should need is the overdrive switch, relay and harness assembly.
The transmission should already have the 3rd/4th gear switch.
There is a factory service bulletin that addressed adding a vent equalization hose to earlier overdrive units. Though this doesnt impact fitment to your vehicle, its a good idea to perform this rework "if needed" prior to install.
The transmission should already have the 3rd/4th gear switch.
There is a factory service bulletin that addressed adding a vent equalization hose to earlier overdrive units. Though this doesnt impact fitment to your vehicle, its a good idea to perform this rework "if needed" prior to install.
You mention "rear end" . Understand that there is no need to change rear ends just to put in a OD tranny. Many (most??) of us prefer a 3.89 axle even with OD and most SVs have the 4.21 axle. So if you have a 4.21 in the car now and have obtained a 3.89, that's a good swap. And it might be easier and better to just swap pumpkins and not the whole axle. Early axles/ bearings are different than later axles/bearings.
Tom
Tom
Mikeflbmer
Bronze Level Sponsor
4:21 ???
Series V alpines have a 4:21? Are you sure? Maybe that is why mine is geared too low for the freeway....I do have a rear end out of a Hillman Super Minx that had automatic tranny...that should be a 3:89 ...maybe I should swap them...also I have a laycock factory manual on the Tyde D overdrive if you need a copy....mike
Series V alpines have a 4:21? Are you sure? Maybe that is why mine is geared too low for the freeway....I do have a rear end out of a Hillman Super Minx that had automatic tranny...that should be a 3:89 ...maybe I should swap them...also I have a laycock factory manual on the Tyde D overdrive if you need a copy....mike
Hi Mike, Yes, consensus of the group seems to be that most SV's in the US came with 4.21 rear ends. General Data section of the WSM says 3.89 w/o OD and 4.21 with OD, but actual practice seems most have 4.21 regardless.
See this discussion :
http://www.sunbeamalpine.org/forum/showthread.php?t=15328
I swapped in a 3.89 AND OD for nicer freeway cruising.
Tom
See this discussion :
http://www.sunbeamalpine.org/forum/showthread.php?t=15328
I swapped in a 3.89 AND OD for nicer freeway cruising.
Tom
George Coleman
Gold Level Sponsor
I know thats right! at 4000rpm you are runing 60 mph! 5speed or 3.70 rear gear is good for this problem.
Alpine Bob
Donation Time
At 3000rpm I running 60mph with my OD. So what rear do you think I have in my early Series IV.
Bob, When have you ever gone 60mph in your Alpine ?
Except maybe through the twistys in the mountains...
When I bought my OD unit
I also picked up a 3:89 r/e when Jim E went to put it in, my SV already had that ratio. Not the quickest around town, but sure cruises the highway at a nice pace.
Tom j
Except maybe through the twistys in the mountains...
When I bought my OD unit
I also picked up a 3:89 r/e when Jim E went to put it in, my SV already had that ratio. Not the quickest around town, but sure cruises the highway at a nice pace.
Tom j
puff4
Platinum Level Sponsor
At 3000rpm I running 60mph with my OD. So what rear do you think I have in my early Series IV.
Kinda depends on your tire size!
If you've got 165x80R 13 tires (the closest you can get to the stock Dunlop R55 590x13 tubeless tires), then in OD in a stock Alpine SV (with 4.222 rear) at 60 mph you should be doing 2923 RPM. If you change to a 3.89 rear that would drop to 2692 RPM. If you use a 3.70 gear set (I think Victoria or the folks overseas have them) you can get that down to 2561 RPM.
Handy, dandy calculator:
tire-speed-calculator-alpine-v2.xls
(The above link goes to Box.com, where I have uploaded the Excel spreadsheet. You can download it from there and then edit and use it on your own PC, as you like. The file is virus-free.)