checklist 4 fitting an overdrive into an S1

[hartmandm]

Is there a chart of the different OD units?. Can one get the model # off the OD unit body or Info plate? ( I only saw patent #'s )
I posted some pics.

I'm not aware of a chart. You can verify it is an all-synchro box by verifying reverse is all the way to the right:



What numbers do you see in the circle below? That will identify the manufacture date.



You said you bought the OD from the UK? Your picture looks like the unit wasn't touched since being pulled from a car. Was any claim made to its condition? If not, I'd personally have it rebuilt before bothering to install it.

Also, do you have a loose nut (circled in the photo above)?
Is that a puddle of oil that leaked from the unit while sitting?

Mike

 

[Cali_59]

Mike, Ebay Seller said he 'went through the gears as it spun freely'. This is my only positive assertion.
The oil leak I do not know, the seller sells many old auto parts, so it could be an old stain.. who knows.. front seal? no oil on body.

I did notice this same seller had a broken OD switch ..one that fits on the Trans, and one 'stated' broken relay.
I attached a photo.. I think from what I could make out 24/5/67 on the date and it does have the circled nut.
Yes I appears that nut is loose, I do not know why.
On rebuilding. I am not afraid to do it myself..haha ..
I use to rebuild my TR3/TR4 trans on a monthly basis to keep them running when I was 19. I was bitten by the sports car bug early on
But, I have no shop space/ press/ exact tools/ gear temp guides/etc....anymore, but amhopeful I can find an indoor space to work at some point. ( I live In San Diego now.. new to area )
I have watched the Youtube videos of John Roseby. A pleasure to watch him work!!
Does he still rebuild units?
Not sure how much a full rebuild would go for. ( possible parts / 2 way shipping.. )
But I know my OD will be here in a week or 2 so and I will more than likely take the most practical of path forward.

View attachment 15907

 

[Cali_59]

I zoomed in a bit and seems like the oil is coming from the cover here.

 

[beamdream]

Thanks for your input Beamdream!,,Ok that brings me to, If I use my S1 bell housing, which the clutch/release arm is attached to, will this not be the ticket? Did they change the bell housing mounting screw placements as the models ascended..1-V?

The bell housing will be fine, however, depending on which clutch you have at the moment you may have issues with the clutch release fork and throwout bearing when changing over the trans.

As to the trans itself, its one thing to shift through the gears on the bench but quite another to assess the OD unit. If you have a look at the other post on OD's, which is running at the moment, you will see a basic bench test setup which I used to check out my own OD box a few days ago.

Without putting to much faith in it, I was able to establish that at least unit is functioning i.e. switching in and out of overdrive, the real test will have to be on the road, but I do know its now worth installing.

Certainly from your photos you dont have a late model SV unit as evident by the output spline, and it appears to be an all syncro box.

 

[Jimjordan2]

I think I'm still confused, maybe my old mind is just not getting it. For my California freeway driving in my series V with OD is it preferable to have the 4.22 or 3.89 differential? Does this mean the wheels turn at the 4.22, or 3.89? or the opposite? I know, this has been all explained before somewhere, but a simple answer for a simple person like me would work.
thanks.

 

[hartmandm]

Chris,

Sorry, I didn't realize you weren't in possession of the OD yet.

Jeff Howarth on this forum works with John Roseby on OD units. You can send a PM to Jeff to inquire about rebuild costs.

Mike

 

[Thor 1211]

I think I'm still confused, maybe my old mind is just not getting it. For my California freeway driving in my series V with OD is it preferable to have the 4.22 or 3.89 differential? Does this mean the wheels turn at the 4.22, or 3.89? or the opposite? I know, this has been all explained before somewhere, but a simple answer for a simple person like me would work.
thanks.

The 3.89 number is the number of times the drive shaft rotates for each turn of the axle. If the idea behind an o/d is to drop the revs at any given speed then the lower the number the better if the engine can handle it. My o/d gives me about 10% reduction on the tac but I have to disengage the o/d on long steep hills.

 

[Jimjordan2]

Got it, thanks. I thought that, but you know, Duh...…..

 

[65beam]

I called Nisonger last week to check on availability of an electronic speedometer for our RHD Harrington since they converted my cable tach to electronic. My reasoning for making the call is due to the soon to be done removal of the 4.22 rear and switching to a 3.89 and possibly a 3.70 gear . Use of the 3.70 means installing the ring and pinion from one of my sedan units. The use of the 3.89 is a no brainer since I have many third members with the 3.89 gearing. Use of either gear ratio would reduce RPM's at road speed. Coker Tire does sell a very tall 13" inch tire that has been proven to lower RPM's .The one variable is that series 1 and partial series 2 production used a coarse spline axle and coarse spline spyder gears in the rear end. I don't recall the exact VIN where the change was made but it is available but the use of a later rear after this change requires the use of the fine spline axles. Series 5 axles can not be used in earlier axle housings due to the difference in axle bearings. Series 5 sealed bearings have a rubber o ring seal. There are no spyder gears available for the coarse spline axles and SS no longer has available the spyder gears for the fine spline axles. The OD unit in the Harrington is the original unit from one of my other Harringtons and has 70 % on the reduction of the OD unit. Some may question that but I don't question TT. My conversation concerning the speedometer was based on the changing of gear ratio, OD mods, difference in tire circumference, etc. They can make an electronic speedometer using a unit used in Cobra replicas and after changing the face to duplicate the early Alpine unit the cost would be in the range of $600 to $800. He asked if I had a Garmin and suggested that if I do that I use it for knowing my speed because their unit would also be a GPS unit.

 

[Cali_59]

Thanks 65beam. very useful info.
I only had a slight hope that one could just swap 3.89/4.22v dif's in and out.
I am leaning towards leaving the stock 3.89 in place, and working / researching the reduction gear route.

 

[Cali_59]

Looking of just a bit of clarification,
If I obtain a 980 speedo, that was made for the OD cars, which were 'all' fitted with the 4.22 Dif,
leaving my 3.89 dif, would still have my speedo off right?, ..but I would be closer than if I had a 1000 speedo correct?

Is there a thread on speedo gear deduction to dial accuracy in?

If having a lower dif ratio with a OD installed , allows the car to go faster in the top 2 gears, then why did Roots install a 4.22 with ODs basically slowing the car down compared to using the 3.89?

Chris

 

[Jimjordan2]

I also always wondered about that, but..... Oh well.
Anyway, I'm running my Series V with an OD with the supplied OD speedometer from Jeff. It was fine until I installed the 3.89 rear end. I'm running about 5-6 mph difference now.
So if I read 65, I'm doing about 70.
I don't know what the math works out to be, but that's what my Garmin says I'm doing. Close enough for me. That's like worrying about the tachometer in my opinion. Do we really drive our cars by tachometer?
I know, everyone wants everything to work the way it should instead of the way it does. Not a problem.

 

[Cali_59]

sorry, 'gear reduction'

 

[hartmandm]

Chris,

Re-read my earlier post: http://forum.sunbeamalpine.org/inde...ng-an-overdrive-into-an-s1.27439/#post-190151

A key thing you are missing is the different rate the series 2 OD unit spins the speedo cable versus a series 5 OD unit. The series 5 OD unit spins the speedo cable about 50% faster than the series 2 OD unit. Your 3.89 rear end will reduce the speedo cable spin rate difference by about 8 percent. A 980 / 1000 / 1020 speedo will read off by about 40% if you don't reduce the speedo cable spin rate or have the speedometer modified to read correctly at the higher spin rate. Or you can go the electronic (GPS) route as 65beam is doing.

Mike

 

[Cali_59]

Thanks Mike , I will read up and learn.

 

[Cali_59]

Gary, My set-up will be the same as yours.. 3.89 + all sync V OD
What was your speedo solution?
Thanks

 

[Cali_59]

Mike, yeah did didn't fully comprehend the first time I read your informative post, now I do. I glazed right over the increase in revolutions.

Where does one install/ have installed the reduction gear? inside the trans or gauge?

I think this is going to be a less expensive route than Nisonger's GPS offering. 6-800 is out of my league.

On a parallel note:
I am tending towards electronic ignition.. I've had nothing but problems with my ignition timing, sputtering at take offs and while driving.
+ I want to have a rock solid charging/ running solution.
I'm looking into what all will be needed to go with an alternator with built in voltage regulator, and how to wire it up to my S1 system.
Off hand, I would think I should change the polarity from positive ground system/ change all gauge terminals and some around the voltage regulators/horns lights..
I'll look for a right-up on this.
going to be a busy summer.

 

[Jimjordan2]

The 3.89 number is the number of times the drive shaft rotates for each turn of the axle. If the idea behind an o/d is to drop the revs at any given speed then the lower the number the better if the engine can handle it. My o/d gives me about 10% reduction on the tac but I have to disengage the o/d on long steep hills.

Looking back on this post, that's exactly the performance I'm getting with my car. I figure about a 10% difference in rpm and I have a large grade by our home. Iffffff I could keep my speed up, it will almost (I think I can, I think I can.) make it up in o/d but not usually. Have you tried just dropping down in to 3rd o/d?

After posting this, I wonder; I don't know the answer, is 3rd o/d higher than 4th?

 

[hartmandm]

Jim,

Here are the gear ratios for an overdrive (from the series 5 owner's manual). Regular 4th is just a little lower ratio than O/D engaged in 3rd.


Mike

 

[Tom H]

Be sure you understand that the ratios described for the OD column, are using a 4.22 rear end. You need to recalculate these if using a 3.89 axle with your OD.