JJ Autosleeper
Active Member
I’m still looking for a gearbox overdrive suitable for my 1970 Autosleeper van. Anyone know of any for sale? If please message me. Thanks.
Overdrive for Commer PB 1970
- Thread starter JJ Autosleeper
- Start date
Is @commeracer still doing Lexus six speed conversions/kits?
JJ Autosleeper
Active Member
Hi, yes Tim is but I am just wondering if the more traditional overdrive route is available.
I have a spare Type D overdrive unit but it is on Series 4 Alpine box and would need modifying to work which is beyond me. Happy to swap with someone for the right one.
I have a spare Type D overdrive unit but it is on Series 4 Alpine box and would need modifying to work which is beyond me. Happy to swap with someone for the right one.
Pootle's Owner
Active Member
I doubt you will find an overdrive box for a Commer. I bought a Hillman overdrive box on ebay but the input shaft and bellhousing didn't suit the commer so I stripped the gearbox to get the overdrive off and remove the long output shaft from it. I then stripped the commer box to fit the long output shaft and overdrive unit. It's not a big job but there are lots of 'bits' and it's very confusing if you have two boxes apart at once! Once you have the overdrive box you need to fabricate a suitable rear mounting bracket for it then get the propshaft shortened by 3 inches. It all sounds a nightmare but it isn't that bad and the improvement once you have an overdrive is fantastic. The last 3 weeks touring 1000 miles in Pootle would have been a nightmare without it!
JJ Autosleeper
Active Member
The only bit I can see me doing is prop shortening and bracket. Opening up the gearbox is not something I have ever done.
I have a spare overdrive (type D) and a gearbox off a 1964 Alpine. But will have coarse splines all round. So I don’t think much use on a 1970 fine spline Commer. Photos attached.
I have a spare overdrive (type D) and a gearbox off a 1964 Alpine. But will have coarse splines all round. So I don’t think much use on a 1970 fine spline Commer. Photos attached.
Attachments
Guess you could fit a the coarse spline output joint to the Commer prop? They fit a new tube when shortening anyway. Mine a rare one with a coarse spline
The modification includes fitting the Commer input shaft so you would only need to find a coarse splined prop end (coarse splined clutch plates are available if required, same one as a Bedford CA). They were used on various props so you should be able to find one.
There were some great strip down and re-build youtube vids in the stickied thread for OD box but they are no longer available
There were some great strip down and re-build youtube vids in the stickied thread for OD box but they are no longer available
JJ Autosleeper
Active Member
I suspect this is the strip down link (to the YouTube Sunbeam Alpine Channel):/
The rebuild ones follow.
Here's the link to the Alpine Channels playlist
OD gearbox re-build
I've updated the stickied thread with these links too
OD gearbox re-build
I've updated the stickied thread with these links too
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Pootle's Owner
Active Member
Folks (including me some years ago) are always afraid of gearboxes because they do seem very complex until you see how they work. In all honesty they are not that bad. If you have no use for the current box and overdrive, then you have little to lose in opening it for a look-see have you? Even if you open it and end up with a pile of bits you are unable to reassemble there are folks around who can! The only tricky bit is making up a suitable dummy shaft to allow you to drive out the layshaft without dropping all the rollers out. I made up a 'perfect' brass shaft and still dropped all the rollers!!!!!! As noted above, the spline type isn't a deal breaker on input or output shaft. The length of the input shaft is possibly a problem if you want to use that box and the Commer bellhousing. Do you have the alpine bellhousing?
If, like me, you can't easily use the 'new' box and overdrive you could dismantle it to remove the overdrive and output shaft then find someone to fit them to your Commer box....
Of course it would be wise to test the overdrive on your existing box before going to the trouble of fitting it to the Commer!
If, like me, you can't easily use the 'new' box and overdrive you could dismantle it to remove the overdrive and output shaft then find someone to fit them to your Commer box....
Of course it would be wise to test the overdrive on your existing box before going to the trouble of fitting it to the Commer!
Making sure it works is important although they can be refurbished. A place in Sheffield does them but at £400+. I got mine done with them and it works beautifully now whereas it used to slip or not change at all.
Dummy shafts are easily made out of a length of 19mm plastic overflow pipe. As said, loads of older vehicles used the prop shaft yokes with coarse splines, and I would think most prop shaft rebuilders would have them in stock. Mine did.
Pootle's Owner
Active Member
just noticed you are in Cardiff Jonathan? We just spent last week around that area in Pootle. Could have dropped by to strip the Alpine box with you!