New OD old Gearbox...With Gearbox Strip Down Vid


Well-Known Member
Had the OD professionally rebuilt this winter due to leaks and being on the verge of slipping however on the gearbox output shaft now the OD’s off there is a fair bit of float - I’m talking 2mm maybe. It seems to be the bearing shell that’s moving in the gearbox case rather than worn inner bearing itself. I have another gearbox but untested and been sat a long while without oil in. I guess the question im asking float like that likely to blow up soon and if it did could it damage the OD? Was hoping I could run it this year and strip and rebuild it or the spare over winter, don’t really have time this year but am I daft bolting a new OD on this?


Staff member
The manual doesn't give any end float measurement other that that it's set by the play in the bearings or 'factory set'. It sounds like the bearings themselves are OK but the outer race is a bit slack, it's normally a tap fit in the case and not a press fit. Is the any way of running a little bit of Loctite in where the outer race fits in the case to help the bearing get a bit of purchase? If you can the clean the area with brake cleaner and dribble a bit in making sure you don't get it in the ball race itself. If you can't then, if it was mine, I'd use it as it is. My gearbox has far more faults and it just keeps going, more crunches than a big bowl of corn flakes, they can take a lot of abuse.


Active Member
I changed my Commer's gearbox as it was jumping out of gear on the overun and noisy :(
Have you checked the spare gearbox isn't seized then? Like the basic gear selection and shaft turning (there may still be traces of oil on internal surfaces).


Well-Known Member
Yer all turns ok and doesn’t sound too bad going to take selector off tonight to check contents further. Doesn’t look as clean as current one looking through the holes in the ends and the output shafts have light tarnishing. These’s no play in both shafts. It’s more time to remove and get a new clutch plate and splines are different. Want to try run this year ideally until can rebuild. Thinking I might use bearing compound on the outer shell to stop it moving in and out or spinning seems like the tolerance on the outer shell is slightly out as the bearing is fine in itself


Well-Known Member
Are we talking end float or side to side here?

The bearing is located by both the gearbox casing, and by a recess in the OD Housing which holds it in place, that and the circlip preventing end float. With the OD (or tail housing) removed there will be 2mm ish of end float due to the outer race sliding in and out of the casing. I've just looked on my spare gearbox. This is normal and quite OK to fit the new OD.


If we're talking about side to side float, then the bearing outer race must be slopping around in the gearbox casing, and it may also be wearing the recess in the OD. If the gearbox casing has worn enough to get that sloppy, the outer race must have been rotating, and this would leave a fair bit of sludge lying around in the gearbox and the OD filter. I don't think I'd want to be risking this with a new OD.

And yes, he photo the big nut is loose, but the box needs rebuilding anyway.


Well-Known Member
Sorry missed your reply Panky...yes thinking to lock it with loctite to prevent spinning and causing any wear. Colin never thought about that with the OD holding it in place! it is in and out movement btw - there’s fortunately no side to side. My spare gearbox has no in and out movement and watched a great set of 4 vids on YouTube about how to rebuild these gearboxes and on there there is no back and forth movement. Sounds like it’ll be fine with the bearing compound and OD back in place though. The spare gearbox I’ll keep as a spare :)

Guys thanks for the quick replies - big help as always



Staff member
That's great Jim :cool:, do you have any links for the other vids, they don't appear after the first one as you would expect.
I've edited the title and pinned the thread.

Paul Goldsmith

Well-Known Member
This seems a good place to include the key information for when using swapping in an Arrows gearbox (Hunter / Rapier)

I recall that on the gearbox we need to swap over the ;
  1. Commer bell-housing - to allow for our vertical engine position, Arrows were slant
  2. Commer top selector - to link up with Commer selector rod mechanism
  3. Commer input shaft (and the rest of the Commer internals) - to a allow for the shorter Commer bell-housing
  4. Potentially need to modify speedo cable or speedo drive coupling on gearbox
Do we also have to swap the synchro gear on 1st ?

If, as likely an Arrows gearbox is used to provide an OD, then also ;
  1. Ensure Commer top selector is modified to take the OD inhibitor switch
  2. Upgrade the Commer electrics for the OD operation, wiring, relay and switch etc.
  3. Fabricate OD gearbox mounting bracket
  4. Fabricate shorter propshaft, noting the number of splines on output shaft
The Arrows cars came with both D-type and the later J-type overdrives, is there any opinion which if preferable for a Commer swap - should there be a choice, as both are fairly rare finds :(

(Please add anything that I've overlooked !)

Point 3. 29/11/2020
Added Point 4.
Last edited by a moderator:


Staff member
Final drive in slightly higher on 'J' type so, if you have the grunt to push it, better for M'way cruising. Downside is replacement solenoids (screw in rather than bolt on) seem to be rarer and more expensive than previous types.