14 replies to this topic

[simplyminis]

Got a gearbox here and it’s been rebuilt by the looks but has no diff casing
I read some places that the gearbox housing is now scrap? As the diff and housing has to be a pair??

Is a A+ engine thanks

[nicklouse]

yes they are a machined pair. you might be able to get a cover that is a good match or one that could be machined to be suitable. so yes a bit of an issue.

[simplyminis]

I have a casing here but how do you tell if there is a problem?
Tighten it and if it tight to turn the drive???

[nicklouse]

offer it up and see how the holes (for the bearings) line up. there should be no visible or feel-able step, after that you could be OK. I did strip a leaky engine that had the wrong cover fitted.so they can be made to work but then you have gears that are misaligned and will wear or fail.or may work fine.

[imack]

I know the diff housings are supposed to be matched to the gearbox cases but in the days before I knew better I would just get a diff housing from the scrap yard and fit it. I did this on 3 or 4 occasions on different boxes to replace housings damaged by broken diff pins.
Maybe I was just lucky but they never caused me any issuse.
As above, careful selection is probably the key.

[simplyminis]

Cheers I’ll take a look tomorrow

[Cooperman]

Measure the amount of any 'step', then elongate the stud holes by that amount.
When you have the huge bearings installed and fit the cover casting it will 'pull up' evenly on the bearings and the seal or gasket, depending on the gearbox type, willnot leak. You will likely not have to elongate the holes by more than a few thou.
I have seen that done and it works fine.

[Spider]

offer it up and see how the holes (for the bearings) line up. there should be no visible or feel-able step, after that you could be OK. I did strip a leaky engine that had the wrong cover fitted.so they can be made to work but then you have gears that are misaligned and will wear or fail.or may work fine.

 

When doing this, remove the two small dowels that are in the case, for alignment of the cap. do an initial 'dry' fit, just with the cap only, then try it with 2 bearings in there (can be old bearings). Just pull down very lightly on the nuts so you can check any gap between the cap and case. If that looks OK, line up on of the sides that the diff side covers fit to and check for a step on the other side. You can get away with small misalignment here (up to about 0.002"). Next up, check for alignment of the Shifter Shaft (without the seal). This is where a worn casing can help.  If it all looks good, then when fitting up for real, leave the dowels out. The Bearings will align the cap in one plain, and the other will need to be aligned by you where the side covers fit up.

 

There's nothing too critical with the Cap. All it does is hold the bearings in place and keep the oil in (preferably!).

 

I've done loads of gearboxes like this, a few have fitted up off the bat, some I've needed to machine a little.

[Rorf]

Just remember that most A plus gearboxes didn't have gaskets between diff cover and gearbox

[simplyminis]

Thanks for this ill have a look tomorrow and let you know

[simplyminis]

whats your thoughts no real lip and seems to match ok

 

Untitled by rhos jenkins, on Flickr

[simplyminis]

Anyone?

[Spider]

What I can see looks OK, but what about from the other side and also the shift rod?

[simplyminis]

All looks fine

[KTS]

as mentioned above, it's only really by trying to install the diff assembly that you'll see if it'll work

 

if the bores are out in the vertical axis you may be able to open out the fixing holes to let the two parts line up, but if it's too far out in the horizontal axis the bearings will either be loose when the cover is clamped down and you won't be able to set the correct preload, or the bearings will prevent the cover from seating against the gearbox and overtightening to make it fit can result in the cover cracking