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1.8S Ratio (3.67:1) Standard Differential.. Maybe A Gte One..


Rick-Manta
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How do! I'm looking for a replacement differential for a Manta 1.8S, given how many were broken for their XE bits, I'd have thought there would be a few about. I suppose I could use a 3.44 one if someone would see it to me cheap as it'd be interesting to see the top speed with that and bigger wheels and not only that, the 'longer legged' an old car is, the lower the engine will rev at the equivalent speed and will techinically last longer. However would prefer the 1.8S ratio..

I'm based in Bishopsworth which is in South Bristol, I can collect if fuel range is less than a courier..

I may also need some fitting advise once I have it as how do you disconnect a solid axle from it? There are no external driveshafts :wacko:

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Thanks mate :-) I'll message the seller to see if he can take the diff out for me. The listing sounds as though he just wants what's left of it gone, he's only a bit over an hour away so a shame I can't transport the entire rear axle.

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Thanks Kev, it's to replace a welded diff that stops the two wheels turning independantly, so would look like I need at least more than one cog.. Crush washer.. Axle mesh.. :wacko: I thought you could just pop one in (to a degree)

The full axle would be great/a bit easier, however it would have to be reasonably local and I'd need to hire a van, so opting for the diff swap.

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It probably would Kev, but it's a project now, not road going, no insurance, etc. It'll never fit in my Chevy.

James, yes mate. It's a beauty, but then what Manta isn't?! I'll be giving it a good once over when I've got a bit more time to me sen, as I've not seen the underside, chassis rails and usual problem areas. The engine is running rather lovely, electrics are good, clutch, brakes, gearbox feel in great order, very pleased with the suspension and although the back ones are knackered because of the diff, it does have racing tyres which I wasn't expecting. Not really a downside as I was skeptical of the 35k on the dash from the start and it wasn't advertised as 'definate', with the tell tale gearknob and wheel wear I'm certain it's 135k but as I say, the engine is running so smoothly (bit of over-run/dieseling but no pinking) it's clearly been looked after. 'Tocca' who I bought it off said the elderly chap that owned it a couple of owners ago had it long term and took care of it, even buying it back off insurers when it had been cat-c damaged, and had it until he passed away. The diff is an absolute nightmare to drive around town, I took it to show my daughter and trying to park it I thought I was going to break the axle, hence why the diff is a priority, also the front wheel alignment has excessive toe out so the steering snatches about but that's good as someone is going to show me how to do non-laser DIY wheel alignment. A Manta for £1000 and even got it delivered for £60 I certanly feel like I've got an excellent car, hopefully you'll see it in the flesh before long mate :-)

Edited by Rick_Manta
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To change the diff you need to

Drain axle

pull both halfshafts out of the axle

move panhard rod

remove rear cover

undo 4 bolts and remove diff

Then swap the crownwheel from old diff to new diff (crownwheel and pinions are matched machined pairs and need to be kept together)

Refit diff and check mesh/backlash

If that needs adjusting remove diff bearings and swap shims around to move the crownwheel a fraction left or right to get the right mesh

Then bolt it all back together.

In theory thats all you need to do, but thats assuming both new and old diffs are exactly the same dimensions and the bearings cases were also exactly the same.

However in practice that isn't always the case.

The shims behind the diff bearings do 2 things, they change the overall length of the diff from outer edge of bearing to outer edge of other bearing (which must match the gap in the diff casing exactly so the whole lot can't move side to side)

Also once you have the correct overall length they can be swapped side to side to move the position of the crownwheel sideways a little (fractions of a mm) to get the right mesh between the crownwheel and pinion perfect.

So the odds of 2 diffs being exactly the same with casings being the same also to a fraction of a mm are very very small and some moving of shims is almost always required.

Taking the bearings off to get to the shims can be a pain and damage to the bearings is a high possibility if you don't have the right tool.

Also in theory you need to check the preload of the bearings in the pinion shaft. That requires the torque tube to be removed and a special tool or setup to check.

If its too low you get whine (basically the bearings a slightly loose) too high can cause premature failure.

If you need to adjust the preload the pinion gear will be moved slightly which will require the shims on the axle to be redone to get the mesh correct again.

Tightening the bearing pulls the pinion gear forwards so the crownwheel needs moving towards the middle of the axle to regain the right mesh/ backlash.

All in all its easier to fit a complete axle in known good condition than have to dig in and readjust the shim etc.

Oh and one final thing the 3.67 and 3.44 diffs are different, and i don't just mean the gearing. The position of the flange that the crownwheel bolts to is different so you can't fit a 3.67 gear to a 3.44 diff or vice versa

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Thanks for all the info Dave, I've been worrying about all this measuring backlash and stuff which I have no previous experience in but seen the shim kits about so thought, how hard can it be? :-D In fact I thought the hardest part was figuring out how you pull the halfshafts out, I'm guessing there's a cap inside the brake drum and an obvious way of pulling it out.. I may end up having to pay to have it fitted professionally, but I'd still need to find a replacement diff. Thanks for the info on the other diffs not fitting, I've been looking at getting a couple of GTE ones I've been offered/seen about. So it must be a from a 1.8..

Chris, thanks for the offer mate but as mentioned, I'm unable to collect a full axle.

Edited by Rick_Manta
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Aw sweet, thanks very much Rob. If you do sell just the diff by itself then I can collect, you're probably a couple of hours along the M4 from me. The full axle would be great though.

If I do end up with swapping diffs, anyone know 1) if the mantas half shafts are held by c-clips or the plate thingy? 2) what the backlash or tolerance should be in .00xxmm? 3) if the Pinion gear, seal, prop and torque tube can just remain in place? (as long as I'm swapping for my own crown gear, thanks David) 4) do I grease the bearings when refitting or does the axle oil do all that?

Thanks again.

Edited by Rick_Manta
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