mx5 diff problems

[Talonmotorsport]

Erm minor edit.....just put the 1.6 LSD next to the open diff, erm so how many different sizes of diff are there?

[PorkChop]

The 1800 diff has a larger crownwheel and is physically bigger (might be a bit longer too). The 1600 and 1800 driveshafts are different, so if you fit a 1600 diff you will need 1600 driveshafts too. On MX5s, the prop must also match, but I don't know whether the prop length is the only difference and therefore not an issue on a Roadster.

Push in driveshafts will also fit bolt in diffs (at least for the 1800s, as I have this exact setup on my Torsen).

[Stot]

[silly ideas]
If you could machine down the bolting surfaces 6mm you could sandwich in the mounting plate to the standard diff.

Or maybe you could design a plate that can be bolted on externally using the existing bolts that hold the diff together. Need to cut it around the casting webbing.



Then cut the wings off.
[/silly ideas]

Cheers
Stot

[Talonmotorsport]

I did consider that at one point I even offered the cover up to the mill, then I had a little think about gripping a brittle ali casting in a machine vice....

[jason 82]

Just re read my gillham guide, and under the section differential, it actually has the nose braced. It says, an additional length on 19mm box can be fixed between BR12 & RS3, with a 5mm packer welded between RS3. The second engine mount rubber can be used to secure the front of the diff. I have revision 3 notes, so maybe it was not in the earlier build spec. Maybe we were all that keen, we missed it. 19mm box & 5mm plate it is ! ( picture in notes is - figure 41 : front lower diff mount position). Tidy on a Friday !

[Davidbolam]

Originally Posted by jason 82

Just re read my gillham guide, and under the section differential, it actually has the nose braced. It says, an additional length on 19mm box can be fixed between BR12 & RS3, with a 5mm packer welded between RS3. The second engine mount rubber can be used to secure the front of the diff. I have revision 3 notes, so maybe it was not in the earlier build spec. Maybe we were all that keen, we missed it. 19mm box & 5mm plate it is ! ( picture in notes is - figure 41 : front lower diff mount position). Tidy on a Friday !

That was what spud and nathan used but it failed. Partly due to the mount and they also didn't use the large plates that go under the diff mounts. Nathan then modified the mount be removing the rubber engine mount and replaced it with a steel bracket. Nothing to stop the diff twisting though

David

[Stot]

Originally Posted by Talonmotorsport

I did consider that at one point I even offered the cover up to the mill, then I had a little think about gripping a brittle ali casting in a machine vice....

You could do it with a steel jig but you would need to do it in 2 or more operations.



Clamp the jig to the table and then bolt the diff casing to the jig from above. I think the hole spacing is equal so if you do 2 opposite sides then turn it 90 degrees you could do the other 2 sides. Probably need to cut the wings off first too.

At a push I could probably do this on my little Sieg SX3 in 8 steps with the head at 90 degrees.

Cheers
Stot