Replacing MX-5 Differential side seal

Posted: 2nd May, 2011 in Cars

Having put a reconditioned 1.8 torsen diff into my MX-5 last year,  it has subsequently sprung a leak from the passenger side.  This is evident from all the oil on that side of the diff.

I set to work with replacing and it didn’t take too long, however I would recommend that if you do get a second hand diff, fit new side seals before using in your car!

I ordered new diff oil from eurocarparts – API GL 5 and a new seal from autolink, part number – MA02-27-238A. (Torsen diff; not viscous, as was originally fitted, so don’t use registration if you have changed your diff!)

  • So slacken the road wheel nuts before jacking up.  (then you are not swinging on it with the car in the air)
  • Raise the car up and support with axle stands.  Do not go anywhere near the underneath until you have thouroughly shaken the car, better it falls off now than when you are underneath!
  • Remove the wheel and undo the four nuts attaching the drive shaft to the diff flange (14mm)
  • Don’t bother removing the axle hub nut as suggested in some how-tos, instead undo the top nut and bolt attaching the hub to the upper wishbone.  I suggest jacking the lower wishbone up to a sensible height to relieve pressure and faciliate removal of this bolt.
  • Lower the wishbone and swing the hub out towards you, this will give enough room to pull the driveshaft off the diff flange.
  • The flange is retained by a circular c-clip.  To remove simply apply a large leverage on the flange.  I ended up with a breaker bar wedged between the diff housing and the top section of flange.  With enough force the flange will pop out.  Check out the c-clip, and dont lose it.  You could replace it but chances are it will be fine.
  • Withdraw the flange ensuring not to allow dirt into the diff.
  • I used a claw hammer to ease the old seal out, take care here not to lose the old spring from the seal you are removing into the diff.  Make sure not to scratch or mark the faces with your hammer!
  • With the seal removed, run a bit of diff oil around the edges of the new seal and locate it squarely.
  • I then used the old seal to press the new one in by tapping with a hammer until it was flush with the diff housing.
  • Locate the diff flange on the splines and push in, holding it in as far as it will go use a block of wood to drift it back in with a sharp tap from a hammer.
  • Reassemble.
  • Drain and replace with fresh diff oil.

All done, enjoy.


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