IRS installation

[MickHope]

I dont know if its me or not but something is not making sense.

We tried to install the Mustang diff, we are still missing parts so did the best we could. We have the front mount bolts, nuts and spacers but the rear bolt and spacer haven't been sent yet. There is a 10mm gap between the diff mount and the chassis mount. Also the bolt holes seem to be out by about 5mm. I cannot get the other side bolt in. What am I missing here?

TIA

Mick

[michael everson]

It can take a lot of pushing and pulling to get all 4 bolts in. The sleeves inside the bushings will slide up to the diff when you tighten everything taking up the gap. Don't tighten any of them until all 4 are in.
Mike

[MickHope]

Thanks Mike. It's a big gap so it's very deceiving. I did see a post somewhere where the ends of the bolts were turned on a lathe to a point to help get them in the spacers. Is this something worth doing? Thanks.

[michael everson]

Yes. That will help
Mike

[JimLev]

Seems to be a common problem with the IRS.
I ground down part of the OD of the bushings that go into the mount holes in the frame so they were sort of eccentric.
I could then rotate the bushings so the holes better aligned with the IRS mounting holes.

[FF33rod]

Ratchet straps and a lot of persuasion to get it in for sure. The gaps can work in your favour, allows for some wiggle room - so don't tighten up the ones you do put in, leave this loose until you get all 4 in. Another thing I did to get the last one in was to out the inner metal bushing part way until I got the bolt into the rubber part and then tapped the metal bushing back into place. Good luck.

[MickHope]

I went to a motor wreckers and measured the diff mounting points from an Australian made 2011 Falcon, same diff as in the 2011 Mustang with the 412HP Coyote I think, looks the same as mine anyway. It's 1/4' longer. I asked if I could borrow it for an hour if I leave my drivers license with him. He told me to F.O. Nice guy. I will get some shims laser cut and machined to take up the gap.