Original IRS Mounts vs. Replacements

Hi Colin - yes, a situation where original parts are still available is healthy. As you note, I’m less confident in replacement parts - according to my tests the parts billed as direct replacements are actually softer than original while so-called “uprated” are, in my opinion, insufficiently different to justify the description. I’m willing to withdraw or correct these comments on sight of better data than mine, but that opportunity has not arisen so far.
There is also a wider point that a stiffer mount should be shorter than the original - to avoid raising the body above its original level - as is standard practice with suspension springs.
I’ve made mounts for bench testing but would not suggest using them on a car, hence I’m talking with an established manufacturer of these parts about making a small batch. They will be rubber, as I feel it’s important to retain the inherent damping that (I believe) rubber offers. As you say, it won’t be a low cost exercise but they will be significantly stiffer with compensated ride height, and they’ll fit easily without pre-compression or cursing. (That doesn’t suggest any lack of respect for your compression device, it’s very beautiful).
Thanks for a good discussion.

1 Like

I finally got back to the tie plate this afternoon.

After loosening all bolts, nothing felt binding up, removed all but 4 in the center and still nothing binding, so removed those also. Easy to do with nothing binding.

Although I found that I am apparently the first person to ever remove it since it was driven out the door at the end of manufacturing in October 1982.

I had to scrap off (used a plastic putty knife) about 3/16" or so of accumulated gunk before I found confirmation … Jaguar DBP!

I will post photos of finished jacking plate with dimensions when done making it.

1 Like

Did you have crayon marks? Mine said XJ6 and 43/13 on the underside. 80s might have had a sticker instead or a different process

Nope.

Just black paint on both sides. NDBP on the bottom and DBP on the top (or was it vice versa?).

If it had a sticker (or crayon), likely dissolved in the crud and scraped off with it without being noticed in the crud (a label).

The bottom of the tie plate was also well protected with a thick coat of oily crud (also scraped off, but it wasn’t as thick) from 40 years of road oiling duty.

I finished and installed the jacking plate.