time for a 38mm hole in something
what could possibly go wrong?
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Just make sure the OD exceeds the ID, otherwise the hole will be on the outside.
No charge for the pro tip!
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The world is in safe hands.
Good to have that assurance from time to time
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Speaking of hands, I’m down to one opposable thumb for a few days. That just might affect the dizzying output from bushing tests. We will emerge from this setback sharper, brighter.
Erm… did you attempt to drill a hole in yer thumb?
A nice lady removed my thumb nail. She said it was for the best
I hope that was done with the benefit of local anesthetic…!
I thought that meant your avatar, but I see it’s unchanged.
I finally got around to testing the bushing that came in the used LCA front dangler-bracket I bought on ebay. I’ve no idea of its history, was surprised to find it significantly softer - both in direct Shore hardness test, and in load / deflection tests - than a new part that came in a Jaguar bag.
I’ve never tested aged rubber parts but casually assumed they would get harder with age - maybe that depends on their history, usage and location? Would be interested in any experience on this.
I would expect dry location harder, oily location softer?
Where they get soaked with oil, they generally get soft and squishy: where they are dry, they usually don’t necessarily gain anything in durometer, but often times gain a lot in craquelure… 
55 year old IRS mounts swapped out this summer. Hard as a rock. But no sign of splitting or separating.
Trans mount was oil soaked dissintagrating mush.
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Thanks, the bushing in question was apparently in good condition with no cracks or contamination. Perhaps it reflects the original spec of the period, while the current Jaguar replacement spec is stiffer. Maybe reflecting availability in a small market, as the new one measures very similar to the Robey aftermarket part
I ordered the standard mounts (60 SHORE) from SNGB after I found they were manufactured by the same supplier who made the stiffer mounts (80 SHORE). My fear was they may have different geometry for the two sets. Both of the two sets are the same dimensions to the eye. So that’s good.
I measured the SHORE of the standard mount and found them to be between 55 and 62 SHORE A. So the Standard mounts are softer by 10% MOL compared to the Stiffer mounts. Not 80 vs. 60, but something less. So the standard mounts will go in the front of my IRS.
Standard mount p/n is: P_C17198_O Cost: $27.16
Stiff Mount p/n is: P_C17198U Cost is: $24.05 They could not explain why the stiff mounts are less expensive!
Shims p/n is: P_C17228 Cost $3.04 ea. That’s an extra $36 for shims one should not need for a dimensionally correct mount!
I also found these mounts, all of them, not only have thicker rubber than the old Metalastik but the frame ears are wider apart and require 2 more spacers. Why is that? Because these mounts are made to fit the Jaguar sedan frames and are wider than necessary for an E-type.
In the pictures the stiff mounts are numbered 1 & 2. The standard mounts are numbered 5 & 6 (the Metalastiks being 3 & 4). The two mounts butting to each other are one stiff and one standard.
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Good information Scot, thanks. My bench tests suggest there is a significant difference in rate (stiffness) between two mounts whose Shore hardness compares as 55-62 and 65 Shore, as you have. I think you have a good direction, will be interested in your driving assessment. The hard part will be saying there’s no obvious difference, if that’s the result after your significant efforts. It’s always possible.
I’m planning a set of mounts with changes to the physical shape to get a more pronounced difference in stiffness than the standard mount will allow.
It occurs to me that the only real way you’re gonna get proper results is by on a track or a traction circle.
I’m sure you already know that, and I look forward to results from those particular kinds of tests.
right and I actually would not know the difference anyway. I have not driven an E since 1984 or so! And never on a track.
Yes, if we were looking for a quantified gain - if, for example, a model year upgrade specified a 20% improvement in a specific handling parameter, that would suggest measurements.
This is a rather different situation - we’re a group of people of varying aims, interests and skills, scattered across the globe talking of non-specific gains supported by a computer model which has not been calibrated against the car in question. It’s inevitable we will use nebulous techniques to follow such nebulous aims.
I think it’s an acceptable level of approximation - guesswork if you prefer - for such a work process. This process is similar to that Jaguar would have employed in the day, perhaps more sophisticated. I’d be happy to push it up to a higher level of precision if someone wants to volunteer appropriate instrumentation, parts, facility…and a suitable car!
Well, if I’m not mistaken, a suitable car to do experimentation upon now exist somewhere in Utah, does it not?
As for instrumentation, you can get over-the-counter stuff that’s pretty darn accurate these days, and I happen to know someone who has a little bit of driving experience…
He works cheap, also!