Getting the best out of standard suspension components for touring driving today

I would be a little wary of full PU mounts, we used to used PU as the stripping medium on tool dies and after a while the constant compression- release caused internal heat to build up and they eventually exploded.
There may not be sufficient reversal forces happening in normal driving to cause it but just a cautionary tale.

Good to know, thanks for that!

Do you recall what level of force and displacement you were using?

Sorry no, this was 25 years ago.

My calculations suggest bending of the 19mm bar contributes about 5-10% of the force from torsion, at the wheel. That’s about the same region as the rubber wishbone bushings, so I’d consider it small but not completely negligible.

Perhaps more interesting than the actual numbers was that the bending action seems to reduce the torsion effect, so the total stiffness is less than would be obtained with the same size bar working in pure torsion (eg D-type?). That conclusion is part objective, part subjective, I’m open to correction from anyone with better data as usual.

So overall the mongrel twisty-bendy nature of the bar makes it slightly less efficient but doesn’t affect its performance much. It does push it further up the short list of things I don’t admire about the E-type.

1 Like

There he goes again, with the engineer speak.


1 Like

Sorry, I had to simplify the vocabulary during my time working with non-native English speakers.

I mean the Michigan years, of course.


A mere six weeks later, with a stand that global consent felt was probably substantial enough, I started assembling the drill press to it, so I could get back to making test supports for bushings and mounts. I am going to find an answer!

The main section came out of the box with the belt cover seriously distorted, not a major setback as I have heavy tools and low sensitivity to paint flakes on the floor. More of a problem is that the input cable has been trapped against the motor body and needs replacement. I don’t see corresponding damage on the packaging so guess it was knowingly shipped to a dumb foreigner who wouldn’t be able to navigate the returns process. Oh well.

Will be back after I’ve tracked down my ex-submariner friend who knows how to dismantle motors and reassemble them successfully.

1 Like

I would think that the bending moment could be measured directly from a torsion bar with the splines removed.

Yes, that’s how I did the estimates…calculations…swags…but with numbers because I don’t have real parts.

I plotted the path of the TB end with suspension travel, then calculated stress from bending for that movement. Repeated for torsion, compared the numbers and confirmed what everyone already knew - effect of bending is a fair bit smaller! But now we have calibration for “a fair bit” - more than not much, less than quite a bit.

1 Like

Does anyone have information on the front LCA lower fulcrum blocks - material or manufacturing process?
Any detail appreciated.
Any old / spare / junk blocks also appreciated, for that matter. I want to modify for a different bushing, might end up making new ones eventually.

I’m very confident the submarine man will fathom it out.

They are steel forgings. Somebody, somewhere probably has a set that they can donate to the cause.

I’m most interested in the front one, which seems to be unavailable from the main suppliers. Dimensions would be helpful, especially wall thickness around the main bushing hole. I need to estimate if it would accept the bushing I’m thinking of fitting.

I have a figure of 1.31 in diameter for the bushing hole itself.

Stick an ad in the classifieds: I bet someone’s got some somewhere.

Ok thanks, I’ll take a look. One of the ebay seller pictures suggests a double taper in the bore of the front lower fulcrum block - is that real, or just the lighting?

I’ve ordered a lower fulcrum block from ebay. My plan is to test it with a bushing significantly stiffer than any variant I’ve found of the standard bushing. If the test and subsequent model look promising I’ll put a set together for evaluation on a car.

:thinking: tough crowd

1 Like

Some related discussion in another area.

It’s a helpful reply from a bushing supplier explaining the difference between semi-bonded and fully bonded bushings.

By my understanding the original E-type LCA bushings were semi-bonded, I’m looking at the possible benefits of a fully bonded bushing. It would probably entail a modified fulcrum block, possibly a custom block. A bolt-on mod in either case.

Probably not an original idea - does anyone have experience of such a move in this location?

Yes, that is real.

The “semi-bonded” bushing referred to by the supplier is double sleeved thus physically similar to their fully bonded bush, but lacking a bond to the outer sleeve - hence lower stiffness and cost. I’d not heard of this before, I thought they either had double sleeves or just the inner like the original Jaguar LCA bushing.

So much more to explore…