Recognize this shock insert?

[Graham B]

Hi Leslie,
quote
'Original Armstrong struts through the 60's and 70's never used inserts always separate components as far as I'm aware'
"That is not correct as far as the Lotus Elan rear strut and housing assembly is concerned. After the original and expensive insert that was first used in S1 and S2 Elans that I pictured above, Lotus then went on to use an insert made by Armstrong, which was non adjustable and not rebuildable. "

A long time ago, probably 35 years, I changed the rear dampers on my 1968 S4 DHC Elan. The bits that came out were as your first pictures, they were not inserts. So I am not sure they were only used on S1 and S2. I did fit inserts but no idea who made them now.
Graham

[monkeyodeath]

Thanks for all the wonderful input, I'll go have a look at the insert again and see if it's leaking and how much resistance it puts up.

One thing -- I've noticed that the insert, once pushed in, stays in that position. On all the other strut inserts I've dealt with for other cars, the shaft will eventually extend fully when left alone. Is this something I should be looking at?

[2cams70]

That’s interesting then because certainly that was not the case for mass market cars fitted with Armstrong struts. Armstrong did supply inserts to the aftermarket as service replacement parts but not as OEM. What may have happened is that when Anglia production ended in 1967 the supply of the original parts dried up and so the service replacement inserts had to be used instead.

[512BB]

'A long time ago, probably 35 years, I changed the rear dampers on my 1968 S4 DHC Elan. The bits that came out were as your first pictures, they were not inserts. So I am not sure they were only used on S1 and S2. I did fit inserts but no idea who made them now.'

There seems to be a bit of confusion over the term insert. My interpretation is that if it slides into a steel tube attached to an ali housing then it is an insert, albeit an earlier version in your case Graham. And for insert also read damper / shock absorber. And as for your S4 having dampers like the first ones I picture, from new Graham, I think that highly unlikely. Did you own the car from new and did your steel tubes have the plugged oil hole?

'One thing -- I've noticed that the insert, once pushed in, stays in that position. On all the other strut inserts I've dealt with for other cars, the shaft will eventually extend fully when left alone. Is this something I should be looking at?'

No Josh, the damper / insert is not like other cars where the rods natural position is extended. On an Elan, if the damper is laid horizontal, the rod will stay in the position that it is left in, be it pushed right in or pulled right out, or anything in between, and that is normal.

Leslie

[Graham B]

Hi Leslie,

Ok, for me an insert is a sealed assembly containing the damper parts and damper oil.
The assembly I removed, as I said in my post, was as your photos. The damper oil was contained in the strut tube but there is NO brass filler plug in the side of the strut tube. The damper oil was poured in from the top, the assembly of bits is inserted and the gland nut fitted.
This is not the same as fitting later OEM and after market inserts, where you pour in oil for heat transfer, drop in the damper insert and fit the insert clamping nut.
My 1968 S4 is an early version and probably had dampers from the end of the run as 2cams70 suggests.
May I suggest that the early versions (S1 and S2) had the oil filler, that was then dropped but used the same assembly of parts with damper oil in the strut tube, then changed to use a sealed damper insert some time in the late 60's early 70's.

Graham

[rgh0]

My Elan S4 was invoiced in December 1968 and had Armstrong inserts from new and used Issue 18 hubs. Maybe the change from the strut tube being an integral part of the damper occured with the change from issue 16 to Issue 18 hubs ? Has anyone seen an issue 18 hub with the tube as an integral part of the damper ?

cheers
Rohan

[StressCraxx]

@Rohan My Elan was invoiced July, 1967. It had the Issue 18 castings and the Armstrong internals using the strut tubes as the cylinders. There were no inserts. I replaced them with Koni inserts in the mid 1980s.

[Quart Meg Miles]

My last set of rear inserts (from Spax) were pressurised unlike all previous units. Monroe supplied my inserts in 1993 and 2005.

[rgh0]

@Rohan My Elan was invoiced July, 1967. It had the Issue 18 castings and the Armstrong internals using the strut tubes as the cylinders. There were no inserts. I replaced them with Koni inserts in the mid 1980s.

Thanks it looks like the Issue 18 hubs came first pre July 67 and then the insert style shocks came later some time pre Dec 68

cheers
Rohan

[Graham B]

Hi Rohan,
I have just checked and my 1968 S4 was registered in June 1968, has issue 18 struts and had the Armstrong internals, not inserts.
Graham

[512BB]

What I am unclear about is this. As you all know, a gearbox uses oil inside of it, as does a differential. Both get hot in operation and the oil and air inside of them expands and contracts. That is why there is a vent in both. After a period of use, and before the service interval, I have a habit of checking the levels in both of those units, and especially before a long trip, ie a foreign holiday. More often than not, the levels in those units will need topping up, and my diffs and gearboxes do not drop oil! I just put that down to losses.

So to those of you who have found that your cars were fitted with the original type damper as in my pictures, but without the fill plug in the steel tube, how did you check the level and top up, due to the bound to be there losses?

Of course, I know the answer already. You didn't. And that is how I know that Lotus never fitted those early units to S4's. They were fitted by DPO's who at the time, MAY not have been able to get hold of the later inserts, or were offered both early and late inserts, and because the early inserts were tuppence halfpenny cheaper to clear them, went for those, not realizing that they were not suitable for their car.

Just like a diff or a gearbox, or an engine for that matter, the oil in those early inserts deteriorated terribly and needed to be changed periodically. But who did that? Nobody, thats who. Just one of the reasons why Lotus stopped using them.

I removed those early inserts from their original uprights, together with the filthy black sludge formerly known as oil. They could not possibly have worked as intended, but with a clean up and plonked in fresh engine oil, surprisingly they do.

Leslie

[rgh0]

Hi Rohan,
I have just checked and my 1968 S4 was registered in June 1968, has issue 18 struts and had the Armstrong internals, not inserts.
Graham

So looks like the inserts were introduced between July and December 68

[2cams70]

Hi Rohan,
I have just checked and my 1968 S4 was registered in June 1968, has issue 18 struts and had the Armstrong internals, not inserts.
Graham

So looks like the inserts were introduced between July and December 68

The date corresponds with when the Anglia ceased production and consequently with when Armstrong probably ceased production of OEM internals for that strut. Having individual components is theoretically better from a design standpoint because you can use larger components for the same size outer strut tube plus the strut will will run cooler. Anglias, Cortinas, Escorts etc. all used separate strut components in their OEM Armstrong struts. Inserts were only fitted for special applications (eg Bilstein sport suspensions). Monroe like Armstrong also supplied OEMS with separate component struts up until the 1980's until around the time when completely sealed struts started to become available.

[bjw]

In response to the original question, they look to be Armstrong 'Big Red Heavy Duty' inserts (box simply labelled as '620'), as per the ones pictured below:-

(For some reason (computer error?) the 1983 invoice from Bell & Colville shows them as AO/50D6007F although the Elan parts manual lists 050 D0007 as the replacement for 026 D0007...? - i.e. the Elan and +2 then used the same insert.)

I didn't check to see if they were stamped, but the '620' matches Rohan's post in 2014:-
viewtopic.php?t=30856&f=42&start=0#p206801

The old shocks which I believe are Armstrongs ( red colour) that I have removed from the Elan are numbered
010672
620
England Patented
IFB 51

But the OP's inserts in question don't appear to be marked '620' so ???

But then mbell's post in 2021 shows inserts from a +2 that look the same shape but painted black, stamped with the same '010672' :-
viewtopic.php?t=49558&f=42&start=0#p359715

So... nothing as clear as it might be - as is so often the case !

Cheers