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MG Midget and Sprite Technical - Shocking shock absorbers

This is just a story about reconditioned shocks. A woeful tale!

So both front shocks on the Sprite had lost the damping action. In another thread Nigel Atkins warned me against getting reconditioned shocks in the UK. He described them as often piss poor. At his suggestion I had a go at reconditioning them myself.

I followed instructions on here and had great success with the RH one but the LH one refused to work properly.

I couldn't find a LH shock anywhere so I decided to get a reconditioned shock from a well-known supplier, fully prepared to waste the £40 if it was no good but hoping I could use it as a base for me to recondition. This is what arrived:

The box was damaged - badly packaged
The housing thread for the clamping bolt for the trunion was stripped
Damping action was poor

On opening up for reconditioning I found:
The oil was black and full of metal shavings - no way had it been changed
The washer for the oil seal on the axle was distorted and would probably leak
The mating surfaces for the cover were like the Scottish Highlands. One corner was so damaged it must have been dropped
There was a chunk of metal embedded in the gasket.

Paintwork was OK 😂

Anyway I put right the issues and reconditioned it myself. My son even has an ultrasonic cleaner. It does actually work really well now. 🥂

Nigel's advice was spot on of course. He is welcome to say 'I told you so😁' but I therefore went in with no expectation that it would work. Luckily I was able to recondition the apparently reconditioned shock at no cost to me because I had all the stuff from the first one.

I haven't mentioned the company.

Caveat Emptor I guess 🙄







B M Le Page

Interesting. I think I’ll be keeping those old ones under the bench to recondition myself at some point!
John Payne

I think it's great you're sharing your information about what you've found - be great also to see a new thread on how you restored your dampers.

As you can now see sometimes my description of parts quality can be a little too generous. :)

There are possibly a couple of posters on here plus suppliers advertising here that could have probably provided you with a s/h damper unrestored in better condition that the reconditioned ones from the well-known supplier(s).

BTW I love the colour of the Sprite.
Nigel Atkins

The guidance I followed for the reconditioning is below. I found it easy to follow. I cleaned the valve assembly in an ultrasonic jewelry cleaner.

https://www.mgexp.com/article/refreshing-your-mgb-armstrong-shocks.204

I fixed the other issues by skimming the mating faces using 400grit wet or dry sandpaper on the granite kitchen worktop while my wife was out, using a squirt of dishwashing liquid and window cleaner as lubricant.

I used a 1" socket to tap in the washer seal

I re-tapped the clamping bolt hole as deep as I could go and made a bolt about 2mm longer so there were enough good threads to grip.

(We love the colour too. It's not so easy to find out the correct colour code even with Horler et al. But it will definitely be that colour when I respray what must be the worst paint job in history.)
B M Le Page

I have been saying the same as Nigel for years too. I once ordered a set of four "reconditioned" shocks that were in equally duff, un-reconditioned condition! I eventually found out that they were all mismatched with different valves and consequent different damping rates across axles. The car handled terribly!

It's good to know the situation is still the same! ;-)

It would be worth checking what valving you have in the shocks before you refit them, make sure they are matched. The springs are colour coded.

After my experience I developed a kit for people who wanted to refresh their own shocks. They are still avalible if you ask me nicely chevalierclassics@gmail.com :-)

Cheers,
Malc



Malcolm Le Chevalier

When the lever arm has slight play when you change direction on manual test but is otherwise damping, what causes that and what corrects it?
Bill Bretherton

I think it's mainly wear in the housing the shaft runs in and wear on the shaft, https://mgaguru.com/mgtech/suspensn/fs207.htm .
David Billington

Thanks David.
Bill Bretherton

Hi

I've read an article which discussed adjusting the amount of damping action by adding or subtracting shims and adjusting the nut on the valve assembly.


That's a bit too esoteric for me at the moment, but how is the degree of damping action measured accurately? I know that the damping in one direction is different in the other direction.

I did mine by 'feel' on the bench. A long slow pull had a good amount of resistance and a sharp tug tightened it up very firmly which seemed about right. (Better then before when the lever arm dropped under its own weight😁)

My dad checked used cars by the number of bounces - less than scientific!
B M Le Page

Brendan,

You need a machine for testing dampers, I think having seen pics they are able to move the arm or damper shaft at various rates and measure the force resulting or with a known force and measure the speed allowing the damper characteristics to be plotted. Some years ago Peter Caldwell sent me the dampers characteristics for the adjustable dampers and I'll see if I can dig them out.
David Billington

I timed mine full stroke in a jig with weight at the end of the arm. Used 30 weight Silkolene in otherwise standard dampers.


f pollock

That's interesting. So if I've got it right then a known weight at the end of the arm and timing it means that you can compare it with others. The pic showed me that I hadn't thought of fixing the it at the same angle as it is on the car!

When I do the rear shocks even if I can't measure the damping vs the spec exactly I can at least make sure the two shocks are the same so that's a step forward.

The car is a bit squirrely if it hits a bump while cornering a bit vigorously. It's not so bad I have to find and fix it, but as I go round improving the shocks, replacing all the suspension bushes etc, checking the wheel alignment (I think the chassis legs will need replacing at some stage so I can check caster angle then). Front springs are cheap so I'll replace those at some point. The tyres have lots of tread but may be old. The wire wheels may need spokes tightening. I guess this will take a year because I spend most of the time with it on the road.

At some point in this process I assume the handling will be perfect!

Please let me know tho if my thinking is not correct.

Brendon
B M Le Page

I'll get on to damper but most important things first - " tyres have lots of tread but may be old" - if so then they may not be good.

Tyres affect braking, steering, road holding, handing, noise and comfort they are an important safety (and performance) component on the car that are very often overlooked, taken for granted or not fully understood.

Tyres can go hard from age and lack of use which greatly effects the performance of the car

Below is a photo a poster here put up as a warning for a tyre that looked good and had full tread on it but was old.

On the tyre will be a date of manufacture code, four digits, first for week of year, last two the year - e.g. 3420 is manufactured this week of this year, 2020.

Four digits have been since the year 2000, if you only have three digits and a triangle, or worse still just three digits then the tyres are over 20 and 30 years old.







Nigel Atkins

Brendon,
if you have a look in the 'MGB Technical' section for a thread called 'Lever Arm Damper test' it will give you the idea. Or IIRC there are similar threads in M&S and MGB sections Archives.

I can't remember if this was covered before but in case not, always worth checking nuts and bolts are tight on the suspension, to dampers and their drop links, U-bolts on rear springs and worn bushes can make a lot of difference, often springs and dampers are replaced on cars when probably changing the bushes would have been best.

Front springs are cheap but I can thoroughly recommend the front spring from Kim Dear of Magic midget and he's a good chap to deal with -
9.5" freelength 360lb rate. Retains standard ride height to overcome sleeping policemen, rough surface autotests/auto-solo's etc, whilst reducing body roll/ brake dive. £27.50 each - http://www.magicmidget.co.uk/suspension.htm

I didn't realise your lovely blue Spridget had wire wheels, it's the law with bright red Spridgets and particularly MGBs to have wire-wheels, usually chrome, but not necessarily with other colours. Personally I'd swapped the PITA w/w for knock-on Minilite copies ASAP. Wire wheels have extra issues with the hubs and the spokes and tubeless tyres and innertubes and rim linings,let alone the ballsache of cleaning them, no I'm not a fan, but others are so will sing their praises.

After checking nuts and bolts are tight then, if required, changing the tyres should be your next step.

Hopefully Cedric might be along to say what a difference better tyres can make.
Nigel Atkins

My goodness, I agree with Nigel on two things.
1) Old tyres. Someone once said "The brakes simply stop the wheel. The tyre stops the car."

2) Wire wheels should be reserved for prams and have no place on a car. Dreadful things.
Mike Howlett

Haha yes I also agree with everything about wire wheels. Resto no 1 was target red so the wire wheels stayed on as instructed! (painted as they would have been supplied. I'm anti bling. The gear lever housing air cleaners and rocker cover on the Sprite have been chromed. Ugh)

But the ww were quite a bit of extra bother.

Yes before I finished I had to replace the rear spline hubs and the rim linings plus inner tube plus tyres ends up expensive but I will have to move it further up the todo list.

Recommended places for tyres? I want an opinion on whether they are old with good tread or new ones being bunged for an mot maybe. Or maybe the writing on the tyre can help identify their age?

I spent many happy hours sandblasting and painting the wwbut they did look good and the ride and steering was actually pretty good. Just good luck really I suppose. I had rebuilt the rack and pinion and front suspension. Replacing the wishbone pinion bolt took years off my life.

I've got a set of 69 steels which would would be fine to swap but even that is not a trivial task? There is an advert with a blue Sprite like mine with steel wheels and AH hubcaps which look very appropriate.

And for sure when the axles come off I will be replacing every single rubber part! They are so cheap it would be silly not to.



B M Le Page

Some data that Peter Caldwell sent some years ago regarding Armstrong damper characteristics, see image, PDF file it's from is too large to upload. I'll see if I can post that in more detail later.


David Billington

Oh I meant to say there were no four digit numbers ora triangle in fact nothing that made any sense. They are arrowsmith which is a budget brand. Also they are not identical. Looks like next months budget will be spent on tyres.

I assume you can't use tubeless with wire wheels. A dumb question probably?
B M Le Page

Adjustable lever diagram.
David Billington

Adjustable telescopic diagram.
David Billington

Interesting graphs. I won't be able to test and get actual figures without a machine but I can get a vague idea of their characteristics and how they were measured.

I think I have to eliminate tyres first. Those photos were horrendous, Nigel. 😱
B M Le Page

Them diagrams are useful. They are for the adjustable lever arms.
Rob
MG Moneypit

Different tyres on the car isn't an encouraging sign for handling, plus.

For the tyres manufactured date - perhaps the information is on the inside of the wheel/tyre, or sometimes it takes a bit of tracking down see links.

http://www.kwik-fit.com/tyres/information/tyre-age

You're looking for 4718 in the photo below, 47 denotes the week of manufacture and 18 represents the year, meaning the tyre manufacture date was the 47th week of 2018.



Nigel Atkins

For the bushes - check rubber isn't piss-poor as it has been in the past, and still is for some stocks of rubber parts at least (exhaust mounts that barely last 12 months, reported here over the years and quite recently too). Unless things have changed and/or you what to keep the car a while i'd go for bushes like Super-Flex or Super-Pro or similar, but not anything too hard or too "fast road".
Nigel Atkins

Back in the day I recall Armstrong had a rig that could test the efficiency of shock absorbers on the car.
I remember taking the car to a tyre shop where Armstrong were offering free checks - can't quite remember if they bounced it or jacked a wheel and dropped it ? the end result was a paper trace of the damping.

This was on a sort of Tuned Morry Minor with 5 1/2 J wheels and lowered etc as was the trend then.
Mine were probably topped up with Glycerine which was often used in those days to improve the shocks - Oh horror I hear Nigel say !

The shock traces were quite good ISTR !

R.
richard b

I bet the add-in made your ride sweet.




I'll get me coat . . .
Nigel Atkins

Just coming back to this after being away on holiday.

Some interesting information there, thanks David.
Malcolm

Bernard
Could probably sourced you a s/h shocker from a Kent Masc member. You will have to get more involved.
Alan
Alan Anstead

This thread was discussed between 19/08/2020 and 31/08/2020

MG Midget and Sprite Technical index

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