"In the spirit of improving the sum of human knowledge, this is what I found. With each damper clamped upright in a vice a 10lb weight (e.g. sledge hammer head) took the following times to pull each lever from the top of its range to the bottom:

"Old N/S damper 6.5 secs
"Old O/S damper 5 secs
"New N/S damper Infinite (it never reached the bottom)
"New O/S damper 28 secs"

And subsequently posted "I should have said that the O/S damper moved slowly through the first 2/3 of its stroke before stopping. It could be pushed all the way down with a firm hand." I think he means the N/S.

Raise the front of the car by jacking under the rear edge of the cross-member (if you jack further forwards than that it will slide further forward in a series of sudden and noisy movements which is a bit disconcerting. Place axle stands under the outer edges of the spring pans, and lower the jack just enough to lift the damper arms off the rebound rubbers. It is important to do this otherwise when you remove the top link bolt the axle assembly and hub will shoot downwards as they are under significant spring pressure.

Next comes removal of the top link bolt connecting the damper arms to the swivel axle. Easy to say, much harder in practice. The bolt runs through the arms of the damper and steel sleeves in the rubber bushes. It is a snug fit in both and unless it has already been replaced fairly recently or was assembled using Waxoyl and copper grease it will almost certainly be well rusted to both. The rubber bushes will probably also have deteriorated and be bonded to the eye in the swivel axle. In two replacements on my cars this has been the case and I have had to hacksaw through the bolt both sides of the swivel axle eye. On a second replacement of one of them everything came apart very easily.

Remove the nut on the end of the link pin, it is usually castellated with a split-pin. Slacken the clamp-bolt holding the two arms of the damper together right off, and drive a thin wedge between them to lever the arms apart a little way and give you more room to cut through the link bolt.

Use a length of cable or whatever to tie the swivel axle to the bracket of the bump and rebound rubbers to prevent the axle falling outwards and stressing the brake hose when the link pin has been cut through or removed.

You can try driving the link bolt out of the bushes and arms, but it shouldn't take much hammering to realise it isn't going to shift. If not, cut the flange off the end of each bush by chiselling and cutting at an angle into the eye of the swivel axle. This reveals a section of link bolt on each side to cut through without damaging the inner faces of the old damper (which might then be rejected as a core replacement) or the swivel axle eye. Use a hacksaw where you can turn the blade at 90 degrees to the frame and this should allow you cut inwards and upwards each side. With a decent blade it shouldn't take many minutes to cut through both sides, and the damper arms can be lifted up from the swivel axle eye. Remove (it really should be that easy) the four bolts securing the damper body to the cross-member. I use a universal joint between the ratchet and socket, it gives that extra depth for all four bolts and a bit of angle for the back ones where the inner wing curves over them. Lift the damper away - it is heavy!

Now you have to drill, cut, twist and hammer the old bushes and remains if the link bolt out of the swivel axle eye, they will probably come out as a single piece, which can only be done if you have previously removed the flange from the bushes as previously described. Remove any lumps of rubber that are stuck in the eye as this will make insertion of the new ones more difficult.

Check the fluid level in the damper now, it's easier. If you find you have to add a lot, or in any case after transportation where they may have been at a different orientation to when fitted to the car, work the arm up and down it's full travel several times to expel any air from the valves. Remove any dirt or grit from the cross-member where the damper will sit. At this point I put a bit of copper grease into each hole in the cross-member, then put the damper in position. Coat each bolt with copper grease and insert just a few threads, don't tighten them any more than that until all four bolts are started. Again slacken the clamp-bolt holding the two arms together and wedge the arms apart to fit over the bushes. This is necessary when leaving sound bushes in the swivel axle, not just for new ones.

Coat the outside of new bushes and the inside of the swivel axle with Waxoyl and insert the bushes. They will probably be much wider than the gap between the damper arms even if they are wedged apart. You can either put one or more large nuts over the threaded end of the link bolt then tighten its nut to squeeze the bushes fully into the eye or use a small sash-cramp or something similar. Eventually you should be able to get the bushes far enough in and the damper arms far enough apart to fit the two together, but before you do so put some copper grease inside the steel sleeve of each bush, wiping off any excess from the rubber.

Place the damper arms over the bushes, put more copper grease in the holes in the arms and on the link bolt. Tap the bolt through the appropriate damper arm the bushes, and the other damper arm. Note that the bolt has a special round head with one flat which engages with a recess on one damper arm. This is the front arm on the right-hand side, the rear arm on the left, therefore the bolt can only go in one way each side. Things might need a bit of wiggling about while you are tapping to get everything lined up.

Note where the split-pin hole is in the bolt and fit and tighten the nut (40ftlb). This has to clamp the damper arms onto the ends of the bush sleeves, and the inner ends of the bush sleeves together, so it does up tight. The final position of the nut should allow insertion of the split-pin, of course. Refit and tighten the damper arms clamp bolt (28 ft lb). As the four mounting bolts allow a little wriggle-room for the damper now is the time to use it to try and correct any tendency to pull to one side or the other on a flat and level surface (note a normal drainage camber will cause the car to pull to the kerb side slightly). Pulling to one side or the other is caused by unbalanced camber, not by tracking as many think. Which ever side the car pulls there is more camber that side than the other, so pushing the damper arms forwards as you tighten the four bolts (43-45ftlb) will tends to reduce it, and pulling the damper arms backwards on the other side will do the same. It may not do much but is worth a go while you are at it. Refit the wheel and away you go. Inspect the new damper from time to time in the early days just in case you have got a duff one, and always before an MOT.

The damper, drop-link, rebound rubber and bump-rubber pedestal (and for that matter spring) must be treated as a set for correct and safe operation of the rear suspension and these vary from model to model. Whilst the damper obviously controls the rate of spring compression and expansion through the normal working range, the compressed limit is controlled by a pedestal on the axle hitting a bump-rubber under the floor, and the expanded limit is controlled by the rebound strap which is fixed between a body and axle. The final component is the drop-link between damper arm and spring/axle assembly. In an ideal world the spring, in it's normal working position, will position the axle about mid-way between the fully compressed and fully expanded positions, and the drop-link length should be such that the damper is also about mid-way in its travel. The loading on the car could be a little as a single occupant, or it could be two people plus tools and luggage with the consequent compression of the spring, so maybe a median between these two is chosen by the designer as the 'central' position. Whatever, it is vital that the drop-link, rebound strap and pedestal are installed as a set so that it is the rebound strap and bump rubber that provide the limits to axle movement and not the damper itself. Get these wrong and the damper will suffer damage. In theory it doesn't matter as much if the spring varies in set or hardness, as the other components will limit axle travel regardless and so protect the damper. But if the spring is too soft or flat you will be hitting the bump rubbers over relatively small bumps (been there, done that, extended the shackles) or at the other extreme the car will have a very tail high ("submissive monkey") stance and be hitting the straps relatively easily. Whilst hitting the bump-rubbers is merely uncomfortable, continually 'hitting' the rebound straps will eventually break them, and then you will start hitting the damper limit and damaging that.

Chrome bumper 4-cylinder cars had one set of drop-link, rebound strap and pedestal, chrome bumper V8 had a different set, and all rubber bumper cars had a third set in this case the same for 4-cylinder and V8. It's well known that chrome bumper V8s had a higher ride height to 4-cylinder chrome bumper cars to improve the exhaust to ground clearance utilising a different front cross-member that was later commonised to all rubber bumper cars. The rear spring hangers were lowered at the front and the rear on all rubber bumper cars i.e. 4-cylinder and V8, hence all rubber bumper cars have the same damper and axle movement limiting parts, even though the V8 springs are harder. What is less well known is that they differed between chrome bumper 4-cylinder and V8 cars as described here. The combination of parts for each model from the Parts Catalogue is as follows:

Peter Caldwell of Wisconsin posted the following information on the MGCars BBS as part of a thread on this subject in December 2006:

Replacement: Ostensibly two bolts and three nuts, but it can still be a bit of a bear to remove. If you haven't changed them before the drop-link nut (11/16") will likely be corroded to the drop-link pin in the damper arm, and nut and pin will turn as one, either that or the nut will come undone but the tapered pin will be seized to the damper arm. Heat not advisable due to the rubber bush in the drop-link. Fortunately it is easy to remove the damper complete with drop-link and bottom plate and deal with them on the bench. Note that the Leyland Parts Catalogue indicates that the damper bracket fits directly against the lower spring pad by stating that only two spring-locating plates are fitted per car but four are fitted - two against the upper spring pad and two against the lower.

Important - chock the front wheels. Slacken the road wheel nuts a smidgen before raising the rear wheels off the ground if the handbrake isn't up to much. Jack under the diff and put axle stands under the springs immediately forwards of the U-bolts. This is necessary to keep the springs compressed otherwise you will not be able to pull the damper plate down off the U-bolts, if the springs are extended the damper lever arm will be almost fully down. Remove the road wheel. Remove the nuts (11/16") and spring washers from the bolts (5/8") holding the damper to the chassis rail, turn the bolts to free them up, but leave them in-situ for the moment.

November 2023:

Bee has the bolts going through the damper and the nuts and spring-washers inside the arch, but Vee has the bolts fitted from the arch side, both always like that in my ownership. However the Leyland Workshop Manual drawing shows the bolts going through from the arch side and nuts and washers against the damper. That way means you either use a spanner (limited leverage) on the nuts on the back, and they are very tight at 55-60 ft lb, and fitting washers and nuts in limited space, or a socket and breaker bar (maximum leverage) on the heads in the arch which means breaking the torque of the nut plus any seizing of the bolt in the chassis rails. Reversed means the socket and breaker bar is only overcoming the torque of the nuts, but the damper must be removed and offered up with the bolts already in the damper. You also need to be sure the bolts aren't long enough to foul the tyres. If the bolts have seized in the chassis rails (copper grease!) then you are probably snookered in either case as there is insufficient room to get the damper off the bolts when they are fitted from the arch, and if from the damper side then the damper will be stuck fast anyway.

Undo the U-bolt nuts (9/16" deep socket makes life easy), and pull the damper plate down off the U-bolts. Pull the damper complete with bolts back from the chassis rail (or support the damper and pull the chassis rail bolts back to release it) and lower the whole assembly down and away from the car.

With a rusted drop-link nut I had to hacksaw at an angle part-way through the nut then chisel the cut open to free the nut. Because the pin had been turning in the damper arm this came out relatively easily. Where the nut came undone leaving the pin stuck in the arm I fitted one of the chassis rail nuts to the pin so it was flush with the end of the pin to spread the load (drop-link nuts are Nyloc), then with a lump-hammer behind the arm whacked the end of the nut and pin with another biggish hammer a couple of times and it popped out.

Check the fluid level in the new dampers before fitting. If you find you have to add a lot, or in any case after transportation where they have probably been lying down, work the arm up and down it's full travel several times to expel any air from the valves. With the top-fill arrangement of the rear dampers leave 1/2" air-gap between the bottom of the threads and the fluid.

If you removed the damper, drop-link and bottom plate as an assembly then assemble them again before fitting, use copper-grease on the drop-link pin and threads, but don't tighten the upper drop-link nut at this stage.

If you can get the damper up against the chassis rail with the bolts fitted from that side then do so, you can get more torque on the nuts if they are in the arch. However with the Ron Hopkinson rear ARB if there is not enough room the bolts have to be fitted from the arch side, and the limited room makes getting a torque wrench and socket on the nuts difficult if not impossible when the nuts are on the back of the damper.

As for removal the spring needs to be partially compressed i.e. with axle stands immediately in front of the U-bolts in order to get the damper plate underneath the spring. Fit the damper plate onto the U-bolts, making sure the spring pad and locating plate are already in place, and the U-bolt nuts. Tighten all nuts - 55-60 ft lb for the damper to chassis rail nuts, if these are not fully tight they can 'knock' over bumps. For damper-plate nuts use your judgement as they are compressing rubber pads and will only tighten gradually. Recheck after a few miles. With the weight of the car on its suspension (i.e. axle stands still under the springs) the upper drop-link nut can be tightended i.e. with the drop-link in about the middle of its travel. If the axle is hanging down the upper rubber bush could tear when the suspension goes into full compression.

As well as what fluid to use in both there is further scope for argument over fluid level in the rears, believe it or not. The Workshop Manual simply says "fill to the bottom of the filler plug hole". But some say it should be half an inch below it on the rears to allow an air space to absorb up fluid expansion on heating up, otherwise it could be forced past the seals. But if that is correct, why doesn't the manual say so? I then started thinking about the positions of the filler plugs, and realised that with the front damper filler plug on a vertical face of the damper body, filling to the bottom of the hole will still leave a significant air-space above it. But the rear dampers have the filler plug on top, which may not unless there is an air-space under the lid i.e. above the bottom of the filler plug hole. When I converted Vee from telescopics back to lever-arms I bought a 'kit' containing dampers, drop-links and bottom plates second-hand from some unknown MG at Stoneleigh, and it was only when I decided to recheck the fluid level some time after fitting them that I discovered the filler plug hole was also on a vertical face, and not on top as they should be! "Ah ha", I thought, that would leave an air-space in the rears as well, and maybe that part of the manual had been copied from that for another vehicle where both front and rear filler plugs are on a vertical face. But looking again in the manual not only does it show a top-fill rear damper, with instructions to remove the plastic plug in the chassis rail to access it, but it also shows the front damper with a top-mounted filler-plug! So from there being an obvious air-space above the fluid on both types, there could be none on either. When Vee's rear dampers started leaking (after having lasted a few years, I was quite prepared to change them at the outset as they were an unknown quantity) I got the correct top-fill ones of course, and checking the level before fitting found that it was indeed about half an inch below the bottom of the filler plug hole. So that's good enough for me, and having found with leaking dampers that the fluid level can drop a long long way before it affects damping, leaving a half inch gap below the bottom of the filler plug hole on the rears is neither here nor there, and at least you are sure that there is then a clear air space, if that makes a difference.

But then replacing Vee's damper valves with adjustable ones the process involves removing the 'lid', and the underside of that has quite a large space above the bottom of the filler hole, i.e. an air space.

As far as getting fluid into them is concerned whilst dribbling fluid in to the top of the rear dampers is possible with great care the side filler on the fronts is another matter. But an 'oral medicine fluid syringe' and short length of screen washer tubing makes both a doddle. Don't get it mixed up with little Johnny's though, and don't let it drip on paintwork, it's as bad as brake fluid!

Fixed:

The V8 came with telescopic Spax dampers at the rear fitted by the PO. After only a few thousand miles one started leaking, and as I couldn't get a direct replacement I had to buy the pair. And at about £60 as opposed to about a tenner for a single reconditioned lever-arm unit I was not best pleased. It also took Moss three attempts to get the right ones to me, there are two different bottom pin sizes and they kept sending me the wrong one, but that is a bit by-the-by. Having driven roadsters and V8s both with and without telescopics and the rear anti-roll bar and uprated front bar, I can say that whilst the anti-roll bars do have an effect on handling and axle location I could detect no real difference between the two types of damper. Click on the thumbnails below for full-sized images.

The replacements lasted for many tens of thousands of miles (no more than one should expect) but I had been aware for a while that the ride was getting quite bouncy, especially over humps and dips. The USP of the Spax is their adjustability, but unless you have them on the softest setting they give a bone-jarring ride, and many testify to this. Thinking that they may have 'softened up' over the 70k or so miles they have been on the car (which itself is a poor 'feature') I tried turning the adjusters, but needless to say they had seized, and I decided that I would not replace them when the need next arose but go back to lever-arms. However I was concerned that if one should fail, unless I splashed out again for a replacement (or possibly a pair), I might have to take the V8 off the road for a time while I sourced a pair of lever-arms together with the drop-links and bottom plates. So at the 2006 Stoneleigh MG Spares Show I was on the lookout and managed to pick up the whole lot minus one bottom plate for a tenner, and got a used bottom plate from elsewhere for another fiver. They were already assembled but I wanted to part them for cleaning and painting, but as usual (IME) the nuts had seized. TIP: Careful hacksawing as far as I could through the nut without cutting into the studs (OK, I just nicked the threads, but that won't affect its strength) then using a cold-chisel to open up the cut cracked the rust and it came undone. Using heat is inadvisable is it is bound to damage the rubber bush the stud is mounted in, which is not a replaceable item. That left me needing a couple of nuts, which being Imperial are not that easy to come by. Popped down to my local Halfords where the chap who usually MOTs all my cars had a root through his toolbox and came up with exactly what I needed (That's another pint I owe you ...).

I then discovered that despite measuring two lengths of drop-link at the show, and thinking I had got the longer V8/rubber bumper items (10 5/16" pivot pin centre to pivot pin centre, thanks Graham), I actually ended up with the shorter CB items (8 3/4"). Only discovered this as part of an email thread with someone else, who had the longer ones and needed the shorter! Sadly he was in America so a swap was out of the question. Rather than buy another pair I decided to try 'cutting and shutting' them to extend them (as I had with the rear shackles on the roadster) by the required 1 1/2" or so. Looking round the garage I found a couple of front suspension bottom trunnion bolts that were the correct (0.5") diameter and did the necessary cutting and welding. Two coats of Hammerite smooth on them and the bottom plates and they were ready to go on.

I was quite surprised to find the U-bolts and the nuts and bolts holding the top brackets to the chassis all came undone quite easily as they had not been touched in my ownership, likewise the replacements went on straight-forwardly, the whole job only taking a couple of hours. TIP: The only thing to be aware of is that the two bolts holding each damper to the chassis rail are different in length by about 1/4", which could cause you some head-scratching if you get them mixed up and the two shorter ones on the same side. At some point the forward bolt was recessed into the chassis rail to give more clearance for tyres, possibly for the wider tyres on GT and V8, the shorter bolt goes in this position.

Took the car for a test drive and immediately noticed that on 'normal' surfaces the ride seemed exactly the same but over humps and dips there was no bounce, just a more appropriate firmness without harshness. The standard lever-arms have a two-stage valve that gives relatively mild damping with short movements and harder damping with larger movements, something I have never seen attributed to telescopics of any type. I was deliberately taking the car over as many speed humps as I could find, and going at them progressively harder, when I actually broke one of the welds. It was my fault, when doing the first one I became aware that I was feeding the wire too quickly, which tends to form bobbles of weld on the surfaces of the two pieces being joined rather than fusing them together. No matter, 1/2 hour to take the broken drop-link off, clean up the joint and re-weld, but this time I slipped the spacer tube from the aforementioned bottom bolt (exactly the right internal diameter) over the shaft first, then welded the shaft, then positioned the spacer tube so it covered both welds, and applied more weld between spacer and shaft. Repainted, refitted a couple of days later, and so far so good.