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MG MGB Technical - Damper travel

Hi all!

Guesting over here from down there in the midget forum!

I have just fitted MGB dampers to my midget, but have just noticed that one damper has very limited travel in the extension dimension of the suspension. One side is perfect and rests on the bump stops, the other is about 2 inches away!!

Any if you guys seen this before? They are used dampers but we're fine when fitted to the b.

Any help much appreciated as I have an MoT looming!

Karl Bielby

I can't say I'm that surprised that MGB dampers don't have the correct travel in both directions on a Midget, especially if they were fine on the B!

You haven't said front or rear.

How are you getting it into the bump stops? Aren't the springs fitted yet? Unless you mean the rebound stops at the front i.e. wheels hanging down.

Sorry yeh front rebound stops.

It's a known mod, otherside is perfect!
Karl Bielby

I presume when you jack the front up only one is dropping the full distance.
Is your A/R bar twisted? Bottom trunnion seized? Other than that unbolt the top trunnion and check whether you can get full movement of the damper lever.
Allan Reeling

A picture speak a thousand words as they say! This is the good side, (lower wishbone supported on jack, upper trunnion bolt not fitted) notice the damper sitting on the pad at max 'droop'.

Karl Bielby

This is the problem side. This is full droop and the damper has reached a hard stop.

It's as though the axle of the damper has been fitted with the crank for the two pistons in the wrong orientation. If that makes sense?

Karl Bielby

But the big question is why, in the Midget, is there a problem, when presumably there was full movement when installed on a B? It would appear from the pictures that the damper is mounted at an angle, while on the B it's mounting is horizontal. The angled mounting would change it's range of movement.
Allan Reeling

As the damper body is 'upright' on an MGB and at around 25 to 30 degrees on the Midget I'm assuming the arms have to be moved on the spindle otherwise they won't drop as much as they need to. The faulty side looks like it may not have been moved from the MGB position. On an MGB with the base on a horizontal surface the arms go up and down by about the same number of degrees.

Is there an ARB fitted? If so unless both sides are hanging down, one side up will stop the other dropping as far as it should ... which is the whole point of an ARB of course :o)

Cheers for the help guys,

I just took them to Moss and got a couple of recon ones that have solved that issue. However I now have the issue of them hardly damping!

Think I'll take the valve out, make sure they are bled and make sure everything is there.
Karl Bielby

The B is a much heavier car than the Spridget so it makes sense that the shock valves would need to be adjusted for a soft ride. This is easily accomplished by running the nuts out on the valve stem.
Glenn Mallory

If they are rebuilt then it's certainly possible to get one that is iffy, less so with two unless the person who did them made the same mistake on both. That would be a case for return, in my book.

So an MGB damper​ should be stiffer on a midget.

The other side is fine though so it must be a faulty damper or something. Off it comes again! Wondering wether to have a go at bleeding it myself or just take it back to moss..
Karl Bielby

If two or three movements through its full travel don't start it damping then its faulty, that's all the bleeding it should need. Also check the middle of travel by waggling gently up and down a little bit to see if there is a dead area as it changes direction. If so, also faulty. Not worth fiddling with in either case, it's a bad one.

As Paul said, probably faulty unit. I've had, and returned, some really bad reconed Armstrongs.
When you actually get two which work without that "mid range" play or axle slop. I would recommend draining and using Silkolene motor cycle fork oil, it's much more heat stable than the stuff installed by re-builders (who knows what some put in there?).
Also balance them; have a look at this link;
You can balance subjectively on the bench, but I used a heavy weight and pulley plus a stop watch to determine rate of travel. Quite interesting really!
Allan Reeling

Cheers fellas,

I think I'll disconnect the upper trunnion again and have another feel of it, I'm sure it felt ok, but I could have been checking the other side before i fitted either.

It definitely fauly as if I bounce it at the correct frequency, it leaves the floor!
Karl Bielby

Well, I took the dampers back.

Got the new ones back k and took the valve out to properly bleed and these two definitely have more travel than any of the others!

So it seems it's pot luck!

However, they are fitted and working beautifully, now I have a nice sturdy well damped midget front end!!
Karl Bielby

This thread was discussed between 11/05/2017 and 19/05/2017

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