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MG Midget and Sprite Technical - 1275 Midget - Vibration / Radiator

Hello All,

First post here, and with a quick question.

I own a 1972 MG midget 1275, Had it just over 3 years and have been loving every moment of it!

Recently, it has developed a strange shudder/vibration that appears to come on between 55 - 62mph. One early symptom of the vibration is that the gear lever starts to rattle. If I hold the gear lever in place, the gear knob rattle stops, the whole car still vibrates.

It only seems to happen when the car is under load. I can't really tell if it's doing it at lower speeds at lower geers. The knob does rattle from time to time during acceleration but the whole car does not seem to vibrate as it does at higher speeds.

My first suspicion is wheel balancing, and need new tyres on the rear anyway, so have the car booked in for new tyres/wheel balance anyway. But wondered if you chaps had any other ideas.

Secondly, something that was somewhat surprising to me.

I a after-market Kenlow fan fitted to the front of the radiator, which seems to give a fantastic airflow. However, the surprising thing is, that after a journey, the temperature reading will be somewhere around the 'N' marker. However, if I feel the back of the radiator, parts of it are stone cold! If I feel the inlet/outlet pipes, they feel warm, and the sides of the radiator certainly get very hot, but the middle at the back certainly feels colder than I would expect.

Is this because of the good airflow going through the RAD, or is something possibly wrong here?

Many thanks for reading all,

J Walker

Hi James, welcome on board!!

There could be a number of things that could cause the vibrations that you are experiencing.

I would sort out your new tyres first as that could be the solution to your problem.

I had similar symptoms to what you described and it might be worth getting a free Moss catalogue as it contains exploded diagrams of each part of the car.

I replaced the series of washers/o rings under the gear leaver (I think its called an anti zizzle kit?) and this kept it at bay for a while.

My vibration was accompanied by the gear lever jumping out of 2nd gear when downshifting and since removing the engine/box from the car I discovered that the clutch carbon release bearing had broken in two.

Mark Whitmore

Your vibration symptoms are certainly consistent with a tyre balance issue. You do not indicate whether you have wire wheels or disk wheels... it can be even more challenging to find someone competent to balance wire wheels than the disks, but even the disks can be hard because they are lug-centric whilst today's equipment assumes that the hole in the center is the thing to use for centering the wheel on the balancing equipment. In either case, advise the guy doing the balancing that he needs to check the rim for runout before he tries to put weights on it. If the rim looks significantly out of round, it is generally because it is not properly centered on the balancer. They can usually do it right IF you find the old guy who remembers when wheels were not hub-centric. Otherwise you are wasting your time ;-)

As far as the radiator, you should be fine. The center of the radiator will normally get the most cooling and therefore be the coldest. The water temperature that your gauge is measuring is that of the engine, which is regulated by the thermostat. the water in the radiator needs to be cooler so that it can maintain the proper engine temps under adverse conditions.
David "in balance and keeping my cool" Lieb
David Lieb

I am not as sanguine as David on your radiator temperature. Cold spots are often a sign of silted/clogged tubes in that portion. The fact that there is some margin in the design can allow there to be clogged portions and you'll still get enough cooling to avoid overheating, at least during these winter months. It is a good idea to make sure, before the hotter summer, and maybe some stop & go driving tells you otherwise:

One quick way to confirm this is to turn off the fan and drive until the car is fully warmed up (keep an eye on the temp gauge, and if you keep moving it ought to be fine), then shut off and do your hand test again. Without the fan the entire radiator should be equally warm/hot to the touch. Any cold areas are then a sure sign of clogging in that portion.

A radiator repair shop can renovate an old radiator (remove end tanks, rod out the core, confirm the fins are not overly rusty, re-solder the end tanks, pressure and leak test) for less than a new one costs.

Though, hopefully, it is like you and David are thinking, that the Kenlow is just doing its job, real well.

Norm Kerr

James. At those speeds I would be looking at a prop shaft U.J. being out of balance as well as checking all the other things mentioned here. If you drive at about 20 mph does the car seem to be wagging its tail, or is the steering wheel moving very slightly side to side in your hands? This would indicate a tyre tread starting to part company with the tyre carcass.

b higginson

Thanks all for the responses.

Norm, I will try your suggestion with the fan off and see what happens. Hopefully it'll all feel nice and hot!

Bernie, unfortunately I'm fairly new to the world of mechanics, I'm able to do simple jobs, such and brakes, radiators/cooling and minor service, but when it gets into it I'm a little lost.

I know what the propshaft is, bt what does U.J. stand for? and how do I check that it is in the correct balance?

Many thanks all,


J Walker

Universal joint.
C Carter

Hopefully this might help?
C Carter

My money's on prop shaft universal joints as well. Mine did exactly that, then got a whole lot worse very quickly. Tyres shouldn't just go out of balance recently, unless a weight has fallen off.

If you go under the car and grab the prop shaft, there should be minimum rotational play in it, if there is then the joints may be tired.
Rob Armstrong

Just did the radiator test as advised by Norm. Happy to report that all feels normal! Went for a short drive to the petrol station, and when I returned I left the engine running for a few minutes with the fan off. After shutdown gave the radiator a good grope and felt evenly warm all over. I think I must be worrying too much!

Getting the new tyres and balance done tonight, should that not resolve the shudder I'll have a look at the propshaft.

Does anyone have any advice for checking the UJ's over?
J Walker

Well, been into the garage and found that one of the rear wheels had been warped! So replaced it with my spare and had it all balanced out. All feels much smoother on the road! Propshaft UJ's have been checked and aren't too bad.

The only remaining problem is, the gear knob! As to be expected there is a slight knocking and vibration when driving along. While I no longer think that the vibration itself is an issue, the rattling gear knob certainly is annoying!

I remember reading somewhere that a rattling gear knob was a known problem on the midgets,and there was something brought out to combat the problem - Is this correct?

Many thanks,

J Walker

Hi James, for the gearstick vibration/rattle you could try the anti rattle kit (part number SGB0002) this consists of a series of washers and springs that seat around the underside of the gear lever.

Moss sells this for 5.23 but you may be able to source it cheaper elsewhere.

As a bonus its also simple to fit!!

Mark Whitmore


I believe your memory is correct regarding reading somewhere about the rattling gear knob. In fact, you can find it in the first response to your initial post, which came from Mark when he said > I replaced the series of washers/o rings under the gear leaver (I think its called an anti zizzle kit?) and this kept it at bay for a while. <

Also, I have that rattle problem on a B, which is the wood knob loose on its threaded insert. So, you might check that too.

I'm not quite sure what you mean when you say your prop UJs aren't too bad. In my experience, there is no perceptible slack in a good UJ, so feeling some slack means it is on its way out. To that I'll add that, while feeling slack means it is bad, feeling no slack does not necessarily mean it is good. Sometimes UJs fail by getting stiff and binding, and there is no perceptible slack.

C R Huff

Right-o, Ordered a new anti rattle kit from the MGOC - Hopefully it'll sort the issue. No idea how to fit it, but I'm sure it can't be too hard!
J Walker

Anti rattler kit- Gear lever QTK5 Price: 3.53 including VAT at 20%

to fit you'll only need a screwdiver and socket

metal gaiter surround,
vinyl cover,
rubber gaiter
metal gear lever retaining plate(s),
gear lever

at the bottom of the gear lever is the O-ring

from inside fish out the nylon/plastic cup/button and beneath this the spring

three years time for a full 36,000 mile service see - (Ref: 0057)

this Handbook will also give you loads and loads of info about your car, its use and maintenance

Nigel Atkins

Hi James have a look at your prop shaft and U.J. being out of balance, I had that on my MG Midget MK3 1969
you can see some photos of my car on my web site
Regards Ashley Hinton
A Hinton

This thread was discussed between 07/03/2011 and 19/03/2011

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