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MG MGB Technical - KNOCK IN FRONT END

My post is similar to Erik Vesterback's. I too have a right side front end knock or clunk in my 79 MGB. The car has 122k on the clock.

Jacked the car today up and rocked the wheel @ the 12/6 o'clock and the 9/3 o'clock positions.

The front end is solid. It was rebushed about 14k miles ago.

I grease the king pin asmbly's generously at every 3k oil change with the car raised up so the weight of the car is off the suspension.

When I do "rock" the car with my knee on the front bumper, I do hear a "squish" sound from the right side front shock.

Pulled the wheel, and all looks fine. My question is what grade oil is used for the shock and where does it get pour into the shock reservoir?

Any other thoughts are welcomed

Cheers

Gary
79 MGB
gary hansen

I seem to remember it is SEA 20. But I use motor cycle fork oil of that viscosity. The uppermost nut.
Allan Reeling

Hi Gary,

Here's a link that may be of some assistance with the lever shock/s.

http://www.mgexp.com/article/mgb-shock-refresh.html

Do you have wire, or ro-style wheels on your MGB?

Larry C. '69 midget & '74 B/GT
Larry C '69 Midget

Allan: I did see a nut that appeared to be approx 7/16 facing me as I looked in the fender well. This was the only top nut I saw.

Larry: I reviewed the link you sent me. My shock does not appear to have the same configuration as the one shown in the link.

Thanks for the info.

Cheers
Gary
79MGB
gary hansen

Gary,

The link was to show the lever shock internals, yours should be similar. This also was to confirm Allan's recommendation for motorcycle fork oil, and I've also used hydraulic jack oil for this type shock absorber.

Here's another link to Paul Hunt's web page with a good deal of useful information for you. Page down to the section on shock absorbers.

http://www.mgb-stuff.org.uk/suspensiontext.htm

Regards,

Larry C.
Larry C '69 Midget

"I did see a nut that appeared to be approx 7/16 facing me as I looked in the fender well"

That's it, which makes it tricky to top-up compared to the rears. I use an infant feeder syringe with a short length of screen washer tubing on the end.

However I doubt that is the cause of the clonk unless the damper is leaking significantly. There can be many causes of knocks in that area rack, track-rod end king-pin, upper and lower trunnions, hub bearings, wire-wheel splines, as well as the damper itself.
Paul Hunt

The passenger's side rack bush (the one in the end of th rack housing) can be the cause of an elusive knock like this. Get someone to rock the wheel at 9/3 o'clock. If it's the bush it won't feel like there's play at the wheel but if you grab the rack firmly trough the boot you should be able to feel whether or not there's a little movement there.
Paul Walbran

Gary-
A possibility that nobody has mentioned yet is excessive vertical play of a swivel hub on the kingpin. This can be easily corrected by means of shimming. The quickest test for this problem is to drive the car over a speed bump.

Take care not to lose the filler cap from the damper as it is fabricated with a 5/16-26 BSC thread which is rather rare. Be aware that some petroleum-based hydraulic fluids are not compatible with the natural rubber seals. Armstrong still makes its own specially-formulated hydraulic fluid available. It can be obtained through Brit Tek at http://www.brittek.com . The factory manual stated that, if necessary, 20W mineral oil could be substituted during warm weather. However, not all mineral oils are the same. During WWII the Germans made a lot of advances in this area, so mineral oils are much more common in Europe than on our side of the pond. Mineral oil with an anti-foaming agent was (and may still be) used in the power steering system of Audis. I suspect that the factory intended for mineral oil with an anti-foaming agent to be what they suggested, and just presumed that the customer would be knowledgeable enough to use the right stuff in a pinch (b-i-g presumption!)
Stephen Strange

This thread was discussed between 31/08/2014 and 08/09/2014

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