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MG MGB Technical - Replacement of Fron Suspension Bushes

I seek advise on the simplest way to replace the front suspension bushes on my 1972 mgb roadster.

Do I need spring compressors or can I jack up the pan.

Help with dwgs would be a ideal.

Thanks
G Hind

I have always got away without spring compressors using a trolley jack and this seems to be the consensus . Lots in the archives
Stan Best

Mr. Hind,

Unbolt the brake caliper and hang it to one side without straining the brake hose. Place the jack outboard side of the spring pan for some leverage. From there it's easy. Just pull the top steering knuckle (trunnion) bolt, loosen the middle shock arm bolt and tilt the kingpin/trunnion towards you. Lower the jack, remove the coil spring and unbolt the inboard pivot assembly from the crossmember. Do all the work on the bench and bolt it right back together. You can visit my website at http://www.dbraun99.com and scroll down to the link "MGB Wire Wheel conversion that has turned into a restoration". I haven't annotated the pictures, but the process is pretty clear. I unbolted the lower trunnion as well because I was doing a total rebuild (a case of 'might as well')

As long as you are going this far, double check that none of the A-arm to A-pan (lower spring cradle) holes are elongated. If they are, correct them before reassembly.

warmly,
Dave
Dave Braun

I agree with Dave, having changed my front springs recently, I pondered the thought of spring compressors. Actually I believe most spring compressors would get in the way it is quite a cramped area. A trolley jack is the answer, or two scissor jacks. When putting the new spring on and aligning the suspension pan, this is when the second scissor jack comes in handy as you can lift the front and the back of the pan independantly to align the bolt holes that hold the pan to the arms. Actually, I have to go thru the process again, as I had not got all the parts for a complete bush change when I installed the springs. Mike
J.M. Doust

Doing it right now. This is the easiest way.
Bruce Cunha

Leave the spring pan to A-arm bolts on one side slack by a turn or two to make insertion of the assembled fulcrum, thrust washers, seals etc. into the A-arms a little easier.
Michael Beswick

A technique that I've found useful is to place the jack under the spring pan and raise the wheel. Then slacken two inboard bolts holding the pan to the A-arms, and remove the two outboard bolts. Lower the jack and the pan pivots while the spring decompresses safely. Refitting is the reverse, but it has the advantage that you can assemble everything else and check that it moves sweetly without any spring tension at all.
Miles Banister

Which bushes? The above is fine for the upper and lower trunnion bushes, but is only part of the story for the inner A-arm bushes. For those you do use the spring-pan method to remove the bottom trunnion pivot and release the tension from the spring, *before* undoing the A-arm to spring-pan and crossmember pivots nuts/bolts. If you have an anti-rollbar the bottom drop-link pin being tapered is usually seized in the A-arm, you can disconnect the top of the drop-link from the bar instead. Both axles need to be at the same height to do this, i.e. both hanging down before releasing spring tension one side, or after releasing it both sides. Rubber bumper springs are shorter and so can be removed simply by pressing the spring pan down, but chrome bumper are longer and do need the pan to be pivotted down on two bolts as Miles says. Unfortunally given the problem with the ARB pin it isn't always possible to remove the outboard pair pivotting on the inboard. Some have said to remove all four bolts and lower the pan out from the A-arms altogether, but not only do you still have the issue with the ARB pin but it is a real fiddle getting the pan level so all four can be got out and back in, needing many micro adjustments on jack height, and chewing bolt threads in the process.
PaulH Solihull

Paul, You're absolutely right about the ARB. I recall now that when I last did the job I disconnected the drop link and so I must have let the pan pivot about the outer bolts after removing the inners. It still has to be jiggled about a bit, but it does make it a tad easier. Oh, also I recall not tightening either the trunnion or inner arm nuts until the pan fixings were tight, and of course with the full weight back on the wheel.
Miles Banister

Gentlemen please, may I ask you a further question on this thread on bushes; Some of you will know what my line of work is,,, anyway There was an ex-mechanic in the chair, and I casually asked his opinion on polyurathane bushes, (before I re-sleeved one of his molars,.... sorry took a tooth out!).He said would not touch them with a barge pole? Oh, why I replied, 'They dry up and start squeaking.' Which, perhaps I might agree with, since they are not lubed, except with the lubricant that is supplied, do they dry up and squeak? I understand that the ride becomes a little harsher, but then nylatron is supposed to be even worse for this. I have not installed the poly bushes yet so now I am unsure? I should add I don't mind a firmer ride. I don't clock up many miles a year and I have poly at the rear already. ( they seem fine!)what do you all think? Mike
J.M. Doust

With regard to the question of polyurethane bushes I have just installed SuperPro bushes (same as SuperFlex?..perhaps our Aussie cousins can comment). The lubricant is silicon based and seems to linger everywhere once it gets on your hands/gloves. As the brakes are involved in this area I suggest that people are very careful where this grease goes. I seem to have carried it to door handles and car keys. I have tried wiping things over with cellulose thinners but there are still traces of the stuff.

The car is not back on all 4 wheels yet (got the front wheel bearings to do tonight) so can't comment on ride quality.
Steve Church

This thread was discussed between 28/02/2011 and 09/03/2011

MG MGB Technical index

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