I just purchased a 1971 MGB. It has the dreaded clunk when i go from forward to backing up and a bit of shake in the front end at about sixty MPH. Is there a way to tighten the large castella nut on top of the king pin to firm things up? If I have to replace the upper and lower bushings does anyone have step by step instructions on the procedure? Any help with this is much appreciated. Thank you in advance.
Suspension King Pin bushings slop
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There is a way to tighten them up.
We can provide details.
Clunk in front can be several things. Are you sure its not in the rear or U joints in the drive shaft?
Clunk in front;
loose shock mount bolts
worn/deteriorated/non existent cross member pads.
Lower trunnion play
shock link bushings
control arm bushings
Do you have a manual? Do you know how to check for kingpin slop?
I think a bit more diagnostics are needed before you start. The clunk could be several things, the shake sounds more like wheel balance....
Its not the U-joints in the propeller/drive shaft. I always check that first. Shock mounts are tight. I had my brother watch and listen as I first rolled the car forward pressed the brake and then rolled the car back and pressed the brake. There is a definite clunk in the front suspension on each side but more on the driver side. Also I can feel it in the steering wheel. When I put a bar on the front swivel axle and apply pressure I can see some movement on the bottom near the swivel pin. So I replaced the bush for the swivel pin down there. The one that is horizontal to the floor. No improvement. So I got my bar and did another check and learned that the movement is in the king pin bush area. The lower one that is vertical. I expect I should first try to tight/snug this up and apply some grease before attempting to replace the upper and lower bushings.
I have a suspicion the prior owner pumped The king pin bushings full of grease prior to putting the car up for sale. The reason I say this is because it was much tighter when I did the test drive. Now after a few hundred miles the front suspension has loosened. Tomorrow I will look for signs that the grease has worked it's way out.
If anyone has information on how to adjust the tightness of the king pin I would appreciate it. Also, as I said in my original thread, I would like to learn what is involved to replace the upper and lower king pin bushings.
You can't just "adjust" the kinpins, and tightening that nut on top will do absolutely nothing. There are bushing in the vertical axis of the swivel axle housing that (if worn) have to be replaced and reamed with a special tool. There are also thrust washers at the top that set (vertical) end-float....these can be replaced at home, but it is probably unlikely that wear in these washers is causing your clunk.
You can't just "adjust" the kinpins, and tightening that nut on top will do absolutely nothing. There are bushing in the vertical axis of the swivel axle housing that (if worn) have to be replaced and reamed with a special tool. There are also thrust washers at the top that set (vertical) end-float....these can be replaced at home, but it is probably unlikely that wear in these washers is causing your clunk."
Agreed. excessive end float (top swivel link) will have a slight, quiet clunk on bumps.
Adding a shim here will have nothing to do with the vertical bushings. If worn beyond
limits, they need to be replaced and reamed.
Do you have wire wheels? If so, it could be worn splines.
I get a clunk like described sometimes that ended up being the front brake pads slopping around a bit in the calipers. No biggie...
The cost of that reamer is what stops most people from continueing on. I have one that has been used a few times, but most people figure it is better to just pay someone for a set of rebuilt stub axles sets and install those, or go to a shop and have the whole thing taken care of.
Does anyone know of a shop that does an exchange on the king pin assembly like the lever shocks?
Gordon at The B Hive does them, but when I spoke to him a few weeks ago, he was out of stock....give him a call.
Check the A Arms by removing the lower trunion bolt and verify if the holes in the A Arm links are not elongated. Remove the King Pin Assy. and bring it to an MG shop. Refer to the Bentley Manual, pp. 237-237. Most kits now come with a nylon lock hex nut and no specific torque values are indicated but verify that you have less than .002" end play (about the thickness of a sheet of paper). Just make sure the swivel pin rotates freely. As you already know, it takes a special reamer to fit the new King Pin bushings. Find a reputable MG Shop in NAMGBR "Service Recommendations & Mutual Aid Directory" that was just recently published.
Dan Wood on this site does that. His handle is DB Wood. If you can't get in touch, email me and I'll send you his phone number.
I offer a rebuilding service using only UK made parts. I charge $275 for the set. For that you get new kingpins, bushings, zerk fittings, dust shields, seals, washers, return shipping in the continental US, and the parts are cleaned and coated in a highly corrosion resistant coating. Turn around is usually 3 days.
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MGB & GT Forum: Suspension King Pin bushings slop
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