Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Kingpin top bolt

Fitted brake reaction bars yesterday. Super pieces of kit from Cain at Wolf.

All going swimmingly until replacing the top bolt back into the kingpin on the second side. This is a fine threaded hollow bolt about 12mm OD roughly 40mm long with 22mm AF hexagon. Very carful not to move anything. Bolt went down the hole about 10 mm and then failed to engage with the kingpin threads. Not really possible to see what was going on even with a mirror and torch. Several attempts failed and trying a hammer blow to the top of the bolt was becoming hard to resist. Last resort was a thorough clean up of the threads and a good squirt of oil. Hey Presto! The bolt then engaged with huge relief all round.

Needless to say this episode generated a few questions:
Is there an easy way of ensuring the bolt engages with the thread without major dismantling?
Why is the thread so fine? A course thread with wire locked bolt or tab washer would be more robust?
Would grinding a taper at the bottom of the bolt assist engagement?

Anyone experienced this before?

Yes, I experienced the exact same thing.
Once loosened with a spanner one side unscrewed using my fingers, the other side needed spannering all the way out.
The threads were damaged, perhaps been like that since inserted in the factory or maybe they're under a lot of force/ movement when suspension is working. Maybe it happened when I was unscrewing with a spanner.
I used a tap and dye to clean up the threads, they actually didn't need much work, I also made double sure everything was in line by using a G cramp to move the suspension until the bolt could be inserted and turned fully home by hand before tightening.

I have ground the threaded end of the KP bolt many times to get it to take hold. I also have 1/2" punch that is tapered so that I can line up the KP into the top plate. Also if this is an old Morgan the KP bolt will be 1/2 BSF If it is a late model Morgan I think it will be 1/2" SAE but check do not take My word for anything. I use a big rubber hammer to pound the spring into position/ I have used a long 3/8" bolt to get the KP lined up. I also used two long threaded rods to move the bottom of the KP into position. By tightening one and loosening the other I can tip the KP a bit. Lots of tricks including letting this job sit overnight and trying again the next day.

I have experienced this before. Damaged threads on one side, fortunately only the bottom half inch. As bolt is long this could be carefully cut off. Reintroducing the bolt took careful checking and double checking. A couple turns, reversing , testing again and so on, before finally being 100% sure all engaged properly then slowly tightening by hand as far as possible before introducing the spanner.

Thanks guys. Not just me then !!

The secret is aligning the king pin to hole its bolt fits through in upper cross head. If brake reaction arms are fitted loosen chassis mount end as the bolt has to fit through hole in kp end first. If you have adjustable camber version ensure the two washers that bolt first fits through are greased and fitted with shaped part against each other.

Buttons suggestion of using a tapered guide to align is probably the best although not much clearance above so it would need to be short. A screwdriver to align is not really up to the job. Ensure whatever tool used, it doesn't drop out of sight into threaded hole. I used a large allen key that snugly fitted into threaded hole in kp, moving it carefully side to side and front to back whilst nugging spring assembly with soft mallet until I was happy kingpin was centered with hole. If bolt doesn't fit easily to touch kp threads you haven't got it quite right. Never even dream of using a hammer

I've also had this problem when fitting reaction bars, and like Button says, sometimes sleeping on it works best.

The kingpin can shift slightly as the bolt comes out, and alignment is crucial to get it back in.

I've an old 12mm screwdriver, cut down to about 3" and a taper ground onto it which I insert when I've taken the top bolt out.

Simple tool very effective

Arwyn

I loosen the chassis end of the Brake Reaction Bar so it floats free of the KP bolt.

Because I make My own King Pins out of 1" Hydraulic Rod I tap both ends 1/2 NF SAE (if I lived in the UK I would probably used Metric).
Instead of the Original KP Bolt I purchase 1/2-20X1.3/4" Set Screw Socket Cup. (The neat things about these set screws is then can be turned with a allen wrench) Top and bottom bolts. I use new stainless nylock nuts each time I remove them and blue loctite on the threads of the setscrews..

Now when I insert the KP I have the bottom plate attached and I screw the setscrew into the top with the allen head cup at the top.
I use threaded rod to move the KP into position using the bottom plates. (Threaded rod about 6" long with two nuts jammed at one end for easy turning - I often use an air wrench for quick work)
Ordinarily the top setscrew finds it way into the top hole. If not I can use a allen wrench to get it into place..

Mind You I live 1,000 miles from the nearest Morgan Dealer. I must be self sufficient. Not hard, just takes a little imagination. Also tools or Morgan Friends nearby who have the tools and expertise.

Some great ideas there! Feel a project coming on for a fabricated podger bar😊😊