king pin thrust washer lubrication

[bex1151]

I am replacing the king pin,thrust washer and bushing on the front suspension of my Bristol.  I noticed that the grease channeling in the bushing allows grease to drain out the bottom of the lower bushing but there is no channel opening to allow grease to flow to lubricate the thrust washer. Both the installed bushing and new bushing only allow grease to drain from the bottom of the lower bushing.  I would think the thrust washer should get lubricated.  Am I wrong?  Do I have the wrong new bushing?  Do I need to install the new bushing upside down and re-drill the grease inlet hole in the side of the bushing? If so , was the existing bushing installed wrong?  Am I missing something?

[ACOCArch]

Before making any changes it is advisable to try and fathom out what is going on within the kingpin assembly.
   
   In general terms, the individual loads on an assembly will only be transmitted between fixed and moving components in a relatively small proportion of the assembly.
   
   It is important that these load-bearing areas are lubricated properly, otherwise free movement is compromised and wear is accelerated.
   
   In joints like a kingpin,  engineering practice is normally for any grooves to channel grease towards, and sometimes right across, the load-bearing areas.  Because the grease is only replenished occasionally, the channels may also act as a grease reservoir.
   
   On the other hand, it is equally important that load-bearing areas are of sufficient size, and not overloaded through being compromised by any grooves etc.
   
   In a kingpin a number of loads are transmitted - including the weight of the car, cornering and braking. All of these loads are variable and, as the car is steered and braked, the load lines between components will also change.
   
   Therefore, before making any modifications I would strongly recommend you look carefully at the loads and where they are taken, and ensure the arrangements for lubrication are adequate and not compromised by any changes.

[Robin A Woolmer]

The later king pin bushes & thrust are 'DU'PTFE impregnated sintered bronze steel backed, the king pin top grease nipple feeds into both bushes with a groove in the pin approximately central to the bush, the lower grease nipple is in effect not required & will not allow grease to get to the bearing surface as the bush housing covers up the outlet!
   Technically these bushes are dry lubricated by the PTFE but some lubrication helps, in the ideal world one would question the use of DU in this dirty enviornment but it clearly has worked over the years, by the way this applies to the 3/4'' diameter king pin size not the 11/16'' design of the earlier cars! these may have had bronze bushes? this probably had the benifit of the lower grease nipple.
   It might be worth discussing what bushes are supplied by Brian Eacott for your car.

[bex1151]

Thanks for the replies.  I am actually working on an early car (bex1002).  It does have the 11/16" king pin and bronze bushings.  It is because I was chasing lubrication channels to the loaded thrust washer that I noticed there was no channel to get grease from the bottom grease fitting through the bushing to the thrust washer.  That is what surprised me.  I thought there must be a problem with my new bronze bushings. But then I noticed that the old bushings have a similar channel configuration with no apparent channel up to the thrust washer.  The top grease fitting only supplies grease to the upper bushing and there is no channel through the king pin for grease to flow down to the thrust washer.  So I'm still confused.  How is the thrust washer lubricated?

[Glen Smytheman]

Hi all - Merry Christmas and Happy New Year from New Zealand.
   
   Please see response from my father Lane who is doing the suspension work on my Ace Bristol BE1175. I hope that this may help others throughout the world - the forum is such a great resource.
   
   Happy motoring for 2012.
   
   Glen Smytheman
   
   Re: The ACE Forum and discussions on king pin bushes
   
   
   
   I agree with BEX1151 - and can understand his confusion.
   
   After some consideration and in order to progress BE1175  ( with disc brakes - out of interest ) I ended up drawing up the front  front stub axle complete with king pin and bushes. The accurate location on the king pin as determined by the position of the cotter pin located in the front upright showed the grease groove(s) in the king pin were about 12mm from the INNER faces of the stub axle - not in the centre of the bush.. This ACE is a 1960 model with 11/16" king pins.
   
   You will note that new replacement bronze bushes have the main grease entry hole about 11mm from one end of the bush.
   
   If you look on page 48 of the AC Bristol General Instruction handbook you will see that the stub axle lower grease entry hole is shown much closer to the thrust washer end of the bush. In reality on BE1175 the reverse is the case and it is closer to the outer end of the stub axle lower face.  I would guess that most stub axles may be drilled that way.
   
   Therefore either the grease entry drilling was not done correctly as originally intended ( which seems unlikely ) or presumably was changed on production. - Who knows what was intended  50+ years later, irrespective of how the original bushes were/are fitted.
   
   My logic tells me that yes, the thrust washer needs adequate lubrication, and not just any leftover grease that may possibly escape upwards from the lower bush - particularly  if  there is a fairly tight clearance with newly reamed bushes.The thrust washer has grease grooves both sides so obviously it was intended that grease would get there ( somehow ?)
   
   Therefore in order to progress the restoration of the ACE without any further doubts or indecision  I have  slotted  the lower bush grease entry hole towards the stub axle drilling and inserted the bush with the initial hole 11mm down from the thrust washer face so that the grease will adequately lubricate the washer.
   
   The upper bush I have inserted also with the hole 11mm  up from the inner face of the stub axle , adjacent to the front upright.  With the bush grease entry hole in this position it will almost line up with the groove in the king pin. However we have turned the bush around so that the hole faces outwards towards the wheel. The grease from the top of the king pin heads out of the pin towards the engine. Therefore the grease ( in part ) has to go to the other side of the pin before it can  escape - mainly because the pin groove is larger than the bush grooves.  The bush could also be inserted  with the hole towards the front or back of the car. I admit that the location of the top bush is not so critical.
   
   That way the non thrust top of the stub axle will also be lubricated  - stopping grease going to waste by easily escaping upwards with the bush installed the other way around ( or some may say the correct way ). Out of interest the top of the upright was fitted with a shim to reduce any excess vertical play. Glens car is a low mileage car in very original condition so I assume that this may have been originally fitted even though it is not shown on the factory assembly drawing.
   
   To me  the new bushes allow new grease to escape too easily ( if installed with the hole towards the top and bottom of the stub axle) and so may not push old grease out of the grooves and therefore not fully or adequately lubricate the king pin, bushes and thrust washer. Long term the assembly may therefore suffer from excess or accelerated wear.
   
   So, for better or worse,  that is what has been done and the reason behind  the decision. This way I am more than confident that the assembly is adequately lubricated.   I am sure this is likely generate further discussion.
   
   Lane Smytheman.