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+--- Thread: Bushes - Reaming King Pins & rear springs (/showthread.php?tid=1420)
Bushes - Reaming King Pins & rear springs - David.H - 05-07-2018
Question #1
How long is a "long" King pin & how long is a "short one? I don't know the history of my front axle/hubs, but my pins are ~3.475" long. They are in good condition with a consistent o/d 0.499-0.501.
The bushes are shot, with the i/d anywhere from 0.5085-0.5105 plus. The axle eyes are not oval, but n/s is about .005/8" oversize. I did not have grease plugs ....the top of the Pin was sealed off with solder & a 0.750" plug jammed into the base! Stub axle numbers are 1A4122/3
Question #2 can I simply obtain a new set of bushes & thrusts with a 0.500 diameter? the suppliers are suggesting that the bushes will need to be reamed (even if I buy a kit with new pins) Why are they not made to fit? leading to:
Question#3 I bought new Rear spring bushes & was surprised to find that they also need to be reamed to fit the (new) 0.500" BR58 Spring pin/rear spring bolt. As the new bushes are a (very) loose fit in the spring eye I cannot drive the bush into the spring to hold it while reaming it (if I had a reamer....) Why are they not made to fit their matching bolt?
RE: Bushes - Reaming King Pins & rear springs - bob46320 - 05-07-2018
When you press a new bush into an old eye, the bush will be deformed by the axle eye. The only way to get each bush the correct size and in alignment with each other is to press them into the eyes and then In-line ream them. Idealy you need the special in-line reamer - like this but wince when you see the price:-
https://www.theaustinsevenworkshop.com/products/fa0902-kingpin-reamer
Most of us ream with an ordinary reamer, but it does not give the best results. If the bushes were supplied oversize to take into account the "possible" shrinkage, then the king pins would not be a good fit and the job done again 10,000 miles or so later.
Its the same for your rear springs - Alignment!
Bob
David, have you read this:-
http://www.austin7.org/Technical%20Advice/King%20Pin%20Renewal/
RE: Bushes - Reaming King Pins & rear springs - AustinWood - 05-07-2018
They need to be reamed for 2 reasons.
1) They must be accurately in line as well as an accurate diameter. The only way to ensure this is to fit slightly undersize bushes and then ream them.
2) They are a press fit in the housing and therefore compress slightly when being fitted.
The short king pins are for Girling braked axles with detachable brake back plates. The long pins are for Austin brakes.
The short pins use a core plug for the grease cap. I've never persuaded them to stay put when pressurised with grease.
Long pins hava a screw in grease cap.
RE: Bushes - Reaming King Pins & rear springs - David.H - 05-07-2018
Thanks... that does make sense...I did not appreciate that is still the case with a solid as opposed to split bush. My car had some of each!
I can get the king pins reamed "off car" into the hubs, but does that address the problem...unless I take the front axle off!
The bushes in the rear spring will certainly not be deformed as I throw them into the eye!, so I can do them off car. It was suggested that I coat them with solder to increase the o/d.....? and then push them in
And still are my pins long or short!?
RE: Bushes - Reaming King Pins & rear springs - GK5268 - 05-07-2018
You need to ream the bushes after they are pressed in, as was said above, they will deform slightly.
I took the plunge & bought the special reamer for the stub axles, it gives excellent results, and well-worth the money. Even if you use it only twice, (each side) you could always sell it on, think how much you would have to pay someone to do it for you, or accept something that is not quite right by making do with an ordinary 1/2" reamer, I did pay someone to fit new bushes in my front stub axles, but they clearly didn't have the correct reamer as after only a few hundred miles there was excess play, so I have now done them myself, I have a second car, so will get used for that and I look after my Uncle's as well, so I thought it a good investment.
The Girling pins are about 89mm long, so the ones you have are the Girling type (detachable back plates). The fillers to the top & bottom are just core plugs, same as that used on the head, the brass threaded ones (electrical fittings!) are for the longer earlier type.
When fitting the new bushes into the stub axle, make sure they are the correct way around, flanged top is the lower bush and align the cut-out in the top bush with the grease nipple. The hardened thrust washer fits between the flanged top and the axle eye (bottom) and just a packing washer to take up any slack, no vertical movement and the stub axle must rotate freely (otherwise the steering will be affected).
RE: Bushes - Reaming King Pins & rear springs - bob46320 - 05-07-2018
Of course, the bushes are only half the story. When I said Axle Eye, I should have said the hub eyes. The king pin should be a light push fit into the axle. If it wobbles about, then the axle eyes should be shrunk (Not an amateur job) bored by machine back to the original size.
RE: Bushes - Reaming King Pins & rear springs - Stuart Joseph - 05-07-2018
Good evening all. A tip about using reamers - never turn them anti-clockwise. Nothing blunts a reamer quicker than turning them the wrong way. Also never use a reamer on brass then steel then brass as it will have lost its brass cutting effectiveness on steel.
Apologies if I am teaching grannie to suck eggs but a well known correspondent to this forum recently told me that 'you old 'uns need to pass your knowledge on'!
And as for the typos in my last posting perhaps age has caught up with me.
Regards from Staffordshire - once the creative county.
Stuart
RE: Bushes - Reaming King Pins & rear springs - bystander - 05-07-2018
(05-07-2018, 03:56 PM)David.H Wrote: Question #1
How long is a "long" King pin & how long is a "short one? I don't know the history of my front axle/hubs, but my pins are ~3.475" long. They are in good condition with a consistent o/d 0.499-0.501.
The bushes are shot, with the i/d anywhere from 0.5085-0.5105 plus. The axle eyes are not oval, but n/s is about .005/8" oversize. I did not have grease plugs ....the top of the Pin was sealed off with solder & a 0.750" plug jammed into the base! Stub axle numbers are 1A4122/3
Question #2 can I simply obtain a new set of bushes & thrusts with a 0.500 diameter? the suppliers are suggesting that the bushes will need to be reamed (even if I buy a kit with new pins) Why are they not made to fit? leading to:
Question#3 I bought new Rear spring bushes & was surprised to find that they also need to be reamed to fit the (new) 0.500" BR58 Spring pin/rear spring bolt. As the new bushes are a (very) loose fit in the spring eye I cannot drive the bush into the spring to hold it while reaming it (if I had a reamer....) Why are they not made to fit their matching bolt?
A perfect kingpin eye (and very few are nowadays!) is .500". Therefore a standard kingpin has to be less than this for clearance - ideally half a thou to one thou under. If you have pins measuring .501" this would suggest that +.002" pins have been fitted in the past (they have been available in the aftermarket for donkey's years). It follows that the axle eyes have probably been reamed out to suit, as an alternative to the suggested closing up of the eye and reaming back to standard.
Rear spring bush a loose fit in the spring eye is also a common problem, the fault being in an opened out or badly made eye rather than an incorrect bush. For this reason I believe rear spring bushes with an oversize o.d. have also been available in the past although I am not sure if they still are - ask the cherished suppliers. Otherwise in an extreme case making up a one-off set of bushes might be necessary.
RE: Bushes - Reaming King Pins & rear springs - Andy Bennett - 05-07-2018
I can add testament to the deformation.
I have just fitted the valve guides to my new block (I used the freeze the bushes and warm the block technique and it worked well).
Before inserting the guides, the valves were a lovely fit. After fitting them the valves wouldn't go.
I reamed 9/16 and created a fair amount of swarf (clockwise in, clockwise out), result is again a lovely fit for the valves.
I was surprised how much cast iron guides must have deformed, let alone what would happen with brass bushes.
When i did my rear springs a while back the bushes were a sliding fit, but I still found reaming useful to align both sides perfectly for new pins.
Andy B
RE: Bushes - Reaming King Pins & rear springs - David.H - 05-07-2018
(05-07-2018, 04:46 PM)GK5268 Wrote: You need to ream the bushes after they are pressed in, as was said above, they will deform slightly.
I took the plunge & bought the special reamer for the stub axles, it gives excellent results, and well-worth the money. Even if you use it only twice, (each side) you could always sell it on, think how much you would have to pay someone to do it for you, or accept something that is not quite right by making do with an ordinary 1/2" reamer, I did pay someone to fit new bushes in my front stub axles, but they clearly didn't have the correct reamer as after only a few hundred miles there was excess play, so I have now done them myself, I have a second car, so will get used for that and I look after my Uncle's as well, so I thought it a good investment.
The Girling pins are about 89mm long, so the ones you have are the Girling type (detachable back plates). The fillers to the top & bottom are just core plugs, same as that used on the head, the brass threaded ones (electrical fittings!) are for the longer earlier type.
When fitting the new bushes into the stub axle, make sure they are the correct way around, flanged top is the lower bush and align the cut-out in the top bush with the grease nipple. The hardened thrust washer fits between the flanged top and the axle eye (bottom) and just a packing washer to take up any slack, no vertical movement and the stub axle must rotate freely (otherwise the steering will be affected).
Thank you for that info...the car has Morris Minor Hydraulics, so Girling stub axles would make sense. At least the lead melted on top of the king pin kept the muck out of the top...better than the whittled wooden core "plug" in the head!
What lubricates the upper bush, the cut out from the nipple only seems to look after the lower bush!
I will take the stub axles, bushes & (hang the expense!) new king pins into the tool-room where they are used to operating in microns (whatever they are...I do know really!)