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MG Midget and Sprite Technical - King pin bushes
|What is the best way of removing old bushes and inserting the new ones into the swivel hubs ? |
Would a long bolt with suitable washes and spaces pull them out and the new ones back in ?
I know they will need reaming.
|A long bolt would probably work.|
I used a suitably sized socket and a 10-ton press.
|Thanks Dave. I do have access to a 10T press, but not till next week. I was thinking I might have a go at it today if the long bolt method was likely to work. As it happens its turned out a pretty foul day for working on the car outside so maybe I will just leave it until it fairs up a bit.|
|I've used a bronze drift to whack out the old ones. The new ones were inserted in a similar manner only I put the bushes in the freezer first and warmed up (hot enough to touch just) the stub axle.|
|I used the long bolt method. Bit wary of the press. The other method I have used was to hacksaw through the bush and then just push it out when it collapses. The January edition of practical classics covers a king pin refurbish and they show all three methods.|
|Well I decided to whip the suspension off and work on it in the dry indoors. 25 minutes total to jack the car up, remove wheel, disconnect calliper, ARB and track rod end, undo top kingpin nut and inner wishbone bushes. Everything just came off really easily but it has been so well greased over the years that nothing is seized - the hardest part was knocking back the tabs on the calliper bolts!|
Now it's on the bench I can have a proper look at it. The little cotter pin doesn't want to budge and I had also forgotten that the hub carrier won't quite lift off the kingpin without removing the disk and backplate. I had forgotten that we problem! It always looks as if a bit of "persuasion" should get it clear but I don't think it will. Pity as I was hoping to avoid having to disturb the wheel bearings, - not least because it is likely to set Lawrence off again and he has been quite quiet and well behaved of late!
|I'm quiet, but I haven't gone away. lol.|
Yup sad to say Guy, hub off. There's no room to get the pin past. Don't worry if the inner race comes apart, just keep it clean and push it back in.
I've used the hack saw method and drift method. Make sure the drift you use to whack them back in, doesn't burr the bushes.
What are you going to use for a reamer? Are you making one from an old kingpin, as per Fletchers instructions earlier this year?
|I had the machine shop do mine... It needed reamed anyway. It was cheap i recall, but cant remember the price tag|
|Prop and the Blackhole Midget|
|Prop, I enjoy the challenge!|
Had to break for a family shopping expedition to the sales, but got back onto it later on this afternoon. Cotter pin out and hub off. Cut down inside the bushes with a hacksaw as Bob and Lawrence suggest and drifted them out easily enough. Pulled the new ones in with a long bolt, washers and selection of 1/2" drive sockets. Then reamed them - what a satisfying job that is using the proper stepped in line reamer. (Borrowed one - thanks P!)
Progress now ceased again as it just isn't right to dismantle these parts without washing them down with degreaser and applying the Hammerite. So that needs to dry and harden off overnight.
How good a fit is the kingpin in the bushes as the last time I had a shop do the reaming with the proper reamer the new kingpin was a looser fit in the new bushes than in the old ones I had done myself.
As it is with a new kingpin, new bushes and reamed the fit is very close. I can feel no lateral slack at all, and the hub carrier turns on the pin smoothly with light hand pressure. For testing, I just gave it a light wipe of LM grease over the pin before inserting it.
I was in fact slightly concerned that it is such a close fit that there is little space for grease. Maybe I should ease it a bit more. Or perhaps lubricate with oil rather than grease, as I know some people recommend.
Can someone remind me where the square section and the round section rubber seals each go? I am guessing that the square one is for the end of the dust tube to seat onto and the round one goes under the bottom of the pin. Is that right?
Regarding your fit that sounds about like the ones I did myself so I wouldn't worry about it. The ones I did myself lasted about 3 times longer than the ones I had reamed by a machine shop. I can blame myself for the ones I did myself going due to not greasing frequently enough and the king pin rusted. While the fit being close could be an issue if they were continuously rotating in the case of the kingpins they rotate slowly, infrequently, and through a limited arc so being on the tight side isn't an issue.
In the case of the bushes I had reamed by a machine shop the new bushes were a looser fit on the new kingpin than the old ones were on the new kingpin so that was rather annoying. I seem to recall that other have mentioned that often the kingpin wears more than the bushes do.
You are correct about the location of the two seals.
When I replaced the bushes in the 'B' stub axles, they also felt quite loose after reaming.
|When i do my front end rebuild. Big brakes, wishbones, addco sway bar, frontline kit, neoprene bushings ect ect|
Do i need to do anything with the king pins...last i looked they where in great shape, no slop or play and still well greased
|Prop and the Blackhole Midget|
|These rubber seals are still causing me to ponder. The round section one I know goes at the very base of the king pin. |
It is the square section one that is the puzzle. I thought it went in the back of the hub carrier, immediately above the bottom bush so that the dust tube seated onto it. That is where I removed the old one from when I dismantled it ('cos that is where I put it some 18 years ago!). When I said this earlier Dave confirmed it as correct, but the Moss exploded parts drawing shows it as going at the top, against the thick PB bearing washer. And that is where Grahame Bristow puts it in his pencil sketch in his book (Restoring Sprites and midgets,p33)
|You are right the first time Guy. The sq section rubber seal goes above the bottom bush and the dust excluder/grease retaining tube sits down on top of it. I always thought it was a crap design, but as it seems to work, I guess it must be a good design.|
|Thanks Lawrence. |
I tried putting it together as shown by Moss and also in Bristow's book but it was clearly wrong! It would have meant that the load transfer between the stub axle/ swivel hub and the kingpin was on the rubber washer instead of the large PB washer/bearing! That would be an even worse design!
|For anyone wanting their own reamer|
|I don't see how that reamer could fit all those models as I understand that disc braked cars have a different king pins to drum braked models.|
|I believe that A40 mk2s have drum brakes and large kingpins|
|I've just had a look at the list and I believe that later A35 vans also had the larger pin, so they are probably correct.|
I'd love to know what an 'INNOCENTI AUSTIN A40S Combinata, 1098cc' is.
|The Combinata was the Innocenti factory's version of the A40 Farina Countryman. Probably a lot rarer than a King Pin reamer!|
|The reamer that Fergus linked, is now going crazy.|
It's a QH reamer and it's def' the right size. The seller sent me the catalogue details. " ---- I have the exact sizes from the Catalogue.......0.781" and 0.625", listed as a stepped line reamer ----- ".
But for 80 quid,-- the current price -- and I suspect it will top a ton --, I think I'll just make one. Moss have the better one with the pilot but 140 quid is too much. Although I'm not sure if the pilot extension is really all that neccessary since the two reamers are attached inline anyway. Just makes it a bit easier I suppose.
|Is the Moss one still available its listed as NLS now . It makes this one seem relatively reasonable. i was thinking it could be lent out to club members to use for a small fee??|
|Yup, looks like it. It was there a week or so ago. If Moss only had nos, then you could be right about the qh jobby. You may never see a new one again.|
If moss don't have any left, and nobody is making them, then it won't be long before nobody is doing exchange stub axles, --- as the reamers become too worn to ream effectively.
I agree, worth a club buying it then. Make it southern club. :)
Now watch it go up another 20/30 quid. lol. Wish it were mine, I'd sell it for 150 :)
|Come on then, fess up. Who paid £123? I had punt at £103 on the basis of rental :).|
|Was the Moss one about £140? so £123 is reasonable i suppose??|
|Yup I think it was over 140, then add postage. So 123 not too bad. Esp if Moss no longer sell them either.|
Time to get my grinder on an old kingpin and make that reamer methinks.
|Moss are showing them again now. Very strange. 142 quid plus postage.|
|Lawrence, are you are going to try modifying a kingpin to act as a reamer? When I replaced my kingpin bushes and reamed them with a borrowed reamer I found that the bottom bush which is steel barely needed any cut at all. It really acted more as a guide to align the reamer as it cut the top bush. The top bush was made of a brass- like material which cut very easily and cleanly. It took only minute or two to ream and the new king pin was a close fit once they were cut.|
I suspect that if making a reamer from an old kingpin you wouldn't need to bother about cutting flutes for the bottom bearing. Just the top one would do it. But you wouldn't want to use an excessively worn kinpin or it will cut the top bush undersized.
|Or use an adjustable one:|
Not sure of the length of this reamer, but in theory one could put a temporary reducing insert into the bottom bush so that it could act as a guide to align the reamer as it cut the top bush.
Certainly a lot cheaper than a Moss stepped one!
|"the bottom bush which is steel"|
They used to be the same top and bottom, brass or the like.
Yup I'm going to follow those instructions from Fletcher. Nowt to lose really. I have a spare old, not too badly worn pin to play with. But that adjustable looks interesting too. I'll ask how long it is.
|OK, not just steel. But its made like a crank bearing with a steel backing and copper or PB lining. Top one looks and cuts like normal brass. (photo)
The Moss reamer shown is for an MGB or C. It has a different part number to the spridget one.
|Guy, what kit are those bushes from? I just checked an original (aka old) QH kit and both bushes are steel-backed and split longitudinally with a bronze coloured lining.|
|Got them from MGOC|
|Ah yeah, so it is Bob. Are you the lucky new owner of the QH reamer then? :)|
You certainly wouldn't want to ream too much of the bottom, the copper/brass is only thin skin deep, but it lasts for years, even if they don't get greased as often as the 'book' says they should be.
This thread was discussed between 28/12/2012 and 12/01/2013
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.