Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing king pin bushes

MG used split down the length bushes, which compressed to close the gap as they went in. They also used a smaller upper bush so a stepped reamer and kingpin. No idea if that's a better solution, but as a 19 year old, the local BL dealer allowed me to use their hydraulic press and reamer unsupervised.

Dave

May I have a copy too please?

Private message sent.

Can anyone please suggest someone for fitting and reaming king pins and bushes in south central (Oxford) area?

I’m happy to strip the stub axles and bring them to the UK, though I’m only over for a week at Easter and am meant to be looking after the grandson so don’t want to travel far. I contacted Alan Claridge as he’s literally on the doorstep but he’s on holiday, Wolf and Mulfab are just too far.

Cain at Wolf will replace and ream bushes while you wait if that mitigates the travel distance. He uses Mulfab kingpins and bushes.

MOT pass yesterday-all good.

Thanks for any advice given.

I'm just about to do the kingpins on my 77 plus 8 and am going to have a go at the bushes/reaming myself this time. Last time I got a local engineering shop to do the reaming. I'm slightly curious about the reaming process though. Not the mechanics of doing the reaming, but managing the tolerances. I have the hardened chrome kingpins which are exactly 1 inch dia as far as I can tell. And I have a fixed 1-inch reamer. Once you have reamed the new bushes in situ - how much tolerance is needed? I would have thought that the bush's inner diameters needed to be reamed to a very small amount larger than the outer diameter of the kingpins. Maybe a thou or two? To allow a good sliding contact. Last time, the local engineering shop did it in such a way that you put a very lightly lubricated kingpin in the stub axle and held the axle so the kingpin was vertical, the kingpin slid very slowly through the bushes (under gravity) - at maybe a cm or two a second. But if the kingpin and the reamer are both exactly one inch, will there be that slight tolerance to allow a sliding fit? Any help much appreciated.

Typically when you buy a fixed reamer you can ultimately specify/order any final hole size that you require, if you want. However a standard 'off the shelf' reamer that you may (probably?) have might typically produce say an ISO H7 class of hole fit which is a close clearance on the nominal, around a thou up on an inch hole. I question if your pins are "exactly 1 inch". If they were manufactured from standard ground shafting they will most likely have a very small minus tolerance. A good micrometer will confirm all of this.

Just my opinion but the actual clearance you end up with is subjective and often described (as you did) rather than quantified. The clearance needed to get that 'described' fit with an adjustable reamer may be different dependent on the final axial alignment of the bushes, should there be any distortion of the tubes. So who really knows what the resultant radial clearance will be after reaming without some very precise post reaming measurements or a session on a coordinate measuring machine. Rightly or wrongly I've made my bushes 2 to 3 thou over size but hopefully they will be reasonably axially aligned to each other after bonding.

Again just my opinion but... You might struggle to get the fit you require with a fixed reamer and particularly if there is any weld distortion in the tubes.

The man that really knows all of this of course will be Arwyn

Good luck!

The reamer I have is simply marked 1". Industrial cutting tools 255FL x 380 0/A. - ie it is 255mm long on the fluted cutters and 380mm overall. If it is H7 then the tolerance is -0.000 + 0.021 mm or just about 1 thou oversize if I've got that right (not a given). This sounds a bit tight. Probably the best thing is just to go try it and see what the results are....
many thanks for your help...