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MG Midget and Sprite Technical - Front Suspension - longevity - how long do you get
been refreshing the front suspension today.
Got me thinking when the last time was I did it.
That would be 8 years ago, around about 50K miles ago. Some of these have been very very hard miles, and I'm able to generate quite a bit of braking torque (see picture)
As some might be aware, I also have an extra link in my front suspension.
I'm of the fairly firm belief that this has stopped the kingpin from flexing, and wearing out. Anyone else got any thoughts on this?
I've discovered a small amount of play in one fulcrum pin, commensurate with a lever arm damper having about 5mm play on the end of the arm.
Everything else is spot on.
How long does everyone else get out of their kingpins/fulcrum bushes?
|Had mine fully rebuilt at 58000 miles from new. Engine needed it too. The fellow who did the work was MG factory trained apparently (it is all he works on) and he said when these cars were made, they weren't expected to do 100,000 plus miles or last 30 years so long life on parts wasn't expected.|
Neglect by DPOs who never lubricated the king pins etc certainly doesn't help things either and the more DPOs, the worse it gets.
Not insinuating you fall in that category, Rob.
|I needed to replace bottom wishbones and fit and ream new king pin bushes at 68,000. Standard suspension set up except for lowering, STP oil in dampers and thicker ARB.|
|so about the same amount of mileage for both Clare and Guy. Guy's ahead by 10K.|
What sort of miles are they? Wondering if mine's made any difference at all now!! (HA!)
|Only 2 track days. Lots of twisty, bumpy back road driving. Generally enthusiastic "stole it" driving.
But I have greased those pins at least every 3 months throughout, to the point of being OCD about them!
I am convinced that greasing the fulcrum pins has very little to do with lubrication and everything to do with expelling grit and contamination and waterproofing the joint.Its the same principle as the bucket pins on a JCB or Komatsu digger and any decent operator will re-grease those at the end of every working day.
|IIRC I got about 50k miles out of the kingpins and bushes I reamed myself but I didn't grease them regularly and when I came to replace them I found the new kingpins still a very good fit in the old bushes as the bushes had hardly worn at all but the kingpins were rather rusty. I opted to replace the bushes and have them reamed by a local company as I no longer had the access to the fractional inch sized reamers and lathe at the local college, I was a bit disappointed when the newly "reamed" bushes had more slop on the new kingpins than the old bushes, it transpires after a BBS thread about the kingpin journal sizes earlier this year or late last that I measured the kingpin journals and found they weren't a fractional inch size and the company that "reamed" the bushes had actually ground the kingpin journals to suit the bushes. Next time I'll do it again myself.
Anyone got the journal sizes handy for the disc kingpin? If so I'll look up prices for the 2 reamers.
|The first set of kingpins went very quick (about 20.000 km). I had the original set up with Armstrongs. When dismantling I found out that the bushes only had a very thin layer of a yellow metal. I replaced the bushes. I now have brass bushes, teflon frontline upper triangles, Barry King under triangles with 2 grease nippels. I use the blue TSL grease 2 times a year. Since then (100.000 km) no play at all! I do not know witch of the above mentioned things made the improvement (5x now and probably much longer).
David The price of two reamers for me was more than 2 complete renewed stub axle/king pin/fulcrum/sets
The original bushes were a wrapped steel backed bronze bush so that would fit with your thin yellow metal layer but that's no reason they shouldn't last far longer as they can easily do so. I have seen the odd picture of replacement sets where it seems one of the bushes was externally brass/bronze coloured so that may indicate the replacement of the steel backed bushes with solid brass/bronze bushes due to them going out of production or just not being available at the time but it shouldn't effect the bush longevity unless a superior material was used for the solid bush. I would suspect maybe the lower bush was more likely to go out of production as at 25/32" it is an unusual size compared to the upper one of 5/8", my normal engineering supplier didn't even list 25/32" so I grabbed a new reamer off ebay for £16 for use in the future.
When I rebuilt the steering box of my Austin A40 Farina I found that used 1/32" thick steel back bronze bushes and they were no longer available, may have been an OEM item anyway, a call to Cam gears in Bristol verified they had no parts but that Vandervell were the suppliers which I knew from the bearings, a call to Vandervell confirmed they no longer made them so the box casing got reamed to suit readily available 1/16" wall steel backed bronze bushes. The college I had access to didn't have a reamer of the size of the steering shaft so the tapered serrated end got used as the reamer to open out the bushes and worked great. I regret selling that car.
How did you centralise the two seperate reamers ?
The factory tool (which is really expensive) is a stepped reamer.
Tracy Tools have the 25/32" listed, straight shank hand or machine and taper machine for about £20-25.
I mounted the reamer in a collet in the headstock of a a Hardinge toolroom lathe and supported the other bush on a live centre in the tailstock and slowly rotated the stubaxle and fed the tailstock quill in to feed the bush onto the reamer, then changed reamer size and did the same at the opposite end. Worked for me, the result was snug but I reckon as it is not really a rotating bearing but a slow speed rubbing bearing a snug fit isn't going to cause any issues with heat build up like if you tried the same tight clearances with a more rapidly rotating bearing. If felt too snug it could always be honed slightly.
Didn't check Tracy Tools but I often buy off then as they are quite good price wise. The 25/32" should be with me soon and I think I have a 5/8" reamer in the inch reamer drawer. The 25/32" reamer was 2MT and I have the adapters to fit that in the headstock spindle and as I try to avoid moving the tailstock from alignment it should be good.
This thread was discussed between 09/09/2017 and 13/09/2017
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