28 replies to this topic

[Cooperman]

There is a bush at one end and a needle roller bearing at the other. It's the bush which needs reaming after installation in the arm.

The biggest difficulty is getting the old bearing and bush out and brute force is often needed.

[mbolt998]

and I'm wondering why they didn't just use bearings at both ends in the first place, was that just cost saving, or does the reamed bush give a slightly tighter fit which offers some benefit ? 

 

Good question. I don't remember Moulton mentioning this in his book. His suspensions were certainly not cheap. Because the springs are rubber it needs to be low travel, which means a long lever out to the actual suspension, high forces, and therefore high quality bearings and subframes to support the actual springs.

[GraemeC]

Ideally two bushes would be used - they support a shaft that is only turning back and forth a small amount much better than bearings.

[Ethel]

Yes,

 

Think I'm right in saying the Mini started life on 2 bushes, then replaced the inner with a needle bearing. Needle bearings can't carry as much load as a bush, but will last longer with poor lubrication. Doubtless there's some production cost saving by halving the reaming operations required too. The Metro was given needle bearings at both ends, along with sealed ball joints at the front end. A major part of its design concept was based around increased service intervals

[coopertaz]

agree a pain to get out and don't forget the grease tube!! i use an adjustable reamer and just set for clearance on new shaft have done both with and without guide and both possilble a worthwhile investment considering price of exchange arms and assuming they are straight! also re. bearings wonder why front arms have rollers at both ends then?

[Spider]

and I'm wondering why they didn't just use bearings at both ends in the first place, was that just cost saving, or does the reamed bush give a slightly tighter fit which offers some benefit ? 

 

As Ethel has mentioned, the early Minis had bushes both ends and as Graeme has said, in this application, bushes are better for supporting the load than needle roller bearings.

 

The production bushes is of the type and design that are pretty much rolled up sheet steel, sprayed over with a coff coff,,,bushing material. The issue if I recall was they would gall on the shaft, effectively seizing to it. If the correct material (or even a better one !) is used, they will support load much better as the bearing area between the shaft and the bush is the same shape and larger than the lines of using needle rollers. One up-side of using needle rollers in this application though is that when greasing, the grease has a better chance of getting through and out the other side on the loaded side of the needles, though, if the right grease is used with a bush set up, it would seldom need greasing.

Some fun info facts;- When NASA first had the Launch Tower made for the Apollo Rockets, they fitted bearings in to the crawler tracks. On it's first loaded test, it only got a few tens of metres out of the Assembly building when they found the bearings were collapsing in a big way. They went over to bushes and never looked back. Those same bushes, while they have been checked many times since the early 1960's are still the same ones there today, after hauling out not just all the Apollo Rockets, but also all the Shuttles too and many other tasks over the past 60 years.

 

Mokes are factory fitted with needle rollers on both sides. Many years ago (nearly 40 !), I made and fitted bronze bushes in the trailing arms of my wife's Moke. They are still there, as perfect as the day I fitted them and also, it's still on the same shafts.
 

[Ethel]

What grease are you using, Spider?

 

I note some manufactures switched from lithium to molybdenum for applications like king pins. 

[Shooter63]

I've seen a rather nifty mod done to the main pin which impressed me, but haven't tried yet. Basically you block the central grease outlet, drill out the inner blind end and add a second grease nipple then cross drill both ends at the bearing points, thus allowing the grease into the bearing points only, seems like a win win mod to me and presumably means thers no need for the crappy grease tube.

Shooter

[GraemeC]

I’d still keep the grease tube, even if just to stop excess grease filling the arm

[Spider]

What grease are you using, Spider?

 

I note some manufactures switched from lithium to molybdenum for applications like king pins. 

 

Hey mate - just back in to civilization - or so they call it !

I'm using a Lithium EP. I've tried quite a few over the years, this has been best yet.

[imack]

I've seen a rather nifty mod done to the main pin which impressed me, but haven't tried yet. Basically you block the central grease outlet, drill out the inner blind end and add a second grease nipple then cross drill both ends at the bearing points, thus allowing the grease into the bearing points only, seems like a win win mod to me and presumably means thers no need for the crappy grease tube.

Shooter

Carried out that mod on my radius arms about 8 year's ago. I left the grease tubes in place. I also added grease nipples to my old Ripspeed HiLo's.

[Shooter63]

I've seen a rather nifty mod done to the main pin which impressed me, but haven't tried yet. Basically you block the central grease outlet, drill out the inner blind end and add a second grease nipple then cross drill both ends at the bearing points, thus allowing the grease into the bearing points only, seems like a win win mod to me and presumably means thers no need for the crappy grease tube.

Shooter

Carried out that mod on my radius arms about 8 year's ago. I left the grease tubes in place. I also added grease nipples to my old Ripspeed HiLo's.

I presume it works a treat then?

Shooter

[imack]

I've seen a rather nifty mod done to the main pin which impressed me, but haven't tried yet. Basically you block the central grease outlet, drill out the inner blind end and add a second grease nipple then cross drill both ends at the bearing points, thus allowing the grease into the bearing points only, seems like a win win mod to me and presumably means thers no need for the crappy grease tube.

Shooter

Carried out that mod on my radius arms about 8 year's ago. I left the grease tubes in place. I also added grease nipples to my old Ripspeed HiLo's.

I presume it works a treat then?

Shooter

Easy to grease, and no play in them yet. But they've only done around 10,000 miles in that time. Angled grease nipple makes maintenance easier, especially when a side exit exhaust is fitted.

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Edited by imack, 27 May 2024 - 03:10 PM.

[Spider]

I've seen a rather nifty mod done to the main pin which impressed me, but haven't tried yet. Basically you block the central grease outlet, drill out the inner blind end and add a second grease nipple then cross drill both ends at the bearing points, thus allowing the grease into the bearing points only, seems like a win win mod to me and presumably means thers no need for the crappy grease tube.

Shooter

 

I've seen a few where the arm was drilled in the top side and 2 x nipples add in there. The nipple need to be just at the inner ends of the bush and bearing and the grease tubes retained.

I've been making my own 'sealed' grease tubes that have O Rings on the ends. Since fitting these, from dry, 3 pumps and it's coming out the ends. I've also found the way the grease flows through and out the ends is more effective since all the grease and pressure pushing it is all ging to these ends and not filling the arm.

Without grease tubes (and sometimes even with them !) you'll find once the arm fills up and the grease separates, you Mini will start leaking oil out both ends.