Repairing & Improving radius arms.

[mk1]

Thanks to Peter Laidler, I am pleased to have been able to add a very comprehensive article on the restoration & improvement of radius arms to the technical section on the main site.

http://mk1-performance-conversions.co.uk/rad-rep.html

[JanWulf]

Very comprehensive and detailed! Thank you both very much for the time to write & publish! Much appreciated!

[scott6058]

Many thanks as well...

[rolesyboy]

Thank you Peter. This job evades me every time I look at doing it. I look forward to reading your article.
Regards
Mark

[Spider]

Great write up Peter, with a few humorous overtones to keep us awake. I sincerely appreciate the work and time that goes in to write up like that.

I like the fix & mod for the pin that the spring goes on to, however, if I can say, I'm not sure that Stainless here is appropriate. I feel a Bronze would be better. Stainless doesn't have much in the way of bearing qualities and is very harsh on any contact steel, particularly in regards to rust and corrosion.

I also like the means of reaming the bush, sure takes some of the sweat out of it. If I can add here, where looking to buy reamers I'd suggest looking for hand reamers as opposed to machine reamers. While frowned upon, you can run hand reamers in machines (I do it lots ) lots of lube or coolant and as slow as the machine will go. The reason I bring this up is hand reamers have a taper on the start end of them and machine ones don't. For doing these bushes, it would help a lot to get it all started.

[Peter Laidler]

Thanks for the comments all. I should say that it was done with a lot of help from a couple of nameless forumers too. I did have to think about using stainless for the bush Spider and did consider brass or bronze but all things considered PLUS he fact that the area is sided by oil soaked felt pads, then stainless was the way to go - plus I had a short bar of it! The same occurred to me that if you simply bushed the already grooved/rutted/damaged HSSP's, brass or bronze might fail quickly.

Take the point about the non taper start machine reamer too, but you go to war with what you've got! But I've got a confession to make..... I ran the bushes in a lathe chuck before we pulled them in and cut a slight, 3/32 in length or so, start taper in the inside surface of the outer rim so that the reamer would start centrally and cut its way through quite easily. Worked a treat, first time.

Don't let it worry you unduly Roly, you live close enough to come for help if you do start. We went over the top because..... anyway! It was a pleasure to do and we're going to do a couple more similar general ones using the others Dolly (wheels?) and Midget (wheel bearings?) over the winter and spring

[canadianminimk1]

I too really enjoyed the article on repairing and improving the radius arms as this is exactly what I am working on and having
just received my repair kits from Mini Sport I was keen to have a go at it. I do have to say that the new pins in the kits I got are Very Hard. I carefully ground away a small spot to be able to drill the new lubrication holes but have stopped now at a depth of about .090" and still it is as hard as the surface. Also I am not able to drill into the centre of the shaft as it too is as hard. That makes me think the entire shaft is hardened. These kits are marked: Classic Mini Radius Arm Repair Kit Reparatursatz Europe. Wondering if anyone else has tried to drill these? So for fun I took the old shafts and following your instructions drilled them out very easily. These shafts are still in usable condition but the new kit uses a larger bushing so I'll have to get some new bushings to suit. Has anyone fitted a needle roller bearing to the outside instead of the bushing? Just a thought.
Thanks again for your great article and any comments would be appreciated.

All the best for 2018,

Andrew

[Peter Laidler]

That's amazing.......... We did ours with no real problems at all. In fact, since the article I have modified/drilled/threaded two more sets for forumers embarking on the same project, all using good quality MS parts. The fact that yours are a larger diameter(?) make me suspect that they're not quite what MiniSpares supply. But to be honest, drilling through and into the ends of the shafts should be simple enough with a suitable centre and drill. Once we broke through the induction hardening it was simple. As was drilling into the end

[Spider]

Also I am not able to drill into the centre of the shaft as it too is as hard. That makes me think the entire shaft is hardened.

All the best for 2018,

Andrew

Cheers for the wishes to all for the year and same to you & your family Andrew.

I'd suggest, if the shafts are indeed through hardened, don't use them as they'll be brittle and from your description, the threaded ends also sound like they are hardened. If that's the case, these ends will break off. The factory Pins had a Case Hardening to 62 Rc only on the ends where the bearing & bush run and to a depth of around 0.030". The core material (EN16T) has a hardness in the 28-30 Rc range.

For drilling hard steels, I've found these work very well;-

http://www.artu.com/multi-purpose-drill-bits.php

Use them with loads of speed & pressure and if wanting to drill bigger holes, don't make a pilot hole as you usually would (not needed for a grease way in a pin !!)

In a normal pin that been case hardened, these drills are ideal for the hole from the surface to the centre, but, again, if the pins are this hard, you won't be able to tap a thread for the grease nipple.

[Peter Laidler]

Yep, right Spider. There's no mechanical or metallurgical need at all for the threaded ends to be hardened at all...., to achieve what?

[canadianminimk1]

Thank you all for your comments, I did have another go at them this afternoon but no luck. I feel I have ground away too much on the new pin now and still even my best drill bits will not even make a mark and if I try centre punching it just flattens the point. So, again I took my second used shaft and ground a wee spot through the hardening and into the drill press and it goes through like hard butter. I centre punch the end without mushing my centre punch and drill right into the shaft no problem at all. So I am guessing that Mini Sport and Mini Spares have different suppliers although on both sites the pins look similar and not stepped like the ones I took out and the ones in your pictures. I assume the original bushing was a bit more robust? but I don't see a different listing for an 'original' size bushing. Do you think a needle roller bearing might work in it's place? Kind of like the front arms or do you think it may get pounded to dust Thanks and....

Cheers,

Andrew

[minimans]

To use a roller bearing at each end would mean a very accurate line bored hole between the bearings any misalignment would destroy the bearings in short order.
A very good informative article! In BMC's defense regarding the grease hole locations, when cars were serviced on a regular basis the rear arms would have received a greasing at least twice a year and in conjunction with the metal sleeves, grease would have got to where it was needed. I don't think they took into account the changing ideas of what constituted regular service
20 odd years after the design ............ My 1960 arms when stripped were perfectly lubricated with minimal grease leakage into the inner recesses of the arm. They were so good in fact I didn't use the kits I had ordered in anticipation of a corroded mess!

[JohnA]

The main problem with radius arms and also ball joints is lubrication
The service interval is 3,000 miles or three months
When properly greased when recommended they weren't a problem
Radius arms fitted with the plastic sleeves often fill with grease with non getting to the inner bush
As with ball joints the quality of aftermarket parts is usually shite causing most of the problems
One of the joys of having parts manufactured on the other side of the world
It's great for quality control

[Peter Laidler]

Off the subject in a sort-of way. I saw that my ball joints weren't being properly lubricated where they ought to be....., between the rotating (spring loaded ball) ball and the locked down cup. So I carefully ground another flat opposite to the existing flat and then deepened that flat too. Now the grease gets all around without too much effort and have been perfect since 1986. I would write a short illustrated report on it but maybe it's a bit too contentious

[rolesyboy]

Peter, it’s a forum. Get the article written man. The last one was excellent. With your article and the help of another forum member I knocked off my first ever refurbished radius arms. Very pleased as this job has been on my bucket list for years lol
I am going to PM you re the handbrake quadrant mod you made.

[Peter Laidler]

Hold your horses Roly...... Just need to gather the enthusiasm, the other blokes as we share brains and cars to test on and Timken to come back to confirm a few things regarding the technicalities of spacers. But Roly did raise an interesting point in his PM. He's modified his shafts etc etc but asks '........ I haven't carried out the handbrake sector/quadrant modification as sadly I don't have access to a lathe but I am ever eager to upgrade my Mini Coopers lol. Would you mind explaining why you regard the original set up as inferior and how the top hat mod would improve matters? Might be a dumb question but .............' Ain't a dumb question at all.

The reason I machined a set of top-hat bushes was simply to keep the swinging handbrake quadrants/sectors .1" away from the radius arm without the need for a spacer washer. It's brass and ain't going to corrode either. And while we were machining new normal bushes for the other end it was a simple matter to do a couple of top-hats. The reason I suggested doing away with the combined quadrant and shaft was that in mechanical terms, it's a crap idea!! I can't see any reason for the mild steel quadrant shaft to rotate within the radius arm. They all rust out and jamb up - that's what mild steel does! Whereas a stainless shaft in the form of an exact diameter and length stainless bolt through brass or bronze bushes becomes the medium for holding the new quadrant/sector and allowing it to rotate. It is just another of my takes on reliability, durability and ease of maintenance.

[AndyPen]

Thanks - super article and the humour is much appreciated

[rolesyboy]

Which way round do the plastic tapered grease sleeves go inside the radius arms? I followed the same order/sequence they arrived in the plastic bags.(they are pre-assembled with thrust washers, washers, roller bearing and sleeve already over the pin- the bronze bush is the only item that is seperate) I had 4 pins which all arrived in the same order.
Assume the grease sleeves are tapered for a reason though??
Cheers

[Peter Laidler]

small ends go in facing the small/bush end and seatrs up against the bush. So that the large diameter sits up against the larger diameter bearing.

Put bush in first, insert tapered sleeve....., narrow end against bush and then the roller.

[rolesyboy]

Thanks Peter. I have done that (thank god) I would be interested to know why though?