Friday, December 20, 2013

Radius Arm Rebuild

If you remember from the post Radius Arm Inspection, my radius arm bearings were a bit knackered and I didn't have the tools to repair them. Well, it just happens that Mini Spares were having a 15% off sale recently, so there was no better time than the present to replace the radius arms.

I took my old arms in for an exchange, and got completely refurbished arms with pins, washers and bolts etc and crucially, the bronze bushes already reamed and ready to fit onto the subframe. Well nearly, the radius arm was black and I want them to be red... many coats of paint were applied.

Hangs quite nicely on the nut.

I used hammerite smooth to paint them and applied about 3 quite thick coats. I masked off the holes to avoid getting paint inside. Then the already assembled, brake backplates were bolted on along with the handbrake bracket. I had to go back to my photos to make sure I put everything on the correct way! If there is a right way and a wrong way, guess which way I will do it!

Backplate on.

Now for the fun bit... The Hub!
I had already inspected the hub's bearings and they looked almost new, so they were going back on as is. What is the fun bit you may ask, well it is cranking the castle nut upto 207Nm of torque (which is way too high, read on...). Luckily, I have access to a long torque wrench, but still it was mental.

I started at 100Nm, then 160, then 180 and then finally 207Nm. It is immensely difficult to turn even with a very long wrench and it also just feels too much, and it turns out it is!!


I double checked the internet for manuals again. But there is hardly any info on the rear hub torque. I tried many Google searches for 'Classic Mini rear hub torque' and the like, but nothing useful. Loads of info for the front hub, hence my error assuming the higher torque setting.

Eventually, I found a reference in the Haynes Manual that agreed with a workshop manual that agreed with a website of somebody else who has done this job. The torque setting is 81Nm!!! (or 60lbf f)

I had been looking in chapter 9 (Braking system) which only has details for the front wheel, which is where I got the 207Nm from. I found the correct setting in chapter 10 (Suspension and steering) where the same front settings are repeated, but it also has the torque settings for the rear. Finally!

So that's over 2 times the torque I have applied!! Agh! Slackened them off again and checked the bearings for damage.  Luckily they seemed okay so I re-torqued to 81Nm.

Pin in

Once the split pin was in place, a good blob of grease was hidden beneath the hub cap which was tapped home with leather mallet.

After that, I attached the old brake pipes and hoses that were previously cleaned and painted. Initially, I was going to replace the brake pipes with home made Kunifer nickle/copper replacements. But to be honest, the old ones looked perfectly usable and it is just one less job to do right now. Maybe a future project. Also the brake hoses, looked fine. I would like to get some nice new stainless braided ones, but I can't really justify the cost right now...   someday, if I make a wish!!

The last job was to put the hand brake quadrants back on. These are held in place with a clevis pin which is itself held in place with a split pit. Pretty simple. Here again I was tempted to get some new ones as they were an a right state, but I decided to clean and repair the old ones and paint them. They were a bit bashed and needed to be straightened out, but nothing major. To clean them, I left them to soak in 'Gunk' overnight and used a toothbrush. The only thing to watch out for is that the quadrants can go back on in one of two ways. I used my photos to make sure they were correct.

All ready to bolt on.

All in all, I am pretty happy with the result and am now looking forward to bolting them onto the subframe. But for now, they go into storage with all the other finished parts.

The final word of wisdom today is: Check, check and check again before you torque anything. And if you are not sure, wait and check some more.

<Next Post> - 'Rear Subframe Recon Complete!!' 
<This Post> - 'Radius Arm Rebuild'
<Previous Post> - 'New Handbrake Cable' 

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