The Dreaded 12k Service - Front-End Overhaul

[awjdthumper]

Although I picked up the new set of valve shims on Tuesday from the main Oxfordshire Triumph dealer, I've decided to overhaul the front-end today before putting the top end of the engine back together.

As usual, I've started the preparation by watching the MuddySump video first - not only are these videos superbly made by an expert at working on these bikes but they save an enormous amount of time wading through the workshop manual or the Haynes manual (in my case).

Rather belated, I've just printed out the tables of torque settings produced back in 2012 by Jonny2001 and am now in the process of laminating them. Once I've done this, I can then leave them in the workshop for future use and there's no possibility of ruining them with oily fingers.

[awjdthumper]

After I'd found a suitable 17 mm Allen key to unscrew the front axle, the front wheel came off after first unbolting the callipers. Steering head then came apart as required after first detaching the handlebars. After re-greasing the steering head bearings, everything went back together and the adjuster nut and lock nuts then tightened to the specified torques. Although MuddySump specifies 15 Nm for the adjuster nut, the Haynes manual specifies 10 Nm which is what I set it too. Having done this, I checked there was not perceptible freeplay in the steering head bearings confirm the 10 Nm was ok.

Top yoke then went on and the top nut was done up to the specified 90 Nm. However, I then noticed that the steering became noticeably heavier after the top nut was done up. I then slackened it off again and then re-tightened it in stages to see at what point the steering tightened which started to happen at about 60 Nm. It appears that tightening the top nut beyond this is starting to load the bearings making the steering heavier.

To rule out any problems lower down the stem, I dismantled it all again and repeated the process with the same result. At the moment, I'm minded to tighten the top nut to only 60 Nm to avoid this problem but I need to think about it over night

[crispey]

Originally Posted by awjdthumper

Top yoke then went on and the top nut was done up to the specified 90 Nm. However, I then noticed that the steering became noticeably heavier after the top nut was done up. I then slackened it off again and then re-tightened it in stages to see at what point the steering tightened which started to happen at about 60 Nm. It appears that tightening the top nut beyond this is starting to load the bearings making the steering heavier.

To rule out any problems lower down the stem, I dismantled it all again and repeated the process with the same result. At the moment, I'm minded to tighten the top nut to only 60 Nm to avoid this problem but I need to think about it over night

On my 2012 roadie  24,000 service Exactly the same happened to me. I’ve left it at 50nm. I’d be interested to know if there is a reason/solution

[awjdthumper]

After sleeping on the problem, I've decided that I need to take a slightly more involved approach to tightening up the steering head bearings. What I need to try to do is to be able to measure the degree of force needed to turn the steering and to make sure that this remains unchanged between torqueing up the adjuster nut to 10 Nm and then eventually tightening up the top nut to 90 Nm. To achieve this, I may well have to slacken off the adjuster nut slightly to account for the top nut being tightened. I thought this was going to be a straightforward job but there is clearly a weakness in the design that is causing this problem

[awjdthumper]

Steering head bearings now sorted

I think the problem was that the adjuster nut and lock nuts must have moved towards the bearings as the top nut was tightened to 90 Nm thus tightening up the bearings. The problem may stem from Triumph having used aluminium nuts which may not like being used multiple times and therefore have weakened threads. Using new nuts might have cured the problem.

To solve the problem, I backed off the adjuster nut so that when the top nut was tightened to 90 Nm, all free play in the steering head bearings was just eliminated. As well as producing a stiffer steering, had I not solved the problem, this could well have led to a shorter lifetime for the ball races.

[awjdthumper]

The front end overhaul came to a bit of a pause yesterday when I noticed that the fan motor was very rusty. My 2017 XCA was very well looked after and this was one of the very few areas where corrosion had set in.

So I removed the fan and motor which was a bit of a hassle having had to displace the radiator first. The motor housing itself which appears to be zinc plated but was badly rusted on both sides. I briefly thought about replacing the motor but quickly dropped that idea when I found out a new one cost ~£250. Therefore, after removing all the rust, the housing was then re-painted in gloss black before everything was re-assembled again.