Refitting the swinging arm, rear shock and centre stand

The swingarm had suffered from scuffing towards the left-hand end. It also had pitting from corrosion in areas where water and salt had crept under the chain guard and gator which connects to the rear mudguard. I treated those areas with special metals primer, topped off with silver Smoothrite. When the mudguard and gator are replaced, they'll be hidden anyway - it's good for me to know they'll be protected from similar problems in the future. 

The main  suspension components for the swingarm include hollow spindles for two drop links that connect to the drag link. The spindles have grease nipples in their outer ends - these appear to have been used as intended.  The spindles fit through three short sleeves in the swingarm casting. These had suffered a bit. The drop links have needle roller bearings at each end and are both protected from the elements with decent seal arrangements.  The top bearings benefit from large steel and rubber seals, the lower bearings are looked after  by pressed-in rubber seals. All were in good condition. 

Drop links - Meriden-style
logo on these early castings

Needle roller bearing was in
great condition, visible here after
cleaning out the old grease with parafin

 I reassembled the drop links with new sleeves and a combination of Castrol LM for the needle rollers and Rock Oil rubber grease for the seals. Torquing up the spindles is a bit tricky - the trick is to use a socket for a 12mm spark plug because these are 18mm across the flats.

The chain has to be looped over the left-hand leg of the swinging arm first. The swingarm slides in between the frame outriggers and steel castings. The castings should be left loose at this stage - a bit of movement is helpful to get the swingarm positioned properly. The swingarm spindle is inserted from the left because it makes it easier for dealing with the chain. Stop when the spindle gets to the first steel casting. An alloy spacer must then be inserted between the steel castings. 

Alloy spacer in place between the two steel
castings. The return springs for the centre
stand are visible, hooked on to small
protrusions on the castings. 

 The rear shock is best mounted after the alloy spacer - there is very little room for manoeuvre when the shock is in place. I supported the rear of the swingarm with bungees looped over the frame. This helped maximised the room I had for wiggling the shock into position, and then to line up the shock's lower eye with the bottoms of the drop links for inserting the drag link spindle.   I put lots of grease on the edges of the drag link that would but up against the drop links and shock. There was a fair amount of corrosion on the drag link there, especially to the left of the shock mounting point. I'd seen this on all three of the drag links I'd looked at previously so it's well worth the trouble of slapping on the LM at this stage.

Inserting the drag link spindle from the right-hand side
through the right-hand drop link, shock lower eye
and then manoeuvring the left-hand drop link into place.

The large hex bolt with grease nipple about
to be wound in to the left-hand end of the drag link spindle. 

I decided to polish up the eccentric adjusters for the rear wheel. They were scarred by heavy-handed attempts to refit the rear wheel in the past. I got most of them out with wet and dry abrasive paper on thick pane of glass. Then I polished them with drill and mops. 

 The centre stand fits to the lowest holes in the steel castings. I found it easiest to attach the return springs by looping a 12mm ring spanner over the lower ends - it meant I could get a good grip to pull them over the prongs on the stand.

All sorted, ready for the rear wheel.

Rear suspension linkage

I've been working on the rear suspension linkages and swingarm. The swingarm operates on the rear shock via 'drop links' to an aluminium casting called a drag link. The drop links and shock are mounted on a hollow steel tube with large hex bolts at either end. I scraped out the (22year old!) grease from this tube with a big screw driver and then flushed it through with parafin.

Once all spick and span, I forced fresh Castrol LM up the tube by pressing it down over the plastic disc that Castrol put in the middle of their grease tubs. Then I refitted the large bolts and gave them a few pumps on my grease gun to finish the job.

I'd previously painted the drag link and was ready to fit it with new needle-roller bearings and seals. I warmed up the casting with a hot air gun to expand it. It was then pretty easy to force the new bearings in with two sockets wound against one another on a threaded rod. Lashings of LM no doubt helped. 

The rear shock's lower mounting had been stripped of its paint by road spray. The shock's spring and damper tube were pretty good.  

The rear shock has a bush pressed into its lower mounting. I couldn't tell what it was made of  but it was in very good condition. There are two rubber O-rings either side of the bush and they'd clearly done their job beautifully. The contrast with the other components was striking to me anyway.  Some drill-and-wire-brush action, primer and Smoothrite treatment later, the whole thing was spick and span once more.

The drag link is bolted to two large steel castings (or forgings - not sure which) that are in turn attached to the frame with the swing arm spindle and two M12 bolts. The castings are listed as 'linkage carriers' in the Triumph parts catalogue. They each have five holes from top to bottom:

• Top hole for the upper engine mounting bolt
• second hole for the swing arm spindle
• Third hole for lower engine mounting bolt
• Fourth hold for the forward drag link pivot bolt
• Fifth hole for the centre stand pivot boss and bolt

These linkage carrier castings had looked pretty nasty at the lower ends to me but cleaned and painted up beautifully - no pitting at all.

So the castings mount the back of the engine to the frame with four M12 bolts. The upper two M12 bolts pass through lugs in the engine's top crank case and a small aluminium spacer before going through the top hole in the steel castings.The lower engine mounting bolts also pass through outriggers of the main frame.

The right-hand lower bolt is similar but longer and fits into a steel sleeve in the frame.

The lower left-hand bolt is trickier all together because it passes through a steel sleeve and an additional aluminium casting for the side stand.However:

• I couldn't fit the side stand yet because it would have made it impossible to refit the sprocket cover.
• I couldn't fit the sprocket cover yet because it would mean I couldn't tighten the drive sprocket.
• I couldn't tighten the drive sprocket because I needed to be able to stop it from turning by hold it still with the rear brake (and engine compression). 

The solution was to do it a bit at a time ...


So I loosely fitted the right hand bolt temporarily to make sure everything would line up properly, knowing I'd have to remove it again later to fit the side stand.

 With the steel castings loosely in place, it was fairly easy to wiggle the drag link's mounting bolt into position. I found it easiest to do this by working from right to left. The factory manual shows it that way around too (bolt head on the left, nut on the right).

It's all starting to look great now, in my humble opinion. Tidy, clean and that bit closer to getting back on the road again. Next... reassembling the swinging arm and installing it in the frame with rear shock.

Welding captive nuts and filling holes on the frame

The rear subframe had a few holes drilled in it for unknown reasons (but probably alarm related) by previous owners. I decided I disliked them sufficiently that I should try filling them with weld. 

There was a large diameter (c. 13mm) hole in a cross-brace with the VIN plate and a small hole next to it, probably for a self-tapping screw. I scraped off the sticker then ground the rust from the hole perimeter with a mini grinder. 

 Next came the MIG work. It went pretty well, carefully adding bead to bead with enough time to cool between each burst to stop the whole thing from dropping through. It only needed a few seconds between each bead for this. Finally, a flap wheel on an angle grinder restored the level of the material. There are a couple of little imperfections in the surface but rather than risk sorting them with more weld, I decided they'd fill with primer easily enough. 

The other welding I needed to do was to restore six captive nuts that had split away from the frame. Three were M8s for the exhaust mounting brackets, two M8s for the grab rail and rear fairing panels, one was an M8 for the left-hand rear indicator bracket, and one M6 for the right-hand rear fairing panel. The mini-grinder came out again to get enough shiny metal for me to weld to. This was very tricky as it turned out because of restricted access to all but the M6. In each case, I wound a bolt tight into the nut to ensure there was good electrical contact, then welded some wire into the frame near it, running up to the nut itself.

A captive nut - that's captive again!

Rear subframe after all welding
and grinding was complete.

Finally, I used a wire brush on a drill to bring all the rust off where it had developed. In most cases, these places were on factory frame welds, in the others it was nicks and scratches. I finished up with zinc primer, pending rubbing back on main spar sections and a coat of black.

Rear subframe after derusting and priming