At last a post on the forks for my Honda CM125C project. Oh what fun I have had!
So just to recap. Thought I would cut a corner and just change the fork oil and leave it at that. The drain plug for the left hand fork just fell out when I touched it and the threads had all been stripped long ago. I drained and refilled the right fork just to check if it was ok, and because it seemed like a good idea at the time. I ended up with one fork with nice new oil in and looking ok and the other fork with no drain plug and no oil.
Thought I would just check the seals and stuff on the right hand fork and give it a good bounce up and down at the front to make sure there was no oil passing the seals. That worked well! Ended up with very well lubricated forks as the oil fairly liberally leaked out past the seals. New seals required me thinks. Promptly ordered a new set from Wemoto which arrived the next day – fantastic service.
With reference to my trusty Haynes manual (have I said how much I love those yet) I set about dismantling the forks and replacing the seals. I supported the bike on my newly acquired centre stand (eBay again) and got the front wheel off the ground with my trolley jack, axle stands, bits of wood and a bottle jack – always like things well supported. Started with the right hand fork. As is often the case with old machines, getting some of the nuts undone was challenging. I slackened the fork top nuts before removing the forks from the bike as its a kinder way for me to clamp the top section of the fork to stop it turning. The wheel nut was, err extremely well done up!
This is a picture with one fork done and loosely back on the bike.
The bottom bolt was also very difficult to undo. I tried all manner of techniques and then propped the forks up on end and filled up the recess where the bottom bolt sits with penetrating oil and left it while I had a cup of tea. Then used the Allen key bit from my impact driver and tapped it in with a hammer so it was well seated in the bolt and applied a decent amount of leverage to it. That did it and they came undone quite easily after that.
Checked the spring free length was according to the Haynes manual and also checked the fork was straight while I had it all in bits. The straightness was surprisingly good. Springs are a few millimetres shorter than new but within the limits according to Mr Haynes. I experimented with a number of implements to remove the old seal and finally settled on a tyre lever. Worked for me anyway. The old seal was well past sell-by date. Tapped the new seal in with a suitable sized socket and reassembled the fork. Something I have never done before but Mr Haynes said to do, was to pack the area above the seal with grease. Couldn’t see any harm in it so obeyed instructions. While I had it off the bike I gave the fork a really good clean and polish before returning it to the bike. I took great care to get it aligned according to the Haynes manual.
Now the left hand fork. I repeated the dismantling process and checked spring free length etc. I then had a really good look at the fork body. The big question. Do I try to helicoil it or do I buy a replacement fork on eBay and fit all my internals to a good body? I deliberated over this for some time. Even asked the wife if I should buy a new fork who promptly pointed me in the direction of the kitchen with reference to the top draw with cutlery in. Thanks babe!
I finally decided to get a pair of old forks off eBay and go down that road to start with. The main reason for this approach was that I really wasn’t sure if the length of the hole was sufficient to take a helicoil insert and not impact on the internals. I may be ok but I wasn’t sure and decided to go for caution – bit out-of-character really. There were various options around on eBay all at about the same price and I just took a punt. They took a while to arrive. Dismantled the replacement forks and just used the body from the Ebay bits and added all my own internals and new seal. Rebuilt everything and reassembled in the bike. That all made it sound a bit quick but this was actually spread over quite a few weekends.
Its not perfect but it is all consistent with my Stage 1 approach. I have new seals and something that looks better than when I started. In the future I will probably get the forks re-chromed and polish them further but I have a working solution for now.
Picked up a few more issues along the way. The screw holding the speedo cable at the wheel end is completed rounded and I cannot remove. The wheel end of the brake cable is starting to fray. The brake cable wasn’t obvious until I took it all apart. Part of my work on the forks also included checking the brake linings and I will need to replace those as well. I had a missing bolt in the sprocket cover and was just waiting for a replacement which arrived last week. Went to put the new bolt in and it wouldn’t go in very far. Closer inspection shows a sheared off piece of bolt in the hole.
Picture below shows the front forks, cleaned and with new seals and all back together.
Next step is to focus on lots of cleaning around the swinging arm, cleaning and repainting the chain guard which will take me up to payday and the next batch of bits.