Hello there.
Put the 400/4 back on the road after winter sleep about a month ago and after dealing with the yearly petrol leaks from the carbs by sternly ignoring them (yes, I drain the fuel when I put it to bed, and it's got a nice set of nurse Julies viton o rings, and I carefully cleaned the float needles and pivots and set the float heights....). After a ride the petrol had cleared and the bike was feeling very nice apart from the very harsh front forks and the dreadfully wooden and squealing front brake. Just for info the bike was entirely overhauled by me 3 years ago. So I had a good look through the stuff on this very useful forum and did the following:
Front forks- changed the oil for 150cc each side of 5W fork oil (was ATF at first fill) that i happened to have around. The result hasn't transformed it to magic carpet status but it's a lot better than it was, the previous post on the forum recommended 7.5W so that may well be better still. For the expense and time taken it was a very worthwhile bit of tinkering.
Front brake- I've tried two previous sets of organic pads from different suppliers and the rest of the front brake set up is new. For both the previous pads squealing starts after about 50 miles and gets more pronounced as time goes on. Cleaning the disc does help for a while. The real problem is the very wooden feel at the lever and the high lever pressures needed to get any realistic retardation. For info I'm used to riding a number of different bikes including pre war machines and I used to have a 400/4 back in the day which was ridden very frequently with a pillion and, apart from the wet, I don't think it was ever this bad. Anyhow, I got hold of a set of SBS 501HF ceramic brake pads from flea bay (Trumpet Tyres) and fitted them. The result after 80 miles is no squeals yet and a rather better retardation. I had a think about the hand lever compared to the span of my fingers, removed the lever and reprofiled the radius where the lever presses on the master cylinder piston, opening the clearance to around 1.5 mm, giving a free play on the lever tip of perhaps 8 to 10mm, rather similar to the clutch when fully warm. This brings the lever a bit closer to the handgrip on first bite and means that I can use more grip more easily. This has improved matters a bit further. Although the woodeness persists it is better and I'm certainly getting better retardation now, much more tolerable. Pads were about £30 including postage so it wasn't the most expensive fix, although it's my third set in 1500 miles! I should also say I haven't tried it in the wet, so be warned. I'll let you know if the squeals stay away.
So thank you to the original contributors on both these issues and I hope that it's useful to get some feedback.
Regards,
Arthur.
