A Winters Tale!
Page 2 – The Front Bits
Fiddling with an FZX750
Now that the back end is complete it’s time to turn my attention to dragging the front of the FZX screaming and kicking into the 21st century! This is a long one…..I’m in verbal diarrhorea mode today, so pop and get yourself a glass and a nice bottle of Cabernet Sauvignon or a beer - pull up your favourite arm chair - sit back, relax and I’ll do all the work ok?
February 2007
First off it had to be decided what front end was going to be grafted onto the bike, so before starting to rip things apart a little research was required.
I had thought of the tried and tested FZS1000 (pre-Exup) forks and clamps, but they’re getting a bit long in the tooth so any that came up for sale would probably be requiring a full re-build now due to their age, therefore I wanted something from a later model bike. R1 upside down forks were considered, which is do-able but would need the FZX steering shaft taking out and re-fitted into the R1 bottom yoke, or having the R1 steering shaft machined to take the FZX bearings. Neither of which was particularly fancied because of the cost involved.
XJR1300 forks would fit but at 43mm diameter they’re made to take the weight of a much larger bike, so they could be a bit on the hefty side for a relatively light bike such as the FZX
My criteria for the new forks was that they had to be: 1) 41mm diameter, any bigger and I think the steering would become a bit heavy and cumbersome. 2)Adjustable for both rebound and damping. 3) Preferably be Yamaha forks capable of taking the early R1 type “Blue Spot” brake callipers. 4) Use the same headstock bearings as the FZX. 6) And finally, as near to the length of the original FZX forks as possible but ideally about 1cm shorter. This would allow the steering to be quickened up a little by pushing the forks up through the yokes slightly, without having a great wodge of forks showing above the top yoke – I want no more than 1cm because any more and they could get in the way of the bars etc..
The idea of pushing the forks up through the yokes is to offset any heaviness or slowing up of the steering due to the much wider rear wheel being used. Going up from a 140 section rear tyre to a 180 is a hell of leap, so I reckoned a total drop of 2cm would keep everything nice and light & positive in the steering dept.
Narrowing it down in this way, it came down to 2 Yamaha bikes, the YZF600 Thundercat, and the TRX850, both of which use versions of the same 41mm forks, but with the TRX being 2cm shorter than the FZX and the Thundercat being exactly 1cm shorter……………… thus making the 78.5cm forks of the T/Cat the perfect length to get a 2cm drop in total, which will give me 1cm above the top yoke. At that length there will also be some room for adjustment up or down. Looks like the YZF600 Thundercat forks it is then!
Now all’s I have to do is sort out what yokes will fit.
Some fork lengths for reference. First is the FZX
Then the TRX…….
Finally – the Thundercat
I was lucky enough to have my son Ben’s TRX 850 in my garage sat alongside the FZX, so measuring the headstock up on that was easy. The headstock bearing part numbers and sizes for the TRX and the Thundercat were cross referenced with those fitted as standard to the FZX, and found to be exactly the same items. Having done that I knew that the diameters of both the TRX & T/Cat steering shaft & tube were the same as the FZX. They would therefore fit the in the FZX steering tube in the frame with no modification required .
The next question was – are the steering shafts / tubes the same length? Measuring up the TRX steering tube revealed it to be exactly the same length as the FZX, and a trip to our local Yamaha dealers armed with a tape measure (and waiting ‘til the sales guy went for a pee pee before whipping it out !) told me that the Thundercat & TDM headstock tubes were the same as well (and also that the T/Cat fork length was 78.5cm, exactly 1cm shorter than the FZX forks) ideal!
In addition to all that, measuring between the fork mounting holes in the top and bottom yokes from centre to centre showed that the TRX, Thundercat and the TDM850 were all the same distance at 20cm – ideal for mixing and matching. (the FZX’s top yoke measures 19cm between the fork clamp holes) .
First though, the old forks had to come off……….
As you can see from the photos, the wires were all marked up as the forks & lights etc were removed. A bit of time spent doing that now saves a lot of time fannying about with a multi-meter later on!
The headstock bearings which came out of the FZX were almost new with no signs of wear at all. They were tapered roller bearings as opposed to the standard ball bearings so I guess they must have been replaced by BAT Motorcycles who sold the bike to the previous owner who in turn had bought it from them. That being the case the bearing outer rings were left in the frame – pointless knocking them out unnecessarily – and the bearings from the FZX were re-used
The remainder of February was spent sourcing the parts needed to continue with the front end. E.bay turned up a TDM top and bottom yoke set, which was bid on and bought for £20. The idea of using the TDM yokes is that the top yoke is already drilled to take the bar risers, hence the reason for them being measured up previously. If a T/Cat top yoke was used I’d need to have drilled it out myself. As well as the risers being present on the top yoke, the TDM bottom yoke is a lot beefier than the T/Cat one.
Below are the TDM yokes as bought
A pair of Thundercat forks described as, “Excellent condition” also came up on E.Bay. I got them for £112, a bit expensive but the ad said they came complete with top and bottom yokes (which could be sold on to recoup some cash). The next weekend son Ben and me took a run down to Loughborough to pick them up. When we arrived there the guy had just the forks – no yokes. He’d sold them separately – so I mentioned it and he said the auction was just for the forks. I didn’t argue, I thought I’d make sure of my facts first when I got home, which I did and I was right, the auction had been for the forks and yokes together.
I intended to ring him the following day to give him some grief for ripping me off, but worse was to come! I started on a trial fitting of the forks into the TDM yokes. They passed through the bottom yoke ok, but when they came to the top one they wouldn’t go in, my heart sank, it looked like the forks were bent. I fetched them out, got them on my bench to check them with a straight edge, and there was about ¼” run out from where they’d been clamped and the top of the forks – both were the same, plus the stantions were also shown to be 20 thou oval after measuring them on a DTI. It was my own fault, I should have checked them properly before I parted with my cash.
I was bloody annoyed though because I’d asked the guy before I bid on them if they’d been taken off a crashed bike and he’d assured me that they weren’t. I rang him right away and his wife answered, she said they were not in the business of refunding the money.,,cheeky cow! After a bit of an argument and some “gentle persuasion” she eventually relented and offered me a full refund! The thing is I had to trawl all the way back down there to return the damned things. Ah well – it all adds to life rich experience I suppose.
That left me with still having to find some forks, and until I’d managed to do that, all work had stopped. I painted up a few bits while I was waiting, but still no forks anywhere. Meantime I did manage to get hold of some “Blue Spot” callipers – again from E.Bay, but these were my bargain of the year. Great nick and complete with a set of brand new brake pads……….£48 the lot. Just a set of pads for these calipers would have set me back around £35 alone.
March 2007
A week or so into March, and as luck would have it yet another pair of Thundercat forks, yokes and a front wheel complete with discs turned up on E.Bay. The guy selling them only lived in Manchester, so at least it wasn’t far for me to go and get them. These forks were off a lowish mileage bike he’d bought from an auction to break, it was a 2001 model and as a tatty as hell. The fairings were all cracked and loose, and it had never been washed since the day it was born, but it had never had any major damage other than it had been totally neglected.
I went over to Manchester to fetch them after successfully bidding on them, I got the lot for £130. The front wheel was straight, with no signs of damage, it was just filthy, the discs were ok – not scored, but they were still on the front wheel which did ring a few alarm bells! Why had he not removed them and sold them separately? These things go for good money! He told me he “couldn’t be bothered” I smelled bullshit!
The forks although really tatty were dead straight and other than the muck, in fine fettle. At last I now had something to work with.
Above: the front wheel as bought and cleaned up a bit…….No cleaned up a LOT
Before painting the forks, the tops were taken off and the old oil drained out. I was expecting something like thick black treacle to appear, but what I got was clean fresh oil! Although the bike was tatty, someone had loved it enough to keep it properly serviced by looks of it.
Below are the painted forks.
The photo above shows the Thundercat forks and bottom yoke as bought (still with original ball type headstock bearings) if you compare that to the now painted and fitted TDM yoke in the shot below you’ll see how much more substantial TDM item is with the 2 bolts per side clamp.
As I mentioned earlier, the FZX headstock bearings were almost new, so they were re-used on the TDM steering shaft. Before fitting the TDM yokes into the FZX frame, the steering stop had to be removed from the bottom yoke with a hacksaw because it didn’t match up with the FZX frame, causing very little turn to the left– and too much to the right!
Using the TDM top yoke wasn’t completely without problems either, the ignition switch from the FZX (which I wanted to retain) is set at an angle in it’s original FZX top yoke. If it was bolted straight into the TDM yoke it would foul on the frame where the steering lock plate is located. To overcome this, the steering lock had to be done away with and the switch mounting ring filed out so that the ignition switch sat at the right angle. The photos below show how this was done.
The shot above shows where the ignition switch mounting ring was filed out. To get the switch to sit at the right angle, the hole was filed underneath at the front and on top at the back.
Two small 1/8th stainless steel brackets were made up as shown above, the switch now sits at the correct angle and height. Because of the vibrations the headstock experiences in use, all 4 bolts / nuts were loctited in, because when everything is fitted they’ll be almost impossible to get at.
As shown above, the switch now sits at the perfect angle. Here the top yoke is painted and forks have also been fitted as things start to take shape. The forks are shown pulled up through the forks too much, the final setting was approx 1 cm above the top yoke – just right!
Now it’s time to sort out the front wheel, first thing to do was take it down to the local wheeler dealer to have the tyre taken off. When I got it home I started to remove the discs so the wheel could be painted. One disc came off ok – so far so good! The one on the other side however was a complete and utter pig. Someone had attempted to get it off without heating it up, the bolts are Loctited in from new and if they’re not heated they’ll never come out. All they’d succeeded in doing was rounding off the insides of 4 of the 6 cap head bolts holding he disc on, so there was no chance of doing it with an Allen key. I managed to get one to move a little with some pipe grips but as it wound out the thread started to “pick up” so I left it alone.
The only thing left to do was to drill off the heads of the bolts then re-drill and tap out the holes. I’ve had to do this on several occasions before so I knew it could be done. I knew the discs had been left on the wheel for a reason. Just goes to prove my bullshit detector is in full working order, the guy I bought the wheel must have tried to get the discs off to sell separately – and failed miserably!
Above is shown the disc bolts with the heads almost drilled out, this makes the metal around them thin and weak so all I have to do now is give them a belt with a chisel and they should come away. The 2 holes at the top of the shot are where the undamaged bolts came out ok after heating them up. These will be used to fasten the disc back onto the wheel, it will then act as a template while I re-drill the other holes. I’m lucky enough to have a big hefty pillar drill, so don’t try doing this with a hand held drill or a little “Hobby” pillar drill because all you’ll do is knacker the wheel. If it gets to this stage you’re probably best off taking it down to a local engineers shop and have them do it.
Below is the wheel after the disc has been removed and the holes re-tapped. Now the wheel can be de-greased and painted. Oddly enough the bearings looked like they’d been recently replaced, so they were left alone……Another few bob saved!
Above, the disc after removal – showing all the battle scars
And, below after they’ve been re-painted
The front wheel was then treated to a coat of paint, this shot below was taken just after it was sprayed so it’s still shiny. When it dries it will turn into a satin finish
Below: trying the front wheel for size. Here it’s temporarily fitted to into the forks
The next job was making up some brackets so that the FZX Front mudguard would fit onto the T/Cat forks. The brackets were made up using some thin stainless steel sheet I had knocking about the garage. It looks like the FZX mudguard was made for those forks. Note the blue spot callipers, they look superb and work even better! Also not the new front tyre, it’s a Metzeller Roadtec Z6 to match the one that came fitted to the rear wheel.
I was bit worried about having it fitted because the paint on the wheel was still quite soft. I’ve been using a place in Leigh (Greater Manchester)for years, called SMD Tyres who specialise in bike rubber. They’re brilliant people to deal with. They take really good care of your wheels and they’ve never put so much as a tiny mark on any of my wheels in the years I’ve been using them. If you live in the Manchester area they’re well worth considering when it comes to tyre renewal time. You can find them here
