Another FJ12 Front & Rear Modification

[FJools]

The time has come. Most of the parts have arrived which means I can embark on the front and rear end updates.
Countless hours reading previous threads on this forum and the details & links from UK FJ Owners site have been very informative and should provide the basic reference for this project. I would like to thank both Barry Edwards and Marc Rittner for the inspirational descriptions of how to carry out the Thunderace rear end mods from www.fjmods.co.uk. Priceless!

The Basic idea was to use as many parts as possible off the shelf in my lock up. Yes, I'm a bit of a hoarder, aren't we all ? This thread may appear long winded but it is how I approach these things so apologies in advance if I cure any insomniacs  

First to seek attention was the Front end. The existing forks were tired and leaking and need a good service. Being Racetech equipped 41mm types they will go onto the shelf for refurb & use on my CMR framed Period 5 race bike build later in 2015.

To replace them I have a complete front end set up from a 1999 R6 including wheel, triples and brakes. I've already stripped the forks for inspection and servicing. They are a cartridge style RWU type 43mm and overall length is very close to the OEM forks.
Checking the spring rate with a rudimentary measuring device – a set of kitchen scales and a scaled drill press, zeroing the scales and measuring the weight after 10mm of quill movement came out at approx. 3kg which is 0.3kg/mm.
That figure sounds a bit low so I ordered some RaceTech 0.85kg which should be in the ball park. I'll test those when they get here by the above method to see if there is a fudge factor I can apply in future LOL. (they worked out to be 0.4kg/mm by this method.....)


Stripping the R6 forks it was evident that the dust seals and oil seals were shot and the retaining clips disintegrated with rust trying to get them out.  A new pair were ordered then I found a pair in my draw of TZ parts.

Motorex 10W fork oil will be used in the assembly and an OEM R6 Dust/Oil seal kit came from a local Yam dealer at $29, which I thought was pretty good. I googled their shop to see if they had FJ sets but nothing doing.
I did have to make up a square ended tool to hold the cartridge so I could get the bottom allen bolts out. This was cobbled together from a few bits of square section bar from the scrap bin with one end ground to a bit of a taper that could be wellied into the square hole on the top of the damper assy, with the aid of a torch. It had to be hollow to allow for the rebound adjuster rod.


The springs arrived between xmas & New Year.  The Fork reassembly was quite straight forward. The downloaded genuine R6 manual was very comprehensive and the only difficulty as such was getting the new seals in. The mating surface for the seal in the fork slider had been cleaned up with a small dremel abrasive wheel which removed the oxidation and the clip groove was cleaned out with a dremel mini wire wheel.

A silicone spray was applied to the area to ease the seals progress – too much as it turned out as my usual method didn't work and after several curses I bit the bullet and ebayed for a cheap seal driver kit. This took 4 days to arrive - good service for  this time of the year.

Once assembled and filled with oil as per Mr Yamaha's instructions, the forks were put aside while the main event began............

[FJools]

Part 2

Juggling bikes around I got the FJ onto the Hydraulic bench which, not used to such heavy beasts, struggled to raise the bike up to working level. With the bike on the centre stand, the front wheel was chocked up and the rear end ratchet tied down to allow front end removal.

Following the Clymer manual the first job was to remove the top fairing which was again straight forward if time consuming, and several bits of plastic dropped away as parts were removed. That will be good practice for the plastic welding kit I bought !

Getting to the fairing inner panels I felt it would be easier if the tank was out of the way (plus it was also time to find out what air filters were fitted !) (Original paper type BTW) This meant the seat and side panels needed to come off too. Easing the panels carefully the LH one was intact but the RH one had the  flat locating piece at the bottom missing – more welding but this will need some donor plastic from somewhere.
The tank should have come off easy except the pipe on the fuel filter was playing up. Eventually after much swearing and yanking with WD40 applied it shot off forcing my thumb along the under side of one of the side panel mount flanges which inflicted and amazing Harry Potter like rip across the length of the thumb.
After stopping for some first aid and some more cool drinks ( I sweat like a male menopausal maniac working in the garage at this time of the year) The fairing was finally off and I sat back and admired what could be described as an ugly duckling with its clothes off !

Next job was to remove the front brakes as a complete unit complete. I may re use the original master cylinder which is 5/8" as it matches the clutch master cylinder. The R6 style has a remote round reservoir and is 14mm. I can't see there being too many problems here. Braided lines arrived from Goodridge and as these are twin direct lines the original splitter will be surplus. I noticed that the original horn had been replaced at some stage in its history with a Fiamm type which sounded like a dog farting so I might look at replacing this too.

Next to come off was the two piece front guard and brace, followed by the front wheel. The bars were then pulled off followed by the top yoke (after disconnecting the ignition switch wiring). Removing all the switch gear I found the reason for the Run switch not doing anything – the wires had been cut off and twisted together in the switch so I'll investigate & hopefully fix this later.

Once the top yoke was off I was able to drop out the old forks then the triple clamp.

Offering up the R6 triple clamp I encountered my first problem: The FJ1200 stem is around 25mm longer than the R6 stem. I pondered this for a while and also noticed that the top bearing was also a smaller diameter on the FJ. The R6 triple has an alloy stem & clamp, the FJ's are steel and I wasn't sure that there would not be problems in swapping them over but after some consultation I was assured it should be ok. Both stems appeared to be held in position by a circlip at the bottom below the lower clamp and more importantly were the same diameter.



I'm fortunate to have a few boys toys in the garage and the hydraulic press was put into good use by first pressing the R6 stem down, which allowed the circlip to be removed, then turning it over and pressing the stem out through the clamp.

The FJ lower triple stem was similarly attended to  except this pressed out in the opposite direction as the stem has a step in it to stop it pulling through. The FJ stem was then pressed into the lower alloy R6 triple clamp and the lower taper bearing installed.

The completed unit was fitted to the FJ and the castle nuts nipped up to hold it in place while the refurbished R6 forks were slid in.

Job done or so I believed. Tightening the castle nuts showed that the steel stem was rotating in the alloy clamp. This was rectified by drilling the clamp through the stem and fitting an M6 bolt to lock them together. I managed to do this in situ.
This was only the beginning of my problems though. Fitting the R6 top clamp required a top hat bush to increase the diameter of the stem where it passed through the top clamp. I first tried machining out the original FJ top clamp to 43mm with a boring bar.

This proved a waste of time and I should have checked first as the fork offset and spacing is slightly different so I was unable to use the FJ top clamp.
Resorting to plan A I machined up a top hat bush and assembled the top yoke before realising that using the FJ ignition switch was going to create more headaches !


I therefore moved on to finish off the easier parts before returning to the top clamp with a fresh mind.



Some aftermarket bars of Chinese origin were fitted to see how they look. I have used these cheap bars on my race bikes with no issues even crash testing has proven them to be pretty tough. They have a problem though as there is no pull back on them and the hydraulic lines are too close to the clocks for my liking. I also suspect there may be interference with the fitted faring, ho hum !

[FJools]

Part 3

Front Wheel

Offering up the polished R6 wheel (not sure if I should keep this and polish the rear to match....)

the axle slid in nice and easily. As I was planning on fitting a GPS speedo I didn't have to worry about the speedo drive and set about centreing the wheel using the discs and inner face of the fork leg as reference. This worked out that I needed 19mm spacers each side with a 22mm hole for the axle, 29mm O/D to fit snugly into the seals.

These took about 30 mins to spin up in alloy on the lathe and I soon had the wheel in and bolted up. Next was the aftermarket R6 front guard that came from Hong Kong. I thought it would be GRP but it turned out to be ABS and needs a bit of finishing and painting later. I also need some collars and grommets to install it properly.

The Blue Spot Calipers were in a reasonable condition, but I thought I would give them a quick clean up. They are supposedly unserviceable but the special tool and seals are available from the UK:
http://www.bikerstoolbox.co.uk/acatalog/Brake_Service_Tools.html
While I wait for these to arrive I continued with a basic service. Removing the pads and brake line and installing a dummy brake line which comprises and old brake line with one end cut off.

I then stick a bastard file in the vice, gripped at the end. I find the calipers without pads sit nicely on the file and prevent the pistons extending too far. Then I hook up the compressor to the dummy brake line and ease the pistons out. Cleaning them and spraying silicone on them before pushing them carefully back in to the body. I usually repeat this about half a dozen times and by the end they are not moving to sluggishly.  Then it's a case of cleaning up, fitting new pads and fitting to the bike.

I also remove the dummy brake line and bleed nipple and spray brake cleaner into the caliper body, giving it a good shake and blowing it out with the airline to get the bulk of the crap out.

Here is the front all (nearly ) assembled

[FJools]

Page 4

Back to the top clamp.......
The biggest issue I now faced was with the ignition lock. The mounting centres are different between the FJ and R6 by about half a hole. The R6 is fixed by M8 screws, the FJ by M6. The location of the lock on the R6 is offset to the left and it has a smaller diameter lock body.
This required the FJ lock I was keeping (The R6 lock is totally different wiring wise !) to be mounted on 10mm stand offs, with the lock mount holes drilled out to M8 and slotted. There was no going back from this...........


The photo actually shows 20mm stand offs but these would not allow the top clamp to fully seat. By changing them to 10mm I had to machine the brace between the two ignition mounting pillars on the under side of the top clamp to allow the wider diameter of the ignition barrel to fit.

Thankfully after many hours adjusting, readjusting I got the damn thing fitted and what's more, as a bonus the lock still engages into the headstock.
While messing around with all this I notice yet another problem – the steering lock limits didn't meet – aaaghh, why did I bother.........but this was simply fixed by drilling the ears on the alloy bottom yoke , tapping and fitting M5 cap heads that protruded on the inside to make contact with the segment on the headstock. Sorted.
Next will be the rear end, after a bit of a break to regain mental and physical stamina that is.

I checked the kill switch and found the switch itself to be intermittent. It was carefully pulled apart, cleaned, tested and the wires soldered back and reassembled. One more job done.  The clocks were also removed ready to carry out the GPS speedo mod as it arrived yesterday.

[FJools]

Page 5

Swing Arm

Its funny – this is the job I had most information about, but the one I was also most nervous about.
I began by removing the sprocket cover and clutch slave cylinder. Then the rear wheel, swing arm and linkages were removed. This also meant removing the silencers, which meant that removing the footrest mtg plates would help. While I was in the mood the exhaust down pipes & collector box was removed. The amount of cack and grease underneath and around the linkages and sprocket area was a bit unexpected and took me the best part of two hours to clean up.
The original intention was to use as much of the Thunderace hardware as possible. After carefully measuring up of linkages and swing arm mounting points, suspension lengths etc this was looking to be a non starter. To many variables to be completely confident.
So, with Thunderace swing arm in hand, and pivot width measured I started to convert Marc Rittners specs into mm as I've been metrified since I left the UK many years ago!
When I opened the swing arm thrust bearings I ordered, there was only one set and checking up on the order I had goofed up and not doubled up on the quantity ( F*ckwit !) So I decided that for a road bike they would be fine with just the flat thrust washers off the FJ swinger. I had ordered a pair of new end caps though to make up for it.
Now for the machining – first up the bearings need to be pressed further into the pivot. These sat 0.7mm below the end of the swingarm and from Marcs' modified specs I had to add this to the 3.55mm needed to be taken off each end which works out around 4.25mm.  Re measuring I opted to use Barrys' 4mm removal to do a first check which would give some leeway.
A press tool was machined up with a 4mm step which would allow the bearing to be pressed in to the correct depth without having to worry about going to far as the bearings do not move freely in the press.
After this the swing arm was set up carefully on the mill to remove the 4mm from each side. A taper plug was turned up to block any swarf getting into the swinger bearings.

This was the scary part and each side took a good 20 mins to set up for the cut.  Once machined the ends were deburred and new end caps and thrust washers fitted. Offering the swinger up to the frame it went in perfectly so I'm glad I didn't go the full 4.25mm after all.
I then went and had a cuppa as a reward for a job well done.

Of course, I had to remove the swinger to grease everything up, fit the chain protector and almost forgot the endless chain, which looked quite new, after a clean up with kerosene. A trial fit of the Thunderace shock reiterated that this was not going to work – all the lnkage widths were off, mounting hole diameters different etc.


The FJ linkages were cleaned up and inspected but the frame mount needle roller bearings were shot. After doing a search I ordered some of the HK1816 type mentioned on another thread on this forum. Until these arrive I'm sort of in wait mode. I can however fit the rear wheel which will require machining of the sprocket carrier for chain alignment.

[Pat Conlon]

Very cool write up Jools, question: What did you do for clearance on the shock spring?
Both my T-Ace swing arms needed a fly cut to clear the Penske Srings, as was mentioned in Marc's write up.

[The General]

Hey Jools. Fantastic project write up. If we ever have a manshed day in Sydney, I bags leaving my FJ at your place for some weeks prior! 

[FJools]

Very cool write up Jools, question: What did you do for clearance on the shock spring?
Both my T-Ace swing arms needed a fly cut to clear the Penske Srings, as was mentioned in Marc's write up.

Cheers Pat.

I'm still using the stock shock and according to Marc Rittners write up, no mods are necessary. I'll let you know if this is the case.
Sooner or later I will have to replace the rear shock so I will probably relieve the swing arm as you mention while I'm working on it.

[FJools]

Hey Jools. Fantastic project write up. If we ever have a manshed day in Sydney, I bags leaving my FJ at your place for some weeks prior! 

LOL, that means you need some work done I'm guessing...............

[roverfj1200]

Great write up


Thanks

[X-Ray]

Man, don't apologise for any "long winded" write ups. WE LOVE 'EM!! Especially with lots of pics.

Some great work going on, would be really satisfying being able to sort out issues on the fly, 

[Flynt]

according to Marc Rittners write up, no mods are necessary...

I have Marc's old T-Ace arm and it is clearanced a bit for the Ohlins that came with it...  he must have done that mod after the initial write up.  You may want to prep for the inevitable upgrade (as you suggest) as the stock shock is pretty much rubbish.  I don't have a pic, but maybe Pat does?

Frank

[Pat Conlon]

No, I have no pictures of the "fly cut" other what is shown in Marc's write up, on the Barry Edward's site.
___________________________________________________________________________________________________________________________________
From Barry's site:
RELIEVE CROSS BRACE – If you plan on using a stock shock, it is not necessary to remove any material from the swingarm crossbrace.  But if you intend to use an aftermarket shock (Ohlins, Penske, etc) where the spring may be a larger diameter and extends further down the shock, you will need to machine a relief in the swingarm crossbrace.  If a relief is not provided, the swingarm will hit the shock spring and will not lower down enough to have proper geometry or ride height.

Pictures do a better job of showing the problem and explaining the solution than I can.  I will provide a simplified explanation of what we did.  
First, we flipped the swingarm upside down and clamped it to the mill table, with the axle end clamped up on blocks.  Total parts angle is 20 degrees.  Cutting head is vertical.
Second, we used an adjustable flycutter set to 3.30" diameter to cut a relief in the crossbrace, extending down 1.125" from the 'top' edge of the crossbrace.  We removed as much material as we dared without breaking through the tubing wall.

Note:  1991-1993 shock links have an 'offset' mount for the shock clevis.  Cut the relief slightly off centerline (1.550" from left dogbone attachment point).  It is best to remove most of the swingarm gusseting material to provide clearance around the shock spring.

It may also be necessary to remove some swingarm gusseting material to provide clearance around the shock spring.






___________________________________________________________________________________________________________________________________

I have the TAce arm on both my '84 and on my '92 and I can tell you that there is a difference on where the cut is made, due to the different location of the Penskes. The shock on my '84 is centered and the shock on my '92 is offset 1.5" to the left (clearance for abs pump) so the cut location is different.

Jools, I agree with Frank, you *will* want to ditch that oem shock, sooner rather later, so I would plan on doing the necessary clearance work now....

[FJools]

I was originally hoping to fit the Thunderace shock as it would probably be an improvement over the stock. The bike it came off was low km's.

Maybe I'll start looking - you guys are going to bust my budget !! But as you say it will be worth it and a bit silly not to tackle it now.

Jools

[jscgdunn]

I have tool and talent envy!  

Looks good...

regards,
Jeff