GSXR K4 Swingarm Swap

[El Gringo]

Hi All

Rather than clutter TJS and Uniques threads i thought i'd start my own thread on my attempts to fit a GSXR600 K4 swingarm to my 91 GSF400

Firstly, this is not particularly straight forward, and requires modification to the frame and the replacement swingarm. This won't work for a standard bandit - mine is being streetfightered so the back end is being chopped about.

Here's how the little Bandit sat yesterday



1. As above, the brace on the GSXR swingarm will hit the battery tray brace on the frame - i'll need to remove this and weld it back in further up.



2. The steel plates of the foot rest hangers will definitely be in the way of the wider swingarm, so these were removed - i will finish tidying up the frame before it goes to be painted







3. The measuring bit.

The Gap in the bandit for the swingarm is 220mm

The GSXR swingarm is 227mm without pivot caps - to keep it central this is 3.5mm per side to be machined off. Fortunately there is plenty of space inside to knock the main bearings further in

The GSXR has a 25mm spindle and the Bandit is 20mm - my plan is to make "Top Hat Spacers" to be pressed inside the standard GSXR bearing inners to sleeve it down to 20mm. The top hat bit is a flat area to act as a spacer each side to spread the load.

These flat areas will be 4mm thick - thus requiring a bit more to be machined of each side. 3.5mm to get it in and a further 4mm for the top hat - 7.5mm per side.

This reduction of 15mm overall means that the centre crush tube will need to be shortened.

227mm - 15mm = 212mm overall final width of swingarm.

The bearing inners are 35mm long each side, i'd rather keep these this length as they are hardened to match the needle bearings.

212mm - 70mm = 142mm for the crush tube. I started to cut the centre tube down but i need to turn some reducing bushes to be pressed into each end to make it 20mm diameter rather than 25mm to centre the tube on the spindle (i could make a new centre tube but i couldn't find any with the correct internal bore)

I will probably make the overall spacer length 143/144 to allow a little scope for adjustment/free play.



I got one side of the swingarm done, bearing knocked in 7.5mm and the outer machined down to match.



The 08 R6 Rear Shock is a couple of mm shorter than the standard Bandit shock and only needs 1-2mm turning off the top bush to make it the correct width to fit the bandit top mount. The Bottom seems to fit perfectly.

I am going to use the inner bushing from the Dog Bone spacer from the Bandit arm with a couple of extra spacers on the GSXR arm as the one i bought didn't come with one (The Bandit one i slightly too short). The lower mount for the dog bones will need spacing out to match.

I will update when i have finished the spacer tube, machined the other side of the swingarm to suit and turned the top hat spacers.

Then it's on to fitting the 750K4 USD Front End

Cheers

Chris

[El Gringo]

After a long evening in the workshop and some slow going on a very old lathe i have some spacers.

One internal spacer - 143mm long



2 x Top Hats with the standard bearing outers





2 x End reducers (25 to 20mm) for the centre spacer - one shown pressed in





How it should all fit together in the swingarm



Hopefully it will all line up to my measurements

[TJS]

Nice work!

[B4Ben]

Good work buddy,

What size rear wheel are you hoping to get in there?  180?

[El Gringo]

Hi Ben

Cheers TJS

Yep going for a GSXR600/750 K4/5 180 rear

[El Gringo]

As with all these things a little modification to the original plan is required.

My measurements were spot on and my machining relatively accurate.

Turns out the extra 1mm i left in the centre spacer for clearance on the ends to the top hats is maybe a little too much so i will take a whisker off it.

Also turns out my mates lathe runs out a way when using the boring bar, so whilst i have a perfect 20.00mm hole one end of the top hats and internal spacers it gets narrower as it goes down, each piece needs reversing and a little more taking out from the other end. No biggie though.

I was within a Gnats Knacker of getting it fitted on Sunday but alas it was not to be.

I've also hit upon another problem. I was going to use the internal spacer from the bandit arm in the linkage bearings of the GSXR arm, it is about 12mm too short but i could take up the gap with some turned spacers.

However this would then mean the dogbones are wider under the GSXR arm than the Bandit linkage. Again, no worries i'll make a couple of spacers for the bottom.

Except that means both the bolts i have for top and bottom are too short.

It Never Ends.

[El Gringo]

Success!! (Of a fashion)

After a little more fettling the swingarm is in!

Issues to be addressed now include the battery box bar definitely needing to be moved and the length of the arm might need increasing.

Will make a start on the dog bone spacers soon and i need to trim a little out of the top shock mount so the R6 shock can pivot properly

[Unique]

No' never ends!! coming long nicely

My mate has old lathe in his garage loft' used it few times, but decided to put the hub out to someone else...nice work on the spacers.

Giving any thought to the chain route yet ? any issues you foresee!.

Derek     

[El Gringo]

Hi Dek

Not yet really, i've bought a pair of wheels but they're down in Plymouth so i haven't got them yet.

I shall wait until i have the wheel in and go from there, probably just swap to 520 and use a Talon off set front.

Cheers

Chris

[nos]

Is it possible to fit gsxr 1000 06 swingarm fit into b400 frame?

[El Gringo]

Pretty much anything can be made to fit with a bit of engineering and planning

First thing would be to find out how wide the swingarm pivot point is and go from there

[nos]

thanks, soon i will open a new thread with my project :) almost got everything.

[El Gringo]

Bit more progress, scored a pair of K3 600 wheels complete with good tyres, discs and sprocket carrier, just waiting for a friend to bring them up from Plymouth.

In the mean time, i had a look at the front end last night and fitted the new bottom yoke, K4 GSXR750.

Yoke with new roller taper bearing



New top taper - All Balls Racing Fork Conversion bearing - perfect fit without the spacer washers that were supplied, it sits nice down inside the cup of the headstock.



I also noted that the original top bearing seemed to be too long, the All Balls outer race came up to the line where the paint starts on the old top race, bit odd but hey....



Inner in



Top cover seal, supplied with the conversion kit



Yoke in and bottom and adjuster nut on.



Locking tab and top lock nut on - like it was made for it!



And done



Marked up for new lock stops, the yoke fouls on the Radiator currently.



Also i notched the top shock mount and test fitted the R6 shock, got a nice angle on the bent up bit and will re weld the sides to keep the strength. I should say that how it is in the photo isn't how it ended up, the angle is much shallower.



And that's about it for now, will be able to make better progress when i have my wheels

[yoda]

Lovely front fork fit, looks like straight swap. Is that the gsxr original stem? and is that the ones with monoblock brakes?

[El Gringo]

Yep, straight swap, the only thing i had to do was swap from the standard ball bearing to a lower taper and use the conversion top taper, the stem is standard.

Been working on top yoke designs, will probably end up with it about 50mm thick but the stem hole counter bored underneath to drop it down over the lock nuts - i want to keep the top yoke as low as possible.

Yep, they're the 4 pot radial monoblocs, should pull it up reasonably well.......