'73 Suzuki GT250 - Part 11 - GT550 front fork swap - 1/2 - Rebuilding front shock absorbers

Some of you might remember me purchasing a set of Suzuki GT550 front forks quite a long time ago. At the time I wasn't sure what to do with them until I got my GT250K project going. First I was thinking of rebuilding GT250 forks for this project but the set I have was in worse condition than these ones. Good thing about these are that they are more rigid than GT250 front forks. Main difference is that stanchions have 35 mm diameter compared to 32 mm ones in GT250. Otherwise main dimensions like spindle diameter and steering bearings are the same so it's easy to swap them. I will feature triple trees and mock up more detailed on next part. This part will cover rebuild process of front shocks.

Suzuki GT550
front forks

Below is a picture of steps how to assembly Suzuki GT250 & GT550 front shocks (left to right). Same process applies also for disassembly but from right to left. I disassembled my forks long time ago I didn't unfortunately take pictures of that process.

Steps of assembling GT550 front shock absorbers

Upper parts of old stanchions were very pitted and rusty most likely due to moisture accumulating inside headlight brackets. Since I wasn't going to use original headlight brackets and wanted to leave them exposed I went ahead and bought myself a new pair of stanchions from eBay instead trying to do anything with the old ones. I cleaned sliders and circlips, which attach to bottom of the stanchions, and installed them to the new ones.

New stanchions for Suzuki GT550 front forks

Unboxed

Comparison of new and old stanchion

Sliders and circlips in order

I decided to shave off ears from outer tubes which the stock front fender attaches to since I didn't have any use off them anymore. I started by cleaning outer surfaces of them with soda blasting gun. After that I removed most of material with a saw and an angle grinder. Since there were still a lot of excess material to be removed I used a file next. I tried to be careful and not remove too much or making too deep scratches while filing so I marked a spot with a red marker pen to indicate when to stop and move on to sanding. I used normal sand paper for rough and wet sand paper for finer sanding. Last step was to polish them with buffing wheel and polishing paste. I purchased new hardware for inner tubes and axle holders and screwed them back on.

Outer surface of outer tubes cleaned with soda blasting

Ear sawed off

I marked an area which I wanted to file flat
with a red marker pen

After rough sanding...

...and finer wet sanding

Buffing wheels and Autosol polishing paste

Outer tubes and axle holders after polishing

New M8x27 hexagon socket head screws
with low head (#51147-48130) and copper washers

Rebuilding outer tubes

Non-serrated M8 flanged nyloc nuts DIN 6926 for axle holders

After getting stanchions and outer tubes back together it was time to mate them together. I started by sliding the rebuild stanchion inside the outer tube. Before installing a new oil seal I made sure that the upper slider was inside the outer tube. Otherwise it would have been a nightmare to get the oil seal out to get it back inside. For this project I chose fork seals made by Pyramid Parts (#FOS 013) just like I did with my CBR600F. After knocking oil seal in place I put on a washer on top of it and installed circlip with circlip pliers.

Pyramid Parts fork oil seals #FOS 013

Box comes with a pair of 35x48x11 mm oil seals,
seal buddy tool, lubricate and a sticker

Slider, oil seal, washer and circlip

...and order how to put them back together

Circlip installed with circlip pliers 

Last step was to install new fork dust seals, slide in springs, add fork oil and screw on caps to top of stanchions. Since these forks originally had boots instead of dust seals I wasn't sure if I was able to find a suitable pair for them. I ended up ordering a set of Pyramid Parts fork dust seals (#DB10) which seemed to work decently well with them. I got myself a one liter bottle of 15W Motul fork oil and measured 2.35 deciliters for each shock. Caps were little bit pitted as well so I took a small piece of aluminum foil and brushed rusty spots with it under a running water. That's an easy trick to get rid off small rusty spots from old steel parts which are chrome plated. Off course it's not a permanent fix but a lot cheaper than new parts or chrome plating. I replaced old O-rings with new ones (#51181-31030) before screwing them back on.

Outer tube dimensions

Pyramid Parts fork dust seals #DB10

Springs, caps and set of dust seals

Fork inner tube caps and O-rings (#51181-31030)

Motul SAE 15W Expert Medium Heavy fork oil (#101138)

Measured roughly 2.35 decilitres of fork oil
for each shock

Rebuild Suzuki GT550 front shocks

Check out also part 2 where I complete this swap after refurbishing top and bottom yokes and fitting it to my GT250K 😎

'91 Honda CBR600F PC25 - Part 2 - Service for front shock absorbers

Here's a short story about how I rebuild my CBR600F front shock absorbers. Other side of them was leaking quite a lot so I decided to rebuild them with Pyramid Parts Front Suspension Overhaul Kit made for Honda CBR600 F2 F3 1991-1998 (IB11 & OB22). You can find part diagrams for '91 CBR600F for example from CMS. Here's part diagram for front fork which helped me for this small project. First step of it was to lift up the front end of the bike and to get the front shocks out.

Hoisting up front end of my bike
with Chain Block & Tackle

I tide a cargo/load strap around front end frame beams and secured it with a knot which I then attached to the chain block and tackle. Piece of wooden block helped keeping the strap away from cables running aside frame beams.

Closer look of cargo strap tide around
upper frame beams

Front brake calipers had be removed
to get front wheel out

Front fender is secured with two bolts on each side of the fork
and other one also holds brake line hose

Both of those bolts can be loosened with front wheel still in place.

After getting the front wheel off I was able to remove forks out of yokes. I started by removing securing circlips (5) from top of each fork and removing clip-ons. Each fork is secured to top and bottom yoke with two bolts (21) and (11). After getting them out forks just slide out.

Front forks are off!

First step of rebuilding them was to drain out
the old fork oil. Oil drain screw is
located below brake caliper mounts.

I used a small screw driver to remove
old dust seals...

...and circlips which secure oil seal below it.

Then I secured front shock absorber to a vise...

...and used an impact driver to get the lower tube bolt out.

After removing circlip and lower bolt tube can be separated
from stanchion just by pulling them apart.

Condition of old slide and guide bushes.

I disassembled the rest of the forks after removing the lower tube and cleaned them with brake cleaner. Springs inside the stanchion are loaded so be careful when you take out the top cap. I applied bit of pressure to them while unscrewing to stop them from flying off. They are made out of aluminum so those fine threads which keep them in place can be easily damaged if you're not careful with them. I decided to reuse old O-rings in them together with copper washers in lower tube bolts.

I used brake cleaner to clean parts of shocks.

Pyramid Parts Front Suspension Overhaul Kit for
Honda CBR600 F2 F3 1991-1998 (IB11 & OB22)

Fork oil seals

Slider and guide bushes

Stanchions rebuild with new parts.

CRC Soft Lock threadlocker...

...for securing lower tube bolts.

Since I don't own any special tools for rebuilding forks I made a washer looking thing out of nylon sheet which I placed on top of oil seal when I hammered them in with a small punch. It kept them undamaged while hammering.

Nylon washer to keep oil seal undamaged
while hammering it in with a small punch.

Circlip back on to secure oil seal.

I used a rubber mallet to gently
hammer in dust seals.

Rebuild shocks ready to be put back to the bike.

Remember to add threadlocker also to brake
caliper bolts. They can easily get loose without it.

I bought 2 litres of Belray 10W fork oil...

...and measured roughly 0,508 litres for each shock 
which was recommended by service manual.

Small funnel helped with refilling shocks with fork oil

Ready for a test drive 😎