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Yamaha FZ750 Rear Suspension Overhaul
DISCLAIMER:
Application of the procedures described herein is at your own risk. I have submitted this information in good faith, without charge but I will be held responsible for any injury, damage or loss whosoever caused resulting from your use of these procedures or Information. This information is not intended to replace your repair manuals, your common sense, or your responsibility for your choices and actions.
These instructions are written with and for FZ 750 2MG (and later) models in mind. The use of which is completely at the owners risk and is meant as a guide only to be used in conjunction with the relevant owners manual. Reading this document is taken as full consent that the user of these instructions you accept full liability. This website and all connected with it accept no responsibility for any damage caused. If your are not confident to carry out the work outlined here then do not do it. Leave it to the professionals. Earlier model (1**) rear suspension linkages differ considerably in the linkage arrangements and are therefore not covered here, even though the same basic principles apply, but cheer up you do have a centre stand which makes this much easier and safer.
Required Tools
A good Quality 3/8" or 1/42 Socket set is absolutely as well as duplicated sockets in the 17 and 19mm sizes.
Axle Stands or some means of suspending the rear of the machine without effecting the Swinging arm (inc Spindle).
Rubber Mallet
Small tray or tub to store parts and fasteners.
WD40 (or similar)
Lithium or Moly Grease (Moly preferred)
Combination Spanner set
Screwdriver set (straight)
A set of Ring or Combination spanners inc 12,14,17 and 19mm sizes.
Copper Grease
Recommended - Compressed air canister or compressor is recommended.
Time Required
An experienced home mechanic should allow 1 full day to complete this job.
Difficulty
Easy to Moderate
Specs
Shock top bolt 42Nm
Shock lower bolt 40Nm
Rocker/frame bolt 48Nm
Dogbone bolts 74Nm
Wheel Spindle Nut 107Nm
Swinging Arm Spindle Nut 90Nm
[Dissemble]
To make working on the suspended machine safer LOOSEN (but do not remove) the following
Fasteners now before the machine is lifted. Rear calliper bolts, Swinging arm nut and Rear Spindle nut need to be LOOSENED.
Remove the sidepanels.
Now suspend the rear of the machine so that the rear wheel is clear of the ground. My preferred method to do this is with some light vehicle axle stands placed on the lower engine frame rails just where the frame bolts to the rails Use another body or trolley jack to lift the bike to place the axle stands. If you have neither then lean the machine over place one stand then rock it over to the other side and place the other. Ensure machine is stable and secure before continuing.
Remove the rear calliper.
Remove the Chain Guard.
Remove the Rear wheel spindle nut and withdraw the spindle. Lift the calliper bracket clear.
Move wheel forward and slide off the chain from the sprocket. Remove rear wheel, taking care not to lose the small spacer (between wheel and calliper bracket).
Remove chain adjusters.
From under the machine you will see a large(ish) alloy rocker arm with two dogbones arms on either side the dogbones which are in turn are attached to the swinging arm. One side of the rocker is attached to the frame while the other end attaches to the lower of the shock. Once under the machine it is not difficult to visualise how the suspension works. Spend a moment looking at the arrangement and visualise what connects to what. I recommend for those without a photographic memory you do a small diagram of exactly what is connected to what. You will understand why when you come to put it back together!
Using a large extension on a big ratchet remove the nut from the top shock bolt. Note the bolt head is captured by a lug on the frame so the correct way is to remove the nut completely then withdraw the bolt. What frequently happens is that the bolt does not capture so you need to hold the bolt head with another spanner/ratchet.
TIP - Use trolley jack to suspend the swinging arm too roughly the same angle as before the wheel was removed. This will avoid damaging the soft alloy arm and make access to the links easier as weight will be removed from the pivots allowing you to withdraw bolts easily.
Now remove the pivot bolt that locates the rocker arm to the frame. This has a small nut on the bolt (14mm) take care not to lose any shakey or plain washers.
Now withdraw the prev loosened swing arm spindle. The whole rear suspension assembly should now be free to be withdrawn as a single unit.
[Inspection and Overhaul]
Rear Wheel
Remove the sprocket carrier from the wheel and clean and inspect bearing for wear. Note the small spacer on the outside next to bearing. From the outside of the carrier prize out the little alloy spacer from inside the seal, inspect for wear on its outside sealing surface ( the spacer is prone to wear). Repack bearing with some fresh grease (if it's the unsealed type) . Clean and replace the spacer (with a dab of grease on the running surface). Check sprocket bolts are secure. Check Cush drive rubbers are undamaged. Take care not to misplace any of the rubbers. Note how the sprocket carrier engages in the cush drive slots. Replace carrier.
Clean Chain adjusters and the cavity in the arm. Lightly grease.
Shock Absorber
Undo rocker/remove shock absorber. Inspect shock for oil leakage. Any leakage means Shock will expire shortly. Check shock inner shaft seals are not damaged. Clean Shock taking note to free off the preload (big c spanner ring) and damping adjusters while you have good access, with WD40 if required.
Swinging Arm
Undo swinging arm/dogbones bolt and remove. Remove the rocker/dogbones bolt also taking care not to lose any washers. Remove the dogbones. Remove bearing inner race. Clean Swinging Arm shock pivot needle bearings out with compressed air and lots of WD40. Clean and inspect inner race for damage (pitting). Repack bearings and refit inner. Clean and refit dogbones and bolt up firm. TIP do not attempt to tighten to full torque until the unit is replaced.
Remove Swinging arm spindle inner shaft inspect and repack needle bearings. Replace inner
race shaft. Take care not to loose the two spacers caps on the end of the arm pivots.
Clean the arm up with degreasing. Taking note of any rust around the chain guard mounting bracket.
Rocker
Undo Rocker/dogbones bolt and remove. Remove inner race. Clean out needle rollers with
Compressed air and WD40/spray deagreasant.
Pull out the shock mount spacers from the shock/rocker bearing. Under the spacers you will find two seals. I recommend you careful prize out the seals with a small screwdriver. The spherical bearing is very prone wear is expensive and not available from your bearing supplier. Inspect the bearing closely and clean thoroughly, pack well with grease. Replace the seals, replace the spacers and slide the shock back over the rocker and put the bolt in. (do this now as you will no doubt loose the spaces without the shock in place, believe me).
Re attach the dogbones noting which way the rocker is oriented (smaller distance toward the frame long toward the swingarm.
[Re assembly]
Before reassembly take the opportunity to clean up the rear of the engine and the frame rails. Inspect for any damage or any oil leaks from the engine.
Replace the dogbones/rocker/shock assemble back onto the swingarm , don't forget the bearing inner race or any of the washers. Do up the nut finger tight.
TIP - it makes sense to slip the bolts in from the LH side as the exhaust restricts access to the RH side.
Making sure you havent lost the end caps off the end of the swingarm replace the swingarm in the mounting. Feed the shock up the hole. Replace swing arm spindle and finger tight the nut.
Replace your trolley jack under the swing arm and move the arm to the approx correct position.
Feed in the top shock bolt, noting it goes in from the LH side, finger tight the nut.
Replace the rocker/frame bolt and the washers and nut.
You should now be able to remove the trolley jack.
Tighten all the nuts to the correct torque. Do not forget anyc.
Swingarm
Top shock bolt
Lower shock bolt
Rocker to frame bolt
Rocker to dogbones bolt
Dogbones to swingarm bolt
Replace the rear wheel.
Replace the Calliper.
Replace the chain guard
Torque up the rear wheel.
Replace the sidepanels
Check operation of the suspension. IF the suspension is locked suspect the spherical bearing, check the spacers have not been lost and the shock fork mounting is not griping the rocker.
COMPLETED
Any queries, errors, emissions or improvements kev@eddnet.com or http://www.eddnet.com/kev/
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