Contents
I’ve removed the airbox, transmission and clutch to gain access to the flywheel. You can see how I did that work here.
- 13 BMW 1983 R80ST Remove Air Box & Pulse Air System
- 23 BMW 1983 R80ST Remove Transmission
- 21 BMW 1983 R80ST Remove Clutch
I also show how to remove the flywheel here.
I’ve published documents on removing and installing the flywheel on other projects. You can see those documents here.
- 11 BMW 1973 R75/5 Remove & Install Flywheel, Replace Rear Main Seal, Oil Pump Cover & Cover O-Ring
- 11 BMW 1977 R100RS Replace Rear Main Seal & Oil Pump Cover O-Ring
- 11 BMW 1983 R100RS Remove Flywheel & Rear Main Seal
- 11 BMW 1983 R100RS Install The Flywheel
Since the 1983 R80ST engine is similar in many ways to the 1983 R100RS, I will link to the 1983 R100RS documents as appropriate in this document.
Parts
I replace the O-ring installed in the guide ring and the five flywheel bolts. I got these parts from Euro MotoElectrics. The “Gasket Ring”, aka, the O-ring, was included in the EME Gasket Kit, EME Part# GSK-EngineKit421.
| Part # | Description | Qty |
| 11 22 1 262 060 | HEX BOLT – M11X1,5 | 5 |
| 11 22 1 337 093 | GASKET RING – 59X3MM | 1 |
Video
Here is a short YouTube video summarizing how I do this work.
VIDEO: 1983 BMW R80ST Install Flywheel
Preparing For Flywheel Installation
I show the preparation for flywheel installation in this 1983 R100RS document.
Polish The Guide Ring To Remove The Groove
- 1983 R100RS: Clean The Flywheel, Polish The Guide Ring
- 1983 R100RS: Remove Grooves In The Guide Ring
Here are some pictures for the 1983 R80ST starting with what it looked like when I removed it.
Guide Ring Discoloration And Groove Worn By Lip Of Rear Main Seal
Front Of Guide Ring Is Rusty
Rear Of Guide Ring
Old O-ring Inside Guide Ring
Removing Old O-ring With Small Screwdriver
Old O-ring Removed
Auto Sol Metal Polish
Polishing Guide Ring
Gunk Removed From Guide Ring
Cleaned Up Guide Ring
Cleaned Up Guide Ring
Cleaned Up Guide Ring-Front Face
Ready To Sand Out Edge Of Groove In Guide Ring
Sanded And Polished Guide Ring Shows Slight Groove
Deburr Flywheel Teeth
There are some burrs on the flywheel teeth. I use a flat file to remove them.
Flywheel Teeth That Engage With Starter Motor
Minor Damage To Flywheel Teeth
Minor Damage To Flywheel Teeth
Paint Timing Marks On Flywheel
I like to paint the timing marks on the flywheel so they are easier to see. I use Testor’s model paint; yellow for “OT”, white for “S” and red for “Z”.
Paint Applied To Flywheel Timing Marks
Paint Applied To Flywheel Timing Marks
Install Guide Ring O-ring
I install a new O-ring in the guide ring. This O-ring provides an oil seal around the crankshaft nose the guide ring fits on. I put a little oil on the O-ring so it will slide onto the crankshaft nose more easily.
New O-ring Installed In Guide Ring
Oil Guide Ring O-ring
Install Guide Ring and Flywheel On Crankshaft
This is how I do this work on the 1983 R100RS.
Here are some pictures for the R80ST. Since I have to torque the flywheel bolts to 90 Ft-Lbs, I use a wood clamp on the left side of the engine to clamp it to the benchtop so the engine won’t roll over when I torque the bolts. On the 1983 R100RS I screwed 2×4 pieces of wood to the bench top and used another 2×4 to brace the right side of the bell housing to keep the engine from rolling over. The wood clamp is easier and quicker and works just as well.
Using Wood Clamp To Keep Engine Block From Rolling Over When I Torque The Flywheel Bolts
Clean Guide Ring and Rear Main Seal Teflon Seal Lip
Before I install the guide ring on the crankshaft nose, I clean the guide ring sealing surface and the Teflon lip of the rear main seal with alcohol wipes to get any dirt, debris and oil off them. You do not want to oil the Teflon lip of the rear main seal or it will not wear into the guide ring properly and it will leak.
Clean Guide Ring Seal Surface With Alcohol Wipe
Clean Teflon Seal Lip With Alcohol Wipe
Tighten New Flywheel Bolts To Pull Guide Ring Onto Crankshaft Nose
I install the guide ring so the hole with the punch marks is aligned with the flywheel hole with the punch marks using new, clean and not oiled, flywheel bolts. I hand tighten the bolts to pull the guide ring all the way onto the crankshaft nose.
Center Flywheel On Flywheel Bolts
I loosen the bolts a bit and rotate the flywheel on the bolts using the edge of the starter motor casting to see how much the flywheel moves. It moves about a flywheel tooth. I move the flywheel so half the tooth is showing which centers the flywheel on the crankshaft bolt holes and gently tighten the flywheel bolts to hold the flywheel in place. This ensures the timing marks on the flywheel are accurate and the ignition timing will be accurate.
Flywheel Movement On Bolts
Flywheel Movement On Bolts-About One Tooth
Centering Flywheel On Bolts-1/2 Tooth Movement Then Tighten Bolts
Torque Flywheel Bolts
I use a screwdriver to immobilize the flywheel and then torque the flywheel bolts to 90 Ft-Lbs in stages: 45 Ft-Lbs, 80 Ft-Lbs and then 90 Ft-Lbs.
Large Blade Screwdriver In Flywheel Teeth To Keep Engine From Rotating
Torque Flywheel Bolts to 90 Ft-Lbs In Two Stages
With the flywheel installed I verify that the punch marks on the flywheel align with those on the case.
Flywheel Installed
Verify Punch Marks Are Aligned
Revisions
2022-03-26 Added pictures of original condition of the guide ring when it was removed.