Author Topic: LeMans Engine & Clutch Rebuild Questions  (Read 431 times)

Offline arbezc

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LeMans Engine & Clutch Rebuild Questions
« on: April 13, 2021, 06:03:48 PM »
Greetings,
I respect the knowledge on this forum & would appreciate advice on a clutch & bottom end rebuild. The bike is a 1980 Lemans II with 94,800 Km (59,000 miles) on it. I have some mechanical skills but have never rebuilt a Guzzi engine. With our Covid restrictions on travel I decided to have a look at the bottom end and lubricate the clutch spines. Engine is removed from the frame & fully disassembled.

The clutch disks have plenty of material left but all surfaces are coated in grease or oil. There appear to be leaks from the breather or cam cover & through the clutch pushrod. The splines are partially worn, they may have been over greased by the previous owner. Heres a few shots:
 
 






 
The crankshaft bearings IDs look very smooth to my eye, they measure within tolerance but near the low end. Main & con rod ODs also look smooth but measure outside Guzzis limits. I picked up a set of shop grade gauge blocks. After calibration & much experimentation I was able to take repeatable measurements to within .0001. Here 3 images of the crank:
 
 






mark gif

 
Clearances measured using micrometers & bore gauge are:
Front Main: 0.0022-26
Big End Journals: 0.0020-22
Rear Main: 0.0037-37 (Look too wide)
Wrist Pins: ≈0.0009-10 (Hard to measure with a telescoping gauge)

What are your thoughts about cleaning up this crank & installing standard (not oversize bearings)?
The strategy I have in mind is:
1.   Clean & reinstall sludge trap plug, apply lock-tite & peen (the old one was loose)
2.   Hand polish crank bearing surfaces
3.   Replace main & rod bearings with standard sizes, eliminates grinding crank
4.   Replace all engine & gearbox seals
5.   Epoxy back of cam plug & seal lower main flange bolts
6.   Upgrade to SD-TEC kit with 4mm splines
7.   Lubricate the clutch splines
8.   Possibly open the gearbox to shim shifter drum & replace return spring

Im not sure what special tools are nice to have vs absolutely necessary. A complete assortment would run about $500 Canadian which is excessive for what could be a one-off. The Haynes WS manual suggests a few DYI tools but few properly designed tools are nice to have. Id appreciate any ideas on the following tools:

   Im assuming that most of engine & gearbox seals can be removed using a std. seal puller.

   Can the rear main seal be safely installed with a section of pipe once the bearing flange is off the motor?

   How effective is an input boss as a centering tool? Is the dedicated tool much better?

   Can the input boss peg-nut be chiselled off & replaced with a standard hex nut?

   What is the easiest way of holding the input boss for removal & installation?

   Can you recommend which tools are worth buying vs making?

Any comments or suggestions would be greatly appreciated.
Charles


Online John A

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #1 on: April 13, 2021, 07:41:46 PM »
The one thing I would say is not to lube the clutch splines. It gets flung off onto the friction surfaces. Some new clutch hubs are dry film lubricated at manufacture but thats the only lube that should be used there. BMWs have a grease for that but in my experience it just makes a place for any wear particles to stick to and it accelerates wear and doesnt last very long..Id put in new discs and a new floater and a new hub as well as seals. Is it a ten spring or the usual eight? Im a fan of the ten spring units, especially if the engine is successfully hopped up. How much out of round are the crank journals? Id be more concerned about that than it being slightly undersized
« Last Edit: April 13, 2021, 07:46:36 PM by John A »
John
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Offline lucky phil

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #2 on: April 14, 2021, 02:58:21 AM »
The crank will be fine with new bearings. Lube the gearbox input splines with a dry spray on molycote. I spray it into a cap and paint it on with a brush sparingly.
Replace the rear main seal when it's off and heat the cases when you install the rear main bearing. Use the std ring nut on the input hub not anything else.
Here's my Daytona engine rebuild, I can't remember every detail about whats in this but the bottom end is virtually identical.
 https://www.v11lemans.com/forums/index.php?/topic/20664-v11-daytona-project/

Ciao
« Last Edit: April 14, 2021, 03:04:08 AM by lucky phil »
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Offline arbezc

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #3 on: April 14, 2021, 08:13:16 AM »
Thanks John,
I was planning to use a light coating of SIG3000 & Moly Paste on the splines but will look into the dry film. The splines are wet with what looks like rusty oil. I'm thinking it leaked thru the clutch push rod seal. The bike has an 8 spring clutch but I'm not an agressive rider. I didn't find any obvious out of round in the crank bearings. The bike must have been well taken care of & ridden properly, ie, no lugging.

Hi Phil,
Is there a moly spray you like? Can I just install a new main seal without a tool by tapping it to flush with the rear bearing?
Thanks for the link to your Daytona build, I'll go through it.

Charles

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #3 on: April 14, 2021, 08:13:16 AM »

Online Kiwi_Roy

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #4 on: April 14, 2021, 09:28:51 AM »
Was the clutch slipping at all?
If not I would just wash them in a degreaser, I have even heard of splashing them in gasoline and setting fire to burn off any oil although I haven't tried that.
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Offline Peter949

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #5 on: April 14, 2021, 09:43:24 AM »
For certain I would simply purchase the new deep spline clutch plates from MG cycle, and a new clutch hub along with a new intermediate plate. I assemble the clutch with no moly type lube, and everything works very smoothly.
Also, I usually just tap in evenly most oil seals, with no special tools.
Peter

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Online John A

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #6 on: April 14, 2021, 01:18:38 PM »
Once again Id like to caution you on using any kind of lube on the clutch hub. If you do want to use a dry film lube type , send it off to have it done at a facility that would vapor degrease it and bake on the film but they will have a minimum so send off the driveline parts with it. I was told that new hubs usually have that already done if they are black. You wont be helping it to put anything on it and they live a good long time anyway.
John
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Offline pete mcgee

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #7 on: April 14, 2021, 02:50:49 PM »
For certain I would simply purchase the new deep spline clutch plates from MG cycle, and a new clutch hub along with a new intermediate plate. I assemble the clutch with no moly type lube, and everything works very smoothly.
Also, I usually just tap in evenly most oil seals, with no special tools.

^^^^^^^^^^^^^^^^^^^^ THIS^^^^^^^^^^^^^^^^^^^^^
The rear main seal is easier to install while the rear main bearing housing is out.
Change the gasket to the breather pipe, think about some JB Weld or similar around the rear cam plug.
Look for wear in the bronze cam thryst bearing.
Fit a chain tensionner.
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Offline jwinwi

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #8 on: April 14, 2021, 03:30:02 PM »
For tips on tools search posts by leroy-can. His post #59 has what you need.  :thumb:
« Last Edit: April 14, 2021, 03:31:04 PM by jwinwi »
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Offline arbezc

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #9 on: April 14, 2021, 08:12:15 PM »
Thanks for the suggestions & leads guys, I'll follow-up. I plan to order what's needed on Friday.

I'm looking forward to getting the LeMans on the road again. Its a great touring bike.

Offline lucky phil

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #10 on: April 14, 2021, 09:38:54 PM »
Thanks John,
I was planning to use a light coating of SIG3000 & Moly Paste on the splines but will look into the dry film. The splines are wet with what looks like rusty oil. I'm thinking it leaked thru the clutch push rod seal. The bike has an 8 spring clutch but I'm not an agressive rider. I didn't find any obvious out of round in the crank bearings. The bike must have been well taken care of & ridden properly, ie, no lugging.

Hi Phil,
Is there a moly spray you like? Can I just install a new main seal without a tool by tapping it to flush with the rear bearing?
Thanks for the link to your Daytona build, I'll go through it.


Charles

Molykote D-321R applied sparingly with a brush. If it's good enough to lube the fan blade dovetails on high bypass jet engines it's fine for the Guzzi input splines.
Should be ok flush but from memory it's usually a mm or two below flush. You can make a one off drifting tool out of anything really to get the extra MM or so if required.

Ciao
If you're not living on the edge you're taking up to much room.

Offline arbezc

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #11 on: April 14, 2021, 09:59:41 PM »
Thanks Phil, I'll try the moly spray. I enjoyed reading through your Daytona engine thread.
I'm more familiar with clutch spline issues with the R1100 series BMW's. Its an ongoing concern since there's very little warning before you are left with no power. They can start failing in as little as 30-40,000 kilometers. The input shaft & splines are much finer than Guzzis. Other than fixing misalignments a sticky moly paste is recommended. Besides being stranded the big issue is the amount of labour involved in getting to the clutch. The bike is essential split in two. The LeMans hub is bigger & the splines are much more robust.
Kiwi, I forgot to answer your question. No, I don't recall the clutch slipping despite the oil. That said, I have several projects underway & would rather not pull the transmission again. For a couple hundred $ I think I'll replace the works & upgrade to 4mm splines at the same time. In any case, the old splines appear to be 20-30% worn.
Thanks again,
Charles

Offline lucky phil

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #12 on: April 15, 2021, 12:46:05 AM »
Thanks Phil, I'll try the moly spray. I enjoyed reading through your Daytona engine thread.
I'm more familiar with clutch spline issues with the R1100 series BMW's. Its an ongoing concern since there's very little warning before you are left with no power. They can start failing in as little as 30-40,000 kilometers. The input shaft & splines are much finer than Guzzis. Other than fixing misalignments a sticky moly paste is recommended. Besides being stranded the big issue is the amount of labour involved in getting to the clutch. The bike is essential split in two. The LeMans hub is bigger & the splines are much more robust.
Kiwi, I forgot to answer your question. No, I don't recall the clutch slipping despite the oil. That said, I have several projects underway & would rather not pull the transmission again. For a couple hundred $ I think I'll replace the works & upgrade to 4mm splines at the same time. In any case, the old splines appear to be 20-30% worn.
Thanks again,
Charles

Thanks, yes the trouble with this approach is the sticky grease/paste just attracts wear particles which then form a grinding paste for the splines. Thats why I go for the dry lube.

Ciao
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Offline jacksonracingcomau

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #13 on: April 15, 2021, 02:13:46 AM »


   Can the input boss peg-nut be chiselled off & replaced with a standard hex nut?

   What is the easiest way of holding the input boss for removal & installation?

   Can you recommend which tools are worth buying vs making?

Any comments or suggestions would be greatly appreciated.
Charles


Bit late to the party but yes, the 27mm hex nut on output shaft is same thread, I use them on mine and others
Dent to lock in place, cant remember if I did anything else but have a spare box on the shelf, can look if you have a question.
Worth getting (buy, make, borrow) an alignment tool, you can use hub but job becomes simple with a bolt to compress springs too. A long bolt (M12 x 1.25mm ?) and washer sized to fit works and all I had for many years.
Clutch holding tool from old plate, two 8mm bolts and nuts, plastic pipe on threads to not damage gearbox casing
I use this to undo/do up front and back nuts
Do post clearances with new bearings, Im doubtful
Id buy big end shells cos theyre cheap but mains only when a problems occurred,
Gudgeon pins, Im fussy, slightest ridge and theyre in the bin, fingernail test
Noise from worn pins is annoying, small end rattle

Is all a doddle, enjoy yourself, watch out for little bits (dowels in main bearings have to go back)
Cam followers can be refaced

On current topic, I never lube clutch splines nor see the need, clutch is a superb design, the wear on yours is not unusual but personally, in 43 years (in 4 days, happy birthday my bike ) and at least 5 clutches Ive never had the slightest wear on mine, Neutral when stopped appears to be answer.
Lube wont help those that wear out clutch splines
Do lube drive shaft splines, different story


Offline arbezc

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Re: LeMans Engine & Clutch Rebuild Questions
« Reply #14 on: April 15, 2021, 11:45:08 AM »
Thanks Phil,
I'm going to try the dry film route on the LeMans. It crossed my mind that the clutch spines on the R1100S are quite small in diameter, more like the transmission output on the Guzzi.
Could it be that the rotational speed is lower therefore grease is not flung onto the clutch parts as readily? The LeMans hub is significantly larger therefore its surface speed would also higher making grease not as useful. My LeMans splines were coated in oil like its self lubricated by the gearbox.
There's an ongoing debate within the BMW community as to what the root causes of clutch spline failure are. The most knowledgeable blame a misalignment of the gearbox to the bellhousing & an overhang of the friction disk outside the input shaft. Its persisted for years & has turned many people off the older R Series. Other than these issues its a great road bike.
Jackson, Thanks for the concise list of work arounds & reminders. Ill be referring to it.
Thanks



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