Moto Guzzi V700 / Ambassador /Eldorado Rear / Final Drive Rebuild

Really this is only half a rebuild as the pinion didn't need any re-shimming and was in great shape. That being said, I haven't found any rebuilds with pictures that cover the early stuff, and I do some things a little differently than others, so hopefully this will prove helpful. I cut my teeth on vintage BMWs so it's only natural that this procedure involves extensive use of the freezer and a heat gun.

Follow these steps at your own discretion and use your head and the proper PPE. I'm not responsible for anyone hurting themselves or ruining their drive.

The rear drive in pieces. Note, I removed the large outer bearing from the flange prior to reassembly. Also note that I installed studs into drive where it formerly would bolt onto the swingarm.

First, we have the replacement drive splines. You'll need to put the inner needle bearing race onto the splines. I perform this by freezing the splines for about 5-10 minutes, then heating the bearing race with a heat gun to the point that you'll need welding (or other thick) gloves to pick it up, you don't have to go crazy. Once it's hot, remove the splines from the freezer and drop the race right on, you shouldn't even need to drive it on, it should just fall right into place.

Next, insert the new splines into the crown gear. Again, this is accomplished with heat and freezing. Put the splines with the bearing race attached back into the freezer and heat the crown gear, again don't go crazy, this isn't a BMW and the tolerances aren't as insanely tight. Drop the heated crown gear right onto the spline piece, it should drop in easily and you'll have plenty of time to rotate the crown gear with ease to line up the bolt threads.

Now it's time to bolt it on. Some people replace the tab washers with 8mm Schnorr locking washers as it's two steel pieces bolting together, but there's nothing wrong with the tab washers, just a matter of ease of assembly. Use Blue Loctite on the M8x1.25 bolts and torque them to 31 ft/lbs. I used an impact gun to remove these bolts during disassembly, but I'm a stickler for torque settings so I used a torque wrench on reassembly. In order to hold everything in place while I torqued everything down properly, I wrapped rubber hose (in this case radiator hose that I cut in half) around the outer diameter of the splined flange (to protect the metal) and put it into a vice (not too tight, just enough that it won't move excessively while being torqued down).

Time for the large bearing to be installed on the crown gear/splined flange. Again, heat and cold are your friends, freeze the crown gear assembly and heat the bearing. I heated the bearing until the residual gear oil that degreasing didn't remove completely just began to smoke a little. When it's that hot it will, like everything else so far, drop right into place on the crown gear assembly. These pieces will have to go back into the freezer, but let everything cool down to room temperature before you go and do that. Go have a beer or take a cigarette break and once it's cooled down enough, put it into the freezer.

After about 10 minutes of letting the assembled crown gear shrink in the freezer, begin heating up the aluminum flange. Get it nice and hot then go grab the crown gear out of the freezer and set it down on the work bench, spline side facing up. Pick up the flange (using gloves of course) and set it squarely on top of the crown gear and position it over the bearing. If everything is heated and cooled correctly, this will require minimal to no force. Once it's on, double check that the bearing is seated squarely in the flange.

Let everything cool down to room temperature again. Once the temperature on both pieces has normalized, you can put in a new inner seal. You're now about 50% done with reassembly.

Next we go to the bare housing for the rear drive. We must insert the outer final drive seal. Unlike other seals, the flat side of this seal must be facing down when you press it in (so the back side of the seal where the spring retainer is kept should be facing you). It doesn't hurt to gently heat the rear drive housing, then oil the seal and use a socket to press the seal into place.


Once that seal is in, I press in the steel axle spacer into the rear drive housing. Again, light heat, cold housing, and it should tap in nice and easy.

Now that the smaller outer seal and axle spacer are in, drop the copper shim that goes between the seal and the needle bearing/race into place.

Once the copper shim is in place, again it's time to apply the hot and cold process. Freeze the outer bearing race and heat the rear drive housing. It should still be warm from the last heat application, but it isn't enough, get it hot enough so that you can't leave a finger on it for more than 10 seconds. When it's hot again and the bearing race is nice and cold, drop that in (it may need a few very light taps from a soft mallet, like plastic or brass at the most). Once in place, you can drop in the needle bearing cage.


After the needle bearing is in place, it's time to reinsert the locking plate. Simply lay the locking plate back into placel; the slotted side is secured by the rib in the housing, and the screw secures the plate against the bearing race. I use blue loctite here and once installed, I put additional punches in the plate to keep it in place.


At this point, it's time to put the gaskets and spacers on the crown gear aluminum flange. I grease both sides of the paper gasket, put it on, put the spacer in place, then grease both sides of the other paper gasket and apply it to the spacer. The grease should keep it in place and prevent the holes for the bolts sliding around when you insert the assembly into the housing.


Once the crown gear assembly is inserted, I insert the bolts and locking tabs (you don't want to use Schnorr washers here as the flange is aluminum) and tighten them down, but don't apply the specified torque yet.


Next I insert the pinion gear assembly (with new gasket and o-ring) into the housing and rotate the pinion gear to make sure nothing is binding up anywhere (note: I installed studs on my rear drive instead of bolting it on, this helps a little during this test as it prevents the pinion gear housing from rotating when you rotate the pinion).

Once this is confirmed, I torque down the crown gear assembly (in a star pattern) to 18 ft/lbs and then bend the locking tabs back into a locking position. Re-test the rear drive motion and test for free play.


Once that all checks out, it's time to fill the drive with 300ccs (approximately, you're filling until it begins to leak out of the level plug) of gear oil. Unlike the transmission, GL-5 is ok to use here instead of GL-4 as there aren't any brass or bronze bushings to get eaten up by the sulfur of GL-5. It should go without saying, but replace all crush washers on the drain plug, filler plug, and level plug on the rear drive before doing this.

And that's that. Make sure there aren't any obvious leaks and you're ready to go.

Moto Guzzi V7 / V700 bottom end assembly

Now that the engine case/covers are back from powdercoating, it's time to reassemble the bottom end. Still need to send out the cylinders for Nikasil plating, repair the generator bracket, then button up everything else on the engine, but here's the basic procedure for reassembly.

All new seals and gaskets. Case and all parts thoroughly degreased and cleaned.

Cam plug JB Welded (as per Greg Bender's ThisOldTractor site), this is a point of leakage that I'd rather deal with now then once it ruins the clutch.

Getting everything lined up, no I didn't reuse those tab washers, but they were cleaned in conjunction with everything else. I'm trying out a new assembly lube, this one made by Amsoil. It's interesting, the previous lubes I used were silver/grey and this one is red which helps a little in seeing the amount of coverage on the parts.

Front bearing flange installed. In lieu of tab washers, I used 0.88mm thick wave washers as per Moto Guzzi revisions.

Camshaft lubed up and ready for installation

Installed

New rear main seal, lubed around the outside.

This is a BMW rear main seal installation tool intended for use in conjunction with the crankshaft. This won't work on Guzzis since the rear crank face is proud of the bearing flange, and the center 12mm bolt area is proud of the face as well. I was able to use the tool by putting a 12mm bolt through the center of the tool and reinforcing the back of the bearing flange with a bar and then tightening it up and pulling the seal in.

Reinstalling oil tubes with new seals and crush washers prior to reinstalling crank.

Placing the case on wooden blocks in prep for the crankshaft install. The case needs to be raised as the front of the crank protrudes from the case by 3 or so inches.

Dropped in.

New seal held on with grease

Bottom bolts for the rear bearing flange with sealant. I used Permatex Ultra Grey.

Con-rod bearings lubed

Con-rods installed with new tab washers. NOTE: When installing the connecting rods, the oil holes must both be facing the right cylinder (when viewed from the clutch area), meaning the right connecting rod's oil hole should be facing down and to the right and the left connecting rod one should be facing right and up. The numbers stamped on the rods should be lined up with each other as well.

Oil pump finger tightened in place. The 9 o'clock and 12 o'clock bolts are the smaller bolts that secure the pump directly to the case, the 6 and 3 o'clock bolts are the longer ones that secure the oil pickup/filter screen to the oil pump/case. The bolt to the right side of the pump is also the shorter type and is the third bolt utilized in securing the pickup to the case.

Pickup in place, assembling strainer.

 Sump area buttoned up.

Timing gears reinstalled. The camshaft timing gear is very, very close to the front bearing flange bolt heads since I used the wave washers in lieu of the thinner tab washers. I didn't fully torque down the nut on the camshaft yet, but I'll need to measure clearance through an entire rotation of the cam once I do to ensure nothing is rubbing anywhere. If it is, I may have to retain the tab washer on the top two bolts solely for clearance purposes.

oooooh yeah...

Time for bottom end assembly and shipping off the rest of the bike for powdercoating

Well...

It's been awhile since there's been any major progress on here and there's a reason behind that. I'm still waiting for the engine case/covers/pan to get bactk from powdercoaing.

When I do stuff, I usually knock out things piece by piece, in a sequence. I hate starting multiple things at once because it's easy to get distracted and lose focus. The engine powdercoat is priority one, once I get that back, I'm going to drop off the frame and suspension bits for powdercoating, and while I wait for them, reassemble the bottom end so it's all done when the other stuff comes back and then I can really start putting stuff back together. Now I find myself with a bunch of crap in pieces and more questions/problems that need to be taken care of.

If you follow me on Instagram, you've probably seen some of these, but at least on here I can provide some more info.

First off, splines. The female rear drive splines were on backorder for awhile, but they finally came in. I like that Moto Guzzi splines are bolted and pressed (at least on the wheel hub) on, the male splines to the far right of the pic are BMW splines. If you want to replace final drive splines on a BMW your options are getting a specialist to weld and machine new splines on the old crown gear, replace the entire crown gear (and pinion gear because they must be replaced in a set), or do what I did and buy a replacement spline piece, where you need to get a machinist to cut out the old one from the crown gear with a lathe, then get the new one pressed and then welded into the crown gear and machined down, The BMW splines are on deck after this V7 build.

I also plan on getting the rear drive case powdercoated to match the engine. So, again, I've got parts strewn about while I wait for one thing to get back before I drop off the rest. I may do a write up on a rear drive rebuild. You don't see that many online and the ones you do see usually don't have pictures. This V7 drive might be a bad example though because it doesn't need re-shimming, which is the more tedious part of a rebuild, especially for Moto Guzzis. BMW final drive cases are marked with a +/- tolerance, as are the crown/pinion gear set, which takes the guess work out of shimming, these Guzzi ones seem to go by trial and error. I do have an Ambassador rear drive that I have to fully rebuild that does need a re-shim, so maybe the write up will involve that one.

More parts strewn about. I am probably going to write up something about fork rebuilding as well, but guess what, I'm getting the fork sliders powdercoated, so that's still in queue...

Here's something I don't need to wait on. I have to sand down and polish these original Borranis as someone in this bike's past wasn't easy on them with tire spoons/irons. There were digs and mars all over it, but they're cleaning up nicely. I'm doing this the hard way, but varying grits of sand paper before a final polish. It sucks, but it'll come out nice.

These were the tires that came off those rims. I joked on Instagram about selling them to Hipsters, but it turns out that some people actually do want old tires like this (I guess for display purposes?). That being said, if you want them, make me an offer, but please don't mount them and go riding.

One more thing. When I bought the V7 it didn't come with keys. I could've cheaped out and bought a generic automotive ignition switch, but MG Cycle sells a newer FIAT switch that was supposed to be a drop in replacement that allows you to retain the old metal securing ring. Well, the switch is obviously deeper than the old one, it's also wider and doesn't fit into the MG dash, and finally the machining of the threads is so poor, you can't retain the old metal ring without modification(notice how it tapers/gets wider the closer the threads get to the base of the switch). I haven't touched this since I made these discoveries, but the plan is to file down the indentations on the new switch and try to get it to at least fit the dash, then I'll worry about cleaning up the threads and trying to get the old ring to fit. If neither of those prove successful, the final resort will be to try and switch lock cylinders from the new switch to the old one. The depth of the new switch worries me and I'm thinking I'll likely find that this can't be accomplished either.

So that's that. Hopefully there will be better news later this week and things can start moving again.

Stuff for sale: Moto Guzzi Wixom Fairing, Gasket Kit, etc.

Grab it now before it goes on ebay (contact for details:

SOLD SOLD SOLD Early MG Big Twin Wixom Fairing (V700, El Dorado, Ambassador). Rough, but usable, black with white pin stripes SOLD SOLD SOLD

Vintage, NOS V7 Sport (the original ones) complete gasket kit. Made in Italy

1967 Aermacchi Sprint 250 SS Generator. No brushes, untested

BMW /5 Flywheel, excellent shape with brand new BMW 10mm bolts .

Moto Guzzi V700 Sludge Trap

The Guzziology book says to just destroy the sludge trap plug when removing. They tend to be seized, besides being punched to further lock up the threads. My plug was punched in the 6 o'clock and 12 o'clock positions and was super seized. Allen key wouldn't free it, hammer impact driver wouldn't work, impact gun succeeded only in messing up the hex slot in the plug. My plug was stuck and I don't have a M22x1.25 tap to remove it, so I took it to the old timer machinist over the bridge to drill it out for me. $20 later I have a nice crank with very little stuck in the sludge trap.

I used a special factory tool to clean out the big pieces of sludge. Chemical cleaning with a brass brush will happen later.

Not bad for a utensil

Digging into the Guzzi part IV - end

Had some time to completely finish stripping the Guzzi this morning, what a beautiful machine.

The brass drain plug was super seized. I tried using an impact gun on it, but all that did was round out the head. Next I ground down the edges to use my long 19mm wrench on it, and that couldn't break it. Since I'm going to be getting a new plug anyway and I needed the oil out, I drilled right through, drained the oil, and will be dealing with that plug later.

Sludgy...

Oil strainer, feed lines, and pump. Looking pretty clean.

 Oil pump gears look good too, but I'll still need to measure the lash to make sure it's still in spec.

Con-rod bearings. No scoring I can feel with my fingertips, but don't look fantastic either. I foresee Plastigauge in my future and possibly new bearings.

Cam and lifters look to be in great shape, not pitting or scoring.

Rear crankshaft bearing removal

The crank looks to be in excellent shape, webbing and pins show no scoring or visible wear

Sludge trap, and the reason I did all this work. Don't have time to open it up and clean it out today, so to be continued on whether or not the complete tear down was worth it.

Engine internals, it looks like there's a lot more than there really is

Next up is the eventual sludge trap cleaning, cylinder Nikasil plating, head cleanup and eventual reassembly.