Gregory Bender

Alignment of the engine to the transmission

Updated:

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Credits

Right up front I want to give credit to several people who went out of their way to help me figure this out (listed alphabetically by last name). Each of these people were instrumental in providing help and ideas, not to mention the numerous phone conversations and e-mail communications discussing this tedious issue. Thank you, gentlemen.

Background

It was in Guzziology (version 5.2, chapter 9, page 13) that I first read about improper alignment between the engine and transmission and the resulting clutch problems that arise. According to Dave Richardson, Bob Nolan discovered that some engines and transmissions are not properly aligned from the factory. This mis-alignment forces the clutch plates to be in constant non-concentric motion, thus leading to very rapid clutch wear. Bob created an alignment jig that allowed him to test for mis-alignment and to also correct it by re-drilling the holes for the alignment dowels (using over-sized dowel pins).

From anecdotal stories, I'd believed this problem to only affect some of the late 850 GT, 850 GT California, Eldorado, and 850 California Police motorcycles (as well as early Tonti-framed models).

The problem

However, I had never encountered this issue myself until I was asked to solve a very troublesome problem on a 1968 V700.

The V700 had an original V700 engine and original all straight cut 4 speed transmission. To the best of my knowledge, this V700 came from the factory with the engine and transmission that was in it when I first saw it. The owner complained of a very loud bird-chirping noise that would go away - only momentarily - when the clutch was dis-engaged and then re-engaged. The bird chirping noise was audible in all gears, though it was much more audible when the transmission was in neutral. The owner had previously installed new clutch components (three times) and the problem had not resurfaced until several hundred miles down the road.

The investigation

When I received the motorcycle I immediately confirmed the bird-chirping noise. It was loud. Very audible even with a helmet on and ear plugs inserted. It sounded like dry metal rubbing on dry metal and, indeed, resembled the chirping of a bird. Something was definitely wrong.

I did all the usual checks to try to rule out the easy possibilities:

None of these tests made any difference in the bird chirping sound. Next, I removed the starter and directed a spray of WD-40 on the clutch input hub. Immediately upon start up, the bird chirping was gone. Aha! The splined interface between the clutch input hub and the clutch plates is what is causing the problem. But why?

I removed the engine and transmission from the frame and disassembled the clutch assembly, carefully inspecting and meticulously measuring each part as I went (even measuring the depth of each spring recess in the pressure plate and flywheel). I could detect no problems with the ring gear, flywheel, pressure plate, springs, or pressure plate cup. The clutch input hub, clutch plates, and intermediate plate, on the other hand, did show signs of wear (and all of these parts were brand new only 2,500 miles earlier).

Tests for alignment

I contacted Greg Field because I knew he and Bob Nolan are friends. I wondered if Greg could contact Bob for me and see if I could get some information on the alignment jig, or even borrow it. Since Bob is in poor health, Greg suggested I'd have better luck contacting George Dockray up in British Columbia, Canada. George had previously borrowed Bob's jig and had made a copy. A couple of quick e-mails with George and the jig was sitting on my workbench ready to test.

George's jig was set up to work with a clutch input hub having 4 mm deep splines. Since 4 mm deep splined clutch input hubs are exceedingly rare for 4 speed transmissions, I took George's jig down to my machinist and had him make a copy that would work on both 2 mm and 4 mm deep spline clutch input hubs. Essentially, the jig is bolted to the flywheel (centered by the design of the jig) and then the clutch input hub (connected to the transmission) is placed inside the other end of the jig. I found this easiest to do with the bell housing studs removed and the engine resting on it's nose (bell-housing facing up).

Clutch input hub side. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.
Clutch input hub side. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.

Photo courtesy of Gregory Bender.

Flywheel side. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.
Flywheel side. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.

Photo courtesy of Gregory Bender.

Removable ring allows fitment on 2 mm and 4 mm splines. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.
Removable ring allows fitment on 2 mm and 4 mm splines. My copy of George Dockray's alignment jig, which is a copy of Bob Nolan's alignment jig. Used for testing and setting concentric alignment between the engine and transmission on Moto Guzzi big twin motorcycles.

Photo courtesy of Gregory Bender.

Perhaps I wasn't using the jig properly, but I could determine no misalignment between the engine and the transmission using it. I know Bob and George have used theirs successfully, but I was unable to do so.

So, I came up with my own means of testing for alignment between the engine and transmission. Please note that my method only checks for alignment, it does not enable correction.

I repeated this test numerous times until I was very confident in the technique and the results I achieved. I made four tests as pictured below. You may notice some size and scale differences in the photos below. You may also notice that some of the single points are larger than others - that is primarily due to the transfer punch being pushed closer into the masking tape. Rest assured the resolutions you are viewing are much larger than normal and that the single points really are single points.

Test 1: original V700 engine with the original V700 transmission

This was the first test I performed. Note the mark is a circle when it should be a single point. The diameter of the circle is 1.5 mm.

Moto Guzzi engine-to-transmission alignment test 1: original V700 engine with the original V700 transmission
Moto Guzzi engine-to-transmission alignment test 1: original V700 engine with the original V700 transmission

Photo courtesy of Gregory Bender.

Test 2: Quota engine with the Quota transmission

My Quota was conveniently disassembled at the same time for some work. I was thrilled to find a single point.

Moto Guzzi engine-to-transmission alignment test 2: Quota engine with the Quota transmission
Moto Guzzi engine-to-transmission alignment test 2: Quota engine with the Quota transmission

Photo courtesy of Gregory Bender.

Test 3: original V700 engine with another 4 speed transmission

I had another 4 speed transmission sitting on the shelf. I bolted it up for a test and found a single point.

Moto Guzzi engine-to-transmission alignment test 3: original V700 engine with another 4 speed transmission
Moto Guzzi engine-to-transmission alignment test 3: original V700 engine with another 4 speed transmission

Photo courtesy of Gregory Bender.

Test 4: original V700 engine with the Quota transmission

For grins, I bolted up my Quota transmission and found another single point.

Moto Guzzi engine-to-transmission alignment test 4: original V700 engine with the Quota transmission
Moto Guzzi engine-to-transmission alignment test 4: original V700 engine with the Quota transmission

Photo courtesy of Gregory Bender.

Aha! I learned something. First off, I learned that the original V700 engine is not aligned properly with the original V700 transmission. Good, we have a cause for all the trouble. Second, I learned that other transmissions align properly with the original V700 engine. This means the culprit is the original V700 transmission, and not the original engine. From this limited data, I would guess that the Moto Guzzi factory drilled all of the engine cases the same, then later aligned each transmission to the engine. This is only a guess, but it seems to follow the data.

Time to fix the problem

I suppose I could have hired a machinist to figure out how to align, drill, and fit over-sized dowel pins (I knew that sort of accuracy was beyond my skill level). That would be expensive and that there was a very real chance of error. Instead, I sourced a good used 4 speed transmission case from Charlie Mullendore of Antietam Classic Cycle. After checking that transmission case for alignment with the original V700 engine, I sent the original transmission and the replacement transmission case to Charley Cole at Zydeco Racing for transfer of the innards, proper set up, and shimming.

What I don't know

What I didn't learn in all of this is the root cause of the mis-alignment. Sure, I believe the root cause is with the transmission. However, I do not know if the mis-alignment is due to:

  1. Parallelism between the crankshaft and the clutch shaft. That is, both shafts rotate in parallel axis, but are simply rotating non-concentric.
  2. Non-parallelism between the crankshaft and the clutch shaft. That is, the shafts do not rotate in parallel. Given the pattern of wear on the clutch input hub, I suspect this may be the case.
  3. A combination of parallelism and non-parallelism between the crankshaft and the clutch shaft