ET: Engine (Twin) Modified ET77 Oil Scroll

[LoneStar]

Hello all,

I'm trying to assemble the crankshaft into the crankcases for my Rapide project, but it won't fit. This turns out to be due, as is often the case, to my overlooking something. On the drive side, I'm using a full-width ET92 mainshaft roller bearing - rather than the special narrower one that was standard. This requires a modified ET19/1 main bearing spacer to match, which I duly bought and installed.

However, it also requires a special ET77 main bearing distance piece, aka oil scroll. This I had not noticed, so the original was in place - causing the difficulty. My local supplier is out of stock on the modified ET77, which leads me to my questions:

- Does anyone know the exact width of the modified ET77?

- Is there any reason the standard one can't be machined down to that width?

Thanks,

 

[Simon Dinsdale]

I have fitted a few of these modified ET19/1 and they all use the standard ET77 spacer/ scroll. Reducing the width of the ET77 scroll will move the crank and conrods sideways in the crankcase. I have never heard of a modified narrower ET77 scroll. VOCS sell both types of ET19 main bearing spacers but only sell the standard ET77 scroll which is used with both types of spacer.
I suspect your problem is elsewhere.

Both ET19 & ET19/1 are exactly the same width in the area where the scroll ET77 fits. The difference is ET19/1 is narrower on the area where the outer track of the roller main bearing fits to allow for using a full width bearing.

ET19:

ET19/1:

 

[Simon Dinsdale]

As you are in USA I just looked up the parts list from Coventry Spares in USA. I see they sell two types of ET77 scroll. the standard one MET77 and also MET77/2M which says for use with MET19MOD. Now this mod is to use a rubber lipped oil seal rather than the scroll and for that you need a special ET19 which is not the type for use with the full width main bearing. Note the M in front of the part numbers just means the part was made by Maughans.

Looks like you are getting different parts from different modifications mixed up.

 

[Bill Thomas]

Just what I was going to say,
The inner bearing must be in the same place,
Have you tried the inner bearing in the outer,
Sometimes if too tight in the cases , The inners won't go in ?,
The big inner bearing , Roller is tricky to slide in sometimes,
The rollers can tip ?, And jam ?,
I poke a long thin screw driver down from above to get them started in .

 

[LoneStar]

Looks like you are getting different parts from different modifications mixed up.

Thanks for the informed replies!

Yes, my assumption that ET77 was to blame was based on the incorrect belief that there was only one ET19 variant, for a wider bearing, and that it required a different ET77 - which is listed by Coventry. But they are reasonably clear in saying it is for MET19MOD, rather than MET19/1.

I understand the unusual feature in the original ET92 main roller bearing is that its outer race is narrower than the inner, with both races the same width in the more common version. The ET77 scroll, adjacent to the inner race, logically would not be different for the two bearings.

So, some other issue exists. The crank settles into the DS case nicely, and the rollers seem engaged - it spins smoothly. But after installing the TS case, and tightening the bolts, the big end rubs against the TS case.

I take this to mean the crankshaft is positioned too far right in the DS case. As I work it out, this position is determined by:

• outer circlip ET125
• inner race of ball bearing E91
• ET77 oil scroll
• inner race of roller bearing ET92

So, one or more of these must be in the wrong position or the wrong width. Does this seem sound, or am I missing something?

Thanks,

 

[Bill Thomas]

Sometimes with a 1.1/4" Big end, The nuts make it too wide,
My first one, George Brown ground the nuts down a bit ,
Other people leave them ,
The other thing is if the raised bit on the flywheel has worn down,
Where the main bearing inner has been spinning,
The flywheels will be too far over on the drive side when the shocker is done tight ?.

 

[clevtrev]

Have you the shock assy in place and the mainshaft nut done up tight ?

 

[Simon Dinsdale]

I take this to mean the crankshaft is positioned too far right in the DS case. As I work it out, this position is determined by:

• outer circlip ET125
• inner race of ball bearing E91
• ET77 oil scroll
• inner race of roller bearing ET92

So, one or more of these must be in the wrong position or the wrong width. Does this seem sound, or am I missing something?

Thanks,

Have you missed the 2nd circlip ET125 that sits between the ball bearing ET91 and the ET19 main bearing spacer?
I grabbed this picture from Vincent.com website:

 

[Robert Watson]

He says on assembly the crank rubs the TIMING side case. most responses are trying to move the crank toward the TS case.

I am in the process of doing exactly that same job. I made some acetal spacers in lieu of using the bearings and then having possibly to remove them after checking the rods for being central in the cylinders. The spacers I made a .750 wide with a 1/6 step at the outer edge on each side so they emulate the fact that he rollers are not as wide as the inner race. so, its this, Crank face, .750 bearing simulator, oil scroll inside the spacer and then bearing up tight against the inner snap ring.

Only thing I can see as an issue is if your spacer ET19 is too wide or not up hard against the inner snap ring. With the wider outer race (3/4 in not 5/8 in) you would need the thinner ET19 then the flywheels could be contacting the outer race on the DS and not allowing the crank to move fully to the DS, hence also contacting the TS.

To check this you could just put the PD 2 and the PD4 in place and turn the nut PD7 around which will then allow you to pull the whole plot tight, and see if the crank is binding on the DS.

Robert

 

[LoneStar]

Thanks for the comments!

- From the scraping marks on the TS case, I worked out that it's an area of the end of the big end itself, slightly proud of the nut, rather than the nut which is contacting.

- No, the primary drive components aren't in place. It appears the mainshaft nut PD7 clamps a stack composed of PD8, PD4, PD2, ET91 inner race, ET77, ET92 inner race and the flywheel. The crank position relative to the case is determined by ET91, fixed between the two ET125 circlips. Having PD7 tight could affect crank position only by removing (unwanted) clearance between ET91 inner race, ET77 and ET92 inner race - this doesn't seem to exist. ET77 slides freely on the shaft, and doesn't bind on ET19; the ET92 inner rollers move freely in their outer race.

- I verified that both ET125 circlips are in place, and there's no apparent clearance between the inner ET125 and the ET91 outer race.

- I measured the width of my ET77 oil scroll: .4525"; not sure if this is right, but don't see how it could be wrong.

- ET92 and ET91 inner races are both .75" wide.

- ET19/1 was sourced from Maughan. With the crank held in place by gravity (shaft vertical) in the DS case, there is no sign of rubbing when rotating it. Might be worth installing and tightening the primary components to check further.

- Is it possible ET19/1 is in backwards? Is it asymmetrical, and the outer recess needs to face ET92? I may want to pull it, examine and measure.