Double Thrust Cam Bearings

[Deefer66]

Newbie here so be gentle....

Been a long time (according to a search) since this was raised as a question...

Is it worth it?
Are people just getting two sets of shells to get two thrust halves?
Why bother putting a tang on it when the thrust sides hold it in place anyway?..(edit. ...ah! rotation.. from another place)




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[Wally]

If you run the spring pressure (like CB650 onwards) to need a double set, you'd better convert to straigth cam gears imo.
Thats what I did eventually on the 9K RPM engine

[Deefer66]

It's pushing a bus so I've only gone 73/86 on the cam , not much extra lift but gone for Scat HD springs / stock gears as I'm not reving much past 4000 (most of the time ) just thinking double thrust as insurance

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[Clatter]

FWIW, the cam thrust eating itself has been the first thing to go on engines built by experienced builders.
I have found the cam thrust growing more quickly than would be imagined.

A common culprit is a rough face or edge on the thrust area of the cam itself.
Unless you polish it mirror-smooth,
it can eat the bearing.

Some have suggested that the cam blank itself having porosity could contribute.

That being said, a second thrust bearing couldn't hurt if you want the motor together for a long time,

[Deefer66]

The WBX double thrust bearings seem to slip in nicely with only a minor case mod

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[raygreenwood]

Take a look at this thread. Yes....they are worth doing.

https://www.thesamba.com/vw/forum/viewt ... p?t=694420

Ray

[Deefer66]

Take a look at this thread. Yes....they are worth doing.

https://www.thesamba.com/vw/forum/viewt ... p?t=694420

Ray

Thanks Ray,
Yes read that a few times, think my install went quite easy compared to yours must have been lucky!.
Making a quick mod to the case was easy compared to punching a cam bearing, I'd be scared of deforming it. The waterbox double set come nicely chamfered at the meeting points ready too. Almost made play with just the end hammering just needed a little wipe on some oiled 600 grit to make it.

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[raygreenwood]

Take a look at this thread. Yes....they are worth doing.

https://www.thesamba.com/vw/forum/viewt ... p?t=694420

Ray

Thanks Ray,
Yes read that a few times, think my install went quite easy compared to yours must have been lucky!.
Making a quick mod to the case was easy compared to punching a cam bearing, I'd be scared of deforming it. The waterbox double set come nicely chamfered at the meeting points ready too. Almost made play with just the end hammering just needed a little wipe on some oiled 600 grit to make it.

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Yep....mine was not actually that hard. It just looked hard from all of the detail I included in the build tread...which I mainly included to help people know what to look for when adding the second thrust shell does not instantly roll smooth...which is rare.

A lot of the data on what distorts and why....is mainly so people understand that they need to "rap" the cam to set the parallel edges and thrust flange...and what is actually distorting when you close the case....or WHY you need to do this adjustment in the first place.

There are too many people who think this mod is a waste of time...and just as many that do not understand why its not just a "load it in and button it up" mod.

There are also too many people who are cheap....and wont buy a good set of already modified double thrust bearings like from the type 4 store....or like your waterbox bearings...or even a while back Aircooled.net sold a set.

The person I am building the engine for is NOT cheap. I only ask for exactly what is required and he never balks. Great guy!
We could have just as easily bought a set from the type 4 store and been done with it....but I had several sets of cam bearings...good ones...including what he sent me which are NOS...and knowing how to do this correctly....I though I would and also be able to teach the "cheap" people how to do it at the same time Ray