Seamless

Yes, yes, yes I read the very useful DIY on p-car after disassembly of the distributor. The emphasis on "pay attention to the order of the washers" is valid and clear

I have searched and found a few pics of exploded views which help, but and looking for the following:

1. The order of each washer (say, from top to bottom (A, C, B.... for example)
2. The location of the bearings in relation to the washers (say, between B & C for example).
3. The orientation of the Bellville washers (small dia up for down).

Any help would be great. Thanks.

IXLR8

Adam, there are some pics that may be helpful and a spreadsheet listing the dual distributor parts and their dimensions on my site.

The Belleville washer is installed small diameter down or towards the inner race of the angular contact bearing.

The thin shims vary from one dual distributor to the next and are chosen to obtain the proper pre-load on the bearings.

Seamless

This was my concern. I am not sure if these thin washers are mounted on the upper or lower side of the bearings. Ie, do they go on the shaft before or after each shaft is slid through the bearings?

Your site helps massively. Thank you.

IXLR8

They go just above the drive gear (the one driven by the engine) on the primary distributor and they go above the circlip on the secondary distributor (between the lower bearing and circlip).

CHJ

Alex:
How do you measure bearing preload and what are the specs?

Chuck

Seamless

Perfect, this is also what I recall during disassembly.

IXLR8

Chuck, I have no clue at the moment. I've been to the INA and other sites that show calculations, but I have to figure it all out. The tribology lab was right next to mine, but I am no longer there having taken early retirement.

The Belleville washer on each shaft acts as a spring to produce preload. The shims are there to "adjust" the preload. I have taken a few of these apart to rebuild them for local 993 owners and not all of them used the same number of shims and shim thicknesses. I'd sooner have a bit less than a bit more preload...obviously not so loose that you have bearing chatter or ***** sliding instead of rolling.

It is not an issue if you are reassembling the distributor using original parts.

As for RPM, the distributor runs at half the engine RPM, so about 3400 RPM maximum.

nine9six

Alex,
Could you not measure the bearing removed, and measure the new bearing to be installed; which should be the same, and not install the shims in the same order of disassembly?

It would seem to me, that the only time an adjustment would need to be made, is if the bearing measurement or stack-up of shims changed.

Is it a strain or pressure transducer gage used to measure preload on these things, which should preclude a successful DIY garage rebuild?

I also suppose a Belleville washer could lose/change its preload tension characteristics over time, yes? Also, there must be tolerances to the preload spec; as you know, there is no such thing as an absolute in this world

CHJ

Seems like those spacers would be effecting gear lash also.

Chuck

EckFe1

Maybe this will help?
Sorry but I don't have anything better. Looks like the smaller one's are gear side.

Seamless

Yes, that picture confirms my order.

With all of these pictures and very careful inspection of the washers (witness marks from neighbouring washers) I was able to reassemble everything perfectly. Bearings showed no signs of damage or wear. Cleaned and re-greased. Everything rotates smoothly. Just have to pickup a 1 1/4" frost plug.