091 clips for 3rd and 4th hub on 002 main shaft

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Bruce2
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091 clips for 3rd and 4th hub on 002 main shaft

Post by Bruce2 » Tue Sep 26, 2017 1:04 am

I don't think a how-to has been done for this modification. If it's been discussed, post the link (I couldn't find it).

Dave posted this in another topic:
dangerous wrote:
Tue Apr 15, 2014 2:57 pm
The 091 circlip is 1mm thicker, (approx. 2.5mm total thickness) so I always begin with a cut of 0.87 to 0.9mm on the 3rd gear side to get it close. Once the end float is set for 3rd, then do similar on the 4th gear side, bit by bit, so the clip is tight, width wise.

You must still check that you have enough end clearance on 4th with the hub pressed lightly against the 4th-side-circlip. By all means, centre the hub after this check, but on operation, it will always end up closing the gap on 4th, so make sure you have the end play in that thrusted position too.(no less than .004", for me never less than .006"!!)

3rd gear can have a little MORE play, since its helix will help pull it into gear, but 4th gear pulls away from the hub, so too much end play means the dog teeth have to work harder to keep engaged when the end play is large.
I bet Dave's lathe is a few steps from his work bench so it's easy for him to cut-n-check. My lathe is about 10km away, so does anyone use a predetermined amount of machining on the hub?

Casting Timmy
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Casting Timmy » Tue Sep 26, 2017 8:36 am

Good timing, I just recently went through this and talked about it with some guys on Facebook.

I premachine the third gear side a little so it sets up and goes better in the lathe. Then I use feeler gauges once third is set to measure between the hub and the end of the clip grove on the fourth gear side. Then measure the clip thickness to know how much to remove/ pocket on the fourth gear side.

David - Every job I do gets the 091 circlip mod, otherwise the hub moves toward 4th gear and 4th is too tight and 3rd has too much end float.
usually, once the mod is done, 4th has too much end float, so the shoulder has to be cut back, and a 2.6 to 2.8 corclip is used on the end to retain the bearing.

Tim - I do cut the third size a hair short for the first mockup as fourth does seem to grow on me a little.


Instead of a lathe why not use a counterbore tool with a custom pilot for a slip fit in the splines of the hub so it automatically centers? Or make a tool like a lifter radius tool for a VW engine case, except sized for the correct diameter of the clips?

I'll also work on posting a picture that shows how I do the calculations, that will be a lot better than me trying to explain without it.

Casting Timmy
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Casting Timmy » Tue Sep 26, 2017 8:53 am

When I go to cut this one I will probably shot for removing .009" or .010" instead of the full half of .0135". Fourth does tend to grow, so I cut it a few thousandths short and then check it, usually this makes it better than going for the full split. (Usually checking shows a even split)

Image

After this I measure between flat hub surface on the fourth gear side and measure the clip thickness, the difference is the amount to pocket fourth gear side to lock it in place. I do see variance with the 091 clips when it comes to thickness, maybe another solution would be grinding the clips to the right thickness.

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Pablo2
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Pablo2 » Tue Sep 26, 2017 9:48 am

The cut on 4th gear side needs to be angled, to allow easier removal of the circlip at rebuild time. The first time I did this mod, even though I angled the cut somewhat, I failed to allow enough leeway for easy removal and man, was it a bitch.
Last edited by Pablo2 on Tue Sep 26, 2017 6:13 pm, edited 1 time in total.
aka Pablo, gears, Geary
9.36 @ 146 in '86

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dangerous
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by dangerous » Tue Sep 26, 2017 5:03 pm

Bruce, I think if you just want to 'improve the situation' from stock,
then some round numbers can be used to make the situation 'better'.

But I doubt you could consistently end up with 'tight' retention of the hub,
unless you do the machining in a few steps, with trial assembly between.

Yes, the diameter of the recess on the 4th gear side needs to be larger
than on the 3rd gear side to enable clip-removal.
38mm on the 3rd gear side and 39mm on the 4th side, but I will confirm these numbers for you later.

edit: 37.1mm diameter on the 3rd gear side and 38.9mm diameter on the 4th gear side.

Knowing what you are trying to achieve,
I would leave the 3rd circlip alone, and just recess the 4th side to use the 091 clip,
and then on assembly, just make sure the hub is pressed lightly back toward the 4th gear side.
(because that IS where it will end up!)

Just as a guess, the 4th side recess would need to be around 0.75 to 0.8 deep, but you may have to develop a method/depth.

If you want to do both sides of the hub,
you could go 0.95 deep on the 3rd side to give yourself an extra 0.05 than what the 002 clip gives,
and then perhaps 0.8 to 0.9 on the 4th gear side.
My guess is, the hub will still have some clearance to the circlips
but at least you are reducing the chance of the 4th gear clearance closing up as much as with the 002 clips.

I will take some notes next time I do one and perhaps edit what I have written.

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Pablo2
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Pablo2 » Tue Sep 26, 2017 6:12 pm

The reason we got in the habit of machining both sides is that we often installed loose needles on 3rd gear side (more to fit low ratios than for "added strength"). The gapless circlips that allowed loose needles on circlip mainshafts only came in 1.25 thickness. Since the 002 circlip is 1.5 thick, the best way to accomplish what we wanted was to machine for 091 thickness and use 2 gapless clips.
aka Pablo, gears, Geary
9.36 @ 146 in '86

Bruce2
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Bruce2 » Tue Oct 03, 2017 1:10 am

Going to do the mod on 4th gear side only. Will let you know the result.
Casting Timmy wrote:
Tue Sep 26, 2017 8:36 am
... and a 2.6 to 2.8 corclip is used on the end to retain the bearing.
Where do you get the thicker clips?

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dangerous
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by dangerous » Wed Oct 04, 2017 6:42 am

they are 3rd gear circlips used on the end of the mainshaft. Weddle and Erco have all the sizes.

Casting Timmy
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by Casting Timmy » Mon Oct 23, 2017 7:21 am

When needing to run the thicker circlip on the end of the mainshaft, is that because you're using stock washers under the synchro cone when putting the 113 gears on the 002 shaft?

I recently did an 002 shaft with the 113 gears and used the conversion washers from Weddle, I ended up having to sand down the gears a little to get clearances where I wanted them. The extra thickness definitely adds and made it where I wasn't worried about adjusting lengths.

I've also been wondering why and how much it takes to move the hub. Does the hub move because of third gear thrusting into it? If the stock 002 clips allowed it to move, but lasted for a while in stock applications. What kind of power levels does this start making a difference?

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dangerous
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Re: 091 clips for 3rd and 4th hub on 002 main shaft

Post by dangerous » Mon Oct 30, 2017 10:33 pm

Yes the hub moves due to 3rd gear pushing against it. I see this even at stock power levels.
(which is why I do the 091 circlip conversion on ALL 002 shafts' stock rebuilds)

The thicker end-circlip is used AFTER you machine the bearing shoulder.
The bearing shoulder has to be machined
because in most cases the 4th gear has way too much end float,(after 3rd float is reduced).

The above is with reference to 002 style gears only.

I have used Weddle's special 113 washers,
and find they make the synchro sit a little high,
even when the gear has the correct end float on its own.
Last time I HAD, to use a worn out synchro because I had already welded the cone on!

For the conversion using the 113 gears on a 002 main shaft,
I only machine the hub enough in depth and diameter
to get the correct end float with unmodified-length 113 gears.
(just the counter bore diameter in the gears)

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