Jump to content
The mkiv Supra Owners Club

Transmission Gear Retaining Ring.


pedrosixfour

Recommended Posts

Hi folks.

 

I'm doing a rebuild on a W58 at the moment with a full synchro ring, seal and bearing kit.

 

I've also had to track down a used but sound output shaft as the original one in my gearbox failed.

 

I've noticed that the 3rd gear retaining ring and groove is of a piss-poor design on the output shaft and will undoubtedly fail with track use as per my original shaft. The sourced shaft is already showing signs of fatigue and the job is not worth doing unless a better way of securing the gear can be found.

 

The problem lies in the strength of the groove wall. The groove is cut into the splines, as is usually the case. But instead of continuing the cut into the solid inner section of the shaft where the wall could better deal with the axial loading of a down-shift Toyota thought it best to stop short of even cutting to the bottom of the splined section. This leaves the snap ring bearing down on a considerably reduced amount of material which over time simply breaks away from the shaft allowing third gear to wander.

 

I've decided to try to remedy this problem by deepening the groove by about 1.5mm into the shaft and getting a snap ring of a suitable size to suit the modification.

 

The original snap ring dimensions are 36mm O.D., 28mm I.D. and a thickness of 2.05mm.

 

The new snap ring would need to be 36mm O.D., 25mm I.D. and a wall thickness of 2.05mm.

 

Can anyone recommend a source for a snap ring of such dimensions, are they even available in this size?

 

Any help would be greatly appreciated.

 

Regards,

Damien.

Link to comment
Share on other sites

Is it a true snap ring, without "ears"? I would certainly source a suitable one *BEFORE* re machining the groove :) I have never had cause to buy none OE snap rings, but will have a look around for you.

 

Yes Chris, it is of the "ear-less" variety.

 

I believe they might be described as an Eaton Snap Ring, a very solid design with a gap betwen the two ends which are finished in a point at the outside edge of the material, although with my very limited knowledge of the subject matter this may be a false lead.

 

I was indeed committed to sourcing a suitable snap ring prior to machining the shaft, any other approach would surely spell disaster. But the internal diameter is fairly restricted to the 25mm/1" area. Much less and the splines are a factor once again, much more and I fear I'll weaken the shaft.

 

But any help is greatly appreciated, I'm going out to check local engineering shops and suppliers myself today but I don't hold out much hope of returning with what I need.

 

Here is a poor rendition of what the snap ring looks like, obviously it is not to any scale you could think of!

 

attachment.php?attachmentid=130172&d=1302509912

 

Regards,

Damien.

Snap ring.png

Link to comment
Share on other sites

I just got a reply from them, unfortunately the snap ring I'm after is outside their range of production.

 

I have a feeling its the radial depth of about 5.5mm thats going to prove difficult to overcome (and possibly to fit!).

 

Oh, to still have a lathe in the garage. Pesky fire!

 

I'm going to head into the excuse for a commercial hub we have in this neck of the woods and attepmt to find intelligent life behind a few trade counters.

Link to comment
Share on other sites

I personally doubt a circlip of that wall depth (OD minus ID) will be able to be "sprung" open enough to get it over the OD of the shaft. Is there any way a mechanically locked clamp (two half circles with tiny cap heads clamping them together perhaps) be used? Or spacer tubes?

 

I had come to the same conclusion myself Chris but was going to make damn sure before I headed down the locking collar route.

 

Because of the way that the input shaft and output shaft are designed and positioned there is very little spare room for anything elaborate to be used but I do have one or two ideas floating around that may need further consideration if the mutant snap ring idea is a non-runner.

 

I'm not sure I'm familiar with spacer tubes or how they might be of service to be honest.

Link to comment
Share on other sites

hi mate. how were the donar parts? all useable i hope?

 

They sure are buddy, I'm just trying to engineer out some of the sloppy design flaws left by Toyota in their rush to produce new cars with sticking accelerators!

 

This way I might get a bit longer out of this gearshaft than the old one.

Link to comment
Share on other sites

They sure are buddy, I'm just trying to engineer out some of the sloppy design flaws left by Toyota in their rush to produce new cars with sticking accelerators!

 

This way I might get a bit longer out of this gearshaft than the old one.

 

thats good to know. id love a stronger w58 because the feel and operation are real good

Link to comment
Share on other sites

thats good to know. id love a stronger w58 because the feel and operation are real good

 

Tell me about it, there is very little point lugging gears around that will never be used at Mondello or Kirkistown so a 6 speed is not really the answer and PPG want nearly £7,000 for an uprated gearset to suit the W58 casing! I smell an R154 in the pipeline.

 

But in the meantime I've been to a quirky little workshop in the middle of nowhere that specialises in gearbox repair and rebuilds and after sifting through 2 big boxes of countless snap rings I've uncovered two that will possibly solve the third gear retention problem.

 

The snap ring I will probably end up using is not quite of the dimensions I was looing for but I feel the compromise is more an acknowledgement of the fact that I was looking for something that actually doesn't exist.

 

Anyway once I grind the groove down to the required depth to suit this new snap ring the load will be better spread over the entire height of the splined section of the shaft while the slightly reduced overall diameter of the ring is still sufficent enough to take the loading of the gear and clutch hub at their strongest point, just outside the splines.

 

Thats the theory anyway.

 

Now all I need to do is fashion a jig to hold a grinder with 3 x 1mm cutting disks on it parallel to the output shaft which will need to rotate freely in a couple of bearings all the while being able to alter the distance between grinder and shaft in very precise increments and fighting the urge to look away!

 

Stand by for the result!

Edited by pedrosixfour (see edit history)
Link to comment
Share on other sites

Success!:)

 

Of sorts.

 

After resigning myself to using a retaining ring of sane proportions the next step was to tackle the groove on the shaft to suit the new ring.

 

In order to do this with any degree of accuracy the shaft needed to be held firmly but still rotate freely while a grinder steadily nibbled away at it.

 

So here is what was spawned this morning. :)

 

attachment.php?attachmentid=130532&d=1302879940

 

attachment.php?attachmentid=130533&d=1302879940

 

attachment.php?attachmentid=130534&d=1302879940

 

attachment.php?attachmentid=130537&d=1302879976

 

attachment.php?attachmentid=130535&d=1302879940

 

attachment.php?attachmentid=130536&d=1302879976

 

Using 3 x 1mm cutting disks together gave me the desired 3mm cut so there was no need to keep repositioning the grinder again and again to get the groove width right.

 

I've test fitted the new ring and there is plenty of tension on it and the groove now extends a couple of thou below the splined section while still having a decent outside diameter to hold back third gear. Its still not ideal but its certainly better than before.

 

Now to put it all back together.:(

 

This should be fun.:blink:

001.JPG

002.JPG

003.JPG

005.JPG

007.JPG

008.JPG

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.