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Discussion Starter · #1 ·
Can anyone describe or provide pictures of the differences in the C clip retaining recess dimensions between the IRS Traction Lok spider side gears and a conventional straight axle Traction Lok spider side gear recess?

I understand the later 8.8 posi units are the same... but "early" 8.8 differential used two different gear styles.

Anyone know what year Ford went to the newer "one size fits all" side gear?

I just received a replacement traction lok differential out of a Mustang of unknown year and before taking my non posi IRS differential appart I wanted to collect all needed parts to make the switch and until recently did not realize there might be a difference in the side gears.

Any experience or insight would be appreciated.

Thanks.

Kerry
 

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Kerry believe the difference will be in the amount of splines on the axle that would also mean a different amount on the inside of the gears. Need to count how many splines on each as one will be slightly larger then the other. 28-31
 

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Kerry,

There is some definite differences in the side gears between the 2.

1) the lead in bore (from the outside of t-loc) is .030" bigger in diameter, and also has more lead in angle at the start of the splines. It also has a good sized chamfer at the very beginning of the bore too.

2) there is a retaining seat cut into the inside edge of the splines (gear side) of 1.235" dia. X .100 deep to retain the splined shaft with the clip.

If you remove the retaining clip you can use it in a regular Mustang t-loc, but I'm not sure if it is a safety issue without the retention clip. It seems as though the halfshafts are captive, so it shouldn't really matter, but obviously for liability reasons, I'd never recommend running without the correct setup.

Brian
 

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Discussion Starter · #4 ·
Mickey... I am not referring to a change in axle splines. Both side gears are 28 spline.

Brian,
Thanks for the info. I may consider remachining the recess of the standard Mustang side gears to match that if the Mark VIII IRS once I have the gears out.

Kerry
 

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Kerry,

I'm currently working on that myself, since the correct trac-locs are getting difficult to find, and I have close to a dozen regular t-locs. Just know that the gears are super hard, so they may need to be ID ground rather than conventional lathe boring methods. I had too much deflection with standard carbide boring bars to even touch the ID on the one I tried. I just ordered a new stronger carbide boring bar,, so we'll see how that goes.

Brian
 

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Discussion Starter · #6 ·
Brian,

I retired four years ago from Kennametal after 24 years as a Senior Tooling Systems Engineer assigned to tactical aircraft manufacture.

You can successfully turn or face case hardened workpieces using Cubic Boron Nitride, Kyon, and Aluminum Oxide coated carbide. Even PCD (Polycrystaline Diamond) will work although technically it is a mis application on steel.
My choice would be the Aluminum Oxide PVD coated carbide. It is more redily available in the geometry, top rakes and edge configuration you want. The CBN, Kyon and PCD inserts are usually negative rake for strength and are MUCH more expensive.

As you have already learned, deflection can be a problem, but you may not need a carbide bar. The trick will be to use the largest steel bar you can obtain that will still radially clear the I.D. of the shallow bore. The key is to extend the bar as little as possible. Mount the bar so that no more than the depth of the I.D to be machined plus MINIMUM clearance between the bar and workpiece. Even if you have to modify the bar holding method...do it. It makes considerable difference. Even a 1" square shank turning tool might work if properly clearanced by hand.

Also be sure your lathe is up to the task. Be sure the gibs are tight and the machine / spindle / bearings are heavy enough.

Also, when turning, facing or boring hardened material, keep your depths of cut light, perhaps no more than .005 DOC and feedrates about .0015 - .003" / rev and be SURE to use a small nose radius insert of approximately .006-.008 if possible. Kennametal makes a NPR series 55 deg profiling insert that has this radius with ground positive top rake that would work well. The more common .015 radius may be too large and may generate chatter.

Don't use any cutting fluid or coolant. It will act like a lubricant at these light depths of cut and feedrates and will try to glaze the workpiece. Run it dry. It will work better.

Be sure that the insert chosen does not have negative top rake. A negative top rake is more likely to chatter. A neutral rake may work and will be a stronger cutting edge than a positive , but I would look for at least 3 deg positive top rake to as much as 15 deg positive top rake.

Also, be SURE to use an insert with NO HONE at the cutting edge. Avoid insert coatings identified as "CVD". (Chemical Vapor Deposition)
Instead look for coatings identified as "PVD" (Particle Vapor Deposition) Sometimes these may be referred to as "low temperature" coatings. But even with PVD coatings they may be honed. To insure a sharp edge, use an insert and try to "shave" material from your thumbnail. If the insert edge wants to slide across your thumbnail...it is probably honed. If you can cleanly generate white shavings off of your nail...the insert edge is considered "upsharp"...and that is what you want.

If you do run into chatter...try to regulate the harmonics by increasing or decreasing speed.

In the past I have machined flamed sprayed carbide 90-92 R(A) with indexable turning tools and maintained ""ground finishes" of less than 10 RMS...in production environments.

I hope I havent confused the issue with terms you may not be familiar with. ON the otherhand you may be an experienced machinist and this information is old hat...

LMK your results.

And thanks again for your help.

Kerry
 

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id be surprised if you cant find one. i sold mine when i went to torsen. which reminds me, rather than some custom hard-to-replace stuff in your car, you can get a torsen or similar!

im using a mark VIII case for my 8.8 IRS
 
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