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Jon,
I really do appreciate the advice but we already make a diff with 2 x different angles machined into the ramp drivers and can custom manufacture any angles that are wanted.
The diff has 6 plates per side in total and does use a Belville for the preload.
As standard we set them to around 35 lbsft but we can increase this if needed.
The torque we always measure is the sliding value rather then the release value as we find that this is more consistent during bench testing and is more appropriate to the diff's function.
We are trying to design a system that will allow external preload adjustment without copying the system used by Drexler but it is quite tricky. Drexler 901 units currently cost around $3750
Our experience with the 88mm diff that we used in Ford Rally Cars has been that wave plates generally seem to offer more consistent characteristics and hold preload for longer than Belville's and the majority of the 'Atlas' diffs used in Escorts use these plates.
The first diffs used in the Factory Fords all had wave plates and this didn't change until the introduction of the 2.8 litre V6 Capri which seems to have used a diff that had been more aggressively cost engineered.
We are going to try a 904 diff with Belville's but I have a client that wants to use Wave Plates and is quite insistent.
I would much prefer to sell him one of our new units that has a Chromoly Body, no welds and a complete back up service in terms of spares but.... he is the customer :)
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Very nice, Chris :-)
Which axle flanges does this unit accept?
I agree with you on the "sliding value", measured with a torque meter and not the type of torque wrench shown in the Porsche manual.
Jon B.
Vista, CA
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We normally use a dial indicating torque wrench but I would really like to build an inverter driven test stand and measure just how the diffs bias torque with varying wheel speeds but to cost is just too great compared to the number of diffs we are able to sell.
We supply them to suit Lobro's generally but we can make adapters to suit Nadellas if needed.
We recently refurbished some competition style Nadellas
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We also made a small batch of Grade 5 Titanium Hub Nuts with washers made from 17-4PH Stainless Steel hardened to 42HRC and A4 cotter pins.
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Can I assume the preload is measured from flange to flange and not body to flange.
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3 Attachment(s)
Gordon, the test method shown in the manuals was to hold either the differential housing or one axle flange in a vise, and then apply torque to a free flange.
Once enough torque is applied to slip the clutches, you'll achieve rotation. The torque needed to achieve or maintain rotation should be within the factory recommended range.
The early manuals illustrate the test using pre-set click type wrenches, but it's more accurate to use a torque meter, or a beam or indicating wrench.
Factory manual test from 1970
Attachment 435751
Factory manual test from 1976
Attachment 435752
A suitable torque meter
Attachment 435753
Jon B.
Vista, CA
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Been using torque meter, flange to flange for 30 yrs, just curious. Never used housing to flange method as damage to ring mounting surface seemed inevitable. G
