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Thread: Pre-Purchase: 32V SR16VE Helical LSD

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Posts: 81-90 of 438
2013-10-02 16:41:16
#81
In the December-May timeframe I'd be able to test the diff in low friction circumstances, but that won't show anything about how much power it'll hold, so I'm not a good candidate to be the tester.
2013-10-02 16:56:03
#82
Originally Posted by Vector
Originally Posted by MFactory
Note: To save costs, you would reuse the bottom part of your oem viscous LSD (it is made redundant anyway).


Interesting. This may actually address one of the issues I face using a helical style in rally. On a typical helical setup, if one wheel has near 0 traction (e.g. in the air, on wet ice), the other will not get any torque (since it's a proportional thing). In that situation, if there were to be the VLSD unit still in place, it would, I expect, act like a stock VLSD diff and send more power to the wheel with traction.

That assumes that the VLSD is behaving and not entirely burned out like mine is, but still. Seems like benefits beyond cost savings. Well done.


I don't believe any of the guts of the VLSD will exist at all I believe it will just be a housing we swap the Helical guts into if im correct, I haven't taken a VLSD apart yet.
Last edited by UNISA JECS on 2013-10-02 at 17-13-31.
2013-10-02 17:11:42
#83
Originally Posted by Dave_SR20
Good stuff. What would be the torque to reattach that bottom part?


Originally Posted by MFactory
I'll need to double check with our engineer that disassembled the oem unit, but most bolts for the diffs generally are torqued to anywhere between 75-85lb


Note how much less torque the VLSD units has compared to the non-VLSD unit

2013-10-02 17:20:03
#84
The diagram you just posted (though for a 70V) shows why this would work the way I think. The unit labeled #16 is the entire VLSD setup, and if you transfer that over to the new unit from MFactory, it's going to continue to act as a VLSD. Look at their diagram and see how it replaces part #5.

It makes sense though that the machine screw holding the VLSD unit to the main differential would use a lower torque. I would expect that you would use the same torque as factory for the VLSD to differential case connections, and then on top of that the final gear is what really bolts everything together.
2013-10-02 17:42:33
#85
Originally Posted by Dave_SR20
Good stuff. What would be the torque to reattach that bottom part?


Originally Posted by MFactory
I'll need to double check with our engineer that disassembled the oem unit, but most bolts for the diffs generally are torqued to anywhere between 75-85lb


Originally Posted by Vector
The diagram you just posted (though for a 70V) shows why this would work the way I think. The unit labeled #16 is the entire VLSD setup, and if you transfer that over to the new unit from MFactory, it's going to continue to act as a VLSD. Look at their diagram and see how it replaces part #5.

It makes sense though that the machine screw holding the VLSD unit to the main differential would use a lower torque. I would expect that you would use the same torque as factory for the VLSD to differential case connections, and then on top of that the final gear is what really bolts everything together.


I see now what your saying now but since part of the diff is going to be new were going to have to some re-shimming (thrust washer) wouldn't we on our end?

2013-10-02 18:18:28
#86
Yes, you would need to measure the back-lash between the diff and the viscous coupling and adjust the shim size so that it stays within the correct tolerance (you need to do this with any LSD install regardless of make/model of car; it doesn't only apply to this).

I agree, it is interesting that the viscous coupling can still be retained and used (of how much use it will be though, considering it is now coupled to an LSD and not an open-diff, I'm uncertain).

Does anyone know the bearing part number for the carrier taper bearings (No. 2/3 & 8/9 in the diagram posted above)? Not the oem part number, but the bearing part number that is etched onto the bearing surface? I want to see if I can source these bearings as well. If I can, and they are not ridiculously expensive, I will include a set of these FOC as well, seeing as it is best to replace diff bearings anyway whenever you install a new LSD
Last edited by MFactory on 2013-10-02 at 18-20-20.
2013-10-02 18:29:56
#87
Originally Posted by UNISA
Originally Posted by Dave_SR20
Good stuff. What would be the torque to reattach that bottom part?


Originally Posted by MFactory
I'll need to double check with our engineer that disassembled the oem unit, but most bolts for the diffs generally are torqued to anywhere between 75-85lb


Note how much less torque the VLSD units has compared to the non-VLSD unit



If the service manual says only 67lbs is required for the ring gear bolts, then that is all that you should use

The 32A uses only 8 bolts, whereas the 32V uses 14 bolts, so I'm not too surprised of the torque difference.
Last edited by MFactory on 2013-10-02 at 18-32-36.
2013-10-02 19:57:09
#88
Originally Posted by MFactory
I agree, it is interesting that the viscous coupling can still be retained and used (of how much use it will be though, considering it is now coupled to an LSD and not an open-diff, I'm uncertain).


Because a helical diff is a torque-biasing diff, it would come into play only when one wheel had very little to no traction. Then I imagine it would act pretty much like a standard 32V VLSD. From a theoretical perspective, that sounds great. In practice it'll depend on the condition of the VLSD, and most of these are well past their prime, and I know of no "new" source.

Does anyone know the bearing part number for the carrier taper bearings (No. 2/3 & 8/9 in the diagram posted above)? Not the oem part number, but the bearing part number that is etched onto the bearing surface? I want to see if I can source these bearings as well. If I can, and they are not ridiculously expensive, I will include a set of these FOC as well, seeing as it is best to replace diff bearings anyway whenever you install a new LSD


That would be great. I did leave the bearings on the unit I sent to you, so you may find you already have them. My only other diff is in the rally car.
2013-10-02 20:04:52
#89
nevermind then. Let me check the bearing tomorrow
2013-10-03 16:21:49
#90
On a slightly different note, does anyone know if the pinion (countershaft) in the 32V and 32A are the same, and is only the ring gear that is different?
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