Use a Subaru VLSD with VW CV Joints

[rpowell25]

Several factors drove the decision to perform this modification. First was the desire to use a LSD that had a 3.54 ratio based on a recommendation from the Experimental Engineering website (VG30.com). Second was to utilize the CV axles that had been fabricated for use with an open R160 per the article from DQ 9.3 which utilized the Mattndew adaptors.

 

Since the inner stub axles were going to be modified, it was determined that the dimensions should accommodate a direct bolt up of the inner CV joint and not require the adaptor. Please note that this modification will not work with the stock 510 half shafts; see DQ 9.4 for how to use a Subaru VLSD with stock 510 half shafts.

 

To achieve the stated goals the modification will utilize the inner stub shafts from a set of CV axles for a 1992 Subaru SVX (Figure A) and the outer stub axles for a Type 2 Volkswagen (Figure B). The pieces will be machined, mated, and welded to create a new inner stub axle that will allow the Type 2 CV joint to bolt directly to it. (Figure C)

 

Figure A

 

Figure B

 

Figure C

 

 

Differential was purchased from EBay for $150. Since these differentials tend not to come with the stub axles, they will need to be sourced and cost will vary. Be aware that the core charge for a set of axles can be significant so sourcing used is recommended. This particular project used axles purchased from a axle re-builder for a cost of $285. VW stubs were purchased from a local VW dismantler for $40. A local machine shop performed all of the fabrication for $95.

 

The first step is to shorten the VW stubs. The only part of interest is the flange itself though it was decide to leave the bearing surface part of the shaft in this instance.

 

 

All measurements are approximates and it was decided that a few millimeters each way would not be problem for the CV's to absorb. The first measurement was taken on the open diff with the Type 2 adaptors installed. Measuring from the side of the diff to the edge of the adaptor gives a distance of ~55mm. This is the dimension that will be matched once the VLSD stubs are modified. To get the next measurement, place the VLSD stubs into the diff, place the VW flange into the end of the stub and take the same measurement as before; side of the diff to the end of the flange. The difference between the open diff measurement and the VLSD measurement is the amount that needs to be machined off of the VLSD stub. After some math was done, it was decided that it would be easier to communicate a overall length of the finshed VLSD stub.

 

 

The VLSD stub will have the excess machined off in a lathe and a 45 degree chamfer machined to allow for more surface area for the weld.

 

 

To allow for the VW flange to set square to the VLSD stub, a register was machined on the back (sorry no pic of that step). Pieces were then slowly tig welded together.

 

 

Every precaution was used to prevent the hardened pieces from becoming too hot during welding which could affect the longevity of the finished stubs. After welding the VLSD stubs were placed into a lathe and the CV mountiing flange was checked for true. Finished stubs were installed into the VLSD diff and that installed into the rear cross member for test fitting with the CV axles and happily everything fit!

 

[josh_t]

Several factors drove the decision to perform this modification. First was the desire to use a LSD that had a 3.54 ratio based on a recommendation from the Experimental Engineering website (VG30.com). Second was to utilize the CV axles that had been fabricated for use with an open R160 per the article from DQ 9.3 which utilized the Mattndew adaptors.

 

Since the inner stub axles were going to be modified, it was determined that the dimensions should accommodate a direct bolt up of the inner CV joint and not require the adaptor. Please note that this modification will not work with the stock 510 half shafts; see DQ 9.4 for how to use a Subaru VLSD with stock 510 half shafts.

 

To achieve the stated goals the modification will utilize the inner stub shafts from a set of CV axles for a 1992 Subaru SVX (Figure A) and the outer stub axles for a Type 2 Volkswagen (Figure B). The pieces will be machined, mated, and welded to create a new inner stub axle that will allow the Type 2 CV joint to bolt directly to it. (Figure C)

 

Figure A

 

Figure B

 

Figure C

 

 

Differential was purchased from EBay for $150. Since these differentials tend not to come with the stub axles, they will need to be sourced and cost will vary. Be aware that the core charge for a set of axles can be significant so sourcing used is recommended. This particular project used axles purchased from a axle re-builder for a cost of $285. VW stubs were purchased from a local VW dismantler for $40. A local machine shop performed all of the fabrication for $95.

 

The first step is to shorten the VW stubs. The only part of interest is the flange itself though it was decide to leave the bearing surface part of the shaft in this instance.

 

 

All measurements are approximates and it was decided that a few millimeters each way would not be problem for the CV's to absorb. The first measurement was taken on the open diff with the Type 2 adaptors installed. Measuring from the side of the diff to the edge of the adaptor gives a distance of ~55mm. This is the dimension that will be matched once the VLSD stubs are modified. To get the next measurement, place the VLSD stubs into the diff, place the VW flange into the end of the stub and take the same measurement as before; side of the diff to the end of the flange. The difference between the open diff measurement and the VLSD measurement is the amount that needs to be machined off of the VLSD stub. After some math was done, it was decided that it would be easier to communicate a overall length of the finshed VLSD stub.

 

 

The VLSD stub will have the excess machined off in a lathe and a 45 degree chamfer machined to allow for more surface area for the weld.

 

 

To allow for the VW flange to set square to the VLSD stub, a register was machined on the back (sorry no pic of that step). Pieces were then slowly tig welded together.

 

 

Every precaution was used to prevent the hardened pieces from becoming too hot during welding which could affect the longevity of the finished stubs. After welding the VLSD stubs were placed into a lathe and the CV mountiing flange was checked for true. Finished stubs were installed into the VLSD diff and that installed into the rear cross member for test fitting with the CV axles and happily everything fit!

 

 

did someone get a hold of solidworks?

[rpowell25]

Oh yeah. Love Solidworks!

[josh_t]

Oh yeah. Love Solidworks!

 

my first project in solidworks was a go kart engine test stand/plate to put in a vise. i printed out the blueprint and brought it to my machine shop teacher to show him i knew how to use solidworks. i never got the material to make it though. it would have been very easy to make though.