Help - Installing a SWB 901 Gearbox into a '69 Car

[tom1394racing]

I have a customer with an early 901 gearbox with the SWB output shafts that he would like to install into a '69T. At first, I thought no problem just install the later '69 compatible output shafts into the gearbox. However, it is apparently not that simple. Do we need to swap a '69 differential into the earlier 901 gearbox? Or do we need to modify the SWB output shafts by welding and machining to accept the '69 CV's?

What is the best approach short of getting a '69 gearbox?

[chris_seven]

Tom,

The SWB drive flange suits a 94mm CV which has a 78mm PCD.

The 1969 CV is 108mm and I think that the PCD is 94mm.

The 1969 diff units we have seen are too wide to fit into a 901 casing and the output bearings are larger.

I had thought that the 69 diff was similar in size to an early 915 Mag Cased unit.

The 1969 shaft is 485mm long and would also come up a little short and this would use up some of the CV joints plunge capacity.

You could easily make a custom driveshaft with a different spline on each end.

If you use a 33 spline 94mm CV from a 2000MY VW Polo on the inboard end it will have plenty of plunge and will easily handle the power.

You can make the shaft a suitable length to install the CV Joints in their optimum position.

The best option must be to swap out the transmission especially if the 901 has the 'simplified' differential installed.

[tom1394racing]

Chris

Thanks for your input.

My research this morning tells me that the differential from a chilled cast Al '68 or '69 gearbox will work combined with the early chilled cast version of the '69 output flanges.

I think you are correct regarding the differential and bearings for the late '69 Mag case gearbox being incompatible with the SWB Al gearbox.

[Matt Monson]

Tom,

Do a search for Grady Clay's explanation of converting a simplified differential. You can do this without replacing the housing, which would require you to redo the ring and pinion settings. Just update the differential internally.