Photo 1: Cutting dowel pin from Rover 4.0 crankshaft
Modifying the Rover Crankshaft for T-5 Transmission Use
as published in British V8 Newsletter, Volume XIII Issue 3, September 2005by: Dan LaGrou and Kurt Schley
The use of a GM style T-5 5-speed transmission for MG V8 conversion use has become very popular over the last several years. The advantages of the T-5 over the more traditional Rover 5-speed box are lighter weight (70 vs. 90 lbs), no internal oil pump to go bad, and that the stock 3.9 rear end need not be changed. The GM style T-5 bolts directly onto either an OEM 215 or an aftermarket bellhousing. These bellhousings, in turn, will mate with any of the Rover V8 engine blocks without modification. However, there is one caveat: at some point in the last twenty years, the Rover crankshaft grew an extra 3/8" at the rear. This longer length causes interference with the T-5 input shaft. The solutions to this problem are not complicated at all. The first option is to fabricate a 3/8" thick aluminum spacer between the bellhousing and the block, thus moving the transmission rearward. The second option is to remove 0.300" from the rear of the crankshaft. (See illustration "A".) This modification takes only 15 minutes or so, providing you have access to a lathe. The following is the technique developed by Dan LaGrou of D&D Fabrications.
1) The Rover crankshafts have a single dowel protruding from the rear flange. This dowel
is cut off flush with the flange face. (See photos 1 and 2.) Do not pull the complete dowel
from the flange as this will noticeably affect crank balance.
2) Dan has fabricated a simple aluminum insert (see illustration "B") to support and index the rear of the Rover crankshaft in the lathe tailstock. The adapter inserts approximately 1-1/8" into the bore for the pilot bushing, with a snug fit (once the original bushing has been removed). The end of the adapter is countersunk to accept the lathe tailstock center. (See photo 3.) A new bushing can be made, with similar dimensions, out of "Oilite" bronze.
2) Dan has fabricated a simple aluminum insert (see illustration "B") to support and index the rear of the Rover crankshaft in the lathe tailstock. The adapter inserts approximately 1-1/8" into the bore for the pilot bushing, with a snug fit (once the original bushing has been removed). The end of the adapter is countersunk to accept the lathe tailstock center. (See photo 3.) A new bushing can be made, with similar dimensions, out of "Oilite" bronze.
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3) A parting tool is then employed to remove approximately 0.300 - 0.320" of the crankshaft
end. (See photo 4.)
4) After the crank is shortened, all of the cut edges should be chamfered with a file to remove burrs.
Photo 2: Trimmed dowel pin
Illustration A (what we are ultimately trying to accomplish): Measure depth of bushing hole to where the inside diameter steps in, as well as depth to bottom of hole, and make aluminum lathe insert deep enough that it nearly reaches the bottom, for maximum support during parting operations. Use the diameter measurements in Illustration B, and adjust the lengths to fit your crank.
4) After the crank is shortened, all of the cut edges should be chamfered with a file to remove burrs.
Photo 2: Trimmed dowel pin
Illustration A (what we are ultimately trying to accomplish): Measure depth of bushing hole to where the inside diameter steps in, as well as depth to bottom of hole, and make aluminum lathe insert deep enough that it nearly reaches the bottom, for maximum support during parting operations. Use the diameter measurements in Illustration B, and adjust the lengths to fit your crank.
Illustration B: Oilite Bronze Insert dimensions. The insert bore or i.d. is 0.592" for a GM style T-5 transmission and 0.674" for a Ford V8 style T-5. For the aluminum lathe insert, use the same diameter dimensions given here, but adjust (increase!) both length measurements to fit the un-cut crank. Instead of drilling a bore, as on the bushing, place a countersink that matches your tailstock taper at the precise center of the outside face of the insert.
Photo 3: Aluminum lathe adapter positioned in pilot bearing bore
Photo 4: Cutting the crank with a parting tool
Photo 5: Modified crank (shown at left) and a stock crank (at right)
Disclaimer: This page was researched and written by Dan Lagrou and Kurt Schley. Views expressed are those of the authors, and are provided without warrantee or guarantee. Apply at your own risk.
