+4 Clutch Info

From: Bob Bowie in Maine

Last update: June 23, 2009

Bob Bowie in Maine wrote up some of the info he found out about the clutches for the +4s while restoring his SS.

The flywheel is same as TR3/4 for all plus 4 years, it has TWO dowel pins and is about 11.25 inches diamter. it has the sweat on ring gear The flywheel is 1 and 7/16 thick at the edge. This includes the ring gear. Number of bolts that hold the clutch pressure plate to the flywheel 6

Flywheels are not listed as available, ring gears had moss and the Roadster factory as sources, some racing outfits offer alloy flywheels. Mistakes
The TR4a flywheel is smaller at 11 inch diameter and has three pin locaters, there is a an MGB pressure plate fix with the 8.5 inch clutch plate from a TR4A/TR6 that requires a new hole in the throwout to give proper throw out clearance (see Morgan Bedside Reader-Greg Solow made this conversion) Clutch Plate:
Originally Borg and Beck 9 inch single dry plate the clutch plate is 9 inch diameter, same as TR4 (actually TR3 from 1955 on at least)
Girling application book: The driven plate is 85824/00RP
Driven plate:
Borg & Beck 50052, Delphi # LL50J
Automotive products HB9715Q
BAP-GEON New part number 45692/15 Rebuilt part number 47344
(by the way lists the same part number for tr3/4 and Austin Healey 100/4 to 1956, 100/6 - 1957-?1962 (I thought they changed to 3000 in 59!) also found CD344

Most all vendors

The TR4a clutch disc is smaller than the TR4! dont use it in a standard Morgan setup. (Greg Solow and Fred Sisson can tell you how to use one)

Pressure Plate:
The Pressure plate is same as early 100-4 Austin-Healey and goes into early 100-6 series as well.
May be Pressure plate: Borg & Beck # 45692/15 and/or 34H44 HA3359Q (?Automotive products number) also reference CC344 found

Linda at Morgan Spares does have these in Stock Pressure Plate 100-372
Moss may have them
Melvyn Rutter rebuilds them
They have been made by Automotive Products plc of Leamington Spa, England.

Dont use a Triumph Pressure plate for TR engine Morgan as the throw out bearing will hit teeth.

I have a note that mentions another source also for the throw out bearing early JAg xk120?

If you measure your flywheel and its just 11 inches consider the Sisson fix, or if thats what all you can find. If you want original, your going to need a TR3/4 two dowel type flywheel 11 inches, a good machinest can also fix this issue. The size of the flywheel and clutch assembly got smaller at the TR4a, but not for Morgans. Now will the M418G (tr4 type) starter fit TR3 flywheel. Bob Bowie

Return to the Index of Tech. articles

To email me with comments or questions.