+2 Diff drive flange

[Hawksfield]

Hi

Has anyone got a differential drive flange to hand to measure the dimensions and the four hole centres 1. diagonally across the hub centre. 2. hole to hole off centre. 3. hole diameter so I can fabricate a tightening bar.
and torque measurement tool.
Thanks for any assistance

[RichardHawkins]

My car is an S4 Elan. I am pretty sure the differentials are the same, so I hope the flange will also be common to both cars. I have measured the prop shaft flange that bolts to the diff.

Flange OD 3.625"

Bolt diameter 5/16"

Bolt hole diameter 21/64"

Bolt pitch circle diameter appears to be 3&3/32" (78mm)

The four bolts are not equally spaced, two are 50mm centre to centre, and the other two are 2&11/32" centre to centre.

These bolt centres seem strange as they do not seem to be a sensible size in either inches or mm.

Hope this helps,

Richard Hawkins

[Hawksfield]

Richard

Thanks for the info, it does seem strange the sizes and also the difference between hole centres

[CBUEB1771]

Differential input flanges with dual drillings (early and late pattern) are available from several sources. RD Enterprises' web site indicates that the smaller pattern is on a 2.750" bolt circle and the larger pattern is on a 3.063" bolt circle. The bolts are not spaced at a uniform 90 degrees in order to fit around the u-joint yoke flange that the diff input flange mates to. A uniform, 90 degree-spaced pattern could have been used but this would have required that both flanges have a larger diameter than necessary.

[512BB]

Make sure that the information you are exchanging is for the correct flange. There are two flanges that are very similar in diameter size, 85mm and 91mm. It is the 91mm flange that is commonly fitted to diffs in Elans and +2's, I have come across 85mm., but do not believe these were fitted by Lotus.

Of course there is the 105mm flange too, as fitted to Escorts, Cortinas and the like, but these will not fit in a Lotus chassis.

Leslie