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MG MGA - Diff flange angle sought

Hi guys, I am trying to establish what the correct angle of the diff/propshaft flange should be in relation to the chassis and gearbox flange before I finally finish off some chassis repairs to the rear and the gearbox mounts. Yes I can fit everything and measure then pull everything out and alter but knowing you guys, one of you has the answer already. I have set the chassis up with the 2 side rails at 0 degrees on a jig but what is the angle of the flange face where the pinion joins the prop shaft and the box at the prop shaft flange? I believe (and have been advised by other racing engineers) that this is a critical measurement as anything more than 3 degrees out from the g/box flange is likely to creat vibration or wear in the uni joints
regards
mark
Mark Mathiesen

Mark,

What are you trying to do?
The angle of the flange for the rear universal joint is unable to be changed, it is set by the position of the brackets for the rear springs. In the same way the angle for the front (gearbox) flange is set by the position of the engine mount brackets on the chassis and the "ears" on the chassis for the rear gearbox mount.

Mick
Mick Anderson

The rule is that the two flanges should be parallel, so it all depends on the Eng/Gbx orientation. I never needed to measure if the crank centerline is exactly horizontal, but that's your reference.
FRM
FR Millmore

Mick, both the rear spring mount and the gearbox mounts are being replaced due to corrosion so I have no reference point to start with
regards
mark
Mark Mathiesen

Hi Mark,

When you say that the rear spring mount is being replaced, do you mean where the spring attaches to the chassis (both ends)?
Does the rear axle casing still have the spring mounting bracket attached. I am sure that this bracket is horizontal. Other members agree?
If so, you could hold the casing with the bracket horizontal and measure the angle of the pinion flange.
The gearbox flange then should be the same angle, the two flanges would then be parallel.
Agree? Yes? No?

Mick
Mick Anderson

Starting with the pinion angle is the wrong way about.
Tell us what exactly you need to locate, and somebody will be able to give measurements. All assuming that you are doing a mostly stock rebuild.

Generally, this would mean locating the crank CL relative to the frame rails. Then the spring front eye mount. Those and the front wheel centerline are the basic ref points.

FRM
FR Millmore

This thread was discussed between 28/05/2007 and 29/05/2007

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