Refer to Moss Motors part number 413-040 Rear Gearbox Mount - MGA

This part is press fit in the hole on the bottom of the rear extension housing of the MGA gearbox. It accepts a cross bolt to be mounted between two steel ears on the MGA frame. Spacing between the steel ears on the frame is 2-1/4 inches nominal, plus a very small amount for assembly clearance. The length of the inner steel tube on this part should be 2-1/4 inches to match the space on the frame. The central tube and moulded rubber should extend equally on both ends, aproximately 1/4 inch beyond the ends of the outer steel shell. This would hold the mount and the gearbox centralized in frame to be suspended on the rubber insert material and to not touch the frame. When the bolt is tightened, the steel frame ears are pulled in slightly against the ends of the central steel tube in the mount to provide a solid mount for the bolt and to prevent motion of the inner steel tube. The original intended dimensions of this part are shown in the drawing below.

Also see picture tour for replacing this part.

The part in the photograph at top of page shows that the central steel tube and moulded rubber do not protrude very much at left end of the part. The center tube is in fact shorter than intended, just 2.14 inches long on this particular part. All of the deficiency in length is on the left end, while the right end does have the correct extension distance. The outer steel shell is also 1/32 inch longer than intended, which further reduces the extension of the inner parts on the left end, then only extended about 1/10th of an inch.

Installation of this part in the car would cause bending of the steel ears on the frame as the bolt is tightened. While this may not cause any significant functional damage (other than bending of the ears and chipping of paint), it is possible that the outer steel shell of the mount might then bump and rub on the left frame ear in operation. The resulting noise (possible noise and/or vibration) could be irritating and a significant puzzlement to occupants of the car until one might finally figure out what's making the noise.

If you need or wish to use this part, it is adviseable to install a spacer (possibly one or more steel flat washers) at the short end of the mount to make up the deficiency of length. The bore of the spacer must be small enough that the thin wall steel tube does not go through the spacer. It would be a bit inconvenient to fiddle with the loose spacer(s), both immediately and for any future servicing, but it will work as long as you can remember to put the spacer(s) back in each time it's installed in the car.

This particular part has been in my inventory for a while, possibly as long as 2 to 5 years. However, I have received a report of a new part just purchased from Moss Motors (late November 2003) which has similar dimensions. This problem has been reported to Moss on Dec 4, 2003. I will post any reply from them here when received.

Addendum May 24, 2004:
I just received a report of another one recently purchased new, also from Moss Motors, still with the center tube too short. Additionally this one is also too large on the OD at 1.890" diameter so it would not fit in the aluminum housing. The expedient solution was to hone the bore out larger to be press fit with the ovesize part. I do not recommend this, as it creates a bastardized housing which will then never again accept a correct bushing. If you do this, at least keep good records of the modification for future servicing. Some years in the future (assuming the parts problem is corrected) you might have to procure another non-molested housing in order to fit another new bushing.

Addendum March 2007:
On again, off again. The overall diameter problem was fixed. The center tube became a little longer but still a bit too short. A friend bought one that was close enough to use (with a thinner shim washer) in January 2007, but when I tried to order another one in mid March the parts were on hold looking for a different supplier again.

At 11:44 AM 3/30/2007 -0700, Steve Berg wrote:
>"LBCarCo has two versions of the mount with the following dimensions:
>
> Non-Bagged 413-040
>
> Black Rubber 1.442
> Big Outside Ring 1.927
> Main Body 1.879
> Tapered End 1.837

That one works. The critical dimension is the main body diameter, which needs to be a smidge oversize for Class 2 or Class 3 interference fit. If the center tube is less than 2.25" long you may need to add a 1/2" SAE flat washer.

> Bagged One 413-040
>
> Black Rubber 1.453
> Big Outside Ring 1.955
> Main Body 1.895
> Tapered End 1.869

That one definitely does not work and should be returned to the source (too large main body).

Addendum November 2007:
I have just received a few parts from most recent Moss delivery after parts have been unavailable or on back order for many months. This batch is good to use, all dimensions correct. After more then three years we have good parts again. Cross fingers and hope it lasts longer than depletion of current inventory. (Yes, I can be a little pessimistic, but only time will tell).