Polyurethane bushes for the TC and TD/TF

Rubber bushes were used for the suspension on both the TC and the TD/TF models when the cars were new.

In the case of the TC, the following part numbers and descriptions were listed:

Front axle

Bush for shackle (top, rear) 4 per car Part no. ACA 5242
Bush for shackle (bottom rear) 4 per car Part no. 99557

Rear axle

Rubber bush for shackle (bottom) (rear spring) 4 per car Part no. 99555
Rubber bush for shackle (top) (rear spring) 4 per car Part no. 99557

For the TD and TF, the following part numbers and descriptions were listed (part numbers from the TF parts List):

Front suspension

Bush bottom wishbone 8 per car Part no. 126914

Rear axle

Bush rear spring 8 per car Part no. ACA 5242

You may have noticed that Part no. ACA 5242 is used, albeit in different locations, on both the TC and the TD/TF.

When I removed the bushes from the front suspension of my TC, they were rather a sorry sight as shown in the following picture:

These bushes were stamped ‘Harris Flex’ (the original makers) and were patented. ACA 5242 was stamped ‘Harris Flex CW8505’ and 99557 was stamped ‘Harris Flex CW719’.

The picture shows how these bushes distort, although to be fair to them, they had probably been on the car for a considerable length of time.

It is possibly true, although I have no evidence to prove it, except several users saying “these bushes don’t last 5 minutes”, that the rubber used in the replacement bushes nowadays is not as good as was used originally.

Due to the seemingly short life of the rubber bushes, replacement polyurethane bushes came on to the market some years ago.

One well known parts supplier offers a ‘one size fits all’ replacement poly bush for the original part numbers ACA 5242 and 99557. The replacement bush measures ¾” (not including the flange). This is fine for the ACA 5242, but the replacement for the 99557 requires a bush measuring 5/8”, so one is supposed to trim the bush to size.

When I looked at this several years ago, I was not happy to trim the bush to size so I decided to have moulds made for the different size bushes. These bushes [my part numbers 0073 (5/8”) and 0074 (3/4”)] are available from NTG Motor Services. The NTG part numbers are R134PT for the 5/8” bush and R134P for the ¾” bush.

Part number 0074 (left) and 0073 (right), replacing original rubber bushes, part numbers ACA 5242 and 99557.

Whilst I was about it, I had a mould made for the large bush that fits the large shackle pin at the rear of the TC (original part number 99555, my replacement part number 0145). This bush is available from the above supplier as part number R134AP.

Part number 0145 replacing original rubber bush, part number 99555.

Turning to the front suspension on the TD and TF, many owners have replaced the original rubber bushes with the polyurethane variety.

Soon after I bought my TF, I overhauled the front suspension with the help of my friendly ‘one-man-band’ garage owner and found the inner wishbone bushes to be sadly lacking (see pic). I was all the more concerned because the car had been purchased as having been completely rebuilt and had done very little mileage since its completion.

The inner wishbone bushes as removed from my TF1500. On the outside left of the picture and the outside right are the swivel pin seals, which were disintegrating.

There are two suppliers of polyurethane bushes for the inner wishbone that I know of. Autobush – see pic (whose bushes I used) and Superflex. The bushes from Superflex were used by Jonathan Goddard in an article referred to later.

The Superflex poly-bushes.

Both NTG and the MG Octagon Car Club stock poly-bush sets for the TD/TF front suspension. NTG’s part number is R135AP and the Octagon’s part number is SAX079A. You need to be a member of the Octagon to buy parts from the Club (I hope you are!). If you’re not, you would soon recoup the cost of club membership through savings on parts.

Other polyurethane suspension parts

As the polyurethane ‘bug’ had well and truly ‘bitten’ me, I decided to have moulds made for the rubber angle pads that fit under the spring clips on the TD & TF rear springs – see pic.

Polyurethane angle pads as a replacement for the rubber pads on the TD and TF rear road springs (Octagon part number SAX031C).

Another likely candidate was the spring ‘saddles’ on the TD and TF rear spring (4 required) and these are sold by Octagon as part number SAX089B.

Polyurethane spring ‘saddles’ replacing the rubber ‘saddles’ on the TD and TF rear road springs.

Finally, although not made of polyurethane, I had some interleaf disc pads made from Nylatron following a suggestion by Barrie Jones, MGCC T Register Technical Specialist, for the TD and TF models.

Nylatron is said to have high mechanical strength, stiffness, hardness and toughness, good fatigue resistance, high mechanical damping ability, good sliding properties and excellent wear resistance. The cost is £2.07 per pad, which is less expensive than commercially available rubber pads and they should last a lot longer!

Twenty-four (24) are required for a pair of TD/TF/Y springs and are available from the Editor.

jj(at)ttypes.org  [please substitute @ for (at).

I have also sold these interleaf pads for BMC cars of the mid 1950s period.

Two ‘how to do’ articles have been published in TTT 2 on fitting front and rear suspension bushes to the TD & TF. Both these were written by Jonathan Goddard – the article on the front suspension with valuable contribution from near neighbour and fellow TD owner, John Hinds.

Front suspension

Replacing MG TD front suspension bushes using modern polyurethane components

Rear suspension

MG TD replacement rear suspension bushes using modern polyurethane components

Returning to the TC, some explanation is needed as to why there are two different bush lengths on the front suspension.

Firstly, the 5/8” bush is fitted to the leaf spring ‘eye’, one each side. As the spring is 1¼“ wide, the two 5/8” bushes fit exactly.

Secondly, the ¾” bushes go through the ‘tube’ in the chassis. As this boxed in part of the chassis is 1½” wide, the two ¾” bushes fit exactly.

The shackle plates ‘join’ the shackle pins which go through each set of bushes and to keep the plates parallel a 0.125 inch ‘washer’ is brazed to one end of the shackle pin (see photo).

In other words, the difference in the width of the chassis tube and the leaf spring ‘eye’ (1½”- 1¼“ = ¼“) is ‘taken up’ by the washer 0.25” (1/8”) thick 2 x 1/8” = ¼“.

JOHN JAMES
March 2020.

One thought on “Polyurethane bushes for the TC and TD/TF

  1. Richard Schmidt says:

    I fit polyurethane bushes in my Range Rover several years ago and they turned to powder in a few years. Hopefully they have improved since. I replaced them with the old fashioned rubber

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