Rebushing Luvax-Girling Shock Absorbers

have refurbished several sets of Luvax-Girling shock absorbers in the past, but always the difficult part for me has been replacing the rubber bushes in the lever arm and link eyes without damaging them.  I know some people claim to be able to accomplish this using nothing more than a bench vice, but I have found that either the bush is damaged in the process or it ends up being displaced axially in the eye rather than just emerging from each end of the eye as it should.  To complicate matters further, there seems to be two different styles of bush on offer from the usual spares suppliers; one that looks like a section of rubber hose of an appropriate length and diameter to fit the eye, or another doughnut style bush, which at first sight appears to be too large in diameter and much too short in length.  It is easy to dismiss this latter style and assume it can’t possibly be right.  An example of each of the two types of bush available is shown in Fig 1.

Fig.1 – showing the two types of link arm bushes available.

Moss offers a set of tools to aid re-bushing but they claim only around an 80% success rate when using them to fit the bushes.  They suggest buying extra bushes to compensate.  At around £6 a bush that’s great if you are selling them, not so great if you are buying them. In fairness to Moss, the tools they offer go a long way to aid the re-bushing process but at the best part of £100 for the set they are eye-wateringly expensive.  The problem with the Moss tools is not the tools themselves, but with the accompanying instructions.

Recently, I came across “Booklet No G94, Technical Information, Construction, Operation and Service Instructions for Girling Hydraulic Dampers” advertised on everyone’s favourite auction site¹ which is shown below in Fig 2.  At less than the cost of a bush it was a ‘must have’ for me and it certainly did not disappoint. It has no publication date that I can find but I would guess it was printed in the 1950s.  Surprisingly, the copy I bought is still in pristine condition.  It includes a description of the various types of Girling shock absorber as they evolved, but more importantly, it includes an illustrated section detailing exactly how Girling intended the bushes, which they referred to as ‘bearings’, should be fitted to their PR6 and other shock absorbers.  (PR stands for Pressure Recuperation, incidentally).

It describes the necessary tools which it says were made available back in the day “strictly to Girling agents only”.  It also provides a useful insight into the techniques used to accomplish the job which I have never seen described elsewhere.  The first piece of useful information to be gleaned from the booklet, which was worth the purchase price on its own, was to confirm that the doughnut shaped replacement bushes are actually the correct shape and the ones to buy ².

Having seen the illustrations in the booklet, I set about copying the set of three simple tools which are described as (1) a guide funnel, (2) a base block, and (3) a guide pin.  They are intended to be used with what Girling refer to as a “press or pressure tool”.  A drill press works well for me.  I assume the original tools described by Girling were machined from steel but I made my set of tools from acetal.  Acetal is a type of hard plastic readily available in bar form and very easy to machine to a fine finish.  It was also something I had to hand.  If you are unable to make these tools yourself anyone with a lathe or a local jobbing machine shop would be able to make them for you, probably for much less than the tools currently available from Moss.  The dimensions are important but not critical, so they do not call for close tolerance machining.

The guide funnel is designed to accept an uncompressed bush at one end then tapers through its short length to compress the doughnut bush so that it emerges at the other end of the funnel small enough in diameter to enter the eye of the lever arm or link.  It has a counter bore on the bottom face of the funnel to register with the outside diameter of the eye.  The Girling’s version of the funnel shown in the booklet has additional machining to the outside diameter but as far as I can see this has no useful purpose apart from possibly making it easier to handle with greasy fingers.

The base block is simply a cylinder used to support the eye while the new bush is inserted into it, but crucially it has shoulder on the top face of the block to act as a stop.  This determines how far the bush is pushed into the eye.  The base block also has a hole through it large enough to allow the guide pin to pass through and can be used upside down to support the link eye during the next operation as the pin is inserted into the new bush.  

The guide pin is simply a short, tapered pin which is used as a pilot to ease the flat end of the link or the pin into the bush once it has been installed in the link or lever arm eye.  My interpretation of the set of tools is shown in Fig 3.

Fig. 3 – Bush insertion tools.

With these simple tools together and a press the booklet then describes their use as follows: 

To fit a new bush.

The eye must be clean, free from grease and any debris remaining from the old bush.  This is most easily done today with a cylindrical wire brush of around 25mm diameter in a cordless drill.  The eye is then placed on the base block with the end into which the next component (in this case the pin) is to be inserted resting on the block.  (Note the direction that the pin is inserted differs for the front and rear shock absorbers.)  The guide funnel is then placed on top of the eye located by the counter bore.  This is illustrated in the booklet and is shown in Fig 4 (shown as Fig. 20 in the book illustration).

To aid the insertion process Girling specified the outside of the new bush should be “dampened with benzene, or petrol or paraffin if benzene is not available”, then “with a quick action” the bush is forced through the funnel into the eye until it comes to rest on the shoulder of the base block.  I found Paraffin works well for me, providing the minimal amount of short-lived lubrication to enable the bush to be inserted easily into the eye.  Washing up liquid, or any sort of grease, especially silicone grease, should be avoided as it will remain in situ forever and the bush would simply be pushed out of the eye again when attempting the next stage of the assembly process. 

To Fit the Pin to the Re-bushed eye.

With the bush in the eye the next step is to fit the pin.  (Note that the bush will not at this stage be at mid position in the eye, but will become centralised as the pin is inserted.) This is done by holding the pin in the press and using the guide pin as a pilot which together are pushed into the eye whist it is supported on the inverted base block. Just the tip of the guide pin should be lubricated with a tiny amount of rubber grease or something similar.  A quick action is again specified to accomplish the task.  As the guide pin is pushed through the bush by the pin it drops into the hole in the base block. This is illustrated in the booklet and is shown in Fig 5. (shown as Fig. 21 in the book illustration).

To Fit the Link to the Lever Eye

With the pin now in the link pin eye the next step is to fit a new bush to the lever arm eye.  This is carried out in exactly the same manner as the new bush was inserted into the link eye.  Then the end of the link is ready to be inserted into the lever arm eye.  Here the booklet recommends fixing the link to the base of the press with its bent section pointing upwards as shown in Fig 6.  This is topped with the guide pin, again with just the tip lubricated with rubber grease.  Then the lever arm is pressed down onto the link.  This is a cumbersome operation now as you need to support the weight of the complete shock absorber in one hand whilst operating the press with the other.  A second pair of hands might be useful at this stage.

Having made a set of tools and followed the instructions described by Girling it is possible to re-bush a set of shock absorbers with a 100% success rate.

Notes

¹ Copies of the Girling Booklet may still be available from redtriangleautoservices eBay Shop.

² Replacement bushes and pins are available from MG Octagon Car Club Part Numbers SAX090 and SAX090D respectively.

Ed’s note: Thank you Peter Cole for a most enlightening article.

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