Polybushes

One of the more popular upgrades of any classic sports car is the fitting of polyurethane bushes. TR7 kits tend to be based on performance rather than touring, giving a tighter, firmer ride. Most of the well known brands (such as Polybush and Superflex) sell complete kits either direct or via specialist retailers and will normally include all you will need to replace the entire suspension set up. These will normally work out more expensive than the factory standard rubber bushes, but as they reportedly last around 5 times longer, it's a worthwhile investment.

Be wary of cheaper kits as the bushes can be very hard and of dubious quality. Whilst the extra hardness might improve the vehicle's handling marginally over another brand, the flipside is that the extra tightness will be translated into stresses, which are then transferred to parts of the vehicle the manufacturer never intended to take them, which may in time lead to metal fatigue (or something similar).

Tips on changing bushes:
Front anti-roll bar
No problems fitting to where it clamps to the subframe - just remove the bar, slide off the old ones and slide on the new ones. Do one at a time though so that you can be sure to put them on the right way round. If you do this they can act as a guide so that you don’t fit the bar upside down! Hint - the flat bit fits to the subframe ! (see Pic.1). The ends where they fit to the track control arm (TCA) though are another matter. The bar has to be compressed inwards which is not easy. My tip is to fit one half of the bushes which will give you some leeway to then just get the ends in the TCAs. Then you can put the other half of the bushes in but you won’t be able to fit all the washers etc straight away. First tighten up with just the nuts so far, this will pull enough of the bar through for you then to remove the nut, fit a flat washer and tighten up again. Finally, repeat the process to get the larger cup washers on.

Pic.1

Pic.2
Subframe mounts
Jack up the car and secure on axle stands on the chassis rails behind the subframe. Next use a jack to support (but only just touching) the engine/gearbox. Don’t do this on the sump! Where the engine meets the bellhousing is a good place (see Pic.2). You can then put the jack under the subframe, undo the four mounting bolts so far and lower the jack about 1 inch. Then remove the bolts one at a time and pull out the old bushes complete with all the washers etc which need to go back in the same order. (Pic.3 shows the old bushes and the nice, new orange bushes). When all the bushes are in place you can raise the subframe back into position and tighten up the mounting bolts, (see Pic.4).

Pic.3

Pic.4
Inner track control arm bushes
These haven't been replaced yet...

Pic.5 shows the finished (well almost finished) front - a blaze of orange

Pic.5

Pic.6

Upper link bushes
Again - support the car on axle stands for your safety when working under it. Pic.6 shows an arm being withdrawn from the car. Once off the car, Pic.7 shows one way of helping the old bushes come out - it’s a lot easier when they have been 'toasted' a little bit. Pic.8 shows the new bushes and sleeve going back in. Unlike the originals, polybushes come in 2 halves. What followed next was pressing the bushes and sleeve into the link in the vice (note assorted other implements which may come in handy). Then it’s just a reversal of the removal procedure - easy! Well, no it’s not easy. The link will locate at the wheel arch end but you don’t have enough strength (or at least I don’t) to pull it down into the bracket on top of the rear axle. So, I used the jack again with the top on a chassis section and the bottom on the rear link. When you wind the jack up the link has nowhere to go but into the bracket on the axle - (it may not be too clear but see Pic.9).

Pic.7

Pic.9

Pic.8

Pic.10
Lower link bushes
These had already been changed and don't look any worse than supporting the axle, then disconnect the arms one at a time, pop olds out, put new ones in and refit arm. You can see the new ones in Pic.10.

Conclusions
What have we learnt... polyurethane bushes are easier to fit than the original rubber bushes, improve the vehicle's handling dramatically and last longer. Occasionally people say that there is an increase in NVH (noise, vibration & harshness) when polyurethane bushes are fitted, but I would have to say there any increase is absolutely minimal, if at all. When travelling in a straight line, there's no difference at all the vehicle just feels a lot tighter and better behaved, with no downsides at all. I know my own car feels tighter and more predictable, with less roll and slackness, than other TR7s I've driven. One of the main polyurethane bush manufacturers say their bushes 'restore that factory-fresh feel', which I think is a pretty good description to sum up what this could do for the handling of your car.