If you’ve read Part I in this interesting series you’ll know that Esprit owner David Lisle isn’t afraid to make a few changes to his car to adjust it more to his liking. In this instalment, Dave talks us through the work he’s done to improve the chassis, suspension and brakes of his Esprit Turbo SE.
The chassis is the back bone to which everything is attached directly or indirectly. This makes it the single most important part of any build and must be 100% as designed.
Once the body was removed a full assessment on my chassis and all the components could be made. As expected although dimensionally correct the original chassis had sustained some previous accident damage. The only thing was to replace it. This gave me the opportunity to change to a later model chassis; this will be better suited to the desired outcome. The advantages being the pickup points for suspension components and power steering would be correct for the larger wheel specification which I intended to fit. I managed to find a 1996 S4s chassis which was perfect and being galvanised only needed a steam clean. There are other subtle differences between the two chassis’s but none that will prevent my early modified body fitting.
Whilst removing each component part from the old chassis they were all carefully examined, this would determine whether they were replaced or reconditioned. The results were that very little of the suspension was retained for recon.
The top wishbone arms were changed for the later adjustable type; the lower arms were changed because the later model anti-roll bar to be fitted had a different bush fitment. The vertical link and hubs were fine but all the bearings and joints were changed as a standard procedure. Interestingly the steering arms were out of spec and had been compensated for in the tracking. Although this is not uncommon it does alter the Ackerman angle which will affect the handling and greatly increase tyre wear. These were changed for new ones. All of the used parts being retained were shot blasted, crack tested, then electro plated or painted to match the new parts.
All of the suspension bushes were changed for the latest polyurethane type supplied by Lotus. Although these were considerably more expensive than other poly bushes on the market, also harder to fit than some of the split types available, they are far superior and designed specifically for the job. Safety and reliability were also major considerations. The dampers were replaced with new adjustable platform type and springs with Eibach.
The top links were replaced with the later spec adjustable type, but the rest of the structure reconditioned. The lower links and the radius arms were shot blasted and sent out for plating to match the new tops. The rear hub carriers presented the usual problems with seized lower link pin. These were removed carefully using the forum article on how to do, as the guide. Once removed the bare castings were shot blasted and crack tested and thankfully ok. As with the front all the bearings were replaced as standard procedure and Lotus polly bush’s fitted along with adjustable platform dampers and Eibach springs.
This was the one area I looked forward to making changes to, I always felt the standard SE system left a lot to be desired especially if you got aggressive with them. The later Brembo system on the S4s was an improvement but still not what I was after. AP was the obvious choice but the price was a stumbling point. My attention was drawn by another forum feature in which PNM Engineering produced alternatives at an affordable price. After long conversations with Pete Musgrove we came up with a spec which would give me the braking I was looking for. The system I chose was 310mm vented front rotors with 4 pot Hi-Spec calipers and 300mm vented rear with Brembo calipers, I later changed these to 4 pot Hi-Spec calipers incorporating the handbrake, with the option to upgrade system again at later stage if required.
The first parts to fit were the through chassis pipes, some of the small originals had shown corrosion so were changed. The large pipes were swapped for the later spec. straight type, all were fitted using new grommets and anti-vibration sponges inside the chassis.
Because I had no references for shimming the geo set up I started by setting the new chassis perfectly level on blocks with correct ride height. This provided a datum to work from. I built up the rear suspension first, but without the road springs; this allowed me to maintain the ride height. By setting the hub centre to the correct height and attaching a custom made tracking bar I could adjust the toe to the chassis centre line and camber to the vertical. This proved to be quite close when professionally checked and set up later.
The front suspension was set up in accordance with the later spec. This is simplified and far easier to adjust the caster angle when the body is fitted. The same principles on setting angles were used and once again proved quite close when professionally checked. The new power steering rack was fitted which is a major upgrade for the SE but straight forward bolt on in this later spec chassis. At this stage all the suspension fixings which were left slack during adjustment were tightened to correct torque. The dampers were removed and the springs fitted. The front springs although Lotus supplied Eibach were too long for the dampers I was using; this would cause the ride height to be too high and on the limits of platform adjustment which was addressed by having the springs shortened. Finally all the pipes and hoses could be fitted and everything rechecked.
We’ll be publishing the final installment of Dave’s build in a couple of weeks where he’ll be showing how he has teased a drivable 412bhp from the 2.2l engine through his many changes. If you think it’s been good so far, wait until you see Part III!