Last year while we were preparing the car between our Pendine runs and loading the car into the container an awful lot of work was carried out.
After our South Wales adventure the only thing that remained in the car was the roll cage. The complete car was stripped down, loads of sand was removed and the car was then painstakingly rebuilt to comply with the SCTA (South California Timing Association) rules for running at Bonneville.
This was such a mammoth task and we were on such a tight time schedule that we didn’t have the time or opportunity to share with you the intricacies of what we were doing. This time we are a little wiser and can share some of the work we have been up to.
As a part of the rules all of the suspension and brake components must be either lockwired together or use aerospace standard locking nuts. Nyloc nuts are not sufficient as the salt actually eats away the nylon core.
This was all finished last year, but in preparation for next year every component has been removed cleaned and rebuilt using anti-sieze grease. Then carefully reinstalled, torqued up and lockwired where necessary.
We also took the opportunity to finish some ‘improvements’ that we didn’t have time for last year. One of these is regarding the front wheel bearings.
We have taken great pride in the fact that we have kept as much of the original design and components from the Jensen brothers ideas. Whilst we have replaced all of the servicable items, all of these have been replaced like for like just new parts.
In mass produced cars of this era, the front wheel bearings which are taper roller bearings are adjusted up to remove any free play and the locating nut is then backed off to the nearest locking pin hole in the castellated nut.
After a conversation with another Jensen owner we hit upon a plan which will allow us to tighten the locating nut but still have free movement of the wheels. We contacted the wheel bearing manufacturers to calculate the correct pre-load for the bearings. The result was between 0.00 mm (0.000″) and 0.075 mm (0.003″) free play with the bias toward the lower end of this figure.
The solution to this is to machine a cone to sit between the inner races of the taper bearings. As you can see from the tiny figures we are talking about this needs to be made to fit perfectly.
Luckily for us one of the unsung heroes of this project for a long time has been our mechanical engineer Brian.
Over the years Brian has made, repaired and advised us on many aspects of the project and until now has remained in the background but without his expert assistance the car would never have made it to Bonneville last year.
The front wheel bearing spacers are simply the latest very complex and technical example of this.
Once the suspension had been refitted we were then in a position to refit the engine complete with our new and improved Dodge Viper six speed gearbox. The engine and transmission as a unit are longer than their predecessor so this was not going to be a simple throw it in and bolt it up.
Harry, Pete and Ian spent a full day moving the engine backward and forwards to calculate exactly which modifications they would need to make to make it all fit.
For the very first time despite all of the work that had been done to this car over previous years this particular gearbox meant modifying the chassis. The rear gearbox mount needed lowering and moving backwards. Under normal circumstances the work involved would have meant mounting the chassis in some sort of jig or frame to prevent anything moving whilst the work was carried out. Luckily for us we have a very substantial roll cage which provided bracing both in front and behind of where the work was being carried out.
As mentioned in earlier notes we have decided to change from our excellent but dated FAST (fuel, air and spark technologies) injection computer to a much more updated Emerald M3D system. This has not meant huge changes to our electronics as most of the sensors and pick ups are interchangeable.
Unfortunately the only sensor that was not reuseable was the crankshaft timing wheel and pick up. For correct spark and injection timing it is vital that the ECU (engine control unit) knows exactly where the crankshaft is. This highlights the difference in technology between the two systems. The older system used four points on the timing wheel ninety degrees apart where as the new one requires one every ten degrees and therefore thirty six points. One of these is removed so that the system knows exactly where TDC (Top Dead Centre of number 1 cylinder) is.
As has become normal for our project while these timing wheels are readily available for both Ford and Chevrolet V8 engines for our Chrylser unit are not so easy to find. Once again Brian came to the rescue and using his skill and experience he was able to accurately produce one to our specifications.
As the wheel needed to be made from a ferrous material that would react to a magnet, this would then be vulnerable to corrosion. Luckily for us our friends at Y B plating offered to zinc coat it for us.
We also have a few new members to these messages. We have included some members of the ‘Bend in the road gang’ to our mailing list. These exceptionally lovely, welcoming and helpful people made our experience last year so special and we are looking forward to meeting up again with them next year.
So, welcome to all!