R2D2

Hitec Motorsport in Cradely Heath have just doen 2-3 jobs for me and are very good.

I run my Twin Cam on Valvoline Racing 20/50 and have done for some time and have never had any problems.

I use a 186 x 60x 13 with Clamshells and have never had a problem with clearance between the wing and tyre. If you have a standard profile 185s then the diameter will be about 75mm more than using a 60 profile. A 185 x 70 will be about 1.5" bigger diameter. It may also be that you have wheels with too much offset. Do you know the ET or backspace measurement of the wheel?

Looked at their website and I think that the science is suspect. It claims to fill the metal 'pores' with a new compound that is formed by a chemical reaction with the surface of the metal. Just more snake oil, I would buy good oil and leave the additives alone.

The value of the Twin Cam really depends on which one you have and its basic condition. If the engine turns over freely by hand but needs a re-build I would guess the value would be £650 ish for Stromberg carbed engine. £850 ish for a standard Weber carbed engine £1000 ish for a "Big Valve" 130 engine. Let me know what it is as I may know someone who is interetsted.

Most mag alloys are precipitation hardened which means they have been carefully heat treated after they have been cast. Heating them up to 250 degC to powder coat may affect their mechanical properties, (depending on the alloy). I know they will only be at temperature for a short time so any change would be small but painting would minimise any risk.

Don't X-Ray them unless you are looking for porosity. X rays won't find the small surface cracks that are the real problem and will lead to a fatigue failure. The dye penetrants that are commonly available from RS aren't too bad but they are not as revealing as some of the dyes used by commercial test houses.

Bodycote, they have several good quality labs around the country and tend to be CAA and FAA Approved.

I do have an "English" axle casing with new Sierra Calipers and soild rear discs fitted complete with all of the handbrake linkages, which I don't need. I want to keep the diff which is a 4.9:1 and the halfshafts. It isn't set up for a Seven but I could weld on brackets if needed.

Elie, Yes that's right. We also bought a plate type LSD with large 'Atlas' size splines and it has been very successful.

Welding cast iron is very tricky and not a good idea.

The Physics that everyone seems to be arguing about is only valid to describe the Limiting Friction condition and is based on a block of wood sliding along a plank. It is only the friction needed to cause the block to slide. As a tyre is always slipping relative to the road at the point of maximum grip I don't think limit friction conditions models are entirely valid. A chap called Amhurst Villiers described the basic manner in which tyres gripped in the 1920's or 30's and this inolved some means of estimating the mechanical grip as well as friction. This is the same Villiers that worked on the Blower Bentleys and ended up at NASA. There must be some record of the papers that he published

Elie, I used a Quaife conversion on an RS2000 in 2002 and broke 3 half-shafts on tarmac rallies using 185x70x13 Yoko's. I replaced the Quaife units with a conversion I bought from Rally & Competition Equipment which has stood up to more abuse and is a bit cheaper. The price of the conversion is about £1100 + VAT including hubs, shafts, LSD bolts etc.

In general terms it seems to me that the entire situation with regard to roll cages has become a bit confused or may be I just don't understand. I don't think that cars used on non-FIA events need to have FIA homologated roll cages. I have been competing on the MSA Historic Stage Rally Championship for the last couple of years and our car doesn't have any FIA marking and we don't have a Roll Cage Certificate. We have never had any problems at scrutineering or with obtaining an MSA Log Book. I think that if you want to compete in FIA Approved events you need an Homologated Cage which must be marked according to Appendix J of the Yellow Book and be accompanied by a valid Roll Cage certificate. I think that this means that not all cages are homologated and that for National competitions this is not an essential requirement unless specified for a particluar class or event. Does anyone know the definitive situation. I also beleiev that the MSA have just insisted that any new Roll Cages that are designed and require homologation must be tested or examined by MIRA and I guess taht this will add a considerable amount to the cost.

You can find that "Tuftriding" a crank can allow some movement to take place but this is less likley to happen on a used crank. I have tuftrided more than 10 crossflow cranks over the years and never had one move but it can happen. If the movement is small most good engine builders can straighten them out and it is worth checking the run out with a dial gauge before you bolt up the mains.