over heating rally car

Hi everyone was at Blyton Rally day this weekend when my MSA pulsar started getting hot after 4/5 laps so had to keep letting her cool down before going out again!
I have just changed the original rad cap for one off one of my spare car's, it said 1.1 Bar on it. I took it out on the back roads flat out for an hour and half a tank of fuel later and temp never went above half way? Is she cured the old cap rubber looked iffy?

It could be ..... im not really sure about track use as i would imagine any car would get pretty hot pushing everything to the max ..... do you have a standard rad etc ???

Could it be a possible thermostat issue? Sticking, working one minute and not the next?

Well having checked the old cap it was a std 0.9 Bar and the rubber was hard and brittle!
The newer one is 1.1Bar rated and the rubber looks and feels soft and like new!

Well if it was the cap probably the easiest fix your come across lol ....

I hope so lol gearbox out next

Why whats up with it .... just a refresh .... or clutch or something ?

Can't sometimes find third happened this weekend and crunches going into 5th gear so not sure if linkage or its inside?

Yes could well have been a weak rad cap allowing coolant back to expansion bottle then obviously losing it via there

With regard to gearbox........could possibly be a worn sloppy external bush, have you a quick shift fitted?
More than likely an internal fault though with selector or synchro, possibly even worn input or mainshaft bearings