Gearbox tunnel heat insulation
 

I drove the 403 for the first time in a few years on a really hot day last week. I had forgotten just how much heat comes up from the gearbox tunnel. I still have the Dunlopillow and cardboard sheet fitted but it's starting to break up and I think there must be a better solution.

Has anyone fitted anything like the "Floor and Tunnel Shield" aluminium / glassfibre mat? Or perhaps found a less pricey alternative?

I can vouch for the great effectiveness of the Nimbus aluminium heat shield materials. They are formable, and with some bolts and washers, easy to mount wherever needed. The two layer G II material is adequate for most situations outside serious racing.

I don't know how this compares price wise as I just came across it while looking for one of their other products, I need to replace the covering on one of the 603's and the two 401's so want to find something that does the job but does not holt water like some of the older materials. The Car Builder Solutions website is worth a look as well.

https://www.dynamat.com/products/dynaliner/

You could try to contact Mark Alford through the BOC. His son/ in law/ nephew? fitted heat reflectors to his 403 and was very pleased with the results.

Spoke to him today and he used Dynamat to insulate the firewall. He is also thinking about adding air conditioning too.

Is the "Dunlopillow and cardboard sheet" an original feature ? I had one of those in the 405, but it is out at the moment due to the foam rubber crumbling away to dust, which gets everywhere.

I believe it is. I'm not sure if it was only used on gearboxes with remote shift as our 401 didn't have it by the time we bought it.. My 403 that had a remote retro fitted by the factory in 1954 had this.

I think you're right. It is for remote shift gearboxes. The workshop instructions for fitting the remote shift mention "item 14, the "Sorbo" rubber jacket" over the gearbox cover. The Sorbo Rubber Company also made the self sealing linings for wartime aircraft fuel tanks, so could have had dealings with the BAC.