Earlier this year, Dobson Gaskets were contacted by Chris Packer from The Transport Museum in Wythall, Worcestershire, about manufacturing two head gaskets for a 1951 Birmingham City Transport Daimler CVD6 bus. This was an interesting project for the team at Dobson's to work on and demonstrates the processes required to precision manufacture a new component from the original.
The number 2707 Daimler CVD6 bus operated in the Midlands from 1951 to 1969, spending most of its working life running from Liverpool Street garage in Birmingham. It was one of 438 Daimler buses operated by Birmingham City Transport during that period and was renowned for being smooth to drive but thirsty for fuel and water.
The museum purchased the bus in 2017 from a private collector, adding to its collection of over 90 buses. Until recently, the 2707 was one of the Transport Museum’s working buses, regularly taking visitors on short trips around the Worcestershire countryside.
In 2022, it became clear that 2707 required major engine work, which included replacing the two head gaskets on the twin-head 6-cylinder Daimler engine.
Chris Packer, a mechanical engineering volunteer with the museum, is part of a small but dedicated team that keeps the buses running. A professional engineer, who worked in the automotive and heating industries, Chris retired in 2020 and wanted to do something to keep involved. “You never stop learning,” he explains.
“I’ve been interested in buses since a teenager as there was a bus terminus outside my school gates. Throughout my life, I’d worked on vintage cars and after retiring I went along to the museum and met up with the engineering team. I decided it was the right place to offer my support and I’m now working two or three days a week on restoration and repair projects.”
Chris was tasked with finding a manufacturer for the replacement gaskets, initially looking locally and then expanding his search to the internet.
“I’d rung around locally but not had a great deal of joy. I found Dobsons on the internet and contacted them. The discussion I had with them was much clearer and offered a far more sensible solution.”
The next step was a visit to Dobson’s manufacturing base in Keighley, West Yorkshire: “I took the original head gasket with me. The team looked at the gasket critically and we discussed the features and materials. I felt I’d been given very good advice and ordered the new gaskets.”
Manufacturing the Head Gaskets
To reverse engineer a gasket from a vintage vehicle requires several phases. The initial phase involved discussions about the materials and build with the client. The head gasket would comprise three layers, two traditional outer copper layers and a thin filler layer of non-asbestos material that is a graphite composite with excellent compression characteristics.
In this case, the client had brought the original head gasket and this was scanned to provide an overall guide. Precision measurements were then taken from the original gasket and these measurements are plotted on the CAD system for comparison to the original scan.
Once the design has been checked, the CAD layouts were sent to the in-house 60,000 psi water jet cutter for precision fabrication of the copper layers. CAD layouts for the filler layer were also sent to the CNC knife table machine for cutting.
Prior to the final gasket assembly, several processes were carried out, including deburring the copper layers. A press forma was used to indent the bottom copper layer, creating eyelets that are used to seal the gasket. The last process involves combining the three layers and hand-finishing using a traditional hammering technique before a final run through a press to create a sealed gasket that will last for many years.
The finished gaskets were then shipped to Chris Packer at the Transport Museum.
Back on the Road
When we spoke to Chris he was in the process of installing the new gaskets. We asked him about his experience working with Dobsons and plans for the refurbed bus.
“Dobsons provided an excellent service from start to finish. I was very pleased with the look of the finished gaskets and I would certainly use them again. We’re hoping the bus will be working and on display at Busfest on July 1st at the British Motor Museum in Gaydon, Warwickshire. The event will celebrate 50 years since the end of Daimler manufacture in Coventry and there are very few of this type of bus with Daimler engines still in circulation.”
For more information about Dobson Gaskets vintage engine gaskets, visit https://dobsongasket.com/products/classic-car-gaskets
For more information about the Transport Museum, Wythall, visit https://www.wythall.org.uk/