Rebuild and modifications to the chassis of the B-Plus

 

As you will have no doubt gathered by the work that I do on these old Duttons I am not so impressed by the original engineering and that there are more than a few area's that can be improved upon and this was the case with the B Plus. The basic structure of the car was pretty good and I am sure plenty of people woulkd have been happy with the car as is and just driven around in it.

The car was very well presented - custom made carpets and leather seat squabs and a padded and well equipped dash made the car look very very nice as can be seen in the pictures below but as you will see further one these hid a multitude of sins.

The basic B-Plus chassis is a sort of cross between a ladder frame and a space frame - It has a large section frame very similar to the hot -rodders typical ladder layout and then perched on that is a flimsey space frame that really only does the job of supporting the surrounding alloy panelling - there is no real structural strength with it. This kind of means that the car is the worst of both worlds as its Ladder frame has no real triangulation as such and the space frame is mainly space and very little frame. the only saving grace is that the ladder is of a sufficient section that the cars do not rip themselves into bits even if they are likely to flex a bit.

The following gallery will shows the chassis, central tub removal and horrors it held and the amount of steel I have put in to acheive true space frame layout.

 

This picture shows the basic Dutton frame but unfortunately I and a previous owner had added a few tubes so I dont have an actual shot of the standard item. however I have highlighted the additional tubes so if you take it that they are not there on a stock B-Plus you can understand why I felt the need to add a few in - and then a few more.

A step back from this was the removal of the central seating tub which forms the transmission tunnel seats seat backs foot wells and fire wall. This part of the assembly is usually riveted to the chassis, the rear body section and the scuttle with the Scuttle then itself rivetted to the top chassis rail.

This central tun was a real horror show with all sorts of bits of junk bonded into it to make the general shape of the inner tub fit around the Rover LT77 5 speed gearbox and bell housing.

 

 

 

 

 

First stage of the real modifications to the central area to start to assembly a transmission tunnel / backbone to stiffen up tha chassis.

I had started the modifications with a mind to drop the seating area by an inch as is now a popular practice with the Caterhams and Westfields and the pictures below are part way through this work you can also see the battery box positoined to the far near side of the rear boot area. Unfortunatley I overlooked the fact that the 2" bore exhausts that I wanted to be rear exists would now be another 1" closer to the road and the rear uprights for the roll bar would pass straight through the battery so a rethink would be needed to resolve these issues.

 

 

A great deal of thought later I decided that I had to have rear exit exhausts because they sound far superior to side exits on a V8 and the sound is what a V8 is all about and that the remanufacturing of the chassis was no great re-work as it was all just tacked on for that very reason. moving the Battery box was also a simple thing to do.

One thing that had been bugging me with the B Plus chassis was the position of the rear chassis rail so close to the axle tube preventing good axle articulation, this was the same issue I cam across when lowering the S4 only with the B Type I had the added probelm that the trailing arms were positioned that they rose at an angle to meet the axle boxes becasue the brackets are placed to low on the chassis.

What I decided to do was add in some good triangulation around the suspension mounting point that would also provide support to the chassis to the extent that I could slim the chassis rail down from 60mm deep to 25mm deep giving me an extra 35mm of axle articulation room and also the ability to raise the suspension pick up points so that at the nromal ride height I can ahve the link parallel.

Another area where this large section chassis rail was being an issue was in the drivers foot well where it was intruding 3/4" futher than is really necessary and with a V8 bellhousing in close proximity every mm counted so that area of the chassis was triangulated to add additional structural strength and the chassis rail was cut in half to slim it down.