Wheels and tyres

The big problem with the original wheels is they are 18" and any reasonably proportioned racer special the wheels need to be smaller preferably 15". I decided on 16" as road going tires start at this size or so I was told. I got Barry Brown in Fife, Scotland to make my wheels. A friend lent me a drawing for the wheels he had made for his special.

The ideal size of tyre would be 165 x 70 x R16 but the only one I could find close to that was a 50 profile. Not a wonderful size for a vintage racer however adequate for my first hill climb.

Here is an Index page for the build

 

 

Taking stock

The challenge in my mind has always been the Bo'ness hill climb,  my entry is now confirmed for this year Sunday 4th September 2016.

The things still to do are considerable.

* Finish welding the roll over protection bar and install seat belt mountings.
* Petrol cap wire
* Tow point labels
* Front bonnet and side panel fabrication (a lot of work).
* Fuel gauge calibration
* Attach the bodywork and floor properly
* Get tyres and tubes for wire wheels then fitted
* Steel wheel nuts


Oh dear what have I done?

Here is an Index page for the build

Shock absorbers

I decided to keep the original friction shock absorbers. They suit the period implementation of a Super Accessories Special from the 1950's. I can always fit hydraulic dampers at a later date.

Front

Rear

The devices are totally restored and in the case of the rear, remanufactured parts were obtained. Painted in red to highlight them against the suspension.

Update 4th Aug 21

The front shock absorbers have been replaced with independent stainless fabrication and was instrumental in the performance improvement I see today. 

Here is an Index page for the build

Testing

The engine has never been run up in the chassis with gearbox and transmission. So it was time to give it a go. Here is the result of the first attempt:

https://youtu.be/-3mJPrFE0eE


Here is a summary of the results:

* The casting which mounts the generator was leaking engine oil.
* The fuel pump was not working, had to use an electrical pump in series with the mechanical SU pump.
* The generator was not charging.
* Fuel leaks in the carburettors
* The choke action is too stiff and unpredictable will not return to off without help.

Update 01/07/16

All the problems are now resolved except the choke action.

Here is an Index page for the build

Exhaust

Every car needs one and the relentless pursuit of a rolling chassis demands one. I picked up a front section from the Austin Seven Workshop, a mid section called a "cherry bomb" with the same pipe diameter from a motor bike. I also obtained a tail section which I cut out of a bend and tagged on to the end of the assembly. A right angle section and two plates turned the exhaust so it exits from the  side. The result looks interesting and can't wait to see how it sounds. The brackets were fabricated and welded as per the usual process.

Update 4th Aug 21

This exhaust design has gone thru several iterations, the last one about 2 years ago subsequent to an engine upgrade.

Here is an Index page for the build

Transmission tunnel

The transmission tunnel is a pretty essential safety feature. However it is also a pretty odd shape, however I am a great believer in that anything you can fabricate in cardboard you can make in thin  alloy plate (1.5mm). It should sop any vital bits getting in contact with the prop shaft.

Here is an Index page for the build

Gearbox problems

Decided to clean out the gearbox internals prior to fitting the engine for the last time before it's first run. The c..p that came out of it defied belief. It was a mixture of gravel, rust and slime. No matter how many times we flushed it (eight times) more magnetic particles came out. At this point it became obvious that a total strip down was necessary.

Being temporarily out of funds for a professional rebuild I decided to do it myself this time. I have never stripped a car gearbox before so I ventured on to ebay to look for a spare to practice on and possibly get some spare parts.  A auction came up for a spares or repair box that looked very similar to mine. It was described as an A7 or possibly A10 for spares or repair and the price was right.

The box arrived, it had quite a lot of corrosion around the clutch release bearing but the internals looked sound. I had a hell of a job getting at the first motion shaft bearing but a plasma cutter and a drifting screwdriver saw the release bearing off without much damage to the first motion shaft.

Release bearing corrosion extensive





Bell housing

Release bearing

After thoroughly flushing the box internally, further work got the gears out thanks to a good description in Doug Woodrow's book on the Austin Seven. A good heat gun is necessary to remove some of the parts especially the layshaft end cap.

Not much left of the clutch release bearing now

Internal gears and syncro clutches still in good condition

Gears  train after strip down and clean

The box is an A10 type with odd ratios of 5.15, 3.10, 2.2 and 1.0 compared to my box of 4.36, 2.63.1.66, 1.0 the only explanation I can think of is it is an A10 van gearbox.

My gearbox rebuild 22/04/16

The A7 strip down was very similar to the A10 gearbox without the drama of having to cut out the first motion shaft bearing. After cleaning all the parts with a ultrasonic cleaner most of the parts looked pristine except the first motion shaft bearing, third motion shaft bearing, inter shaft bearing, one end of the lay shaft bearing and the detent ball and springs.

The essentials for doing such a rebuild job was:

* Set of bearings, detent balls, springs and gaskets (readily available from Austin Seven Workshop)
* Some steel shim sheets (ebay)
* Assembly tool for third motion shaft output bearing (35mm bar with 26mm x 65mm hole cut in end). I am sure other bits of pipes, 1/2" sockets  etc can be used I just choose no to as it is a fiddly job.
* Selector rod detent assembly tool (drawing in Doug Woodrow's manual). I cannot imagine doing this rebuild without this tool, a major time saver.
* Synchroniser detent assembly tool, apparently a outer from a metal food tin of the right size will suffice. (I made one out of copper sheet and soldered it as I could).
* Access to some machining services for the casing indent  for the 3rd motion shaft bearing clip.

Special tool collection



Selector rod detent spring and ball assembly tool

Third motion shaft indent for cir-clip

The first job is to extract the bearing on the engine side of the lay shaft, clean up the bearing surface and make up a steel shim and fit to the back of bearing to compensate for the wear and scoring suffered by years of use/abuse. Ideally you need to ream the bearing once you have reinserted it but I used a small flap wheel  to remove any ridges carefully. The shim at the back of the bearing was 20 thou thickness in my case. The shim was cut out of 20 thou steel shim plate inner hole was 22mm the outer diameter was 36mm. I used Mag drills to cut this as they cut thin metal sheet better than twist drills.

The next job is to renew the synchroniser detent balls and springs. This requires the special tool which is basically a hollow cylinder that just fits over the synchroniser gear and 7mm hole to allow the ball to pass through. One you have done one ball and spring just move on to the next one.

synchroniser detent ball and springs tool

The fist motion shaft bearing was pressed in easily with two 1/2" sockets of the appropriate size using a 6" Record vice as the press. The third motion shaft bearing has to be done with the front part of the partially assembled gear train in position in the casing. I found the  special tool I made to be helpful as the whole lot was put in a hydraulic press. Once the bearings were assembled on to the shafts the bearings were inserted into the casing with the help of a heat gun applied onto the alloy casing surrounding the bearing seat.

One further note about the bearings: The spring cir-clips supplied with my bearings were too large to fit the detent in the casing, the clips were recovered from the old bearings, so don't throw them out. On the third motion shaft I had to increase the detent area in the casing by 50 thou to allow for the cir-clip despite using the smaller original clip. The groove in the bearing was 25 thou less.

Once the bearings and gears were assembled the lay shaft was inserted through it's gear assembly. If the gears bind for any reason then a thicker or thinner gasket can be used on the end plate (or none at all). In my case I increased the gasket thickness.

The next job was the selector rods. These all have to be pre-fitted before you attempt to install the detent balls and springs. This definitely requires the special tool and a lot of patience. I only dropped one ball inside the gearbox that was promptly retrieved.

The rest of the build was done as per the manual with no further difficulties encountered.

The final task is to adjust the selector rods detent position relative to the casing. A screwdriver slot is provided in each rod for this purpose. Each gear is selected in turn to ensure there is no drag in the box as this will not enhance you gear changes.
.

The completely refurbished box

I have to give full credit to Jim P for giving up his time to help with the build particularly the gearbox.

Update 4th Aug 21

This box remains as a spare part subsequently replaced with a "dog" racing box.

Here is an Index page for the build