Friday 26 August 2016

Taking stock (2)


1937 Austin Seven Ruby

converted to

Super Accessories - (Super 750) Special



  • Chassis, back axle, steering, engine and transmission all from 1937 Austin Seven (955 UXF).
  • Engine rebuilt by Alba Austins in Glasgow, Super Alloy head, twin 1-1/8” SU carburettors, custom exhaust.
  • Front suspension: Bowden independent from the 1950's.
  • Wheels 4-1/2” custom built by Barry Brown in Windygates, Fife.
  • Racing seats manufactured by Hunts, USA.
  • Fuel tank custom built by Simon Hall, SiFab Ltd Warwickshire.
  • Custom roll over protection bar by Performance Protection.
  • Bodywork by Reynolds Fabrications with the help of Aliblast and David Taylor, Linlithgow.
  • Cherry Bomb” exhaust.
  • Radiator to fit custom cowl by Newquay Radiators, Cornwall.

To do:-

  • Fit mudguards all round.
  • Repair the bodywork removing unsightly holes.
  • Lights and indicators before running on public roads
  • Vintage tyres for car trials
  • Aero-screen and rear view mirrors




The images shown above were taken just prior to entering the Monklands Sporting Car club Hill Climb event 27th August 2016.

Here is an Index page for the build


Thursday 4 August 2016

Seat belts

As part of the safety on this build seat belts have been conceived from the start. The lower mounts are on the chassis and the top mounts are part of the roll over protection.


Here is an Index page for the build

Creating a front body

The kit of parts I purchased did not include the front metalwork, all of that has had to be fabricated from scratch. Super Accessories never supplied the front metalwork as every car was different according  to their build guide from the 1950's.

Fortunately I had a good place to start in that I created the front skeleton of the car in tubular ERW steel box section on which I can now hang the alloy panels. I used ERW box as this I hope will help stiffen the chassis. I deliberately kept the design simple and very close to the original design. I therefore envisaged  only 4 main panels at the front.

1) Side panels 2 off with a bulge in the lhs to increase the foot well area and a cut-out for the SU carbs on the rhs.
2) Front bulkhead cover panel or instrument binnacle.
3) Bonnet (one piece).

The rear bodywork needs tidied up but that can wait for now the challenge is to enter an event this year.

I decided that both the side panels would be made from 1mm alloy and be wire edged to improve safety,stiffness and durability. The first image shows the usual starting point a cardboard model. I must have made a good job of the ERW fabrication because the cardboard model was sufficient for both sides.

Simple cardboard model is sufficient

Panells cut out and wire edged and protected with tape

First offering up rhs.


Bolted in place lhs

The bonnet

This part of the build was most feared by me as distortions in forming it would be most obvious to anybody looking at the car. I decided to make a "buck" to assist in this part of fabrication. A buck is necessary in order to try out the fabricated bonnet for shape before trimming it to length. The bonnet sits in the instrument binnacle and radiator recesses. The buck was made out of scrap bits lying about the workshop namely some scaffold poles and some angle iron left over from a motorbike packing case.



What started out as a cardboard model of the front side panels and the fabrication of a buck has resulted in a pleasing front bodywork.

Here is an Index page for the build

Friday 22 July 2016

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


 
 

Friday 1 July 2016

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

Monday 13 June 2016

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




Tuesday 26 April 2016

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





Wednesday 13 April 2016

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

Thursday 7 April 2016

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



Friday 1 April 2016

Carburettors

I obtained twin SU's Carburettors from Ruairdh when the engine was being rebuilt I already had the fuel filter and all I need to do now is connect up the cables and pipework.

Twin SU offside

Twin SU's near side


Bracket to support cable controls

Choke mechanism and throttle connected

Initially the carburettors leaked quite badly, the float needles one of which was quite badly worn, gaskets were missing at the tops of the float chambers and the main jets leaked fuel. A call to Burlen fuel systems https://burlen.co.uk/ resulted in all the parts being still available and shipped promptly. I also obtained a pair of fuel filters of Austin Healey air filters from another source which makes a tidy job of the installation.





Here is an Index page for the build

Thursday 3 March 2016

Front fire wall

I decided to make the front firewall out of alloy sheet. The cutting of the alloy sheet around the steering box and pedals was a bit of a challenge but the end result is very pleasing. I have also take the chance to do some of the wiring including the12V regulator.




Inside bulkhead


Outside with protective film in blue

Side view internal
 
Here is an Index page for the build


Saturday 20 February 2016

Fuel tank

The tank in this special was always going to be bespoke. There was no chance of the standard Ruby tank fitting the space in the Super Accessories bodywork. I was going to get Bryn Jones of AliFab  in Wales to do it but he appears to have gone out of business. I was given the name of Simon at Sifab who does an equally good job. The drawings went through a couple of iterations but produced a good tank in the end result.

 

Jim Pettigrew gave me some help to run the fuel lines and the wiring harness along the chassis legs.

Next job is to obtain a sender and make some rubber gaskets to mount it on.

Here is an Index page for the build

Friday 19 February 2016

Wiring harness

The Seven Workshop sell a very nice PVC insulated modern fabric covered wiring harness optioned with flashers and dual filament dipped headlights P/N AE0346 +  options. They also provide a diagram to decode the colours but the options are missing from the diagram. The harness installed very nicely in the chassis but I had to figure out by deductions how the options were configured.

To help you should you choose to do it this way I have included a diagram modified from the original John Comforth diagram but adding the changes associated with:

* Flashers
* 12V conversion
* Dip headlights using a relay and a switch

 

Here is an Index page for the build




Friday 5 February 2016

Radiator

The 750 Special I am building requires a radiator cowl 22 3/16" high. These are very rare these days as they were fitted to much earlier cars so I took the standard ruby radiator and lopped 2" off it. Then I made custom side supports. The radiator core was also reduced in height to accommodate the new cowl. The radiator mounting brackets remain standard.


The next job is to paint all the chassis components ready for the fuel tank return. Then a test drive.

Here is an Index page for the build

Thursday 28 January 2016

Starting handle

One of the parts missing from my engine was a starting handle brass bush. It is a fairly rare beast being 1-1/4" x 18tpi. I asked around the s/h dealers but had no luck so I decided to make one. I have a thread cutting gearbox on my Myford so time to make good use of it.

Here is the resulting part off the lathe

Hex brass bush
 
 
Fitted part
Here is an Index page for the build

Friday 8 January 2016

Steering wheel

The standard A7 steering wheel is 15" and does not give a good driving position (too close to chest and hands too far apart). I decided to search the inter-web and found a 13" wheel from a US hot-rod site, the only problem is there is no compatible boss. Nobody appears to make a boss for an Austin Seven (that I can find). The spline is 50 x 0.5mm deep grooves and 22mm in diameter.

I decided to make a boss and mount the steering wheel on the bottom of the boss to gain greater arms length distance from the driving seat. It turned out to be the most tricky engineering job so far in the build.

 Well I could bore you with the detail of how to go about this but it is difficult. You must have access to a shaper machine and either a CNC controlled rotary table or  a division plate (or be very good at setting 50 x 7.2 deg using a manual rotary table. Here is a picture of my CNC controlled setup.


The tooling manufacturing just to start making the part would put most people off:

* rt angle shaper tool + HSS steel cutting tip (foreground).
* shaper steady fabricated out of 5mm steel plate to support the job (the crap bit of welding surrounding the job).
* Shaper bed extension fabricated out of 10mm thick steel plate and a piece of substantial "I" beam (to support the rotary table etc).

That took me two days making things + a day to set it up and do a test piece and then manufacture the boss.

The result turned out better than my wildest dreams, it fits the A7 steering column like a glove.

Finished steering assembly

Complete with 750 club fixing nut motif
I have to thank Aliblast services (Ali McGill) for the use of his time and shaping machine.

Update 4th Aug 21

The steering wheel remains but has been made removable on a splined shaft as part of the Hilman Imp R&P steering upgrade. The shaft was made of round bright steel bar with McGill Motor Sport splined removable steering wheel kit, the other end was fitted with a knuckle joint. The hollow shaft was made out of a  scrap standard lamp tube and the ends were made out of machinable plastic. The alloy spacer was made recently to make the car more drivable.









Here is an Index page for the build