Rear bulkhead and floor supports

This is the final piece of fabrication work that involves welding directly to the chassis. I am trying to keep the overall weight down as the engine power is not going to be great for the time being. No doubt I will get around to doing something about that but not in the near future.

The rear fire wall is constructed out of 1" x 1.6mm ERW square tubing. I will do the corner weights soon and see what it all comes to.

The requirements are 1) A place to attach the seat belts 2) A place to attach the seats. 3) Support for the wooden floor.

Here is an Index page for the build

Steering arm and linkage

I discovered the steering arm and linkage I acquired appeared to be from another model and did not fit my A7. The steering arm however was not that far away from what was needed but  needed a 90 degree twist at the end. It also needed an adapter to connect to the upright. I had a look at the standard A7 ball ends and I am not that impressed with the design such that I decided to use  a pair of M10 ball joints from McGill Motor Spport and a CDS 22mm bar in between them.

The design for the adapter is shown below, it is designed to take my now twisted steering arm and connect it to the offside upright forging hole.



The 10mm had to be reduced to 5 mm to make space for the brake cable.

Adapter in place

Steering arm in place

Subsequent measurements show only two turns lock to lock.

Update 4th Aug 21

This modification is now replaced with updated Hilman Imp steering conversion.

Here is an Index page for the build

Rear radius rods

The Austin Seven rear suspension suffers from bending sideways on corners. This results in excessive overseer. If you view (http://austin7special.blogspot.co.uk/2015/07/considering-rear-chassis-modifications.html) I have now considered all the options and I have decided on the A frame implementation.

On the chassis part I have decided to make a ball joint similar to the front tie bars. The first job is to make a ball on the lathe to mirror the ball on the torque tube. Obviously the ball on the left is rear facing and has a 10mm hole to take the radius rods.

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 The tie rods are manufactured from 22mm CDS tube with custom turned ends. The chassis ends are simple cups to take the ball shaped A7 joints and the other end is a 30mm bar turned out to an interference fit of the Metalastic bush. The metalastic bushes are std10mm x 23mm x 28mm bushes off ebay probably used for a quad bike or the like.

Tie rods in place

Tie rods

Clevis plates added to diff casing

Update 4th Aug 21

This  subsequently proved to be a big mistake and updated with a Panhard Rod see further posting. The old mountings on the diff were ground off.

Here is an Index page for the build

Throttle pedal

I have been looking at various A7 specials and I must say the pedal arrangement has less than generous space for your feet. I am used to  small pedal boxes being a kit car enthusiast but A7 specials are even more of a challenge. To get a more usable pedal box on the rhsI decided to put a power bulge next to the throttle. Browsing the ebay adds for throttle pedals I found one for an Austin Mini from the 60's that looked interesting so I took a punt. I had to bend the shape a bit with extreme heat and shorthen it a bit but nothing drastic.  Here is what I came up with and I must say I am very pleased with the result.



Here is an Index page for the build


Custom tie bars

The front suspension has tie bars from the chassis (centre point ) to the stub axel mountings. These tie bars prevent the geometry changing under load. The suspension was manufactured by Bowden in the 50-60's as such the track width is greater than standard A7. I could not find any such wider tie bars on the usual s/h sources so I had to fabricate some. The suspension end had to be heated to yellow and bent. The tie bar tubing was cut out of  25mm x 3mm thick CDS. The cup ends were turned out of 38mm bright bar and the axel ends out 25mm bar as pre attached diagram. After turning the 43mm long section it was grooved and bent to the correct angle. The groove is necessary to keep the bend angle tight, I welded it up afterwards.



Chassis end

Upright end



The finished tie bar vs original

 

To secure the tie bar end I used a full nut and  one half nut made out of an old castle nut but with the same thread and a larger spanner size cut down on the lathe. The half nut is on the inside. There are two thrust washers cut out of 30mm bar 3mm thick. The thread by the way is a 5/16 x 16tpi UNC thread form available from Tracy Tools.



Update 4th Aug 21

The tie bars were subsequently modified to have jack screws to adjust their length as part of a Rack and pinion upgrade.

Here is an Index page for the build

Brakes

The brakes have been a bit of a trial for me, there are so many permutations even if you stay with the original mechanical systems. My system is a mixture of Bowden mechanical at the front and an early A7 mechanical system at the back. The brake drums are of two different types. The front brake drums don't fit the back and vice versa. The front brake shoes (3off) were missing and as far as I can ascertain are unobtainable. I decided to get a set of eight s/h alloy 1 1/4" and  move on  from that point and make everything fit.

Rear brakes

The cams at the back were not even running in a brass bearings, just holes in the forging and seized at that. As these were badly worn these had to be drilled and bushed and reamed to size. The cams that were initially supplied, were the wrong type and had to be changed again for an earlier type. This of course results in another strip down of the hub carrier.

Rear brakes connected up and working

Front brakes

The front brakes were another  challenge, requiring the 1) fabrication of a new back plate. The standard A7 oem back plate had to be cut away to accommodate the Bowden forging protrusions and mounted on the back to make room for the non standard brake drums.  I have no idea what the drums are off but they do not fit the Bowden assembly ideally.  2) The  pivot point for the brake shoes had to be moved to accommodate the smaller A7 alloy shoes. 3) I had to increase the internal contact width slightly and fit a 2mm spacer on the wheel studs to make them fit with the 1 1/4" shoes. The drums were also well off the concentric being about a mm of wobble. This had the effect of locking up the brakes. 4) The drums were trued up on the lathe.  The front brakes, now at least, go together and look as if they may actually stop the car.

 



Front drums fit after truing up on lathe

Hand/foot brake

The handbrake started out devoid of modifications other than shortening the leaver to allow it to reside under the bulkhead. I tried the standard parts for the Bowden cables operating the front brakes but was hugely disappointed by the lack of any fine adjustment. I can see the rear bakes have this problem but the front brakes are somewhat more critical as 80% of the effectiveness comes from them. I decided to modify the balance bar and add a full length cable from an Austin Maxi.



Modified balance bar to front brakes

Previous adjustment

Previous balance bar arangement

Update 4th Aug 21

I have subsequently updated the brakes to hydraulic twin leading shoe at the front and single leading shoe at the rear, the brake liners have also been updated to Mintex high performance racing material.

Here is an Index page for the build

Brake pedal and steering box mounting

Now that the front bodywork frame is in place I can set my sights on the intermediate goal of getting a rolling chassis with brakes and steering.

The next job was to mount the steering box at the required angle for an open topped special and get the brake pedal mounted correctly relative to the bodywork also.

I have the alloy wedge, the normal way of changing the steering angle but that has proved to be a poor solution as the angle provided is not quite low enough and even when all bolted up looks rather flimsy (will not take a good shake without everything moving).

I decided to make a new steering box mounting and modify the brake pedal position to suit my front bodywork. The pedal  had to be bent with some heat from my acetylene kit to achieve the desired pedal layout.

Slight bend to pedal

Steering box mounted

Now connected to the hand brake

Update 4th Aug 21

The steering has been converted to Hilman Imp rack and pinion the steering wheel is now smaller and removable. See later postings.

Here is an Index page for the build

Front bodywork

The front part of the bodywork was missing on my Special, that allows me to invent what you like in my opinion. I decided to add the missing panels bulkheads etc by fabricating the frame in 1" x 1" x 1.6mm  ERW steel square section hollow tube. I have started with a fairly simple structure but the improvement in torsional rigidly is already apparent. I tied the long longitudinal into the top of the cow horns. At this stage the joints are all just tack welded in case I change my mind.

I will add images here as I go along to help keep track of my progress.

Here is an Index page for the build

Transmission

The transmission fitting issues were initially thrown up by the engine trial fit (previous blog).

1) Diff: I needed to get Ruairidh to bail me out here by getting him to fit the inner seals. He fitted modern lip seals for me and yes there is a trick to it, and no I cannot explain adequately here, you have to see to believe it. Otherwise I assembled it as per the manual and some more bits from the Seven workshop.

2) Gearbox output flange: Ruairidh came to the rescue again, I managed to trade some windscreen supports for a gearbox output flange.

3) Torque tube flange: The dealer who sold me this did not have a four hole flange and was unable to supply one. I however managed to make an adapter plate out of steel stock.  I decided  I was not going not to just drill four holes in it and hope all aligns, I machined the differing indents for alignment into either side of the 6mm steel plate.

4) Rear springs: To check all the transmission interface and body fit issues I needed to trial fit the rear springs as well. I obtained new springs from Ruairidh's dad Ian. And assembled it using HTS U bolts.

5) Gear Linkage: Worked on the remote linkage for the best part of a day. The linkage, the selector blade and top spacer plate had to be modified.

Otherwise it all went together after a day and a half most of the time taken up by the diff refurb.




New gearbox flange + sliding joint position acceptablele

Torque tube adapter plate

Spring attachment points

Gear linkage

Problems

Clutch engagement

When I first mated the engine and gearbox, the operation of the clutch appeared very strange. Further discussions with  Ruairidh the operation of the clutch was deemed to be normal. The first inch takes up the free play in the pedal to thrust bearing contact. The next two inches takes up the thrust bearing to clutch leaver contact, the last inch (or less) is the actual clutch release plate compression area. I am an event competitor, and having the clutch take up in the last 0.5" (or less) is not what I am used to, I know this is going to cause me problems.

Solution:

I made an alloy round washer shaped spacer approx. 70mm od and 51mm id and 9mm thick and located it behind the release mechanism. I experimented with the thickness until I got what I think is an acceptable clutch feel. It now disengages less than  an inch after taking up the pedal free play. The pedal free play is eliminated using a spring pre tensioner having no adverse effect on the release bearing.

Update 4th Aug 2021

The gearbox was subsequently upgraded to a dog box that no longer needed the spacer or the spring fabrication. I know not why and will possibly remain a mystery.

 Here is an Index page for the build

Engine trial fit

Now that the engine has returned from Alba Austins in Glasgow it is time to trial fit it to the chassis and see if it all connects up. The purpose of all this is to throw up the problems and design the missing parts of the bodywork.

 

 

Engine running: https://youtu.be/23W3Rpedm4s

Diff flange 6 holes and prop shaft 4!

Gearbox tripod thing

Diff in place but not cleaned externally but  needs refurbed

Problems

The engine fits in the chassis, however the adapter plate coming out of the gearbox has 3 thingy's (meant to interface with a rubber flexi joint), the prop shaft has 4 holes in either end plate and the torque tube adapter has 6 holes.I have managed obtain from Ruairidh (Alba Austins) a 4 hole flange for the gearbox output, I may have to make an adapter converter plate for the torque tube flange.

The back axel was full of water, discovered at the blasting stage and has to be cleaned internally stripped down. Ruairidh replaced the inner seals for me however I need to adjust the inner bearings after rebuild and get the brakes working. The pivot pins are two different sizes neither of which fits the brake shoes I have.

Update 4th Aug 2021

The engine was fine as a restoration but I have had the engine further developed to produce an estimated 3x the original power with racing pistons, high lift cam shaft, lightened flywheel and racing gearbox.

 Here is an Index page for the build

Cown horns and front suspension mounts

Progress is slow on this project so far with major bits still all over Scotland. The objective is to get the car ready for a hill climb next year and time is marching on.

The engine returns from Ruairidh Dunford (engine restorer) at the weekend so time to get some stuff done before it arrives.

Cow horns

The "cow horns" are the means of terminating the bodywork in a Ruby to the correct width to integrate with the radiator. The cow horns I have are from a different model. They are forged pieces and about 8mm thick. One of the holes is correct the other was about 15mm out. Despite that they are perfectly usable and easily modified. Just weld one hole closed and drill another.

Front suspension mounts

The front suspension on this build is a Bowden independent setup from the 1950's . I have had all the parts cleaned and blasted it is time to start putting it all together. The first job was to order 40mm high tensile square U bolts. Unfortunately square U bolts are anything but, they have curved corners. When clamping the front suspension it is important to clamp things over a wide surface area, and ensure the bolts don't move in the event of a small impact with kerb or such like. I made up saddle using 4mm steel plate with curved corners to match the U bolts corner radii.

As I don't have any wheels yet the front hub assemblies final fit will have to wait for now. Next job mount the engine gearbox and back axel to visualise and plan the chassis modifications.

 Here is an Index page for the build

Roll over protection

I consider the matter of roll over protection on these cars quite important. Here is an illustration of when it all goes wrong.

I designed a Roll over protection bar and sent the drawing off to be made by a company called Performance Protection.

The parts arrived a couple of days ago and here are the bits welded in place.

View from the front

Chassis location

Some mods to the bodywork are required, note one of the wooden cross braces were in the way.

Here is the forward cross brace to the passenger footwell.

 Here is an Index page for the build

Dashboard

Like the Ruby this 750 Special came with a nice dashboard panel, just needed a quick lick of paint. I managed to get an original A7 Speedo, AC Petrol gauge and a rather nice looking oil pressure gauge from various ebay auctions. The ammeter is reproduction Massey Ferguson unit (at least the pointer is a vintage shape). The red waning lamp and panel illumination switch are reproductions. The lights switch came in the parts box. The blank holes are for the choke and starter pulls. I had to make an adapter washer for the warning lamp and fabricate at least three of the retaining brackets. Look forward to mating it with a wiring loom some time.

Here is an Index page for the build

Steering

I was given an alloy A7 steering box and column as part of the parts purchase. I had it cleaned up by Aliblast Services. I then striped it down to clean all the cr..p out of it using a parts washer. The parts looked in good condition but the thrust washer was missing. I made a new one on the lathe.

The next task was to secure it to the body and chassis. This may tell me if the body belong to this chassis. The two critical dimensions are the distance from diff to rear tub (120mm minimum) and the position of the column as it attaches to the dashboard.

To facilitate a lowered steering column I had the Super Accessories mounting wedge. There was some evidence of a further rake beyond that as the lower part of the steering box flange had been  filed. I decided to make an additional 10mm wedge to match that shape as I am tight for the body fit on that chassis.


Steering box, SA wedge and my 10mm spacer

Subsequent to this experiment I made a custom fabrication as the steering box had a habit of flapping about a bit under load.



Steering box mounted

Steering wheel

The steering wheel looks a bit of a challenge. It is 15" in diameter and is of a nice vintage 3 spoke period design. It came with a rather nice wheel "tilter" mechanism and latch (to help get you in and out) but I have no idea how to fit it, in my application. It looks like you weld it on to the column directly but that would eliminate any servicing possibilities for the steering box. The diameter is a bit large without a "tilter"  to get in and out easily. More thought required.

Update 4th Aug 21

The original style steering wheel was sold off on ebay and The steering has been redesigned and converted to Hilman Imp rack and pinion the steering . The new steering wheel is now smaller and removable. See later postings.

 Here is an Index page for the build

Body fit

I have been torturing myself in thought about the body fit since purchase, in reality however  the only issue is the length of the body front part vs the chassis. If I am required to lengthen the body, . all the alloy panels are single curved design so remanufacture is in fact quite simple. However after fitting the steering column all appears to fit quite well.

The most elegant solution to the body fit is to cut  cut and bend the rear chassis legs 22deg inwards (instead of outwards), simples! The petrol tank will eventually fit between the rear chassis legs as before, even if it is a different shape.

Before chassis mods

After chassis mods

 Here is an Index page for the build