Considering the rear chassis modifications

There is a book called Austin '7' Specials by L.M.(Bill) Williams that illustrates the issue. The A7 leaf springs can cause significant over-steer due to shortening on one side versus the other. To remedy this an A frame can be fitted as illustrated in the fore mentioned book .

The issue surrounds the fitting of the 750 Special body that narrows in at the back, the addition of shocks, petrol tank and last but not least a roll over protection bar.

Douglas Anderson says"The A-frame in your the above illustration  does not look like there are enough degrees of freedom for the axle to work without twisting the frame or bushings. The Panhard rod is a far simpler idea. The A-frame looks like it would interfere with the torque tube as well."

Panhard rod

Watts linkage does a similar thing


Watts linkage

RD part for Escort?

  Here is an Index page for the build

 

 

 

Initial summary

To summarise what investigations have revealed so far:

* The chassis looks sound and consistent with it being a Ruby chassis from 1937. It is currently being sand blasted at Aliblast Services in Linlithgow to see how sound it actually is.
* A major unknown is whether the Super Accessories - "Super 750" special bodywork fits the long chassis of the Ruby. After adapting the rear chassis to fit the Super 750 bodywork all appears to be fine. It would appear the differences between the short and long bodies are all at the front.
* The engine block and castings look in good condition with some interesting tuning bits however it is  just that, a kit of parts.  Ruairidh Dunford in Bearsden has agreed to completely restore the engine including a "Phoenix crank".
* The differential and axel which I thought was almost complete is missing some very expensive parts like the crown wheel, pinion, hub assemblies and brake parts. Replacement diff assembly is now purchased.
* The brakes are were almost non existent apart from one corner, offside front. All the parts are now obtained from Tony Betts.

A lot of work still to do...........

Here is an index of all the blog pages

Date	Link	Description
11 July 15	The start	Purchasing the car
12th July 15	Inspecting the gearbox	Gearbox 4 speed
13th July 15	Front suspension ident	Bowden front suspension
13th July 15	What brakes	Lots of brake problems
13th July 15	Index	Initial summary and index
15th July 15	Body fit	Will the body fit the chassis
27th July 15	Considering rear chassis mods	Sorting oversteer problems on A7
1st Aug 15	Body fit to chassis	Will the body fit the chassis
14th Aug 15	Steering	Alloy steering box overhaul and lowering
15th Aug 15	Dashboard	Dashboard
16th Oct 15	Roll over protection	The roll over protection bar design
4th Nov 15	Engine returns	Trial fit of engine
8th Nov 15	Transmission	Connecting up the drive train
16th Nov 15	Front bodywork	Replacing the missing front bodywork
24th Nov 15	Brake pedal and steering box mounting	Brake pedal and steering box mounting
2nd Dec 15	Brakes	Refurb of the brakes keeping them mechanical
9th Dec 15	Custom tie bars	Front suspension custom tie bars
12th Dec 15	Throttle pedal	Throttle pedal from a Mini fits well
13th Dec 15	Rear radius rods	Rear radius rods to cure famous over steer
15th Dec 15	Steering arm and linkage	Steering arm and linkage mods/fabrication
23rd Dec 15	Rear bulkhead and floor supports	Preparation for floor and seatbelt mounts etc
8th Jan 16	Steering wheel	Changing from a 15" to a 13"
28th Jan 16	Starting Handle	Starting handle
05th Feb 16	Radiator	Resizing the radiator size and making mounting brackets
19th Feb 16	Wiring harness	Standard Ruby harness with flashers and dip headlights + 12V conversion.
20th Feb 16	Fuel Tank	Custom fuel tank
3rd March 16	Front fire wall	Adding alloy panels to create a fire wall
1st April 16	Twin SU carburettors	Adding twin carburettors
7th April 16	Gearbox problems	4 speed gearbox corrosion problems
13th April 16	Transmission tunnel	Another safety feature and keeps the rain out.
26th April 16	Exhaust	Cherry bomb exhaust
13th June 16	Testing	Testing the engine, fuel system and electrics
1st July 16	Shockers	Replacing the mechanical shock absorbers
1st July 16	Taking stock	Preparing for the first hill climb in September 16
20th July16	Wheels and tyres	Difficult choices for tyres
4th Aug 16	Creating the front bodywork	Four panels to complete the front bodywrk
4th Aug 16	seat belts	Seat belts for safety perhaps
26th Aug 16	Taking Stock-2	Entering the first hill climb, reflections
21st Feb 17	Cycle wiings and modified exhaust.html	Start of the winter 2016/17 upgrades
23rd March 17	Mirrors and aeroscreens	Essential to complete the vintage look
14th April 17	Battery drain problems	Battery drain from electric water pump
14th April 17	Summary after redesign of critical items	A full seven issues identified after Forrestburn trial
5th May 17	Lights	Adding road legal lights
24th June 17	Battery charging revisited	More problems with battery charging
14th July 17	Starting issues	Starting issues with 6V starter
26th July 17	Tool storage	Place to put tools if you drive it on the road
14th Aug 17	Brakes binding	Plagued by brakes that bind
28th Aug 17	Electronic distributor	Upgrading distributor
21st Jan 19	2017-2019 Upgrade	2017-2019 Major upgrade, tuned engine, better brakes etc
29th Jan 19	Tonneau cover not quite	Home made tonneau for trailering to events
28th Feb 19	Dynamator	Dynamator and water pump thermostat
9th Mar 19	Cushions for racing seats?	Gail from GJ Upholstery makes me some seats
22 Mar 19	Temp, Volts,USB	Temp and Volt gauge from Chinese cigar adapter
2nd Aug 21	Rack and Pinion Steering	Rack and pinion steering conversion using Hilman Imp parts
4th Aug 21	Adding Caster	Setting the caster angle of the steering to 6 deg
.	Shock absorber improvement	Improving the Friction Shock absorbers in the Bowden front suspension
.	Rear Panhard Rod	Revisit the rear Panhard rod
.	Improved Headlights	Improved headlights to help with MoT
.	Petrol Pump	Fuel Pump Upgrade

The brakes

The brakes is another subject that has provoked much thought recently. With the acquired Bowden front suspension came half the parts for the Bowden front brakes which are reckoned to be superior to the original A7 OEM ones. The rear differential and drive shaft assembly, all the brake parts are missing including some very expensive machined bearing hubs etc. In the long term I may fit hydraulic brakes all round.

I have three hub assemblies that fit  the front axel, only one has ball races that rotated. I removed all the offending bearings for replacement. The priority is to find a)missing parts for the front brakes b) a set of brake parts for the new rear axel.


Rear hubs no cams/pivots

Bowden front axel 1" brakes



Bowden cables

 Here is an Index page for the build

Update 27th Aug 15

I have decided to upgrade the brake shoes to 1.25" with I have purchased from tony Betts. I have also got all the parts now for the rear hubs on the new axel. I also picked up a spare set of drums from Tony. Rolling chassis here we come!

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.



Front suspension

My attention has now turned on to the front suspension. The suspension in the kit of parts I bought is an independent unit supplied by Bowden Engineering Company. They were a significant after market supplier in the 1950's for A7 upgrades. If you are building an uphill racer then this is the suspension to have. It is now at Aliblast Services.

 Here is an Index page for the build

Inspecting the differential

Next on the list for appraisal is the differential, it is documented as a "D Type" they produced three varieties of this particular type shown below.

Unfortunately I don't have a crown wheel so I cannot identify the part from measuring the ratio. I have an image of the internals missing the crown wheel.

The unit looks partially restored but missing the Crown wheel and matching  pinion. I have 4 x 18" wheels I guess that may set the ratio in the end. The rear brakes, hubs and back plates are also missing.

 Here is an Index page for the build

Update 27th Aug 2015

I costed a new crown wheel and pinion for the diff and the hubs and concluded the cost would be in excess of £800 to continue with what I have. I managed to pick up a very good second hand part from Tony Betts, the above item will go on ebay eventually once I make sure no other bits of it are any use. The ratio of the unit I have purchased is 5.125:1 and with 15" wheels would give a top speed of 67.4mph at 5000rpm or 75.5mph with an 18" wheels. For my application I think 15" wheels is what I need. However road legal competition tyres could be an issue unless I go to 16".

 



Inspecting the Gearbox

I decided to start investigating what I have purchased in terms of parts and what work needs done. I started with the gearbox. It looks complete and is a four speed variety from 1933 onwards, it has a remote shift from a company called Wooler. I took the lid off and it has been cleaned of all oil but unfortunately it was seized (as a result of lying around with no oil I guess). I put some WD40 into the input bearing, attached the spare clutch plate with the spline and rotated it slowly using the clutch plate as a leaver. With minimal force it eventually freed up and I was able to measure the ratios. I put a piece of tape on the input and output and estimated the number of turns like a clock face noting the turns to the nearest 5 mins.

First  = 4.33 (* 4.36)
Sec    = 2.58 (* 2.63)
Third = 1.66 (* 1.66)
Top   = 1.0   (* 1.00)

* From manufactures spec

In summary I have a bog standard 4 peed box from 1933 onwards with a remote gear change. It looks like it needs a refurbishment from the bearing point of view if nothing else. It is also missing a drain plug. It appears to have a s/n of 37877

 Here is an Index page for the build.