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+--- Thread: Push rod rear brakes (/showthread.php?tid=2197)
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Push rod rear brakes - agmatthews - 06-01-2019
I have recently 'inherited' an Austin 7 chassis with unusual brakes and was wondering if anyone can help me with identifying where they are from.
I'm only new to the Austin 7 and still on the steepest part of the learning curve, so would appreciate any wisdom you can share.
The brakes appear to be solid push rods that run back along the chassis rails to the rear brakes - photos below.
The only reference I've been able to find to any sort of push rod style brakes on an Austin 7 was a hybrid rod and cable system that ran a single rod back to somewhere near the rear chassis cross member then cables to each wheel.
This chassis appears to have been extensively modified during its life with welded on reinforcement, a strange boxed in cutout in the rail on the front left under the engine, plenty of muck and grime, and no obvious chassis numbers to find - yet.
regards
Andrew
RE: Push rod rear brakes - John Cornforth - 06-01-2019
I haven't seen that arrangement before, but plenty of contemporary cars used rods.
I suspect the rods work in tension, i.e. in the "Pull" rather than the "Push" sense, otherwise they would buckle on application. They need good support near the "hinges" in front of the rear wheels, to avoid bending.
RE: Push rod rear brakes - AustinWood - 06-01-2019
A neighbour when I lived in Cambridge bought a Swallow saloon with a similar set up.
Ray Walker put it back to cables for him straight away. The brakes were affected by the suspension - not good.
The neighbour bought the car from a dealer Norfolk way from whom I bought a Nippy. He was a very big man, I have no idea how he got into the car let alone drive it.
My Nippy left a lot to be desired too.
RE: Push rod rear brakes - Chris KC - 06-01-2019
Yes, what John said. That layout is poor as the rods will be subjected to friction, bending, and ultimately fatigue. This might have been avoided using a bell crank or similar mechanism at the point of angle change. Simplest thing to do is chuck the rods and reinstate cables (readily available from Seven Workshop and others).
RE: Push rod rear brakes - Ian Dunford - 06-01-2019
My wife had a 1936 2 seater with just this arrangement but as John says above they worked on the pull system rather than push.
I use the word worked amusingly.
RE: Push rod rear brakes - Zetomagneto - 06-01-2019
(06-01-2019, 01:20 PM)agmatthews Wrote: I have recently 'inherited' an Austin 7 chassis with unusual brakes and was wondering if anyone can help me with identifying where they are from.Nice proper short chassis 28ish?.Looks to have been patched/ boxed at front crossmember probably due to cracking
I'm only new to the Austin 7 and still on the steepest part of the learning curve, so would appreciate any wisdom you can share.
The brakes appear to be solid push rods that run back along the chassis rails to the rear brakes - photos below.
The only reference I've been able to find to any sort of push rod style brakes on an Austin 7 was a hybrid rod and cable system that ran a single rod back to somewhere near the rear chassis cross member then cables to each wheel.
This chassis appears to have been extensively modified during its life with welded on reinforcement, a strange boxed in cutout in the rail on the front left under the engine, plenty of muck and grime, and no obvious chassis numbers to find - yet.
regards
Andrew
RE: Push rod rear brakes - Bob Culver - 06-01-2019
The brakes are an inept technically wrong modification. The rods are subject to bending. A local RN car has a similar mod but with anchored pivoted arms at the change of direction.
I recall being charged a then eye watering 14/- in the 1960s to have a cable made up. For a practical impecunious soul it would have been tempting to make up a rod system. The shortcomings of Seven brakes do not arise primarily from cable stretch!
RE: Push rod rear brakes - Chris KC - 06-01-2019
(06-01-2019, 07:18 PM)Bob Culver Wrote: The brakes are an inept technically wrong modification. The rods are subject to bending. A local RN car has a similar mod but with anchored pivoted arms at the change of direction.
I recall being charged a then eye watering 14/- in the 1960s to have a cable made up. For a practical impecunious soul it would have been tempting to make up a rod system. The shortcomings of Seven brakes do not arise primarily from cable stretch!
In fact it's been made worse, instead of cable stretch there is now bending of the rear rods as they try to straighten out under load...
RE: Push rod rear brakes - Dennis Nicholas - 06-01-2019
The springs both appear to curve inwards from chassis to axle. Could this be a wide chassis with the narrow rear axle bodged on?
RE: Push rod rear brakes - Charles P - 06-01-2019
(06-01-2019, 08:19 PM)Dennis Nicholas Wrote: The springs both appear to curve inwards from chassis to axle. Could this be a wide chassis with the narrow rear axle bodged on?
If so they've bothered to graft on an uncoupled handbrake as well.
However they have modified the handbrake ratchet to be independent of the gearbox mounting so the chassis has some "history".
I suspect the "spring curve" is a photographic distortion
C