12/4 castor angle

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John65a
Posts: 3
Joined: Thu Feb 27, 2020 1:41 pm

12/4 castor angle

Post by John65a » Thu Feb 27, 2020 1:50 pm

I have a 1934 12/4 Ascot which has no self-centring on the steering, and is prone to wander. We have checked the toe-in which is fine. So clearly I need to adjust the castor angle, and the ATDC tracking information sheet talks about making up 3-4mm wedges. I would like to get those made before taking things apart, but don't know the measurements. Can someone supply a drawing of the spring packer and spring centre hole measurements so that I can get wedges made please.
Thanks

bob_allison
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Joined: Wed Nov 27, 2019 3:20 pm

Re: 12/4 castor angle

Post by bob_allison » Thu Feb 27, 2020 7:33 pm

It is simple to make a pair of wedges to try . You can use a piece of decent hard wood for a try out . A reasonable tenon saw will be the weapon of choice , then you can divide a block on the angle to give you two identical wedges .
Measure around where the spring seats on the axle , and cut a pair of rectangular wedges to suit , with a 3 or 4 mm taper on them , from end to end . Jack the car up at the front and support on packing to allow the axle to drop half an inch clear when you remove the nuts from the U bolts and tap them clear . Slip a piece of card in and pencil through the four holes to give you the hole centres to drill the wedges for the U bolts . Slip the wedges into place , thin end forrard . Refit the U bolts through the wedges and tighten the nuts evenly to nip the wedges nice and squarely . Use spring washers to lock the nuts in place .
Chek that the steering works freely before dropping the car .
Try around the block cautiously . If reversing be aware that the change of camber will mean that the steering will be self UNcentering in reverse , so hold the wheel firmly .
That is what I have done on my 12/6 , but it will be months before I have it on the road to try , so I cannot report .

simonbradford
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Location: Sleaford

Re: 12/4 castor angle

Post by simonbradford » Fri Feb 28, 2020 8:55 am

I made some from oak and it definitely helped but remember to keep checking u bolt security as the wood settles. Incidentally I found a Land Rover spares supplier that make steel ones but they would neither give me the dimensions nor sell me some to try - should’ve lied and said I had a LR :o

John65a
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Joined: Thu Feb 27, 2020 1:41 pm

Re: 12/4 castor angle

Post by John65a » Fri Feb 28, 2020 3:07 pm

Many thanks Simon and Bob
I had not thought of trying hardwood wedges.

John

david_castle
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Joined: Thu Nov 21, 2019 11:03 am

Re: 12/4 castor angle

Post by david_castle » Fri Feb 28, 2020 5:51 pm

Hi. Land Rover camber wedges are available via E bay see item 142861616626 (£12.60 per pair) There are a few other on there as well. They are cheap enough but no dimensions are given, so may be of no use ?.
Regards David

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stephen_voller
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Location: Polegate.

Re: 12/4 castor angle

Post by stephen_voller » Fri Feb 28, 2020 7:06 pm

I 'd be surprised if you couldn't use those Landrover wedges - I may get some for my 12.
Just a couple of comments:-
1. you only need one hole in the wedges and that is in the middle for the end of the bolt that goes through the spring.

2. The sharp end of the wedge always points to the front of the car!


3. A drawing was published in earlier club mags and in the Technical reprints volume 1. Dimensions quoted were 2 and a 1/2 inches long by 1 and 9/16 inches wide. Thickness at the fat end of wedge according to the latest technical sheet between 3 and 4mm.

Over the years various materials have been used for making the wedges from hard red fibre, hard wood and steel.

Steve.

bob_allison
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Joined: Wed Nov 27, 2019 3:20 pm

Re: 12/4 castor angle

Post by bob_allison » Sat Feb 29, 2020 12:46 am

Whereas oak is probably fine for this job , in general avoid oak and steel together . This is because oak is full of tannic acid , which will quickly start rust . Oak sawdust will quickly rust tools ( For oak and iron ' sandwich ' loco frames the GWR used to char the holes in the oak for the connecting through bolts , to kill the acid )

simonbradford
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Joined: Fri Nov 22, 2019 8:56 am
Location: Sleaford

Re: 12/4 castor angle

Post by simonbradford » Sat Feb 29, 2020 8:42 am

bob_allison wrote:
> Whereas oak is probably fine for this job , in general avoid oak and steel
> together . This is because oak is full of tannic acid , which will quickly
> start rust . Oak sawdust will quickly rust tools ( For oak and iron '
> sandwich ' loco frames the GWR used to char the holes in the oak for the
> connecting through bolts , to kill the acid )

Interesting but it won’t rust the springs and the axle is about 2” cast so not much chance there either. I think it’ll be safe enough just get hard oak not soft

John65a
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Joined: Thu Feb 27, 2020 1:41 pm

Re: 12/4 castor angle

Post by John65a » Sat Feb 29, 2020 3:37 pm

Plenty of good ideas

Many thanks

John

simonbradford
Posts: 86
Joined: Fri Nov 22, 2019 8:56 am
Location: Sleaford

Re: 12/4 castor angle

Post by simonbradford » Wed Aug 31, 2022 6:09 am

As a sequel to this, whilst the oak wedges helped I wasn’t satisfied it was as it should be so I bought the Land Rover wedges, get the ones with the smaller hole, you’ll need to trim about 5mm off each side as they are too wide but I’ve fitted them now and it has transformed the steering, I’m really pleased.

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