Spring Shackles & Bushes - greased or silentbloc

[GaryCullen]

Doris passed her WOF, NZ equivalent of the UK MOT, yesterday. But driving has revealed loud clunky noises from the rear when going over bumps.
After checking other items I am sure it is some or all of the rear spring shackles and bushes. Greasing same did not reduce the Clunking. It is not the friction dampers as I have renewed these. Tightening these did not cure the noise either!
So onto the next big job. I will have to disassemble them to see what I have.
Gary

[Rod]

If I were in your shoes Gary, I would be very tempted to ditch the threaded technology, unless you're a stickler for originality, and either look at rubber bushings (either bonded into a steel sleeve like the OE silentbloc or two piece top hat ones like more modern cars) and fabricated plain pins. Even Nolathane if you don't mind colourful bushes!

[GaryCullen]

Rod, I am not a stickler for originality, as long as the outward apperance is still 1933..!
Just to establish my car: late 1933 Chassis number G26821 Criciform chassis with tubular cross member.

Lifting then right rear by hand and watching the shackle arrangement it is obvious things are not good. The pins move sideways and there is some up and down movement.
So I have undone and removed the right rear shackle and pins and I have pretty worn pins. Don't have the bronze bushes out so can't tell how much they have worn.The top pin shank that is inside the Bronze bearing was rusted so not a lot of grease went in there over quite a few years I think. The scrolled grease groove has mostly rusted away.
Bottom one also worn but only on the area that moves in the shackle ends.
I like the idea of replacing with SilentBloc bushes but which ones to by?

1. if the car is an export model like mine shipped with greasable shackle pins what size Silent block will press into the spring end?
2. Searching Alderton, ATDC and Arley sites doesn't help me much.
3.The pins listed at ATDC: 701 1932-39 1G5014 3 3/16'' length (measuring under head) 6 needed. ( 6 is wrong as 8 are required for the back end ) My spring width with each shackle end only measures just over 2 1/4 " overall so 3 3/16" pin from ATDC is to long. Also they don't list the pin diameter but they do for the silent block.
3. I don't suppose anyone in the UK has done a greased pin to silent bloc conversion since greased model were export only.
Any advice gratefully accepted.

Gary
Auckland'
VAR

[peter_winney]

....
The pins listed at ATDC: 701 1932-39 1G5014 3 3/16'' length (measuring under head) 6 needed. ( 6 is wrong as 8 are required for the back end ) My spring width with each shackle end only measures just over 2 1/4 " overall so 3 3/16" pin from ATDC is to long. Also they don't list the pin diameter but they do for the silent block.

Gary
There should be only 6. One in the eye at each end of each spring and 1 each side where the rear shackle is attached to the chassis - (2 x 2) + (1 x 2).

The centre metal tube of the Silentbloc bush is wider than the spring to ensure it is clamped firmly into the chassis or shackle, and this requires a pin that is wider than the spring. All movement is taken by the rubber, not by any greased bearing surfaces.

[peter_christie]

Hi Gary,

Why do you say you need eight pins and bushes for your back springs? The springs are pivoted at the front and shackled at the rear so you need three pins and three bushes for each spring. I very much doubt that the screwed bronze bushes used on export cars were different in external diameter from the external diameter of the Silentbloc bushes fitted to Home Market cars. The problem will be that the screwed pins would have to have been of a greater diameter than the plain pins to accommodate the extra diameter of the coarse thread. I note that the shackle plates have tapered holes into which the tapered ends of the screwed steel tubular part of the assembly fit; the whole being held together by the steel pins as numbered below.
According to the parts books the design was changed from 1936 and the Cambridge type cars had Silentbloc bushes at the pivot end and screwed bushes on the shackled ends only. The earlier ones appear to have six identical spring pins [GT108] for the rear springs and shackles and five identical spring pins [GT105] for the front springs and shackles and a single different spring pin [GT112] for the front spring rear bracket, steering side.
For what it's worth, in my opinion, you should measure the diameter and length of the bush housings of the springs and find what (preferably Silentbloc type) bushes are available and what suitable material pins or bolts are on the market. I think having screwed phosphor bronze bushes and matching hardened threaded pins made up specially would be a labour of love, only practicable if you have available the required materials and engineering equipment and specialist personal skills.
Good luck,

Peter C. [6515]

[GaryCullen]

Many thanks for the advice and explanation Peter and Peter.
I went and checked out the front attachment and as the parts manual and ATDC list there are only 6. My mistake making assumptions!
I will need to dismantle again and push out the bronze bushes so I can measure the spring end eye.
They seem to be a top hat type so are there two of these, one pushed in from each side?
If so then how do you push them out?
Gary

[peter_christie]

Gary,

If they are 'top hat' type, you've got to lever them out against the flange and if that isn't successful, cut off the flange and drive the bush out with a suitable drift. The Silentbloc type are sometimes (!) very stubborn and you have to burn the rubber out with a blowlamp and then use a hacksaw to split the outer shell, taking care not to damage the eye of the spring or the chassis bracket.
I have no experience of the earlier cars, but my impression, reading the appropriate Parts Books, is that the early bronze bushes were plain with unthreaded pins and that the design was changed about '34 to provide a spiral grease path and in '36 the two piece [threaded bronze bush 2H2031 and threaded steel spring pins 2H2035] with clamped shackles was introduced.
I have taken some photos of the three different versions and will post them when they are available.
Peter C. [6515]

[peter_christie]

Gary,
For some reason the message board will not accept the illustrations that I wanted to show you.
If you send me your email address I will send them to you as attachments.
Please send me an email at woodside.glencairn@gmail.com
Regards,
Peter C. [6515]

[GaryCullen]

thanks Peter.
Sent you an email.

I have a design to make a tool to push out the bearings from the springs. I can cut the lip off the bronze top hat bearings no problem.
It consist if a long 7/6" HT bolt and nut, a couple of small steel plates, a 1" tube to push on the bearing or silentbloc and a larger tube on the other end to receive the bearing as it is pushed out.

I think I copied this from the old ATDC web site.

cheers
Gary

[Rod]

Chiming in late Gary, leaf spring makers (like Bellamy & East or Archers') from past experience appear to have access to a variety of ready-made eye bushes of the rubber top hat/solid metal/silentbloc type which might save you some lathe time.
Also worth leafing through the Nolathane catalogue for something close, the material can be machined on a lathe (or so I've been told by people who've done it) with knife edge tools.