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Manufacturing the arms for Andrex shock absorbers

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Reno Avatar
Reno Reno Cassar
Zabbar, Malta   MLT
Good evening.

I would like to manufacture 4 arms for my andrex shock absorbers. I did find two arms but I need 4 so If I have to manufacture 2 I can as well do the rest.

I can do everything but I can not figure out a cost effetive way to do the internal splines.

Does anyone knows wht splines are used on the Andrex shock absorbers?

Regards
Reno Cassar

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TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
A machine shop that does axle splining may be able to assist you but I imagine that some sort of broach would have to be made to cut the internal splines. The Andrex shocks when new had a marginal effect at best. Many have been destroyed due to over tightening the friction plate adjustment, poor maintenance and seizures from lack of lubrication causing stripped splines as you have found out. There are no known replacement internals or seals available and the wood shim packs that were being sold are not of the proper material. Worldwide has been known to rebuild good cores but I believe Peter prefers not to. Peter, if I’m speaking out of turn please let me know.

Apple also claims to rebuild these and even advertises sets for sale. I do not recommend them in no uncertain terms. A friend had sent Apple a set many years ago and they were destroyed in short order upon their return. Upon further inspection after the Andrexes ultimate failure it was discovered that a plastic type material had been substituted for the wood discs. Seizures occurred causing failures of the splines, end caps and housings. The owner was not a happy camper to say the least.

As these Andrex pieces are getting increasingly rarer to find in any condition most people who own andrex equipment and who are not competing them in vintage class racing are simply fitting the internals loosely or gutting them entirely and performing an external sympathetic restoration to maintain their appearance If you are intent on making them functional and whole again it has been suggested that a Hex stock be used in some fashion and the arms broached to fit accordingly. I have not seen this done or read a detailed write up if indeed it has been done. I believe the idea was floated by Tom Lange some time ago.



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

J Stone John R
Aptos, CA, USA   USA
You can cut the internal splines using a shaper/slotting attachment on a Bridgeport mill with an indexing rotary table. Not such a big deal.
If I was making them I would probably make 4, stack them and do them all together.

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Mitchman2 Avatar
Mitchman2 Mitchell Andrus
Mills River, NC, USA   USA
Assuming you mean Andre Hartford friction shock absorbers (as is Bill Chasser, above) I'm installing 4 on my TC Special. I bought them new here (link below), but there are other places to go. Perhaps they can furnish parts.

Hartford shocks

If you mean Andrex hydraulic shock absorbers, you'll have to explain what splines you're asking about.



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'30 Model A Ford Town Sedan
'48 MGTC Q Special
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plus4moggie Tom Lange
Bar Harbor, ME, USA   USA
As he writes, Reno is talking about Andrex hydraulic shocks (for his TD/C), specifically the splined arms that bolt to the housings.

Tom Lange
MGT Repair

TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
Hi Mitchell, the prewar Hartford friction shocks I believe you are referring to are not Andrex shocks as used in 1950s era Brit performance cars



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

Reno Avatar
Reno Reno Cassar
Zabbar, Malta   MLT
Good afternoon

Sorry for the late reply but I was at work.

I have an MG TDC which stands for MG TD comptition model.

I do have the shock absorbers but I do not have the links or the arms

I found from where I can purchase two arms but I need four so if I have to manufacture, I will build all of them.

The shock absorbers are Andrex and they are 1950 's style shock absorbers. They are very rare and very expensive.

The arms are easy to produce since I have a CNC but I do not have a slotting machine which makes manufacturing the splines very difficult for me. They are a lot of possible short cuts. But keeping this car is a hobby and it does not makes sense deviating from the original.

It would make sense a lot if I can find a splined nut and manufacture the arms around it but the splines are so small that | can not understand how to measure them.

So I am bit lost from to start.

Regards
Reno Cassar


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TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
Reno re-read posts 2, 3 & 5. Your answers are contained there



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

Mitchman2 Avatar
Mitchman2 Mitchell Andrus
Mills River, NC, USA   USA
It's entirely possible that a part from another car has the same splines.

TCs and some Volkwagons can share steering wheels for instance.

Below is a steering arm from a TC (fits below the steering box). The splines may fit. If so, they are readily available because original boxes and shafts are interchangeable with the much better VW steering columns. This makes these arms orphans when TCs are upgraded with VW parts. Manufacturers hate re-tooling and design engineers know this. Re-using existing tooling keeps the costs down.

If you can, count the splines and make a careful measurement of the arm and diameter of the opening. We'll see if you can adapt these. ....might get lucky.



The Flat Earth Society has members from all corners of the globe.

'30 Model A Ford Town Sedan
'48 MGTC Q Special
'58 MGA roadster
'66 Series 1, 4.2 Jag E-Type OTS



Edited 2 time(s). Last edit at 2019-01-16 03:35 PM by Mitchman2.


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Fsisson Avatar
Fsisson fred sisson
nashville, IN, USA   USA
1938 Morgan 3 Wheeler
1950 MG TD "007"
Interesting Bill Chasser mentioned hex instead of splined. Several years ago Tom Lange loaned me a couple of Andrex. I had a set with destroyed innards and Tom was kind enough to loan me a better set to analize. After a lot of resarch and study I figured out how and why they work.. and why they didn't.. There is a lot of BS, misunderstanding and eronious statements out there about Andrex dampers. They absolutely worked... but not for long.

I redesigned the innards slightly using a hex drive instead of the weak splines, solved the leak problem, used better bushings, etc. They are 'hydraulic vicious friction dampers' by the way.

I built a set that actually work and have been using them for several years with no problems. It was an expensive, time consuming project. If you are determened and half nuts, I can.. help you.

If you look close you will find that the front of the shaft is splined and then has a short ring pressed on over the back end of the (front... arm) spines I too wondered how in he-- the front spines were cut. It looks like they end abruptly but look close and you will see a line in the shaft about 1/4" back from the end of the spline end... that is the ring. Usually the splines for the arms are OK.

It is the splines for the two rotating disks inside of the body that are the Achilles heel of the design. Impossible for those fine tooth splines in the thin metal disks to hold up. Bad engneering.

If you have shafts with good splines to mount the arms... I can show you how to build a shaft utalizing the old shaft and good internals that really work. The pair of Andrex that I rebuilt (from a TD/c) are on my 1938 Morgan race trike... Been running them for several years.. they really work, they do not leak a drop of oil.

Andrex are NOT the same as Andre-hartford dry friction shocks. Completely different friction and resistance characistics. (Hydraulic viscous friction vs: Colume friction)

Wood disks are fruitwood by the way. Most any fruitwood is fine. Nothing exotic about them... has to do about the grain structure of fruitwood..

Inside the Andrex case are four floating fruitwood disks, two rotating steel disks, two sliding stationary steel plates and adjustment plates (two). Adjustment is VERY sensitive... 1/16th turn makes big difference.

.. instead of the weak internal splines, I use a hex shaft and thicker driven plates (stainless) with
matching hex holes rather than splines.. Also use better quality bushings from McMaster Carr that are made for high impact application. They take a lot of abuse. The original design was so weak that any too stiff adjustment would rip out the splines in a few miles... or the first good bump. Add an oil fill and vent on the top also... otherwise you have to remove them and lay them on their back to fill them completely.

They are fiddly to assemble



Edited 5 time(s). Last edit at 2019-01-27 01:12 AM by Fsisson.

Fsisson Avatar
Fsisson fred sisson
nashville, IN, USA   USA
1938 Morgan 3 Wheeler
1950 MG TD "007"
Here's a photo of a extra set of my internals for Andrex... I made them from stainless but steel is fine. Note hex drive for rotating disks. The plates and disks are laid out in order left to right is front to rear.

The drawing is of a stock shaft and how I modified the shaft to a hex drive.

This was not a cheap project to do it right but I wanted two dampers that really worked. Disks and plates were laser cut but water jet would work too. Plates must be smooth or they will eat the wood disks. It is the shearing of the oil film between the wood and steel surfaces that provides the friction.

After a couple of years of street driving and vintage races, my wood disks show no wear at all. I soaked the disks in ATF for a week to saturate them before sssembly.

Assembly is awkward but not hard. Replace old bushings, my shafts are machined for o-rings for oil seal. Originals used a rubber condom which was pitiful. As the dampers warmed the air inside expanded forcing the oil out past the rubber boot. I added a vent/fill cap to the top of the case and fill them to the top. Mine have not leaked a drop in several years.



Edited 3 time(s). Last edit at 2019-01-27 01:23 AM by Fsisson.


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Lotus Avatar
Lotus Silver Member Roy Hodgson
Villeneuve, VD, Switzerland   CHE
1974 MG MGB "Butterscotch"
I know that this is unlikely to help much but the parts and diagram that Fred shows look for all the world like the multi-plate wet clutch on my old Norton 750 bike. (haven't had it for over 40 years so I am going by memory). It was about the only part of the bike that didn't fall apart at some point so perhaps finding some pics or diagrams of one of them would give you some ideas about how to make the Andrex shocks better?



We have two lives. The second one starts when you realize you only have one.

Reno Avatar
Reno Reno Cassar
Zabbar, Malta   MLT
Good morning

Interesting project. The internal of the shock absorbers are perfect. I need the arms.

The shaft external diameter on top of the teeth is 15.85.

The shaft external diameter with out the teeth is 15.75.

The external shaft has 35 teeth.

I have decided to use a EDM to manufacture the internal splines.

Now what I am miissing are the linkages.

Does anyone knows from where I could buy them?

Regards
Reno Cassar

TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
Fred have you considered offering this in a kit form for us guys who wish to have a durable set of friction dampers. I have 5 full sets and three cars that I would like to have this modification done.



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

Fsisson Avatar
Fsisson fred sisson
nashville, IN, USA   USA
1938 Morgan 3 Wheeler
1950 MG TD "007"
Bill... like your car with the side panel removed. Here is mine . One owner, passed in 1996, stored in a dry shed. I bought it several years ago. No intention of 'restoring' it. Patina is earned and the car has soul. I have replaced all suspension bushings, new leather interior, ring & pinion, supercharger, brakes of course w/Wilwood disks in front, stainless exhaust, twin spares, top, oil cooler, twin vintage BiOscor lights, etc. No idea what's in the engine, daughter told me her father rebuilt it several times. Original owner was a machinist... even made his own steering wheel! Been running the blower several years, no problems. My favorite daily driver..

Back to Andrex... I considered the 'kit idea but it took me a lot of study and discussions with a retired Cummins engineer to figure things out. The two 'adjustmet' plates are a beautiful, simple bit of engineering/design. You need to understand how they work to assemble everything right. Not sure it's a job everyone could tackle and I think I'd probably get negative feedback. I have a couple of lathes and a plethora of tools collected over 64 years of automotive obsession so 'fine tuning' the assembly was fun for me. Not sure many people would want to spend the time...


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