Front Dampers

[mike.perry]

I have noticed that there seems to be a great variation in the strength of the front dampers on Minors. When pushing down on the front wing on some cars there is virtually no movement whilst on other cars the wing can be pushed down three inches or more. The wing always rises with almost no oscillation. Is the difference due to the viscosity of the oil used?

[bmcecosse]

Yes - especially if it hasn't been changed recently..... The long-chain molecules of the oil get ripped apart when they are squirted through tiny holes inside the damper valves - the old oil smells terrible when drained off.. Drain and fill up with SAE 40 and enjoy GOOD damping!

[RobThomas]

Could it also be that the rubber bushes are also performing some 'damping' by clamping the suspension pins in position?

The dampers do have a certain amount of adjustment if you are prepared to pull the valves out of the bottom but I wouldn't recommend it. I do wonder if people used to paly around with these in days gone by.

[IslipMinor]

I do wonder if people used to play around with these in days gone by

They certainly did! I bought a pair of new 'heavy duty' front dampers in the early 70's and in addition followed the then current advice of using engine oil, instead of damper oil, and they worked very well indeed. They continued to do so for ~50,000 miles, until 1992, when the car came off the road for the restoration.

As part of the restoration I fitted Koni dampers all round, so needed to remove the valves from the front dampers. On removing the valves, I found 2 small washers under the valve spring each side to put a bit more pressure on the valve. Simple, but effective?

[bmcecosse]

Yes you can (and I have) added washers and also screwed up the little nut. But these are only increasing the relief valve setting - at which point they open on a severe bump. The biggest improvement comes with the more viscous oil. Any 'gripping' by bushes will be insignificant on the road.

[mike.perry]

Setting up the dampers must be a compromise between good handling and the ability to drive over road humps at more than 10mph

[Judge]

Perhaps I should tell you Mike, I have tele's

[mike.perry]

I know Bill. I tested yours as a comparison with ordinary dampers

[bmcecosse]

The standard dampers are simply 'folded up' teledampers - with the advantage of being able to adjust the damping by use of different viscosity oils. Some of the teledamper kits are not well designed - and I believe some use Mini dampers which do not have sufficient travel for the relatively long travel Minor suspension, unless fitted in such a way that they only travel a reduced range of movement with consequent reduced ability to do any useful damping! Caveat emptor before buying any such kit......

[klm]

I recently filled different grades of oil in my collection of rear and front dampers to test and found all of them leaked from the shaft seal. The grade of oil originally recommended is SAE20 or ISO68. I trialled with Castrol hydraulic oil AWH68 which I believe is equivalent to the viscosity of original Armstrong oil. It provided a smooth damping rate in comparson to other grades of oil used. The hydraulic oils contain anti foam and anti wear additives and I understand they would withstand high pressure without breaking down. Engine oil does not contain the additives recommended for the shockabsorber application and may be the reason for breaking down.

Oil leakage from the shaft seal is a major problem and I note from reports that some of the reconditioned shocks start to leak after a short period in use. Does anyone know if the reconditioners replace the shaft seal?

[bmcecosse]

Not much other 'reconditioning' they can do....I suspect they don't bother to do anything about the wearing/bearing surfaces, and just about ALL they do is clean them, and change the oil - and 'possibly' the seal.......

[klm]

I contacted ESM and BM in the UK and few reconditioners in Australia asking for information on reconditioning. ESM and BM could not confirm what components are replaced as part of reconditioning of Armstrong dampers. One company here in Australia advised me that they machine the housing and install a phosphor bronze bush and an oil seal. The bronze bush requires lubrication and it is necessary for oil to leak though the shaft to lubricate the bush. Their prices are exhorbitant and I then contacted two companies in the US, Apple Hydraulics and World Wide Auto Parts. I could not get much information on what Apple Hydraulics do as reconditioning but found that World Wide Auto Parts undertake reconditioning to a high standard as detailed on the following website:
http://mgaguru.com/mgtech/suspensn/fs207.htm

Any comments or feedback would be much appreciated

[bmcecosse]

Did you see Declan's excellent DIY damper overhaul expose??

[mike.perry]

Have you got a link to it?

[bmcecosse]

Not good at 'links' Mike - was a long running thread on here recently.

[klm]

Declan's damper overhaul procedure is at the following link:

http://www.mmoc.org.uk/viewtopic.php?f= ... r+a+damper

Declan's procedure involves removal of the welch plug at the back of the housing and using a press to push the shaft. I believe the reconditioners use a puller similar to the one shown below to extract the shaft and arm as one assembly from the damper housing. I fabricated the puller shown below from 6mm plate and used high tensile bolts to extract the shaft. Although not 100% successful I was able to extract the shaft by 4mm before the plate started to bend. I am now fabricating a plate with 12mm thick plate to give more strength.

Declan also reported that he could not source an oil seal to replace the steel ring and rubber washers originally used on Armstrong dampers. I understand that World Wide Auto Parts machine the housing and install a stainless steel sleeve to the shaft to take an oversized double lipped oil seal. They claim that they completely eliminate the leaks such that no topping up is required.

[Declan_Burns]

For the front damper we couldn't find an off the shelf seal. But if anybody wants to attempt the repair I can make the mould for solid seals.
On the rear damper this is what we used:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
It's a Deutz tractor pushrod seal. It needs a few thou taken off the metal ring to fit. We found trying to press it in splits the casing.
Here is another source:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

Regards
Declan

[mike.perry]

Thanks for all the information. I think that I will drain the dampers and refill with SAE 30 so that there is a bit of give over the local road humps and see how it handles.
If I fitted 5 leaf springs to the Traveller would it improve the handling at the expense of load carrying capacity?

[klm]

Thanks Declan for your response and the information on the seal used on the rear damper. I note it is a single lip oil seal recommended for a push rod application. I have some questions.

Has this seal been successful in eliminating leaks through the shaft?
Are you presently using the overhauled damper?
Did you notice any score marks on the shaft where the original metal ring and rubber washers were in contact?
If the shaft was scored did you machine it to remove the score marks before fitting the seal?

Thanks

[bmcecosse]

My 7 leaf Trav is perfectly compliant - until it hits the bump stops, which it does all too easily.. So no - I wouldn't advise 5 leaf springs - I would advise making sure you have a decent amount of free travel between bump stop and chassis leg. If necessary - cut a good inch off the tip of the bump stop.