NOS Hydrolastic displacers markings

[Peter Laidler]

A zillion thanks to you all. Much appreciated. Thanks again.

[STG95F]

Well my "Green" displacers have red markings on the hose

Craig

Thank you

Ian

[Aussie Bill B]

I'm glad Daz raised the point but I've often wondered why the spring is there? Any ideas?

I am guessing that the spring is to allow the strut to be removed from the displacer socket. Even with full vacuum on the suspension, there isn't enough clearance to slide the strut and dowel out of the displacer so the dowel has to be pushed back against its spring into the strut to make that clearance. The length of the counterbore in the strut has to be long enough to take the spring under compression and most of the dowel.

[Peter Laidler]

Yep, that must be the amswer. Thanks Aussie Bill. Pete the Pom. (Australian Army 1967-70)

[Aussie Bill B]

Yep, that must be the amswer. Thanks Aussie Bill. Pete the Pom. (Australian Army 1967-70)

...and that was a busy army to be in during those years!

[Dearg1275]

I'm glad Daz raised the point but I've often wondered why the spring is there? Any ideas?

I am guessing that the spring is to allow the strut to be removed from the displacer socket. Even with full vacuum on the suspension, there isn't enough clearance to slide the strut and dowel out of the displacer so the dowel has to be pushed back against its spring into the strut to make that clearance. The length of the counterbore in the strut has to be long enough to take the spring under compression and most of the dowel.

To gain enough clearance to remove the displacer, the official workshop manual says to remove the rebound stop fixed to the front of the subframe. With out removing this the radius arm can't drop far enough. To my mind the spring is there to effectively increase the length of the rod when the arm is at full drop to ensure that it doesn't drop out of the displacer. You may be able to push it back into the recess in the Rod against the spring to remove the displacer but it would not be easy and that is not how BMC envisaged the disassembly process.

[CALIMKIIIS]

Dear Dearg1275, Bless you for the information you provided in this thread!! Here was my problem:

P1012962.JPG

The "Oh Dear" moment after the green puddle on the garage floor. I've found out that the hose usually fails at the displacer end, not at the other end like this one. Since then I set out to remove the L/H rear displacer, first jacking up the car and putting it upon jack stands after de-pressurizing what little was left in the system, then removing the wheel, releasing and disconnecting the handbrake. The next task of removing the clip from the lower helper spring took more time than I care to admit. The next thing was to release the spring loaded pin that interconnects the strut and displacer. Not so easy, in fact impossible! I have 2 workshop manuals, the "Haynes" and the Kenneth Ball one. Each describes different ways to proceed. One says that when the swing arm is in the lower position the pin will release and the strut can be removed. The other manual says to extract the nylon cup and knuckle joint at the front of the subframe to remove the strut, something I didn't try as I struggled with what you call 'mole grips',('vise grips' on this side of the pond) to try to move the spring loaded pin far enough into the strut to release it away from the displacer with no success. Before the point of throwing spanners around after multiple attempts, I gave up for the day. After trying to stay calm and carry on I decided upon more research. Since my repair manuals were insufficient I searched for a proper one and found this:

s-l140.jpg

It should arrive within the week. After more searching the 'net for more info to no avail, I remembered this site and decided to become a member hoping that I might find a clue here. After perusing so many pages about everything 'hydrolastic' I happened upon your post from 2017 that made my day, mate!
Just your mention of the second bump stop hidden behind the swing arm pivot point, changed everything! No wonder the shop manual instructions didn't work, there's no mention of the small bump stop that will enable the swing arm to a further lower position when removed, insert vulgarities here!
Now that I know what to do, I'll remove the bloody strut, then figure out removing the displacer from the subframe. It's all on a rust free '70 S, silver band displacer with smaller tabs at the subframe end to hammer upon than pic's I seen of older units. Adding difficulty is that the car was undercoated
in the U.K. before I got it. Nice, it surely helped keep rust away from the underside but the asphaltic undercoating got sprayed upon the subframe as well as the portion of the displacer where it connects to the subframe, basically glueing it on. Anyway that will have to be addressed by removing the undercoating at the connection point with many types of tools on hand that may ultimately resemble dental tools, to free up it's removal. When finally extracted it'll be sent off to Hydrolastic Services in the U.K. for a new hose and refurbishment. Wanting to do a proper job and only having a hand pump to pressurize, I found an auction for a factory unit capable of evacuating as well as pressurizing to do things right, one of these:

264 GBP.jpg

. Thanks once again for the post, a gold nugget for me indeed!

[CALIMKIIIS]

Update on displacer removal. As previously mentioned, my shop manuals didn't mention removing the small bump stop on the subframe, the new B/L manual does. Once that was removed, the swing arm did lower a bit. Still needed the mole grips to push in the spring loaded pin but then the strut fell away. The next issue was to remove undercoating around the subframe mounting point of the displacer. Since the displacer has been un-disturbed for 50 years it didn't want to release without a struggle on my part. After trying many methods without success, I remembered a tool I had ordered last year from Mini Spares, an oil filter wrench. I got it in part as using a normal 'band' type of tool isn't user friendly on a mini van without a removable grille. Still in it's packaging I found it, hoping it may be the key to removing the displacer. As far as I know, the factory never made nor used a 'rear displacer extraction tool' but then why would they. Fortunately this device is made to order for the job. After applying penetrating oil to the area, no rust involved really, and using a hair dryer to warm things up a bit, the tool and substantial force released the unit at long last! Now this 'silver band' displacer will be on a plane to the U.K. to have the hose replaced and the unit refurbished. The photo says it all...

P1012976.JPG