16 replies to this topic

[marcw]

Hi all, calling from California ...

 

Been searching the forum for answers to my question… "what are the symptoms if air is in the Hydrolastic suspension ?”     My car has no leaks but i think it has air contamination,  I can pump the suspension up but the rear is 50% higher than the front always. Any thoughts?  I have released fluid and pumped up several times via the grease gun pump method. 

 

Any wisdom appreciated ...  I have a stock 1968 Morris Cooper S

 

 

Cheers

Marc

 

[Spider]

Hi Marc,

 

Air in the System is unlikely to be the cause here, though if it has been drained, I would strongly recommend having the System evacuated under Vacuum to be sure there is no Air as this is what causes rusting inside the System that can lead to failures of the interconnecting pipe work and the hoses to the bags.

 

A number of items can be the cause, and it's suggested that they are all checked;-

 

Worn Knuckle Joints,

Mis-match between Bags,

Sagged Bags (and this is the likely cause),

Wrong Upper Front Arms (Dry instead of Wet),

Wrong Rear Helper Springs,

Wrong Rear Struts

 

Probably what's not always realised with Hydro is that just like the Dry set up, it does sag over time, but usually takes longer. While Front and Rear bags are different when new, you'll likely find by now the characteristics between them are about the same, so swapping Fronts to Rear is a viable option. To check for this, leave the Front end on a Jack, front wheels in the air, for 3 - 4 weeks (or longer if you can), be sure to leave the Rear on the Ground during this time. This will to a small degree let the Fronts come back a bit. If when you do put it back on the Ground, and roll it around a bit, you find the Front is up, then that's the likely problem.

 

You can also fit some spacers (washers) between the Front Bag and the Knuckle Joint, however you are limited to a total  of 0.150" of Spacers (which theoretically will Raise the Front by ~3/4"). The factory express Warning against fitting any more than a total of 0.150" of spacers here as it can break the socket inside the bag. Having said that, there are late Knuckles which already have a spacer included and you can add 0.150" safely to these as the Pin is still the standard length, so engagement will be OK.

[marcw]

Thanks for the advice... thinking i most likely have worn knuckles and sagged bags (car sat for 25 years in barn) .  Thinking about converting to dry system then boxing and storing  all the wet stuff.  Seems hard to keep the wet  setup going without a good supply of displacers.  Is that what most do?  

[Spider]

If you can persevere with the Hydro System, it does ride better than the dry, it was after all what the Mini was always originally designed to have.

 

In regards to keeping a stock of Displacers,  you really only need to do that if yours are in bad condition, typically rusty.

 

I did mention in my first post, that the system does sag, but I probably didn't explain enough in that. Since the system is interconnected front to rear, while the front sag down, the back sag up (probably not the right way to put it). Just swap the fronts to the rear and it'll be good for another 10 - 15 years. If you do go down this route, as I mentioned, I'd strongly recommend having the system evacuated under vacuum and then pumped up again.

 

If you do decide to swap to dry, be aware that pretty much everything is different and not readily inter-changeable, so that being the case, you'd be looking pretty much at complete front and rear subframes, with arms etc. Also, see if your body shell has the threaded holes for the front shocker brackets as few hydro cars had these fitted, not the end of the world if it hasn't, but while the front frame is out, you'd want to fit them.

[Cooperman]

I converted a 1968 'S' to 'dry' and it was a relatively simple job. I used 'dry' front top arms, the correct bump stops and knocked back the retaining lugs in the sub-frame tower. The holes for the damper brackets were already there so I just had to clean out the threads.

On the rear I used 'dry' radius arms complete with damper studs.

It really was very simple.

I hate hydro, probably unfairly, because I had to retire from a major rally in 1967 in a 1275 'S' whilst well-placed because the hydro kept de-pressurising. We converted it to 'dry' and it was then super reliable.

[Spider]

I converted a 1968 'S' to 'dry' and it was a relatively simple job. I used 'dry' front top arms, the correct bump stops and knocked back the retaining lugs in the sub-frame tower. The holes for the damper brackets were already there so I just had to clean out the threads.

On the rear I used 'dry' radius arms complete with damper studs.

It really was very simple.

I hate hydro, probably unfairly, because I had to retire from a major rally in 1967 in a 1275 'S' whilst well-placed because the hydro kept de-pressurising. We converted it to 'dry' and it was then super reliable.

 

While the frames can be 'converted' to dry, the bases for the displacers / cones are actually in different locations. The lugs for the displacers can be bent back and I have done this conversion myself a few times, however the front wet frame is just a tad over 1/4" taller and the rear wet frame displacer base is (from memory) about 3/8" shorter. With the right set of Hilos, not an issue. Also, a Wet Bump Stop needs to be retained and they don't readily fit the dry front arms, none the less, these are what I run on all my Dry set ups in any case. Drilling the Bump Stops doesn't get them to fit either as the holes are on different centres    

 

So, yeah, can be done, but not straight forward or 'exact'. Not something I'd readily recommend.

 

Bhahaha,,,,,  Hyrdo is awesome,,,,,, for the Road, but I don't think It was much good in competition!

Edited by Moke Spider, 02 November 2015 - 07:35 PM.

[carbon]

Slightly off-topic... Agree hydro can be really good for road car set-up, but I think it benefits from shock-absorbers (just standard type) fitted to the front and also set of competition bump-stop rubbers to give firmer and more progressive feel. I have not yet tried using neg camber front arms or fitting rear anti-roll bar.

[Spider]

Slightly off-topic... Agree hydro can be really good for road car set-up, but I think it benefits from shock-absorbers (just standard type) fitted to the front and also set of competition bump-stop rubbers to give firmer and more progressive feel. I have not yet tried using neg camber front arms or fitting rear anti-roll bar.

 

I agree completely. The other  thing I've always felt is that the Rear 'Helper' Springs either need a heavier rate or be shorter than what they are, though that will also increase the system pressure. I've not tried a Rear Anti-roll Bar on it, but some of the guys who have them say it further improves handling. though It's pretty good in standard form.

 

<Edit: One other 'thing' regarding using it for Competition - How do you adjust corner weights?  Yeah, can be done, but wholly cow, how much work is that!   It's also a fairly heavy set up, from memory about another 140 lb. >

Edited by Moke Spider, 02 November 2015 - 07:43 PM.

[carbon]

Going off-piste... How much more does 'wet' suspension set-up weigh compared to dry.

 

The wet set-up weighs more than dry, but I don't think the difference can be more than 50lbs. The hydro bags probably weigh in at 10lbs each more than a rubber cone, and then there is all the piping and about a gallon of hydro fluid. And you save on the weight of the shock absorbers.

[floormanager]

While on the subject of Hydros, can the rear knuckles be replaced without de-pressurising the system, but by removing the helper spring and allowing the radius arm to drop, a la on a dry set-up?

Thanks,

Paul

[Spider]

While on the subject of Hydros, can the rear knuckles be replaced without de-pressurising the system, but by removing the helper spring and allowing the radius arm to drop, a la on a dry set-up?

Thanks,

Paul

 

Hey Paul,

 

I have to say, not something I've tried. You'd have to get the front wheels in the air, might be possible, you'd have to remove the rebound stop from the rears and then remove the rear arm to do the job I would think.

[Spider]

Going off-piste... How much more does 'wet' suspension set-up weigh compared to dry.

 

The wet set-up weighs more than dry, but I don't think the difference can be more than 50lbs. The hydro bags probably weigh in at 10lbs each more than a rubber cone, and then there is all the piping and about a gallon of hydro fluid. And you save on the weight of the shock absorbers.

 

I hear you. The figures where I got that from was from the workshop manual (and we know how coff coff good that is). There's also a bit more metal in the front frame which also adds up.

[floormanager]

 

While on the subject of Hydros, can the rear knuckles be replaced without de-pressurising the system, but by removing the helper spring and allowing the radius arm to drop, a la on a dry set-up?

Thanks,

Paul

 

Hey Paul,

 

I have to say, not something I've tried. You'd have to get the front wheels in the air, might be possible, you'd have to remove the rebound stop from the rears and then remove the rear arm to do the job I would think.

 

Thanks, I think I will depressurise then, never like to be the first to try anything Luckily, I got a Liquid Levers pump up / release / Vac out unit with the car.  Just wondered if it was necessary.

[marcw]

My problem ended up being bad nylon bushes and VERY poorly fitted displacers. ...  the car now sits flat :) The displacer are strong,  no rust.  One hose has split outer rubber above where it is press fitted to the canister.  I will tackle that as i  refurbish the front suspension.. all the bushes are tired.    Then of course i need to evac the system.

[Spider]

Good work. Thanks for letting us know.