Hydro rear disassembly

[KR200]

Gents,

I wish to drop the rear of my Mk3 S. Not by much. I do not carry luggage, full tanks or passengers in the rear (ooh err missus!).

I know the ratio is 1 to 5 so 5mm will be give or take an inch down. Thus level. I will leave the front alone. On a dry car one can remove the top damper mount and it pretty much all falls to bits. On a hydro car there's a helper spring under tension. How does it come off? By jacking up the rear as a dry car and then jacking up the rear arm after moving the tank to get at the top nut? Or can I take the spring off the arm somehow thus not getting busy with the tanks…

Will the displacer be OK just sitting there and will the rod come out the displacer OK or are they swines? I have access to a lathe to turn down the rods. The car was properly restored a few years ago and nothing seems seized etc.

Oh and just noticed the front knuckle boot is split. Can you get the front arm out by taking out bumpstops or is it a draindown? If it's the latter it can wait 'til winter and I'll keep it clean and greased..

Thanks

[InimiaD]

From past experience the only option is for a "draindown".
The rear tyre needs to be sitting well into the wheel arch before the tension in the helper spring is reduced enough to unclip it from the trailing arm. It would probably be easier to take the wheel off and use a jack to raise the trailing arm higher, that is if the bump stops don't get in the way.
Forgot to add, the lower part of the helper spring is held in place by a wire type circlip which is simple enough to take off.

[KR200]

So if I take the wheel off and jack up the arm with a bit of luck the spring will slacken off enough to pop it off the arm after taking off the circlip? Or will the car simply go up as there's little weight to hold it down.

The spring does look under some tension.

Draindown etc is a right royal PITA.

[Gray]

The suspension will not come apart without a draindown unfortunately, I have got quite use to it the last couple of months!When you depressurise the system the rad arm will retract back up into the arch if supported on stands, you them need to support the arm/hub whilst you remove the nut from the top, I found I could not get enough movement to get the spring off the stub axle at the bottom before it hit the arch.

[carbon]

Personally I would be really nervous about depressurising and adjusting the length of the push-rods.
You can raise or lower the back a bit by playing around with the pressure in the Hydrolastic system. When you pump up the back tends to go up more than the front and vice versa.
Other option might be to see if you can get a 'fresh' pair of helper springs for the rear, these might be a little tauter and help pull it down a bit. I think the later springs were a bit stronger than the early ones.
You mention that you have the dampers on the front. Have you also got the 'competition' bump stops fitted?

[66S]

I have modified the rear struts and fitted a sliding collar. This collar holds split spacers in place that can be removed or added to as necessary with nothing more than dropping the fluid and removing the wheel.

There are two styles of springs, early and late. The late springs are stronger and have more coils. They were fitted to try and solve the "tail high" attitude of the earlier Hydro cars.

My car now sits pretty level, although it does sit slightly lower at the rear with full fuel than empty. The photos attached shows it sitting with around half fuel. I run an increased system pressure too (300 psi) and I am very happy with the improvements made.

Al

[KR200]

Personally I would be really nervous about depressurising and adjusting the length of the push-rods.
You can raise or lower the back a bit by playing around with the pressure in the Hydrolastic system. When you pump up the back tends to go up more than the front and vice versa.
Other option might be to see if you can get a 'fresh' pair of helper springs for the rear, these might be a little tauter and help pull it down a bit. I think the later springs were a bit stronger than the early ones.
You mention that you have the dampers on the front. Have you also got the 'competition' bump stops fitted?

The springs look quite new even though they are probably 18 years old. The front is at a good height. But the rear is a tad too high. I have comp bumpstops all round with spax on the front.

If I let out some pressure then whilst the rear will come down so will the front to some extent. I don't want that.

I actually have a Churchill pump which I bought off Ebay. I have been assured it works. It looks OK. If I do drain the system then I suppose I can tackle the front knuckle boot too. Plus a displacer boot on the front is split.

So that's it! I have to depressurise the system. Then I'll take out the rods at the back after removing both tanks. Then I'll take 4-5mm off each rod. It should be OK then.

Oh 66S I like the Ozzie Mk1's and those perfect arches. They are the best arch out there and factory too!

[graham in aus]

I'm pretty sure Al is in New Zealand, The Mk 1's over there are closer to UK cars than Aus, we got the windy windows from the start (65) The arches are Aussie though and I agree, the best!

Actually started in SA South Australia when their State road regs decided Mini's wheels stuck out too far, then when the Aussie Mk2 came out in 69 they all got them.

Love the set up and stance of your car Al.......well done!

Cheers!

[Spider]

In addition to different spring lengths, there where 2 different strut lengths.

[Gray]

Good point Spider, as well as 2 different size displacer pistons, the central boss that meets the strut varies in length by about 3mm

[66S]

Guys, I found struts of about four? different lengths, I have no idea what belongs to what year. The variation between the longest and shortest is not huge and would have made little difference. Gray, correct, the competition displacers have a shorter piston and all S displacer pistons seem to be shorter than standard displacers.

My car is a UK one but the previous owner put the Aussie flares on when he fitted the Minilites, years ago. I like them too. Thanks for the positive comments guys.

KR200, if you drop the height by letting some pressure go, you will soften the system. Note that I have increased the pressure by some 40 psi. If you have competition bump stops on the rear, you need to make sure the tail of the car is not being held up by them. I know of the rear bump stops being cut to get around the problem. Note, I have what we called "Scandinavian bump stops" fitted, they are lower.

Al

[Spider]

Interesting 66S that you've found 4 different lengths. Any ideas what they came from? I said 2 different ones as that's all that is listed across the applicable parts books and I have only found 2 different ones, not that I've played with lots of them. Not being funny, but some of those you have haven't been shortened? If they did it in a lathe, it would be hard to tell. Got any lengths on these? There may well have been 4, the parts books aren't necessarily the most accurate source.

[66S]

The struts in my collection are from many different cars (mostly 850's) and I have no way of establishing what belonged to what. I think the variation in length is probably more to do with manufacturing variations than any intended alteration/modification to production. I don't think I have kept the measurements but I will look.

Regards
Al

[JC T ONE]

Dont know if they are the same ? but there was a longer rear strut for the Van,s .

[carbon]

Vans and estates did use a longer suspension trumpet, but this was for the 'dry' cone suspension.