Hi All

I have installed the batteries into my electric mini. The battery pack is installed on the rear set self and weighs 150kg. As I suspected the rear suspension will need upgrading to handle the extra weight. The car is running standard hydro suspension, but what I was thinking about doing was adding a spax coil over kit to the rear only in conjunction with the hydro suspension to boost it up.
Any thoughts or advice would be great

Cheers Phill

_________________
KillaWatt Converions


"E"Mini, 144volt, 600 amp, 86kw from the get go

Are you still running the helper springs? Could be a quick fix (although I'm sure you've already looked into it).

some nice rear competition bumpstops (if not already fitted)

_________________
Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

You cannot fit shocks to the rear of a hydro Mini, it needs the "helper" springs to work. They stop the car from being a see-saw, without them there is no resistance in the suspension, it needs them.

You can fit a washer to the strut to lengthen it so that it raises the rear.
You can fit competition bumpstops.
You can't leave the helper springs out and expect the hydro to work the way it was designed.

I always thought the helper springs were to compensate for the weight of the engine (to make the force on the hydro bags roughly equivalent). It would depend on how much the batteries weigh though.

I guess you could do what a well known Suzuki Mini builder in NSW does- remove the 2 F/R hydro pipes and pressurise each corner separately.
Then you could fling the helper springs and fit shocks....

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The "helper" springs are not there to compensate for the weight of the engine, the different ratio of the front and rear suspension arms do that.
The helper spring are there to give a rate to the suspension. If you didn't have "helper" springs you could hit the sump on the ground under brakes.
Also if you didn't have "helper" springs the passengers could get seasick on a drive down the freeway as the car would rock back and forth with a crazy motion.

Aslo, if you are doing to block the pipe front and rear you may as well ditch the hydro and use rubber suspension as that is what blocking the pipes does anyway.

I have seen a mini or two with this mod, but how effictive can it be. the way i see it the liquid wouldnt have anywhere to go, aka wont compress, so you would either blow out the bag or it would be as rough as rubber??

_________________

*Reasonable pricing
*I come to you..
Jay: 0431404607

For a bloke that specialises in hydro you don't even know how it works.

Hydro bags have rubber springs. If you jump a hydro car and land all four at the same time what will happen? All four springs will deflect, just like any other car.
The hydro just equalises the front and rear, when the front wheel goes up slowly it will pass fluid to the rear, if the front wheel goes up quickly it will pass as much fluid as it can and the spring will deflect to take car of the rest.

A hydro displacer is a rubber cone with a flexible hydraulic bladder interposed between the rubber cone and suspension arm attachment.
If you block the pipes you really have rubber suspension as Morris 1100 says, however you can still raise or lower the car by putting fluid in or out.
As for handling being better or worse, perhaps Bluemin can put his 2c into the discussion.
I have not driven one like this, but we have chased each other around Wakefield Pk once or twice. Handling did not appear to be too bad.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

But how is it over speed humps?

Probably about as good as my wife's rubber coned and Koni'd 1275S replica, = bloody terrible.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

That is the thing, the handling comes from the rubber spring and the smooth ride comes from the hydro.

The downside to the hydro on a Mini is the helper springs, they are a big compromise, they assume that the braking force is larger than the acceleration force. The drag Minis prove this wrong for drag use but it works for normal road use.
If I was dragging a Mini I would fit helper springs to the front instead of the rear.

from what has been said i gather the hyro transfer is like a shock absorber and the rubber spring gives it handling


This statement doesnt make sense to me as you say the helper spring doesnt compensate for the engine weight, and then you say under braking you could hit the sump without the helper springs installed, isnt this compensating for the engine weight???
I do understand how the helper spring would give the front suspension a degree of rate.

The 150kg battery pack has a fairly low centre of gravity so Im hoping the weight will not transfer to much to the front under braking. I have been quoted $750 for a spax rear coil over kit. What to do????

cheers for the input
Phill

_________________
KillaWatt Converions


"E"Mini, 144volt, 600 amp, 86kw from the get go

No, it is not compensating for the engine weight, it is compensating for the braking force. The whole car is going to try and rotate from braking, the nose dips and the rear rises. Even rear engined cars with coil springs do this. It has nothing to do with engine weight.