11 replies to this topic

[coolbreizh]

I have just bought a 1968 Morris Mini minor for complete overhaul. I would like to upgrade the suspension to 12 inch wheels, more modern suspension, disk brakes and subframes off a more modern mini. If this is possible, what modifications need to be done to the body? Do the more modern subframes bolt right in?

[Cooperman]

Geometrically and structurally the near sub-frames are all the same, the only differences being the exhaust pipe hangers for the exhaust pipes on the later cars.
With regard to the front, a later sub-frame won't fit at all. In fact, the earlier front frames are mounted in a much better way as they are solidly bolted in and don't have the rubber mountings as the later frames do, which makes the steering better and you don't then get the rubber mountings failing. Also, the mountings through the floor on the early cars is stronger and puts the loads into the strongest part of the floor, unlike the later frames.
The suspension is all the same unless you have a hydrolastic suspended car, in which case a mod back to rubber cone suspension is a good idea as it improves reliability.
10" wheels are generally regarded as the best size for a Mini in terms of handling.
The best mod you could do is to up-grade the brakes to Cooper 'S' 7.5" discs and fit suitable 5" wide wheels with 165/70 x 10 tyres.
Also a set of better dampers would help if you have dry suspension.
The hydrolastic sub-frames can be easily converted to take the dry rubber cones, but you do need new top arms at the front as well to get the geometry right.

[coolbreizh]

What is involved in replacing the hydroelastic suspension with the rubber. Do they just swap out.

[998dave]

What is involved in replacing the hydroelastic suspension with the rubber. Do they just swap out.

No, sorry.

The hydrolastic cones have different sized bases to the rubber doughnuts.

need to replace or modify subframes.

[madaboutcherry]

keep your 68 mini standard. mk2 mini,s are becoming very rare now. hydrolastic partd are easily available seconhand.
it will go down in value if you modify it.

[maph2]

if your hydro system works, then keep it. they are a great drive and you can do some subtle mods to control the "bounce" for enthusiatic driving. if you have one displacer not working then try to get another. if 2 are down, then its aborderline "chuck" depending on the state of the subframes.

[dklawson]

As above. It's your car but please consider keeping it original. If you do decide to convert it, please consider keeping your modifications "reversible" and keep the old parts for a future owner.

[coolbreizh]

if your hydro system works, then keep it. they are a great drive and you can do some subtle mods to control the "bounce" for enthusiatic driving. if you have one displacer not working then try to get another. if 2 are down, then its aborderline "chuck" depending on the state of the subframes.

When you say "chuck", do you mean the car, or the displacers? What is a displacer? I am just discovering minis. I have been a spridget maniac for 25 years. Please explain.

[Cooperman]

Hydrolastic Minis have a fluid displacer unit in place of a spring unit and a fluid transfer transfer system between front and rear suspension 'displacers'. In effect, when the front wheels are displaced in the vertical plane by a bump, fluid is transferred to the rear suspension to reduce the impact of the bump on the rear. In theory it's fine, but it does make the car 'bounce' up and down on a bumpy road. However, fitting dampers to the front will cure the worst of this.
You don't need new subframes to convert from 'wet' (hydrolastic) to 'dry'. The hydro subframes have small lugs which the hydrolastic displacers (that's the liquid-filled suspension units) clip into. To fit dry cones, you just have to knock back or grind off these lugs and the dry cones fit perfectly. On the front, to convert from wet to dry it is necessary to have 'dry-type' upper arms as the geometry is different on the hydro cars. The dry arms will have the damper bolt fitted already, so then all you need is a damper bracket each side. On the rear you need trailing arms with the damper bolt.
It is true that it's not really possible to convert a 'dry' subframe to a hydro one as the lugs are not there and cannot be added. Why anyone would do that is not clear anyway.
The main disadvantage of hydro, for those who work on their cars themselves, is that to do any work on the suspension it has to be drained of fluid, then re-filled with fluid using a special pump unit at the correct pressure to get the correct ride-height.
Hydro does, in general, give a smother ride.

[dklawson]

For an overview of Hydrlosastic suspensions, how they work, and what the components look like, visit my friend Todd Miller's web site for the Austin America.

http://www.austinamericausa.com/

Look for the links down the left side of the screen. Select "Technical", then from "Categories" select "Suspensions Brakes & Steering". He has lots of info on hydro suspensions.

[coolbreizh]

What model year dry suspension rubber is best adapted to the 68 mini. Do they vary over the years?

[998dave]

they're pretty much all the same.

If you replace the front subframe I think a pre-73 one is easiest, (twin bolt instead of single).