Fitting Protech Shocks to MK 1 High Pivot Suspension

[John A. Ross]

See here

REBUILD OF DDG 220 C

A comment from Dan High_dan was that using standard 1" or so shorter Monte Carlo springs ( the "standard" Imp mod springs supplied by Malcolm Anderson Imp Parts )
was that the Protech Shocks supplied by Mike Dent at Imp Competition Parts moose549 ran out of adjustment.

Mike has a selection of shocks and springs to solve this as well as plenty advice to share on spring weights to get the best performance from the shocks.

For now on DDG it has the standard slightly lower monte carlo springs I suspect like many others do.

The shocks have already been fitted by Dave Lane and with great results in similar setup but on MK2 suspension as Dave changed it I believe to MK2. Dave might find time to share his experience but by all account changing from Mk 1 to MK2 is a complete ball ache of a job

So do not think changing MK 1 to MK 2 suspension may be any easier than changing springs if needed, after all if you look after the top suspension mount nuts and bottom shock bolt, you only have the shock to remove

Will share the updates

- John

[Dave Lane]

So fitting MK2 suspension ( low pivot ) on a MK1 car ( high pivot )
Reason at the time was I had all the parts , my MK1 wishbones were shot and the front track on a MK2 is shorter plus a lower centre of gravity - after all Rootes didnt do all this for no reason .
Anyway heres what i remember as it was done decades ago on both now .

Differences are .
Wishbone length ( early wishbones are slightly longer )
Rear steering rack and suspension mount.
Front mounts .
Fixed length track rod ( early one is too long ).
Steering column inner and outer length (early one is too short )
Speedo cable is technically too long but could be used.

So you will need
The COMPLETE suspension from a late car
The steering column inner and outer from a late car
The shorter fixed length track rod from a late car or better still fit adjustable to both sides
Stub axles will fit either but its best to fit the greaseable later ones .
You cannot mix and match any part from a MK1 High pivot to a MK2 low pivot apart from the stub axles , NOTHING WILL FIT

So basically the whole suspension has to come off .
The four very front mounting holes by the number plate line up and are unchanged .
The four bolt holes on the rear { steering rack mount ) accessible from UNDER the car line up and are unchanged
The four bolt holes accessible from INSIDE the car DO NOT,
These will have to be welded up and redrilled .
The steering column hole needs to be welded up and moved down about an inch , its best to work out the exact position once the suspension is fitted , captive nuts for the outer column will need refitting .
That is basically it . , its best to fit the new suspension using the 8 bolts that do line up then drill the new holes through the captive nuts that dont from underneath the car , you can also work out the column hole move at the same time., then drop the suspension and sort out the welding .

Good comparison shot , both are MK1 Singers , Its obvious which has been modified

Camber is 1 1/4 degrees negative after a full de-camber

[John A. Ross]

Cheers for the extra write up Dave, top man

Will need to work with what I have, I had Mk2 stuff coming out my ears as well but as the MK1 stuff was mint it went back on so we will see how it pans out

Camber will be my enemy I reckon which if I adjust it might push it out a bit. I dont want to do the "adjustable" camber mods done by those that like the low look as they have a gap between the "foot" of the stub axle and the wishbone metal, bolted from either end to me just screams insecure as its not pinching down onto another surface so forces either way might bend the bone.

I am sure the folks doing this will defencd it to the end and likely have done 1,000s of miles and no ill effects but I would rather it pinched the bone skin between solid surface and nut. If that means I need to do some shimming I will at least be happy

[Dave Lane]

The shorter wishbones are an advantage for any camber mod

[Colimp66]

Good write up and explanation Dave with what needs to be done for the conversion from mk1 to Mk2. A lot of work required for sure.

John, I am sure you will get your Mk1 sitting sweet without going to that extent, good luck.

Col.

[PMCG]

Excellent info. Dave Lane

[moose549]

I think you can get away with the adjustable mod on a road car just relying on the thread holding the position but one big pothole ?

I would never do it to a motorsport car.

If you need some shorter springs John just ask, if you have movement to lower your car on the springs you have by lowering the spring platform but end up with too much camber you need to do the camber mod with spacer washers remembering to do it the reverse of the millington book.

Set the ride height to what you are happy with, if you run out of spring pan travel i will sort you some springs, if you have range left set height, roll car backwards and forwards turning from lock to lock with the usual weight in the car i.e. two people and full tank of fuel, leave the people in car and now look at your ride height and camber angle (measure it do not go off looks) you want 1/2 to 1 deg negative max.

I suggest you take a spring off one side of the car at front support shell on a jack at the normal ride height then take another jack under the wishbone and slowly jack up with damper on softest setting and look at the camber angle you get too, try to imagine the angle it gets too when there is two people in the car a full tank of fuel and you hit the brakes and the nose dives.

The amount of negative camber that comes on is a lot more than most people think.

Hence why you do not want too much neg to start with.

It is balance that you have just enough for high speed corner where you won't load the front end of the car up too much when you turn in.

With modern radial tyres and lower profile tyres there is not much give and roll in the side wall like higher profile radials and especially crossplies so you need less negative camber to counteract the positive camber the side wall roll is adding.

It is all about keeping the footprint of the tread as wide as possible under all circumstances to have maximum grip.

If you have too much negative at static and you brake hard at full weight and turn in hard you will only have say the inner 3/4 of tread in contact with the road and not enough grip to roll the side wall so no more tyre gets to the road and the more front of the car nose dives the more neg is added and then you get even less tyre contact patch therefore less grip.

The amount of NEG you have with the car empty compared to two people in it is more than you think.

When making any adjustments to ride height after adjusting roll car backwards and forwards turning lock to lock to allow tyres to settle then re-measure.

when you have ride height and camber set, dial in the tracking to 3mm total toe in.

[John A. Ross]

Cheers for that Mike. top man.

Potholes

I would say scourge of the modern day but its only really been more noticed now where folks have wheels and tyre profiles with an inch of rubber, first pothols and the alloy is a gonner

But yeah, the wishbones are decent gauge steel but nowhere near robust enough with a nut/bolt and some gaps, one side will give but I dont want to go out and kill a wishbone or myself to prove the theory, not a risk I will take anyway.

Will update when I get to fitting them