Suspension at last!

[Blubayou]

Following the general rebuild of my MkIV a mere 9 years ago, apart from the usual sonsumables & a general de-crud of everything, the suspension was left as it came, working but ugly. I've finally got round to fitting the OE spec springs (std 180lb) and shiny Unipart dampers!

Looks better now, really should get my paintbrush out for the other parts tho'

It now rides smoothly & level at the front. But the back?

The spring is very saggy, I will try replacing the rubber buffers & top rubber as money is tight, but I think I will need a new spring. Any recommendations here?

Most firms seem to sell 159640 for around £100 but I'm pretty sure I need 159654 (long shaft MK1V) which Canley's have for £150 ish, is it worth the extra?

Also, are the cheap all black dampers found everywhere for around £30 a pair any good?

[Blubayou]

Sorry, can't get the second pic on, try this.

[heraldcoupe]

3669 wrote:

Also, are the cheap all black dampers found everywhere for around £30 a pair any good?

Quality of those I've seen recently has been OK, but check the diameter of the lower spring seat matches the internal diameter of your spring,

Cheers,
Bill.

[aar0sc]

I got a set for £20 off ebay, I can't see any problem with them, although they were slightly shorter than the old (original Girling) ones at full extension. I'd like to try a car with a new/good rear spring and more expensive rear dampers, to see if there is a noticeable difference though.

[Freebird]

heraldcoupe wrote:

Quality of those I've seen recently has been OK, but check the diameter of the lower spring seat matches the internal diameter of your spring,

Cheers,
Bill.

Hi Bill

I think he is asking about rear shox.

[starman]

3669 wrote:

Following the general rebuild of my MkIV a mere 9 years ago, apart from the usual sonsumables & a general de-crud of everything, the suspension was left as it came, working but ugly. I've finally got round to fitting the OE spec springs (std 180lb) and shiny Unipart dampers!

Looks better now, really should get my paintbrush out for the other parts tho'

It now rides smoothly & level at the front. But the back?

The spring is very saggy, I will try replacing the rubber buffers & top rubber as money is tight, but I think I will need a new spring. Any recommendations here?

Most firms seem to sell 159640 for around £100 but I'm pretty sure I need 159654 (long shaft MK1V) which Canley's have for £150 ish, is it worth the extra?

Also, are the cheap all black dampers found everywhere for around £30 a pair any good?

What's your rear camber?  Some modest negative camber helps mitigate the intrinsic jacking nature of swing axles.  Swing axle camber is determined by differential height relative to the hubs (i.e., rear height of the vehicle because the diff is attached to the chassis) and swing axle length.  If your rear camber is like 2 degrees negative, that's not bad (I use 4 degrees negative on purpose myself).  Near zero is actually not so good, and positive is asking for poor handling.  If the rear is really too low, consider renewing the thrust buttons that separate the leaves and act as the sliding/bearing surfaces between adjacent leaves.  Simply renewing these, or replacing the original rubber material with something like little machined Delrin buttons, can make a significant difference in the arc of the spring and hence the static ride height and therefore rear camber (as well as how freely the spring flexes).  

159640 and 159654 swing springs are supposed to differ in the thickness of the bottom two leaves.  159640 have 0.25" thick bottom two leaves, while 159654 has 0.3125" thick bottom two leaves.  The result is that the 159654 spring has more roll stiffness (that's not what you want on a swing axle rear, but it's still less roll stiffness than the much less stiff early Spitfire fixed spring) but also more vertical (bump and droop) stiffness (that's good on a swing axle rear in that it results in less suspension travel for a given load and thus less camber change for a given load, i.e., a lower rate of change of camber vs. load).  Free arc of the two is supposed to be the same, so simply replacing a 159640 with a 159654 should result in a little higher rear ride height (less sag) and a change in rear camber away from negative and toward positive.  You can always adjust final rear ride height and camber using a lowering block if necessary.  

Using a genuine 159654 is worth the extra cash IMHO if you have stiffened and lowered the front end.  The extra stiffness of the 159654 will help keep the front-to-rear stiffness bias from getting rather large/out of balance (and hence increases the tendency to understeer--perhaps too much) as can be the case when you install much stiffer front springs but don't change the rate of the rear spring.  Sounds like you've gone with stock spec front springs, so the extra stiffness of the 159640 isn't necessary.  Is the extra roll stiffness more of a negative effect than the positive benefit of the extra vertical stiffness?   It depends on other things in the setup, so it's difficult to answer definitively, but the best way is to try it and experiment.

Lastly, beware some of the basic black dampers because some have the bottom spring seat in the wrong place, i.e., up too high.  The bottom spring seat should be 3.25 inches above the center of the lower mounting hole (where the lower end of the damper attaches to the lower A-arm).  If it's more (e.g., 3.875"), don't use them.  As far as damping ability, they are adequate i think for a regular street vehicle without a bunch of suspension mods.

[Blubayou]

Cheers Starman, I've set about doing the rubbers in the rear spring today, trying to stall the inevitable new spring. Current camber is around -4 degree due to the sagging, exhaust too close to the ground.

So anyway, old spring out, easy peasy, stipped it all apart. Little spring ID tag confirms it is indeed the 1973 original. The existing rubber top mount looks like a thin skid mark & the 114006 rubbers are mostly ground away. Got new rubbers off an ebay seller, they are around 2mm too big. Shaved them down to fit, stuck them in place with a little bit of silicon glue & took them out into the garden for a trial fit. Cleaned all the threads on ths studs up, cleaned the springs down etc.. started assembly...... only 3 little buttons!!!

Looked everywhere, gone forever. What to use....standard tap washer? Perfect fit, could have saved a fiver there.

Anyway, all back together but there is a problem. The box the leaves sit in does now not sit flush on the steel plate underneath, 6mm gap all around and its done up tight. The new thick top rubber is stopping it from seating all the way. Is this ok? I mean, how on earth do you fit one of those springs with an extra leaf in the box?

Incidentally I'm down to about -2 deg camber with the car sitting a little higher, so all is good apart from the box not seating.

Any advice please!

[Blubayou]

Ok, sussed it.

The steel plate goes between the bottom 2 leaves not below them.

Pity I didn't study my own photo earlier.

Duh  ;D