Rubber supports under the front spring

[Peter Cripps]

I took another look at this today.

First of all, I was able to hold the spring back by placing a block of wood between the underside of the spring and the top of the upper A-arm pivot axle. Then I lowered the suspension, with the buffer top bolts loosened. I expected the buffer to come away from the spring ... instead it just stretched out. Maybe I need to hold the spring further towards the top of its travel?

Anyway, while in this state, I loosened the 4 center bolts on the U-piece, also the 4 side bolts. Then I walloped the top metal part of the buffer with a big hammer. To my delight, the spring moved! A few more blows and it was nicely centered. I then tightened up the U-piece center and side bolts, reloaded the suspension, and removed my piece of wood. The spring stayed centered.

Remains to be seen how long this lasts, but for now that little problem seems to be solved.

Peter

[tim]

I noticed similar a few days ago servicing my HF. Decided to leave alone but will have a go with your method of straightening when next motivated.

BTW I alway use a block of wood (oak as soft wood will split sudeenly) to hold the spring off the top suspension when replacing ball joints etc.

Tim

[Peter Cripps]

Tim, I'm not sure whether holding the spring back was a factor in straightening it ... quite possibly all that's needed is to loosen the central bolts and then tap with a hammer, as William suggests in his post.

Peter.

[Huib]

If it works, fine.

However the book specifies the position the spring should be in when torquing the bolts. It specifies a distance between rubber bumper and lower A arm for S1 and between rubber bumper and upper ball joint for S2 (and late S1). This in itself is a useless specification as the rubber buffer is inside the "equation". Its length depends on age and load. The load can vary considerably. It may on one hand carry its part of the weight of the car or on the other hand if the spring is supported the suspension may hang from it.

If one figures a nominal height of 65mm under load for the rubber buffer the specifications from the book can be read such that the spring should be entirely horizontal when torquing the bolts. Not having done so in the first place may be the reason the spring moved.

[Peter Cripps]

Huib, that's very interesting. Whether or not it 'works' is still to be determined, since the spring seems to walk forward over a period of time. So far all I've done is drive it down to the hardware store and back again.

I assumed (always dangerous) that the bolts should be torqued when the suspension was under normal load, which is what I did. Under these conditions, the spring still has a bow to it.

But if I understand you correctly, the spring should actually be loaded more than that?

Thanks,

Peter

[Huib]

Right.
Page DT - Fulv. 07/0020 takes some puzzling.

The title is: Front Leaf Spring, Static Load Dimensions and Leaf Spring Mounting.

The first table defines the static load values and gives the corresponding value for the curvature, which is -6 mm for most and +6 for the S2 coupe. Note that because the diameter of the S2 wheels is 1" larger than for the S1 wheels the spring has 1/2" more curvature.
For the coupe's that static load is 860 kg. This is a lot. An empty coupe is around 960 kg. With 60% on the front wheels you have 580 kg on the front spring. You would have to stack 3 complete engines on the cross member holding the sping to get to the static weight.

The second table gives the values for "locking the spring". What is "locking the spring"?
I assume it means bringing spring in the position with the fixture mentioned in table 3 to get the spring under static load. That position is thus more or less flat, -6mm for S1 and +6mm for S2.

The "dimension C to lock the spring" in table 2 is rather useless as the rubber buffer is in the loop as I explained above.

Note that the long M8 bolts have to be torqued with 2,5mkg which is a lot for M8 bolts. Good practice is not to re-use the old bolts but use new ones of at least 8.8 grade.

Also note that "Dimension C with car unladen" in table 2 seems to be quite different for S1 and S2 cars. This is not the case. On S1 cars the rubber bumper is halfway the bottom A arm. On S2 cars the rubber bumper is at the end of the upper A arm. This explains the different values. In reality the free upward travel is identical.

[Peter Cripps]

Huib, thanks for your usual very detailed and helpful reply. I really must go through the dati tecnici and make sure I know what information is already there!

As I read the description next to the bottom diagram on page 07/0020, it seems to say that the spring should be loaded to the static position before tightening the bolts. And, yes, quite a load would be needed to get to approx zero curvature. I don't think the 'block of wood' method will work here.

Oh well. If my spring starts to walk forward again, I'll think about making a tool to substitute for the fabled 8043117.

Peter

[Huib]

Well, the Data Tecnici is the bible for every Fulvista. As any monk will tell it takes many years to fully understand it. I am learning day by day and still only half way through. I am not sure if in this case it has any influence but you will know in what direction to look next.

[tim]

Well I now remember that to relieve the front spring I use a i/2 tonne hydraulic tower jack (its small) between the subframe and the spring and I ensure the thing cannot fire out unexpectedly. It works a treat to jack the spring up free from the rubber mount.

Extending this idea one could a) jack the spring to the appropriate (negative) camber each side, or b) use load cells to equate to the static load in the manual (1/2 each side). I suspect this camber info is just to check the spring performance however.

Isnt it curious that the static loads for each model of fulvia equate to approximately that models unladen weight.

Cheers

Tim

[Peter Cripps]

Tim, I'm not sure I can visualize this ... wouldn't the driveshaft get in the way of the hydraulic jack?

Thanks,

Peter