Race Engine Forum UK

Guy, castor has been set according to factory specs. I planned to increase it a little bit, but just a bit more and I have tyre to wheel arch interference situation on full turned wheels. It might even get worse with my wider summer tyres, so I had to satisfy with stock castor.

Regards,
Nikola

Nikola.
Does it not prove, when your bottom arm extends downwards[road rut], that it is maybe going beyond RCP? Classic bump steer occurs.
Only way to correct, is to stiffen springs and shockers to minimise the arm movement, or lower RCP. Also, a touch of castor would help also. Have a look at the wheels from the front, and see how they sit. Are they perpendicular or the top of the wheel/tyre sit inwards or outwards?

Andy.

Andy, the top of the tyre sit inwards, when viewed from car front. Isn't that camber?

Regards,
Nikola

Yes, camber. Now how much camber and castor is being created when wheel at lowest point of travel? This is the key to your problems i think.

Andy.

Hi Nikola

enclosed is the description of the geometrical construction of the suspension pickup points for the Mc Pherson, avoiding bump steer, i.e. for zero toe-changes during suspension travel.

It comes out a german book, so i translated the procedure.
Now you can measure on your car and draw your suspension.

Then you will know in which direction you should move things.

It may be easiest to move T, usually steering and idler box have large holes which allow some adjustment. Be sure both sides are symmetric.

Moving U reqires CAREFUL altering of the steering arm. Only an expert should do such a bending/rehardening job. It may be possible to move U by exchanging the Fiat spherical-bearing with conical fit to an standard sperical bearing with a straight hole, so that you can use spacers to change the position of U. Again, be carefull, steering and brakes must work properly!
In "How to Make Your Car Handle" by Fred Puhn you can find good explanations of how-to-do.


Hope that helps.

Thomas

Thomas,

this is one good piece of information!

Looking at the PDF, it is obvious what went wrong! As I lowered the car, steering rod position became inadequate! I've just made a sketch, according to the angles that I well remember, so at the moment, it is pointing well below the P1.

I will check the possiblities to relocate the steering rack, that would be the most convinient one, as you said. As for U location, I could actually check whether there is a compatible part for some other member of Fiat 128 related car, that has lowered U position.

Just anyone lowering the car should read and understand this!

Regards,
Nikola

Nicola

what I usually do the following to get the geometries if I dont have a drawing (it helps if you have a pit, so that the car stands at normal ride height and you are free to move...):
- fix a large paper on the floor beneath the front axle
- then get the center by marking a left and right bearing point using a 90‚° angle or a lead on a string
- then mark all necessary points on the floor and note the height from the floor to the bearing, which then gives you both coordinates to make the drawing.
This is a bit of work, but it is really worth it, especially on old cars, where the building accuracy may have been lower priority...or the owner before you bumped somewhere...

Looking for compatible parts is a good idea, Fiat has many exchangable parts "in the family".

By coincidence I just found a drawing of the Fiat 128 front suspension in my book, its on the PDF together with the geometric roll center position of the McPherson.

Have fun!

Thomas

Sorry to drag this post back out but it is extremely interesting reading. I am particularly interested in the Yugo front sway bar. On my 128 the front sway bar has a very distinct inwards bend on it. The bend is on the bodywork attachment-lower suspension arm length and it is about half way along that length. Am I right in saying it looks like the Yugo one hasn't got this inwards bend? I am very interested to see if using this sway bar on my 128 allows me to install a 5 speed box (it would foul on the sway bar in standard form). Can anyone tell me if this is posible?

thank you Scott.

Hello Scott,

Front sway bar for 5-speed Yugo has slightly different shape (in comparison to 4-speed one), to clear 5th gear extension on gearbox. However, you can't use this sway bar on F-128, as there are (subtle) differences in front suspension dimensions between those two platforms.

Nevertheless, there exists a 5-speed sway bar for Zastava 101. I believe it would be a direct fit for F-128.

Hope this helps,
Nikola

Very interesting!

We didn't get the Zastava range here in New Zealand, are those sway bars easy to find in Europe? I will be there in June, maybe I could make a special trip to pick one up.

Hello Scott,

Please take my apologies for late reply, somehow I managed to miss your post.

Yes, those sway bars can be sourced in Europe. Where exactly in Europe are you going to be? We tend to think that Europe is big :).

Best regards,
Nikola

That's quite funny as I haven't looked at this post for the last 4 months or so as well!! I will be going to the UK and Hamburg, and that is it unfortunately.

Ps;(I hope you turn the weather on for me Guy!) Going to Goodwood FOS on the Saturday which I am so looking forward to.

Scott

Scott,

I am afraid I am unaware of where you could source the sway bar in the UK or Germany. And having in mind its size, it is not an easy item to ship across Europe.

Cars having this sway bar were (or maybe still are) produced (and mostly sold) in South-eastern Europe, and this is where the part can be ordered for sure.

Sorry that I couldn't be of more help,
Nikola

Thanks for that. Your post as been more than helpful. Plus, I have found that the 128 is still being made! Nasco in Egypt still make it. It's called the Nasr 128 with 1298cc engine, 5 speed and sway bar attached. Now that will be mighty!

thank you

Scott.

Hi Myte. Even more bizarre I'm coming over from Ireland to Goodwood F.O.S. for the Saturday also. Small world!! Anyway try here (http://www.fiatmotorclubgb.com/) and on the forum ask about an anti roll/sway bar for a 128. Someone will have one I'll bet. If you're going to be in the UK someone should be able to help. Must try and meet up with you over there.
Paul