Strut brace.

**Steve Webb** · 12-12-12, 11:39

This is just something that I've been thinking about for a while, obviously the most common strut brace for the 155\Q4 is the Sparco item which is a solid bar. However there are other braces out there for other cars that have a threaded connection in the middle of the car that allows you to bolt the brace down then tension it up.
How much difference do these bars make? Is it a noticeable difference?

Secondly are there any other easily available braces for the 155\Q4 that have the centre adjuster?

This looks like it could become a more pressing issue for me soon as I'm fitting a Kappa inlet to the Q4 and it looks like the standard Sparco item is no longer going to fit.

**mpampis_** · 12-12-12, 20:45

Something that may help! I have a momo one from alfa romeo 156. It fits directly to our car. As about kappa manifold i modified mine so it is shorter and i have no problem with that

**Evodelta** · 12-12-12, 20:49

How much difference does a strut brace make from none at all? Until someone does a proper test you will never know.

**Steve Webb** · 13-12-12, 09:50

Originally Posted by Evodelta

How much difference does a strut brace make from none at all? Until someone does a proper test you will never know.

Not a proper test but, jack up a 155 without a strut brace and you probably won't be able to open the front door on the side you've jacked up.
Fit a strut brace and jack it up again. Not perfect but front door will now open.

The front structure of the 155 just doesn't have the rigidity. I was just wondering whether the type of braces that allow you to fit them and then tension them up would improve things further.

**Evodelta** · 13-12-12, 10:15

Yes you're right, not a good test. If we were to act on it's results then we'd be buying strut braces just so we could make door opening easier while changing a tyre, because of course, we don't ride down the road on jacks attached to the cills.

This was half of a two-way test I did on a Coupe which is I believe, the same chassis:

Result? The matchstick lived, unharmed.

Go and study the strut top and see how well it is attached to the rest of the car. Do you have a pic of one bare, particularly where it goes back to the windscreen area?

**Steve Webb** · 13-12-12, 13:53

Originally Posted by Evodelta

Yes you're right, not a good test. If we were to act on it's results then we'd be buying strut braces just so we could make door opening easier while changing a tyre, because of course, we don't ride down the road on jacks attached to the cills.

Unfortunately my torsional stiffness testing jig is out of action at the moment so one has to make do with what is at hand. I was just trying to point out how floppy the front of the 155/coupe/tipo/dedra/etc.. is, especially when one front wheel of the car is being loaded up with extra weight. The sort of situation you get whilst under heavy cornering in a car that has a tendancy to understeer.

Originally Posted by Evodelta

This was half of a two-way test I did on a Coupe which is I believe, the same chassis:

Result? The matchstick lived, unharmed.

Interesting, I'm assuming from the pic that you glued the matchstick between the ends of an adjustable strut brace with the adjuster removed.

Out of interest did you try the test on the bench, clamping one end of the bar down and then moving the other end to see how far you needed to move the other before the matchstick broke?
Given that you can flex a matchstick in your fingers without it breaking, I would imagine that once you added the extra lengths of the strut brace into the equation, you could move one end of the brace quite a distance before the matchstick broke.

Originally Posted by Evodelta

Go and study the strut top and see how well it is attached to the rest of the car. Do you have a pic of one bare, particularly where it goes back to the windscreen area?

From having poked around the topmount location before, it looks pretty similar to a lot of cars, personally I would say that the weakness comes from relatively small chassis legs going forward from the bulkhead coupled to an insubstantial front crossmember.

**Evodelta** · 15-12-12, 20:17

I thinks it's an interesting topic and certainly one which is up for further debate and testing.

The door closing test is nothing to do with the struts or braces connected to them, what you have done there is jacked up on or near the cill and the A and B pillar have become misaligned. This is due to the spotwelded seams around the door shuffling and allowing some movement.

I guess a good test would be to try and open the door whilst cornering hard, i'll let someone else try that one though!

The shells are not as weak as you make them out to be, if you jack any car up of a similar era and even newer the doors won't shut when it's up on one jack, think about it, you've just picked up one corner of a nearly 1.4 ton car where it's not going to see any stress under normal service, of course there will be movement, it's a bit like picking someone up by their ears and ripping them off.....

Take a look at these pics:

See how close the strut top is to the bulkhead which is a very strong part of the car, also note how it is braced very effectively as standard. Can you imagine that moving? If it did it would be rusty or cracked.
How can one strut top become closer or further away from its partner? It's nigh on impossible for much movement to occur.

If you suspect the matchstick test to be not good enough what would you suggest? I briefly considered a piece of glass, but thought it might shell and crumble where it connects to the bar, might be worth a try though.

There are basically two types of movement, one is as I mentioned, where two panels which are connected by spot welds that can shuffle or move along this joint as it isn't solid enough.

The other is where the metal actually bends and gets flexed, this can only go on for so long before the metal suffers from fatigue and cracks so you eventually know when this is happening. Q4s don't suffer from this, integrales do.
Below is a pic of a joint from top of A pillar to roof, you can see how it was badly constructed with barely any overlap of the panels and just a few spotwelds tacking it together:

You can see the crack starting to appear, when you look at the outside you can see just how bad it gets:

You think your shell is floppy? Nope, look at this, it's where the seat was bolted on:

Now that's a soggy bodyshell!

**abarth 22** · 16-12-12, 07:43

I have Fiat Tipo 3 doors, and unlike Q4, doors can be open when is jacked at one corner.

my opinion is that is not needed strut brace in Q4 and other Tipo platforms

The only thing to prevent door not to open is installation rollcage, I think strut brace have nothing with that, but my mind is always open for some testing....

**Varypodaros** · 16-12-12, 12:01

I did that test with the car on the jack and all the doors opened and closed fine.
my car is a skinny 8v. where exactly do you put the jack? I put it under the places that manufacturer suggests.

**Evodelta** · 16-12-12, 13:06

Originally Posted by abarth 22

I have Fiat Tipo 3 doors, and unlike Q4, doors can be open when is jacked at one corner.

my opinion is that is not needed strut brace in Q4 and other Tipo platforms

The only thing to prevent door not to open is installation roll cage, I think strut brace have nothing with that, but my mind is always open for some testing....

Yes I can see that adding another two door openings would effect the strength in this (side) area, there is another way of strengthening it back up though without resorting to a roll cage (which I agree, is the ultimate move) and that is to seam weld and/or weld plates over the jointed areas.

Put your thinking hat on and lets see how we can test for movement across the strut towers.

**Steve Webb** · 16-12-12, 13:52

Originally Posted by Evodelta

Put your thinking hat on and lets see how we can test for movement across the strut towers.

I was thinking about this, and rather that the matchstick, could you use something reasonably strong but brittle, a ceramic rod perhaps?

Or, and this would take a little more engineering, on one side of the brace a flat surface perpendicular to the brace, on the other a spring loaded marker pen of some sort resting against the flat surface. Then as you drive, and\if the two ends of the bar move relative to each other, the pen draws a line on the flat surface.

Or if you want to go high-tech find a spot for a gopro under the bonnet pointing at the two end of the bar, set it off at low-res 100fps and go for a drive. With a suitable light source under there as well.