ALFAGTV6.COM

Post by **Zamani** » Wed Jun 06, 2007 12:50 pm

How about a metal insert where the bolts go through and make the bar wider so there is more material between the hole and the edges.

Micke · Post by **Micke** » Wed Jun 06, 2007 10:20 pm

I see, your making a the ultimate ar bar, with infinite stiffness

Wrong. It will NOT do that. On the contrary it will actually reduce the effect of the current AR bar as the inside wheel doesn't droop. So, the inside wheel will actually have more compliance than before. However, this is not the point (just a side effect).

But nice try so continue thinking (I know - it is supposed to HURT)

Mats · Post by **Mats** » Wed Jun 06, 2007 10:59 pm

Sounds strange, the spring rate doesn't change just because the inner wheel can't droop so it will still be as stiff as before, probably even stiffer since it's "higher up on the spring" and therefore needs to be loaded more before it moves - not compliant.

Micke · Post by **Micke** » Thu Jun 07, 2007 1:48 am

You need to read again Mats. Not the springs. They won't change a squat.
The AR bar will.
Well, you are correct that the spring rate won't change. However, the force acting on the outer wheel will as the inner won't move in the opposite direction.
Quite a theoretical issue - huh.
And what do we learn from this? Absolutely nothing.

Jarle · Post by **Jarle** » Thu Jun 07, 2007 2:02 am

Maurizio: Why would you not trust aluminium? Your wheels are aluminium, so are many suspension details for newer cars as lower/upper a-arms

If i am thinking right here i asume the biggest load at the aluminiumbar will be at the outer wheel when cornering, then the forces will push the aluminium against the orginal steel frame construction? can anyone estimate the load at the lower a-arm?

Micke · Post by **Micke** » Thu Jun 07, 2007 2:21 am

Here's a very rough estimate:

force=mass of front of the car * lateral acceleration * 1.5 (ratio UCA/LCA - don't remember exact number and this I pulled from my Stetson)

Typically then 700 kg * 13 m/s^2 * 1.5 = 15 kN. Add a safety factor of 4 and you are up in 6 kN.

Barry · Post by **Barry** » Thu Jun 07, 2007 7:31 am

Maurizio,I agree..My worry here would be that ally fatigues almost as badly as Stainless steel..If the ally has NO bending force what so ever,ok,it will do the job.
Here we have a slight lever action everytime the car corners left and right..
Id check it every now and again just t be sure..If You now could tie the bracket in to a back plate on the inside,yes,I would go for that every time.

Now I'm just a dumb South African wif almost no education here..What do the engineers and clever (Not you Mats!

)say about this??

Barry · Post by **Barry** » Thu Jun 07, 2007 7:33 am

For those who have not cut a GTV up and disposed of it,the reinforcing piece in the chassis leg for the 2 LCA bolts is no wider than the heads of the bolts-her on our cars at least..So theres really no backing up for the plate (on our cars)in the configuration used here..

My goodness-spelling!!edit....

Jarle · Post by **Jarle** » Thu Jun 07, 2007 8:01 am

Thanks Micke and Barry. I am just a dumb viking trying to make a nice handeling 116 chassis

.
Just throw the alu out the window? Mats?

Barry · Post by **Barry** » Thu Jun 07, 2007 8:51 am

Jarle,No!..I would simply fit a back up plate on the inside of the leg and extend the bolts to go through the chassis leg.No need to throw it away..Its a good idea.

The leg will be hollow but you now have two rather solid ally plates on either side AND bolted into the original locations as well..That would ,imo,give me peace of mind.

Jarle · Post by **Jarle** » Thu Jun 07, 2007 10:00 am

Barry: As the setup is now the bolts go through the leg and are attatched by nuts on the inside. Your suggestion is to also add a backup plate on the the inside with the nuts to strenghten the leg?

Barry · Post by **Barry** » Thu Jun 07, 2007 10:20 am

J,The inside plate could encompass all 4 the bolts.The idea for me would be to have the top bolts go right through the chassis leg and tie up with the backing plate.
Looking at your pics the setup is pretty strong.I would still be wary of fatigue as its setup now.
Come to think of it,the inside does not have to specifically have a plate as such,you could simply use large machine washers under the bolt heads..
Recap-four bolts,bottom 2 as they are now..Top ones going through the LCA imo,should also go through the chassis leg .

You follow what I'm rambling on about?

Does anyone else have an opinion here??

Jarle · Post by **Jarle** » Thu Jun 07, 2007 11:40 am

Got ya! Nice idea, i will get som longer top bolts to get all 4 bolts through the leg! Thanks

Barry · Post by **Barry** » Thu Jun 07, 2007 11:43 am

Shoot some pics when you done..Id realy like to see what you did..
Already thinking of doing my Giulietta..Thanks.

Maurizio · Post by **Maurizio** » Thu Jun 07, 2007 2:03 pm

Here we have a slight lever action every time the car corners left and right..

@Jarle, this is the problem. I'm not that afraid of using alloy or stainless steel. Just use them within their limits

Get the cantilever effect out and your probably in the safe zone.
The suggestion of the backing plate is a good one! But still there is the problem of the thin sheet metal. I would like a metal tube inserted around the bolts you added which go toward your backing plate. Weld the metal tube in the original sheet metal. The tube will connect the inner and outer sheet, which give more stiffness. Under your alloy plate use rivets towards the chassis, that will make defined lay on point to introduce the forces!

@Barry: I'm an engineer, but clever...., Micke's challenge hurts like hell