105 Competition Suspension Set Up

[turbolarespider]

Zal- is that a welded rear, or modified LSD?

Interesting set up- so simple...

Negative camber- done at a mobile home repair shop, right? I've heard they can bend the axle tubes easily. And I understand that -.5 is not hard on the splines at all....

Eric

[turbolarespider]

Quote:

Originally Posted by Keven Great discussion here. I found a site from a guy in Norway that made his own Watts Link, looks really nice. Although I dont speak Norwigian(sp?), the pics tell it all. Can anyone on the board translate the info for us? Here's the link (Watts link that is ) http://www.brandmaker.no/bertone/watts.html

[74GTVEEE]

It is a modified LSD shimmed for more LO. The trailing arms are modified to accept circle track springs so as to have many selections...

It is very easy to modify the axle tubes. Just set up a rolling assembly. Use your toe measurement set up vertically. Suspend the assebmly on jack stands and lower the car lift with a verde (as was my case) onto the point near the pumpkin, then heat with torch and cool while applying pressure with the lift. You will have to heat and cool many times as shrinking the metal is a slow process. but with excellent results.

Quote:

Originally Posted by turbolarespider Zal- is that a welded rear, or modified LSD? Interesting set up- so simple... Negative camber- done at a mobile home repair shop, right? I've heard they can bend the axle tubes easily. And I understand that -.5 is not hard on the splines at all.... Eric

[PSk]

Quote:

Originally Posted by turbolarespider There was a great series of articles in Racecar Engineering about assymertical cars- non fomula cars. One whole article was about solid axles, and it did mention how you can use the geomertry to help plant a tire. On the trunion set up, the force of the car on the top of the axle will always try to lift the inside tire. With the lower roll center- you can make it pull it down.

[PSk]

Quote:

Originally Posted by turbolarespider Now that is very interesting. Putting the watts link on the chassis- normally it's done the other way around. BUT- this is the "correct" way, as the roll center WRT the chassis never moves. E-

[Max Banks]

George,

The best thing for the rear end is a pair of coil over shocks with adjustable spring platforms. It is critical that when you are sat in the car, the inner pivots of the front wishbones are exactly the same height as each other, then the front geometry is the same. Then adjust the coil overs on the rear to get the weight distribution as good as possible.

We are currently manufacturing a foam filed fuel tank to sit in the spare wheel well to help people with LHD cars cornerweight their cars better. It will be about 25 litres. The original set up of battery, tank and driver on the left causes real problems with set up and is the reason a LHD car is much slower than a RHD car round clockwise circuits.

I'd be interested to hear how that guy got negative camber on the back of his car... I have heard about people saying they have developed it in the UK but when I have come across the car and checked it, I have found it to be complete bull$hit!!! The same going for a squeak of toe in on the rear.... again in theory it may have its advantages, but I have never seen it executed in practice... despite claims!!!! What do you guys think!?!?!?

[turbolarespider]

Zal pointed out one method- which I'm not entirely clear on.

But Jim Steck tells me that one can go to any shop that repairs mobile homes, and they can bend axle tubes. There is enough slop in the splines that .5 deg any direction is not a problem. He mentioned doing this to one of his customer cars (Colizi sp?), and it really helped on tire temps- I can't recall if there was a change in lap times.

I'm going to start a new subject, which is a subset of this one...

Eric

[MichaelB]

Has anyone tried " 5 linking " the rear suspension. ie have the two Alfa lower trailing arms and then put a top arm on each side and a Panhard rod for lateral location.

My car has the Harvey Bailey additional top arm on one side of the car, mounting inside the wheel arch on the bolts that hold the trunion running back to a fabricated mount ontop of the rear axle on the drivers (RHD) side. This bar at present is light gauge, as it only assists the alloy trunion but there is enough room for a beefier bar if needed. If a similar setup was used on the other side and a Panhard rod/Watts link fitted, Hey Presto a 5 link set-up as used by most serious Mk 2 Escorts.

Has this been tried before?

[Sprintn]

If parts availability was not a problem, cost was not an issue, (aside from trashing the current rear end and puting in an independent rear suspension) Is there an ideal solution that everyone would agree on??? It seems that all modern day race cars have a way of setting up the rear end (structurally)... but this thread has a whole slew of ideas.?.? IS it due to cost? Parts availability? Or was there never really an iron clad meathod for this type of rear end????

Sprintn

[genericwood]

[quote=turbolarespider]Zal pointed out one method- which I'm not entirely clear on. But Jim Steck tells me that one can go to any shop that repairs mobile homes, and they can bend axle tubes.

Eric, I know of a Giulietta race car that had the rear end "cambered". Since it was found to be difficult to accurately bend the tubes, a very thin pie shaped cut was made in the top, the bend was made and the tubes carefully welded. With careful measurement before the weld, it apparently worked quite well. I had not been aware of the mobile home shops capabilities!

Erik

[turbolarespider]

I'll call Jim tomorrow to get details. Sounded promising.

From what he told me, it donesn't take much.

Sprintn- the problem IS that there are so many options. For trailing links- you can stay with the 3, modified 3, or even 4. For lateral- sliding block, watts, panhard, mumford (nobody brought that up yet...). Most opt for basic 3 trailing and panhard as that is easy to fabricate, and reasonably cheap. Our friend Andy Kress is making the decision a little harder now that there is a reasonable kit for a Watts link.

Originality seekers use the sliding block.

The ONE time I've seen a mumford device- it was on a 105 GT in Germany featured in Racecar Engineering (car also had a modern 4V engine in it). This is a set up that can very quickly move the roll center...

Options confuse people... don't they.

Eric

[PSk]

Quote:

Originally Posted by MichaelB Has anyone tried " 5 linking " the rear suspension. ie have the two Alfa lower trailing arms and then put a top arm on each side and a Panhard rod for lateral location. My car has the Harvey Bailey additional top arm on one side of the car, mounting inside the wheel arch on the bolts that hold the trunion running back to a fabricated mount ontop of the rear axle on the drivers (RHD) side. This bar at present is light gauge, as it only assists the alloy trunion but there is enough room for a beefier bar if needed. If a similar setup was used on the other side and a Panhard rod/Watts link fitted, Hey Presto a 5 link set-up as used by most serious Mk 2 Escorts. Has this been tried before?

[genericwood]

Thought I would reinvigorate this thread with some front suspension data. I finally got all my data into a suspension software program. My front control arms are stock with adjustable upper of course. The spindles are stock length between the control arms, but have been cut and rewelded to lower the car an inch. I don't know the spring rate, but they are 10 inches free length. This provides a lower a-arm inclination of 3/4" from the frame mount to the ball joint.

According to the software, the roll center height is -0.7 inches, or just below ground. It moves to -2.2 inches with 1 inch of dive, and to -3.7 inches with 2 inches of dive. 1 inch of dive gives -0.39 degrees of camber change and 2 inches gives -0.96 degrees. 1 degree of roll results in +0.86 camber change on the outside tire and -0.89 on the inside. 2 degrees of roll gives +1.70 degrees and -1.82 degrees. Putting the two together (as in trail braking), 1 inch of dive and 1 degree of roll gives +0.41 and -1.21 degrees of camber.

The only thing changed from last year (how I bought the car) is the drop spindles. The only real impact they should have is to lower the CG and slightly lower the roll center. So I don't expect much of a change. But it is nice to have a baseline from which to work. I will probably try about -1.75 degrees of static camber with the Hoosier Street TD's and then measure tire temps to fine tune.

I always enjoy the discussion from more knowledgeable racers, so please jump in if you think I have anything really screwed up here!

Erik Wood
'69 GTV vintage racer

[Berlinista]

Hi guys,
I'm new here on this forum, and was attracted by this topic right away, as this is an issue here too!
Okay, in Holland we have the Trofeo Championship, for out-of-production Alfa's. Three classes: Mod,Mod. Classic and Modified plus.
Mod. is mostly 75's, Mod. plus; Anything goes (ie 155 STW, 75 IMSA , wide body 105, TS conversions etc) and Modified Classic is 105 with loose rules.
Big fields, fast cars and just to give one example: On the Nurburgring last year we were outrunning E30 M3's, Audi Quattro's , Sapphire Cosworths and a host of six cilinder Alfa's with our Giulia supers and Bertones.
Now, I build bodies for these cars, and know a bit about setting one up. (Built the 01 Champ, 02 runner-up, 04 runner-up)
As far as I know you guys in the states run rather loose rules, not like FIA Historics.
we run coil overs front and rear, 15 inch slicks, adjustable Stabiliser Bar up front (is that a track bar?), no bar at the rear, uniballs in the trailing arms and in the triangle out back, and a heavily modified front suspension.
I read the comment about coilovers being nonsense on a 105, but we used the former setup,using 450 kg springs up front (1100 lbs?)
On coilovers we're 3 to 4 seconds faster.
Why? Unsprung weight dudes! Also: much finer suspension tuning. We can run 180 Kg springs now,what with the mount center being much more outward.
We also modify the wheelbase by removing the lower joint, replacing it with an aluminium joint between the lower arms, with a Uniball in it. So we can also adjust Camber from the lower arm. This too has an advantage in not placing the arms upwards. You can adjust track this way as well by screwing the Ball out. Of course you have to modify the shock absorber turret, but you have to anyway, to give strength to the chassis. (and the steering box). Usually you pull the roll cage through the firewall, and have it end on the turret. Also, a 2 mm. plate is welded between the firewall and the susp. mounting. On the front susp. top arm: Remove the rubber bush, mount a lower A arm bush (same size) and poly urethane reaction arm bushing.
So : question: Why not you guys?? What have we got wrong?

[ECARRILLO]

Berlinista,

We wold love to se LOTS of pictures, not only of the suspension but of the complete cars you have; engine, interior etc!!!

PICTURES

Thanks,