'59 Sedan HP Alignment Tuning

[HBRag]

I am working through some alignment tuning on a '59 sedan. The car feels a bit light at 70 MPH and believe it is the rear alignment. Before setting up the strings again and changing toe settings toe to zero, I figured I might gain a bit of food for thought from the gurus here. Anything I missed, like tire pressure? I started with 1mm of toe-in at zero degrees of camber, which I suspect is causing the lightness of feel at speed. Current configuration is as follows;

Car: 1959 Ragtop with 2776cc Engine (190HP@crank) and 3.88 R&P Trans in street configuration

Wedge: 0.8 degrees front down

Front
o Tire: 17 PSI, Micheline XZX 165R15, on stock 4.5" wheels
o Caster: 8.3 degrees
o Camber: Left 0.5 / Right 0.5
o Toe: Left +2.4mm / +Right 2.3mm
o Link pins and Steering Box adjusted to remove play (fresh build and bushings)
o Shocks: KONI Classic shocks adjusted for 2 of 4 on firmness (half)
o 5/8" Sway bar
o Beam is 2" narrowed with drop spindles and CB-Wide 5 brakes
o Ride height adjusted to clear head light buckets, car sits near level.

Rear
o Swing Arms: Ground alignment slots for toe. Bushing black Prothane Urethane
o Tire: 29 PSI, Michelin Defender 205/65R15, stock centers and 5.5" negative offset custom shell to look stock from the side.
o Camber: Left -0.8 / Right -0.12
o Toe: 1mm @ 0 degree camber
o Shocks: KYB Gas Adjust
o Original EMPI camber compensator with new bushings and straps
o Custom Kaefer brace and frame horn stiffeners (No wheel hop on launch)
o Bug Pack Flop Stops and up travel limited with custom snubbers/brackets
o '68 wide track axle arms, with T3 drum brakes
o Stock torsion bars

Weight: Tank full, toolbox and spare present (Full street options)
o LF 398 Lbs / RF 393 Lbs
o LR 602 Lbs / RR 580 Lbs
o Left: 50.7% 1000 lbs
o Rear: 59.9% 1182 lbs
o Cross: 50.4% 995 lbs
o Total: 1973 lbs

[HBRag]

Look like I posted in the wrong forum, if the Moderators can move this to 'Suspension, Handling and Brakes', that would be appreciated.

[Steve Arndt]

This forum is ok for the topic.

29 PSI rear maybe a bit high. Try dropping to 25-26 and give it a feel.

[HBRag]

Thanks Steve. I adjusted rear toe, to -.5mm per side at -0.5 camber. I have to grind the slots to get any more. It was at 1mm positive per side. With tire pressure at 26PSI, it feels better but not there yet.

Shock rebound is too light, as the car osculates in the bumps and is wind sensitive on steering. I think I will try stiffining up the front Koni shock one setting, they are on 2 of 4.

Everything I am reading, the car would do better with the front a bit higher. However, I cannot get there with drop spindles and a 2” narrowed CB front beam.

Alan

[FJCamper]

Gentlemen

The painful truth about shortened front axle beams is at base you really mess up your suspension geometry. I cut my teeth on VW-356 and 911 suspensions in the 1970's, at the factory racing level, VW and Porsche both, Jo Hoppen on. Look him up.

When you shorten the VW axle beam, you change the relationship between the steering box ratio and response, making the steering more sudden. This translates to making the rear end of the car slightly fishtail as minor steering corrections are made. It's a vicious cycle.

Shortened axles are popular because they make wider front tires possible. Most short axle guys just live with poor handling, But cosmetics oftentimes win out over function,

FJC

[HBRag]

I narrowed the beam 2” to make room for drop spindles and disk brakes, at about 1” per side. It wasn’t about looks, as much as keeping the wheels inside a stock fender.

I’ve got a second car setup with stock spindles, lowering done on stock beam and steering box rotated to line everything back up. It is much more stable, at relatively the same height.

I’ll fiddle with this setup a bit, then think about rebuilding a stock beam and finding a different setup of front brakes. I wouldn’t say it’s oversteering, just way to sensitive, and light on feel.

Always learning something, next up might be mapping out all the steering angles to figure out what’s been compromised.

Thanks for your input.

[Ol'fogasaurus]

Gentlemen

The painful truth about shortened front axle beams is at base you really mess up your suspension geometry. I cut my teeth on VW-356 and 911 suspensions in the 1970's, at the factory racing level, VW and Porsche both, Jo Hoppen on. Look him up.

When you shorten the VW axle beam, you change the relationship between the steering box ratio and response, making the steering more sudden. This translates to making the rear end of the car slightly fishtail as minor steering corrections are made. It's a vicious cycle.

Shortened axles are popular because they make wider front tires possible. Most short axle guys just live with poor handling, But cosmetics oftentimes win out over function,

FJC

(second try)

It's been a long time but it is possible that there are other things that need to be done to correct the geometry when you shorten the length the front axle beam and torsion bars.

Steering box might need to be moved and/or the steering arm might need to be shortened to get the geometry back to where it was. Remember one side is shorter than the other, so the spindle arms geometry might need to be relocated a bit and so on.

This is from ancient memory and on other vehicles, but it might be worth looking into.

Lee

[FJCamper]

There are too many known and unknown variables in getting the front to rear suspension geometry right. I know you're frustrated fighting this problem. My heart goes out to you. I've been there myself.

[Ol'fogasaurus]

Since I have never seen a shortened front beam or have done/looked onto doing one so I did so a search about the subject.

There is a 15-minute video on the subject I got but got out post of it (there was an ad as part of it) but what I did see and hear was that there was a previous video on lowering the beam had been done plus it looked like both tubes of the beam has already been marked (2 inches) in the center of the beam for cutting; e.g., similar to cuts for putting adjusters in. In the short part of the discussion, they also talked about moving the mounting plates over also.

Since I didn't watch the whole thing, it was the work on resetting the steering box and (potentially) modifying other parts that I was concerned about. If the alignment of the steering box, the potential shortening of the adjustment arms and the adjusting/shorting of the spindle arms plus the (potential) alignment of the steering arm (or not) is what would be something that would bother me as the alignment could then be out of whack if not done or done right.

This is a just a guess but based things I had to do when I was working/designing things on aircraft.

Lee

Suspension then comes into play. Torsion bars... probably not but air of gas shocks are often used if a beam is still used. Air shocks I have played with and was not too happy with what I got. Watching and listening to guys setting up rails using gas shocks or gas with coil over shocks was interesting to listen to. Once they got it pretty close... they seemed to go in another direction . Most of them now days are a bit younger than me and don't come around as much as they used to.

IFS is also being gone to which is another subject.

The sway bar is something I haven't seen but assuming you can buy a short beam, I would suspect that sway bars are probably out there but their torsional strength (et-al) would be interesting to hear about.

It is an interesting subject to play with for sure.

Lee

[HBRag]

Lee,

In this cases is a new manufactured CB 2” narrowed beam, with Avis adjusters set to stock height, new torsions, narrowed 2”, new tie rods shortened 1” on each side and a steering dampener. Steering box and arm in in the default location. For a sway bar, it has a 16mm (5/8”) Whiteline bar. I am pondering trying a 3/4” bar.

It was done to fit a set of CB drop spindles and wide five disk brakes, which offset the wheel just about 1”. In theory the shorted tie rods and increased angle to the steering arm, is the only geometry change. Torsion spring rates are a bit stiffer too.

I’m gonna stiffen the Koni’s up a notch and drive it to a few shows this weekend. I’ll keep my foot out of it, and the shiny side up

Alan

[Ol'fogasaurus]

I may be wrong here but there could be the possibility of the arc in action with the steering part of the problem. Notice that the stock Pittman arm has off-set holes for the two tie-rods and... I doubt that the unusual off-set is just for room for the connector of each tie-rod.

Again, this is just "stinking" out loud.

Lee

[Ol'fogasaurus]

Sometimes one or two seemingly minimal changes to something can require other changes to be done. When movement of things (such as dealing with arcs) are involved (like the steering) what happens to the other seemingly minimal changes that were not made. Sometimes these changes can seem to be so minimal that the other needs aren't seen that easily.

I did layouts (drawings) many years ago then when CAD/CAM came out it became a bit easier to see things but even then, other stuff could be easily missed.

Things, as they are, could be OK but the new "chattering" in the changed front end might be a message that some other things like the steering arm off the steering box or the tie-rod arms on spindles might need to be looked into.

This is for what it is worth.

Lee

[Ol'fogasaurus]

Just for giggles, what is the alignment of the now modified front beam?

If the beam was welded up properly and the angle of the pan head is the same as it was, the angle of the rake could be part of the problem. Too much rake without beam angle corrections was a problem heard years ago while listening to VW guys jabber. This was before I got into dune buggy's.

Doing a search for the angle of the pan head that the beam mounts I found this (right/wrong or in-different):

https://www.thesamba.com/vw/forum/viewt ... p?t=394831

There is some interesting conversation going on.

Lee

[Ol'fogasaurus]

There is one thing I think I would change if one does do this, and that is to move the cut of the top piece of the axle mount to the Nepoleon's hat area. The bottom plate could be bent to the proper angle then the angle cut in the rear of the top piece supporting the main part of the pan could have the welding. I think it would be stronger in several ways and alignment would be easier to do.

I think the mount would be stronger with the longer load before the join going into the main part of the pan. I was talking to an owner of a VW junkyard many years ago and one thing he said about the buggy pans (glass body... no steel and no roof for load transfer) is that the front of the pan from the Nepoleon's had area to the shifter area had a tendency to sag. Again, the problem was front to rear and across loading transfer in a bug was less than in a stock top bug so it was the twisting that caused the problem. The way the front of the pan's small area of connection to the rest of the pan is the reason I think would prefer doing the mod by the Nepoleon's hat area.

Lee

Remember that the front of the pan assy starts to taper down starting at the forward end of the doors so loading there is more compact.

Anyway, something to think about.. for what it is worth.

Lee

[Steve Arndt]

I have almost the same setup in my 65 bug. The 2" narrowed beam isn't the problem.