I am attempting to reassemble the 39 Poncho front suspension. Holy Rube Goldberg Batman! What a conglomeration of moving parts. First and foremost- yeah, yeah...go get an updated front end. But then again, that's why I'm posting under TRADITIONAL HOT RODS. ;-) Anyone have any insight on assembly? It appears Caster and Camber are adjustable using an Allen wrench on the top pivot by removing the grease fitting for access. But everything is threaded to everything creating a challenge getting it to a null position for alignment....wherever that null is... Any crucial measurement I need to dial in so I don't have a re-do on the spring install...etc? Just tossing it out there. I may have to track down an original shop manual? Also, looks like a similar setup on the bottom.!?
A factory shop manual is exactly what you need. They used that type of suspension in most if not all GM cars in the 40's and 50's.
Information you need should be the same as Chevy. http://chevy.oldcarmanualproject.com/shop/1941/41csm061.htm
I should have an old Chiltons that covers that if ya need pics. if anyone asks ya what kind of suspension you used, tell em 1st gen corvette.
I have a 39 and a 50 so am glad to see this information posted. Changing the rear gear fluid twice a year or every 10,000 miles is something I didn't expect to see.
These are the Pontiac suspension pages out of my 1946 Motor manual . If this doesn't work I can try scanning them.
Well poop, those are upside down neumarically but I think you should be able to read what it says. update: I got that fixed now. Caster is adjusted with the threaded bushing. Camber with the "cam".
That is the same basic set up that was used on the early 50's Chevy, as well as the Corvette from '53-62, which may help. Lots of info. on the web. Here is the link to the service manual. Bob 1953 - 1962 Corvette Servicing Guide ST-12 (oldcarmanualproject.com)
I fixed it and have the pages in the right order now but the first page is rather useless in this case. I tried to edit it last night and my internet was acting up at times.
I fabricated a couple of aluminum flat bars to "static" set the caster on my Buick. Both bars have a set of scribed lines on them the same distance from the center of the appropriate size hole on the end. I put one bar on the spindle and snug with the nut, and the other bar held by the upper upright clamp bolt. I level both bars facing forward, and drop a plumb bob to the floor from the same scribe line. My lower bar is offset so the bars are in the same side to side plane. Zero caster hits the same point on the floor, and positive caster or negative caster will be forward or behind. This method gets me very close and I follow it up with a gauge later. While a lot of folks say upgrade, I find this "knee action" shock/ kingpin suspension to be very well designed. It does have its limitations, and there are changes that can be done and stay HAMB friendly. 1958 Pontiac suspension can be used to convert to a ball joint set-up, but requires a fabricated bracket for the upper arm, and Chevy dropped spindles.
Do you ever induce extra caster to improve handling at highway speeds? I replaced my steering box with a power unit, so low speed is no issue. The info I’m seeing says 0- 3/4 degree caster. How much can I realistically dial in?
The original specs of 3/4 degree negative caster worked fine with original size tires. I set mine at 1/2 degree positive caster for the wider tires I have. Most experts say positive caster has an effect of loading the outside tire in a turn, and even causing oversteer if excessive, but since I don't have the car on the road yet, I cannot evaluate it. I did use the bar set-up on my 53 Ford, which has a similar king pin design. Set at 1 degree positive, it drives fine. If staying negative, I would limit it at 1 degree. If positive, maybe a degree and a half.
The Jalopy Journal
