Sniper Posted January 19, 2020 Report Share Posted January 19, 2020 Load shifting under braking is handled by the anti dive built into the front suspension, not by spring rates. I linked to the specifications for the Aerostar spring in the third post in this thread. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted January 20, 2020 Report Share Posted January 20, 2020 9 hours ago, Sniper said: Load shifting under braking is handled by the anti dive built into the front suspension, not by spring rates. I linked to the specifications for the Aerostar spring in the third post in this thread. Unfortunately for the 1940's Chrysler front ends...there is very little anti drive built into the placement of the front upper control arms as far as I can tell. What little there may be is sharing the duty with front coil spring. If anything the front of the upper control arm looks level to down bubble a bit, suggesting little to no anti-drive. If they is the case, then it is all spring. One would have to measure it to see if there is 3 to 6 degrees in there or not and then go through my chassis books to do the math to see how much is anti drive and how much is spring rate. James. Quote Link to comment Share on other sites More sharing options...
Sniper Posted January 20, 2020 Report Share Posted January 20, 2020 Proper anti dive is determined by the suspension design if you have none and are relying on spring rate for control it is a poor decision. In order for the spring rate to be able to control braking dive is would have to approach an infinite rate. Which is why our rides dive in braking, because it doesn't have an infinite spring rate and no anti dive. Not to mention the floaty feeling our rides have, a combination of soft springing and poor upper shock mount location. I suppose one could try to shim up on the front of the upper control arm inner pivot to instill some anti dive, but with the design of the uprights you will most likely side load the outer and/or inner pivots. Which is probably part of why they went to ball joints. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted January 20, 2020 Report Share Posted January 20, 2020 11 hours ago, Sniper said: Proper anti dive is determined by the suspension design if you have none and are relying on spring rate for control it is a poor decision. In order for the spring rate to be able to control braking dive is would have to approach an infinite rate. Which is why our rides dive in braking, because it doesn't have an infinite spring rate and no anti dive. Not to mention the floaty feeling our rides have, a combination of soft springing and poor upper shock mount location. I suppose one could try to shim up on the front of the upper control arm inner pivot to instill some anti dive, but with the design of the uprights you will most likely side load the outer and/or inner pivots. Which is probably part of why they went to ball joints. Agreed that one of the reasons they went to ball joints was to get more anti-drive without having to go to stiffer springs. Remember, that until the ball joint era, speeds were a lot less. Before the advent of the Interstate Highways and the increased speeds...high speed (over 50 MPH) braking was rare. I suspect that a number of changes came about due to the higher speeds. I know that there is a MOPAR technical note someplace that talked about the higher speeds and the heat build up on the rear axles. They suggested to increase the Axle shaft end play up from about .008 or do to almost double that. Apparently, the Axles were growing so much in highway driving that they were binding on the center block in the pumpkin. My point is that I think the anti-drive in the older cars is not as great as people think, I really would not want to spend a month taking measurements and doing the math to definitively find out. Since there is a reasonable chance that the anti-drive is a combination of suspension "A" arm placement and spring load...and minus any hard data on it...I would not substitute a spring that did not have the same load and rate as that which was done by the engineers at Chrysler. One may get lucky and it will work great or one may not. Since most people reading this probably do not have a bunch of chassis books on the shelf nor have every designed their own chassis...below is a link to a short article on Anti-Drive in Hot Rod that goes over some of the issues. https://www.hotrod.com/articles/antidive-suspension-tech-parameters/ James Quote Link to comment Share on other sites More sharing options...
Sniper Posted January 20, 2020 Report Share Posted January 20, 2020 I agree with what you say but would add that the nose dive my 51 takes when stopping is more noticeable than later ball joint era cars I have driven. Might be wore out springs contributing to it and I haven;t really gotten it up past 50 either. But I will also say it goes over speed bumps a lot smoother than any ball joint era car I have driven as well, till the rear axle hits that bump then it's the same or even a bit more noticeable. Is it enough to get me out there to do a bunch of measurements and math to relocate the control arm mounting points? Not at this point. Though I do plan to rebuild the front and I might take those measurements then. Quote Link to comment Share on other sites More sharing options...
40desoto Posted February 16, 2020 Report Share Posted February 16, 2020 On 12/28/2019 at 5:45 PM, Andydodge said: Sniper.........I'd be surprised if a coil over setup would be as straightforward as you may think as the shock relocation arrangement if it included a coil over might locate the coil over too far away from the pivot points of the lower A arm.......I've thought about this myself over the years I must confess although I only recently did the shock relocation about 12 months ago and to be honest I'm not overly impressed with the difference tho' that maybe because of the use of short shocks, 13" overall length, rather than the much longer ones that seem to have been used in most swaps I've seen on here..............I had the short shocks and they appear to be a good fit but am not 100% convinced of the worth of the swap............I have had the 1" thick sway bar on the car since the mid 70's and it certainly helps in the handling department..........the car has 1940 lower a arms, 41-56 upper A arms, 1940 spindle with 1941-56 style stub axle, rack is a 9" shortened Austin 1800 rack with 1" shorter forged steering arms, stock shaped 1" thick sway bar with heim joints...............regards, andyd Andy, what year sway bar did you upgrade to? 1998 Jeep Cherokee? Quote Link to comment Share on other sites More sharing options...
Andydodge Posted February 16, 2020 Report Share Posted February 16, 2020 Nope.........when I built the car I lived in Sydney a large city even then of about 2 million and close by was an aftermarket suspension company called K Mac who marketed all types of steering and suspension upgrades....I took the stock 5/8th thick sway bar to them and they made a new one 1" thick with the same shape but flattened the ends and drilled a hole in each end so I could use bolts and I had the heim jointed links made to suit......its the stock shape using larger clamps where the bushes are at the chassis..............dunno if this helps................andyd Quote Link to comment Share on other sites More sharing options...
greg g Posted February 27, 2020 Report Share Posted February 27, 2020 Tell us about the way the exhaust manifold was done. Did you do it or did you pick it up done? What goes on inside the heat riser chamber? Quote Link to comment Share on other sites More sharing options...
Andydodge Posted February 27, 2020 Report Share Posted February 27, 2020 Greg.......I assume you mean this setup..........here in Oz the 23" engine used at least 3 different exhaust manifolds.........each had a different located outlet.......stock 41 Plymouth had the outlet between cylinder 5 & 6....so I obtained one with the outlet between cylinders 2 & 3 and another with the outlet between cylinders 5 & 6 and cut the heat box etc off each and then had the local blacksmith weld up the ends , by doing this I was assured that the outlets would clear the RHD steering box which would live between the fuel pump and oil pump.....the exhaust pipe that is shown is angled back at that angle to clear the steering box.........I would have used Fenton style cast headers BUT the front set would not clear the steering box and the rear set would have been hit by the clutch pedal follow through...........as I live in a sub tropical area I felt that the heat box would not have been needed.........if it turned out that it was needed then I was going to make a water heated plate to bolt onto the bottom of the intake.........but I ended up selling the 41 Plymouth this was to go into and also sold this engine.........sometimes you(me) do stupid things......lol...............andyd Quote Link to comment Share on other sites More sharing options...
greg g Posted February 27, 2020 Report Share Posted February 27, 2020 Andy seen that one before, was referring to the one with the tattersfield intake. It has the second outlet exiting from the heat riser. Quote Link to comment Share on other sites More sharing options...
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