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Re: I drove a hundred miles today to be told,
WE b OLD #1328638 Thu Oct 03 2019 03:17 PM
Joined: Dec 2002
Posts: 3,661
Moderator - The Electrical Bay and Rocky Mountain Bolters
My Plymouth rides like a truck. It is also way too low. The oil pan is the lowest part of the front of the car and almost has a hole worn through it. The oil pan plug looks like it is ready to get ripped out. I'm going to leave the rear suspension as is, but I'll be putting on a new set of front spindles to get the front end up an inch or two.

Have you thought about having a 4 link rear suspension installed? Or is that what was prohibitively expensive?


Another quality post.


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Re: I drove a hundred miles today to be told,
WE b OLD #1328640 Thu Oct 03 2019 03:24 PM
Joined: Mar 2014
Posts: 1,535
J
Shop Shark
I agree with moparguy. Go back to original. Steering geometry isn't for shade tree mechanics or pretenders...especially on a vehicle built with a solid front axle and built on such slim tolerances as the AD truck was and with so few adjustable factors (2). The pure fact is some dangerous mistakes can be made and some of the people who are doing this in my estimation have not the first idea of what they're doing. For over 50 years I've watched people try different tricks to make these trucks ride better, particularly at freeway speeds. And as we all know freeway speeds aside from the years of the Arab oil embargo have been increasing. Unless you take the entire truck off and mount it onto a completely different frame/etc a safe and secure ride at 70 mph isn't going to happen. Speeds over 60 mph for these trucks were not considered in the front end design. Look at the caster angle. To run safely and straight at 70 mph, you're going to have to increase that angle notably and that's going to make your steering in town really hard. The whole front end was designed specifically for this truck and specifically for what the engineers thought the trucks would be used for. Any student of front end geometry will tell you that. This isn't to say a front end with a solid axle can't be designed to drive well at higher speeds. It is to say this front end has some very specific limitations that overcoming will be quite expensive and will require some very sophisticated equipment (and knowledge) only possessed by a few. These were designed to drive most safely and properly at max speeds of 50 to 60 mph. If the height of the truck is seriously altered, all sorts of things change instantly. I won't go into them...it would be a very long discussion, but it is a fact all the changes make steering worse. Go and study this stuff if you're so inclined...start with axis inclination, then go to camber and then go to scrub radius just to start. See what a height difference does to these factors. Ron, the first thing I see is your rear tires are taller than your front tires by over an inch. Even 1 inch difference in your rear to front will reduce your caster angle and that will cause wandering and steering that feels loose and goosey...especially in a truck which has such a tiny caster angle to begin with. Good luck.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: I drove a hundred miles today to be told,
WE b OLD #1328647 Thu Oct 03 2019 04:01 PM
Joined: Feb 2001
Posts: 6,798
W
Master Gabster
No problems with front suspension, AMC pacer IFS. I have thought about it Jeff, but yes for the expense. The spring shop recommended adjustable coil-overs or air suspension. The tire's height is to be changed soon to the same dimension. They are getting a little old, at least 10 years but only about 36000 miles. I have no issues at speed I hace run it all day at 70 mph. It is just the in-town ride that seems to be different or I just might be paying more attention. I have a 20-gallon fuel tank in the rear when it gets low on fuel the ride seems to deteriorate.


Ron, The Computer Greek
I love therefore I am.

1960 MGA Roadster Sold 7/18/2017
1954 3100 Chevy truck in the Gallery
2017 Buick Encore
Pix on Photobucket
Re: I drove a hundred miles today to be told,
WE b OLD #1328653 Thu Oct 03 2019 05:12 PM
Joined: Mar 2014
Posts: 1,535
J
Shop Shark
Originally Posted by WE b OLD
I have a 20-gallon fuel tank in the rear when it gets low on fuel the ride seems to deteriorate.



In an ideal world you want your vehicle weight distributed equally over each of your 4 wheels. Obviously the world isn't ideal but the engineers of the AD truck definitely took weight and steering geometry into consideration...at least as much as they could. If you've moved the gas tank to the rear (where the spare tire used to be) your ride will always change depending on full tank or empty tank. That is because with a 20 gallon tank (roughly 170 pounds including the tank) you are pushing down on the rear and in turn (unavoidably) pulling up on the front end. Think of it as more or less a see-saw. A full tank causes your caster angle to increase making steering more stable and at the same time you're redistributing and reducing the downward pushing weight making your front end feel lighter (because it in effect is). As your tank gets less full, the downward pressure in the rear (and upward pressure on the front) disappears and you once again have the wrong caster angle (because of the 1+ inch higher tires in the rear). With the tank in the center (as designed to be), it is just like having an extra passenger who weighs about 100 pounds when the tank is full and it makes no difference at all on the steering.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: I drove a hundred miles today to be told,
WE b OLD #1328654 Thu Oct 03 2019 05:26 PM
Joined: Mar 2014
Posts: 1,535
J
Shop Shark
If you want to see a real-world example, go get a complete 235 and load it in the bed of your truck...about 6 inches from the tailgate sitting transversely in the bed. Now start driving. Your steering will feel more accurate (less wandering) because your caster angle is increased but it will also feel like your front wheels are floating on the highway and that may be very disconcerting. You may think you have power steering or something. Or swap the 235 for a lighter engine. You'll see right away the truck doesn't steer as it used to and your springs are much too stiff now. There are plenty of posts here about this. Good luck.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: I drove a hundred miles today to be told,
WE b OLD #1328665 Thu Oct 03 2019 06:11 PM
Joined: Feb 2001
Posts: 6,798
W
Master Gabster
The spare is in the front of the bed. In some respects, it does not drive a whole lot different than my 2017 Buick Encore. I remember the days of the big boats and think they called them that because they wallowed all over the place. My first new car was a 1969 Plymouth Sport Fury 2 dr. and it was a beast to drive until I put radial tires on it the second year I had it.


Ron, The Computer Greek
I love therefore I am.

1960 MGA Roadster Sold 7/18/2017
1954 3100 Chevy truck in the Gallery
2017 Buick Encore
Pix on Photobucket
Re: I drove a hundred miles today to be told,
WE b OLD #1328702 Fri Oct 04 2019 01:02 AM
Joined: Dec 2015
Posts: 2,085
Big Bolt Forum Moderator
Ron, what tire pressure are you running in your tires? You might try dropping them to 30 or even 27psi and see how it does. That is a free thing you can do!


Mike

1955 Chevy 6400 ex-flatbed (no bed now!)
In the Stovebolt Gallery


1958 Chevy 6400 flatbed W/dump
In the Stovebolt Gallery

1959 Chevy Suburban Owned for almost 20 years, Daily Driver -- sold May 2016
In the Stovebolt Gallery

Sufficient unto the day is the evil thereof
Re: I drove a hundred miles today to be told,
WE b OLD #1328894 Sat Oct 05 2019 03:20 PM
Joined: Feb 2001
Posts: 6,798
W
Master Gabster
69Cuda. I should have done what you said right away. I cleaned the tires this morning and decided to check the tire pressure and I was shocked. I checked them before going to KC and they were at 32psi. Today they read around 22psi across the board. Coming back from my trip Wed. I noticed a little squirrely movement in the front end. Of course I thought I would check them when I got back but of course, I put it off. I am sure it explains some of the changes in the ride that I noticed. I have a compressor in my other garage and will rectify the situation when I decide to go out.


Ron, The Computer Greek
I love therefore I am.

1960 MGA Roadster Sold 7/18/2017
1954 3100 Chevy truck in the Gallery
2017 Buick Encore
Pix on Photobucket
Re: I drove a hundred miles today to be told,
WE b OLD #1328966 Sun Oct 06 2019 03:42 AM
Joined: Sep 2013
Posts: 1,028
M
Shop Shark
Ron, you said your truck with a AMC Pacer front end and a full lowering kit did fine on good roads but potholes and or depressions and bumps could cause it to feel unsafe and out of control. If that's an accurate summary this is what I'd do and why. I'm betting your truck is running out of suspension travel and hitting the bump stops, hard. In other words the suspension is bottoming out and then it's basically No suspension, just solid steel on steel with perhaps a rubber bumpstop for front suspension.

My guess is your truck weighs around 4,500 lbs wet. A 1979 AMC Pacer can weigh from 3,000 to 3,500 lbs depending on trim/engine/station wagon or not. This link shows front coil springs for a '79 Pacer wagon with V8 and AC that gives a 2" lift.

The Price isn't bad (IMO) on the springs in the above link. With the additional 1,000 lbs. or so your truck has on the car the springs are spec'ed for, you could easily wind up setting at stock height or hopefully a bit higher than current springs allow. The additional travel would make for a better/safer ride. Specking spring rates, progressive or not, rebound rates, vehicle height, is a science with a lot of engineering involved by the manufactures. I'm not an engineer but It sure sounds like there's a lot of room for you to improve things and if me, the path above is the one I'd go down.

OR, you could call the linked company at the number here at the bottom of the page, talk to one of their tech guys and see what they recommend. I agree with your thoughts, it's the springs.

Last edited by moparguy; Sun Oct 06 2019 03:56 AM.

1951 3600 with Clark flatbed, T5, 4.10 rear
1970 340 Duster
1990 5.0 V8 Miata (1990 Mustang Gt Drivetrain)
1951 Farmall Super A



Re: I drove a hundred miles today to be told,
WE b OLD #1328978 Sun Oct 06 2019 11:44 AM
Joined: Feb 2001
Posts: 6,798
W
Master Gabster
I had the truck weighed a few years back and I think it was around 3500 lbs. I think what I alluded to before that the tire pressure may have caused the loss of feel going over big bumps. I will fill it up with gas later today and see. Also, the angle of the shocks may contribute they are way off from verticle. I might try to have the mounts rewelded closer to verticle per the chart I received about efficiency do degrees from verticle. The less verticle the less efficiency.


Ron, The Computer Greek
I love therefore I am.

1960 MGA Roadster Sold 7/18/2017
1954 3100 Chevy truck in the Gallery
2017 Buick Encore
Pix on Photobucket
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