Matt Harwood

Why does my 1929 Cadillac ride so poorly?

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I've been thinking about this for a few years now, but it was especially noticeable today. I got the '29 Cadillac out for the first time since last July and I'm planning on using it for a friend's wedding on Saturday (the '41 Buick was choice #1 but a problem with the rear shock links has it incapacitated). I took the Cadillac for a drive today and it started and ran like it always did--hello, old friend. But as I'm driving, I'm reminded of just how lousy the ride quality is. I'm thinking about my friend and his bride bouncing around in the back and I'm listening to all the joints squeak and rattle. Every bump I hit feels like it's going to smash something. I mean, it feels like I'm abusing the car just driving it down a regular paved road with a few bumps and heaves--not like driving in downtown Beirut or something. I even aired the tires down to about 28 PSI and while it removed some impact harshness, the rock-hard suspension still felt abusive.

 

There's just no way it could have been like this in 1929, not with the poor quality roads they had back then. I certainly don't expect it to be modern car perfect, but I honestly feel like I'm bashing the car to pieces as I drive in a normal environment.

 

My shocks appear to be in good shape. I put fresh oil in them recently, they travel smoothly, and don't leak. They're fairly stiff and I'm thinking maybe some thinner shock oil (I'm using hydraulic jack oil) ,but how much of a difference can it make? 

 

I did notice today while I was under it that one of the rear shock links came off the axle. I was able to push it back on, but however that link holds itself on the ball doesn't seem to be grabbing properly. I can't really see what's going on in the link--can anyone describe how the socket should be holding on to the ball? Is there a spring and a cup or something? Should the outer sleeve rotate to grab the mounting ball?

 

We have a good spring shop that does springs for semi tractors. I'm thinking that I could have them remove a leaf from each one or even make new springs that are softer. What else is left? What am I missing? Now I remember why I don't want to drive the car--it's tearing itself apart.

 

What am I missing? Why does this car ride like crap?

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Some manufacturers recommended that leaf springs be lubricated.  I would think your owners manual would tell you that.  I always use graphite grease in the springs and they are also very quiet.

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I jokingly say to my passengers 'to hold on to your hats', while holding on to my Boater hat going over speed humps or rough terrain....:)

 

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Lubricating the springs is a good idea. I reviewed the 1929 shop manual and it says exactly nothing, but I also have a '27 Cadillac shop manual that's far more comprehensive and it says to use a stiff brush to brush motor oil on the springs and let it soak in. Do this every 1000 miles. It also has a section on adjusting the spring hangers, which are somewhat more complex than those we have today and one of the causes of excessively stiff springs can be over-tight spring hangers.

 

So I'll try both of these things tomorrow and see what I get. I'll also double check the pins themselves but I think they're OK just because of how these are designed--there are grease fittings everywhere and I've been lubricating it every spring since I got it. 

 

Any other ideas? Thanks for the feedback!

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Matt,

 

While my 1937 Buick Century still rode pretty well, the springs used to squeak on every bump which irritated me. After my current restoration project gave me personal experience with the great results from a 50/50 Acetone and Automatic Transmission Fluid mix as a solvent. I jacked up the rear of the 1937 so that the leaf springs were suspended. I liberally hosed down the leaf springs from a couple of different angles. The solvent soaked in, freeing up the previous rusty sections of the springs, shackles, etc. The noise went away. I think it probably rides a bit smoother too. If you just use oil, I don't think it will effectively soak into the springs to free up the rusty leaf springs as well. I would seriously suggest you use 50/50 Acetone and ATF instead. I think you will be happy with the results.

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1 minute ago, MCHinson said:

Matt,

 

While my 1937 Buick Century still rode pretty well, the springs used to squeak on every bump which irritated me. After my current restoration project gave me personal experience with the great results from a 50/50 Acetone and Automatic Transmission Fluid mix as a solvent. I jacked up the rear of the 1937 so that the leaf springs were suspended. I liberally hosed down the leaf springs from a couple of different angles. The solvent soaked in, freeing up the previous rusty sections of the springs, shackles, etc. The noise went away. I think it probably rides a bit smoother too. If you just use oil, I don't think it will effectively soak into the springs to free up the rusty leaf springs as well. I would seriously suggest you use 50/50 Acetone and ATF instead. I think you will be happy with the results.

 

Thanks, Matt.

 

I was just reading another of your posts about a leaf spring spreading tool. Do you think your technique of acetone/ATF to loosen it up and then a spreader of some kind to lubricate the springs would be a good approach?

 

I was thinking of trying one of these tools and squirting some grease in between the leaves:

 

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On a set of frozen rusted leaf springs, the acetone works wonders in getting the lubricant in between the leaves. If your springs need it, I am pretty sure any paint removal is not an issue. In a perfect world, either the leaf spreader and grease would be good. In the real world, the Acetone/ATF is a great treatment for a really quick effective treatment. With the amount of grease on the outside of an average set of leaf springs on an unrestored car with this issue, I doubt any paint removal will be evident. I know it was not in my case. Since I have driven the car about 1000 miles in the past two weeks without any squeaks returning, I am happy. 

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Did they use sliders at the tips of the spring leaves in 1929? If they did they are probably long gone. And, the tips of the leaves have probably worn notches in the next longer leaf.  When you hit a bump the springs don't work smoothly. They are stiff because they are rusty and when the leaf hits the notch BANG.

 

The solution is to take the springs apart, clean off rust and smooth out the notches with a disc grinder. The street rod guys use thin nylon strips between the leaves so the work smoothly. I think you can still buy it from street rod shops.

 

Old tech is to put brass window screen between the leaves packed with graphite grease. Then cover the spring with a leather gaiter. Without the gaiter you were supposed to pry the springs apart with a cold chisel and pack with grease every few thousand miles.

 

So clean and paint and add sliders or grease and gaiters, your choice.

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Graphite grease is fine but remember to keep them lubricated. If that grease dries out, galvanic corrosion will eat your springs.

 

If you oil your springs, they will hold all dust that hits them. Oil is a wetting agent so the dust sticks and becomes grinding paste (e.g. at the ends of a leaf where it works on the longer leaf above).

 

Your shocks might seem to work smoothly and not leak, but do they work? Does the car bounce after going over a bump? Our test was to jump on the bumper and then hop off; if it keeps bouncing, the shocks are shot.

 

If it were mine, I would inspect all the spring shackles for wear and find a way to test the shock absorbers. We had a motor home that dived and rolled all over the place; new front shocks fixed it. Different vehicle with new shocks. My Dodge has early rubber sandwich shackles ("SilentRubba"); they were separated when I bought it and it hopped around on the road as the springs wobbled and bounced around in the shackles.

 

What this comes down to in my opinion is that your suspension needs an overhaul. And maybe the steering too.

Edited by Spinneyhill (see edit history)
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After all this excellent advice last night, I came in to the shop early this morning and poked around under there. One the springs are definitely NOT rusty, although there is a lot of ancient grease seeping out from between the leaves. It feels more like RTV silicone than grease now, but its presence suggests that the leaves are not rusted together. My mechanic and I disconnected the shocks and bounced on the bumper and there MIGHT be 1/4-inch of give in the suspension with nearly 400 pounds bouncing around on it. THAT seems very wrong to me. That's why changing to a lighter oil in the shocks made zero difference. It's got to be the springs. But what do I do about it? They're not rusted together and there are no ruts cut into the leaves by the ends of the leaf on top of it. They should move smoothly. They're just too firm to move at all.

 

The car does not bounce at all and the shocks seem to have smooth resistance when I move the arm by hand, but with so little give in the springs, who knows? Right now it appears that the tires are 98% of my suspension. Even with the shocks disconnected, there is no give and no bounce.

 

I called a local leaf spring shop that does semi tractors and did the rear leaf springs on Melanie's station wagon. The old timer there said that rust and old grease wouldn't make it ride like that and it wouldn't seize the springs. They said they could take a leaf out to maybe soften the ride, but it would also lower the car, which I don't really want. I looked at the shackles and they are well lubed and don't seem to be loose or tight, but I might put a wrench on them and loosen them a few clicks--they have a castle nut and a cotter pin. The rears have some kind of adjustment to them, but not the front, although the front suspension seems significantly worse than the rear.

 

Detroit-Eaton Spring just confirmed that prying them apart and lubing them won't do anything. They said they might be able to make new ones if I send them but they also said that if they duplicate them and they're still too hard, I'm back where I started. I don't think there's any way these are the wrong springs, but I guess that's possible, too.

 

Could this possibly be how the car was built in 1929? I've never been in another 1929 Cadillac so I have no basis for comparison, but when parts of the car start popping off from the pounding (the trim nailed around the perimeter of the rear windows, for example) it says to me that something is amiss. This thing should have been able to gracefully crawl over rutted dirt roads in 1929, not crash so violently that the windshield glass cracks.

 

Any other thoughts?

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Your Cadillac should float silently over road irregularities. It seems the best and only thing left is to remove the spring assemblies and disassemble as suggested above. Grind flat, polish and paint. On later Cadillacs, (Late thirties, but I may be confusing that with an English car I had) I recall interleaf liners of some slippery material. I wouldn't use buttons or the rope thing as above, as that would induce point loads, or fulcrums that would derange the spring rates. Of course, as the spring's load increases, in cornering, for example, the spring flattens so all the leaves must be free to slip over their neighbors.

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Hi Matt, just throwing this out there as you are very experienced and I am not a 1929 Cadillac expert. 

 

Your own comments got me thinking.  In the late 1990s Ford released a new generation F450/F550 truck and we got complaints about them sagging lower under load compared to the previous model which was like a buckboard.  It was explained that the springs had been designed for more movement to provide a better ride but this extra movement gave them more “give” under load.  Seemed logical to me as the result of the never ending need for compromise between load carrying and decent ride characteristics.  This must have been a major concern in designing cars in the 1920s too, especially a luxury class car.  You needed to make springs heavy duty but also give them a cushioning action, much as the trucks of today, and it sounds like your biggest problem is that yours are too stiff and unyielding.  I wonder if you can find any original specs that would tell you any original measurement of deflection that you could compare to your existing springs as I just bet they were replaced in a 1960s or 1970s restoration with whatever was close and would maintain the ride height—probably stiffer truck springs.  I can’t know of course but sure seems plausible and maybe the truck spring shop or Eaton would have the specs somewhere, will be very interested in what happens, Todd C       

 

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If you want a 30 minute education on leaf springs, take the time to watch this video.

 

If nothing else, go to about 22 minutes and watch it from there.  It will tell you that modern spring steel, starting in the 1950's, will fatigue and fail if petroleum products are used on it.  Thus, if you have new springs made for your car, DON'T oil them.

 

That's not my advice, it's the advice of a spring expert.

 

  

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Thinner oil is not the answer.  It is possible that you have too much oil in the shocks.   If you fill the shock and bounce the car and then top the oil up and then bounce the you can make the shock action very very stiff.

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Good video.

Historyses.

 

My spell check doesn't like this one.

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I am 98% sure it is the leaf springs. We disconnected the shocks and it drives exactly the same. Jumping up and down on the bumper, shocks or no shocks, results in zero movement of the suspension but some compression of the tires. We just loosened the shackle bolts and I'm going to grease the heck out of them this weekend, and we'll see if there's any improvement. I may invest in one of those spring tools up there and just lube the hell out of them and just see what happens. It certainly can't hurt.

 

In addition to speaking with the two spring shops, I spoke with Jim Capaldi, who is a noted restorer and a friend, and he says that this is a frequent problem with old cars. They disassemble the leaf springs, sand blast them, match them from side to side, paint them, and reassemble them with a teflon tape between the leaves and that smooths them out. So in the fall I guess I'll take it to him and have him tear it apart and rebuild the springs and see what happens. I may also have the shocks rebuilt just because--they're $400 each, but hey, it's just money, right? We also discussed taking a leaf out of each spring and if it drops the ride height, simply put a block under the spring to raise it back up. Not exactly right, but perhaps a reasonable solution if rebuilding the springs does nothing.

 

The only reason I really noticed that it rides so horribly is because that 1929 Pontiac 2-door sedan I just listed rides beautifully. Same engineers, same year, same roads, but the Pontiac glides over bumps and the Cadillac crashes. That's not right, something is amiss and has been since I acquired the car 9 years ago. I just was able to ignore it and pretend it was normal until now. 

 

We'll rebuild the springs and go from there. That has to be it, right?

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42 minutes ago, Matt Harwood said:

We'll rebuild the springs and go from there. That has to be it, right?

 

Sure sounds like it based on your observations above.  I looked at the 1929 Cadillac service manual and it looked like it said the original springs include 10 leafs in the front and 9 in the rear?  Yikes, I would think if they did that with springs of modern material it would be very stiff, good luck, Todd C

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You say the old grease oozing out of the springs is more like silicon now. Are they all glued together by this muck?

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I would jack it up on the frame and oil the springs and then shoot some Bust er loose or WD-40 on to make it suck it in and then try it before replacing the springs. If you determine the springs are original to the car they can be re-arched or modified to your ride choice. Removal of a leaf can be compensated for by adding shim above the last small leaf. Maybe it will come down to removing a leaf and also re-arching to give the desired results.

Edited by JFranklin (see edit history)

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13 minutes ago, Spinneyhill said:

You say the old grease oozing out of the springs is more like silicon now. Are they all glued together by this muck?

 

Certainly possible. I ordered a set of those leaf spreader tools up there and I'm going to clean them up and try to put some kind of lubricant between them to see if that helps. What can it hurt?

 

17 minutes ago, poci1957 said:

 

Sure sounds like it based on your observations above.  I looked at the 1929 Cadillac service manual and it looked like it said the original springs include 10 leafs in the front and 9 in the rear?  Yikes, I would think if they did that with springs of modern material it would be very stiff, good luck, Todd C

 

Yep, 10 in front, 9 in back. I believe these are the original springs--the design of the ends and the bands used to hold them together looks authentic and not like some kind of repro. I can't find anyone who can even make springs like these today, so 40 years ago there's no way they found someone to make new ones. They have to be original.

 

10 minutes ago, JFranklin said:

I would jack it up on the frame and oil the springs and then shoot some Bust er loose or WD-40 on to make it suck it in and then try it before replacing the springs. If you determine the springs are original to the car they can be re-arched or modified to your ride choice. Removal of a leaf can be compensated for by adding shim above the last small leaf. Maybe it will come down to removing a leaf and also re-arching to give the desired results.

 

That's the plan. Clean, lubricate, evaluate. Let's see what happens, I may try to get to it this weekend, but more than likely it'll be next week. I have so many unfinished projects. I still need to finish the headers for the '41 Buick Limited and get them sent out to be ceramic coated. And install the rear shocks on the Limited. And replace the rear hub on Melanie's wagon. And the 5-speed in Melanie's Mustang. And test the new mechanical overdrive on the '29 Cadillac. And...

Edited by Matt Harwood (see edit history)

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