How to Fix Awful Ride - 1991 Grand Wagoneer

[Brynjminjones]

Hi all,

I've always heard that these Grand Wagoneers are supposed to have a lovely smooth ride, but our 1991 rides pretty awfully.

It's so firm and harsh that I can feel every imperfection in the road and every bump makes my CDs skip! It's okay at highway speeds, and towing a trailer seems to smooth out the rear.
It also has much less body roll than I would expect, so seems overall very stiff.

By comparison, we also have a 1974 F100 on its original shocks. That is much more soft and likely to bottom out, but the ride is so much more comfortable. It feels like riding a cloud by comparison!
Even my 1998 Jeep XJ rides nicer than the Wagoneer, and doesn't jolt half as much on smooth roads.


The Wagoneer is on stock springs (slightly saggy in the back) with Monroe Gas-Magnum shocks (34958, listed as heavy duty on RockAuto).

I know the springs are worn, but I'd guess that they'd become softer with time rather than firmer.

Are these Monroe Gas-Magnums known to be firm shocks, and would changing them likely sort my problem?

[J76137]

Since I don't know the history of the vehicle I am going to answer in a generic manner...

There are a number of factors that can contribute to a harsh ride. The short answer is likely a combination of shocks that are too stiff (probably to compensate for sagging springs) and tires that are over inflated for the load that is on them. The springs are designed to carry the load and the shocks are meant to control tire contact with the ground.

I would simplify the diagnosing process by removing the shocks and going for a drive. If that clears up the issue, you should look for a shock that is closer to original equipment design. My guess is that the shocks are valved for a heavier vehicle, like a truck, that carries heavier loads. That would be the most likely reason that the trailer smoothed out the ride.

Another issue would be the type, size, and settings of your tires. If they are larger or heavier that can change things a little. For example, on my 2016 JKU I went from street tires to a 35" tire with a higher load range. The higher load range meant a stiffer sidewall and harsher ride when set to the factory pressure setting of 36 PSI. I reduced them to 28 and it helped a great deal since the stiffer tires were designed for a larger truck and my Jeep doesn't weigh as much. Air pressure in tires is meant to carry the load so higher loads require higher pressures. Your specific pressure requirements may not be that drastic of a difference but it is worth considering.

I would also look at the springs. If they are sagging to the point that the spring pack is resting on, or close to, the overload spring you should look into replacing them. Some spring shops can re-arch them and set them up for a specific ride height and spring rate (softer or harder ride) for you. Shocks shouldn't be used to compensate for worn springs.

[fulsizjeep]

It's from driving on the wrong side of the road. OK, not that funny.

What is the tire pressure for all four tires right now? When I was running a stock 88 GW with 235-75x15 tires, I found that 28 pounds of pressure made the best ride. 32 pounds was always too harsh unless I was loaded for a road trip. Then I discovered the track bars. I had owned a few FSJs by then and none of them had track bars. I took them off unless I was towing. Kind of a hassle but it made the ride a bit smoother when the Jeep was not loaded.

[wiley-moeracing]

Use non gas charged shocks for the smoothest ride, make sure you mounting bolts for the springs/shackles are not to tight and adjust tire pressure, that's all you can do for these rigs.

[letank]

I suspect that you did not buy this gem brand new, how many leaves on the springs, for the front and the rear.


My 74 was OEM with a 2 spring leaf up front, called heavy duty in the TSM ...and it was really hard even with the recommended pressure of 32... yes 29 was better but the mileage loss was noticeable.
when an encounter forced me to buy new springs, a new world of comfort opened up... more springs -at least 4-



As said above may be the spring/shackles are too tight is your first step...

[rocklaurence]

You should have the soft 7 Leaf springs up front. My guess is that your bottoming out on the bumps due to sagging springs. With good springs you should have 3-4" of space between the axle tube and the bump. If your at 2<" it'll transfer all that energy into the frame.

[Brynjminjones]

Thank you all for the responses.

I'm currently running 33 psi on original size (and style) 235/75R15 tires, which is what I thought the owners manual suggested. I often do long, high(er) speed runs in it so I've never had the pressure lower than that.

I will go out later today to count the number of leaves, although I'd be very surprised if they weren't original.

I'd also like to add that I don't think I'm hitting the bump stops. The ride feels so firm that I honestly don't think the wheels travel far enough to do that, and it's mostly small imperfections that are uncomfortable.

The sag in the rear is only really noticeable when loaded up or towing, but when towing it actually rides better in the rear!

By the sounds of it, I'm leaning towards the shocks being the issue.


Can somebody confirm one thing for me though:- As the springs age, would I be right to think that they usually get softer?

[J76137]

As the springs wear they would begin to lose their ability to flex and ultimately get softer and sag. That is more to do with how many cycles they have been through when moving as the suspension travels. Age in terms of years would have little effect.

Even though the tires are the same size as OE the compound of the tires and the construction of them would not necessarily be the same. Tires have made some great strides in the last few decades. It is possible that they are the same size but much harder for better tread wear.

[Brynjminjones]

Thank you, I see what you mean. I should have clarified that I meant age in terms of use, rather than years!

The tires I have are Cooper Trendsetter SEs, the same as Wagonmaster put on their Grand Wagoneers.
The load rating (105) is the same as the tires on my XJ, which rides much better with the same tire pressure on the same size tires, even though it's a lighter vehicle.

I've just had a look at the springs and can confirm that they are 7 leaf, so appear to be original.

[bufurd]

Get rid of them shocks, cheap stock replacements will help a lot. Leaf springs when doing their job slid against each other, removing friction there can make a big difference in ride compliance. Cheap and easy is pound a screwdriver between leaves and spray fluid film between them, don't use a petroleum product as it will weaken them. Long term best solution is pull spring packs apart and get full length Teflon (or whatever, they make kits to do this) spring liners and put between every leaf, the difference will surprise you. Oh, and most people do run too much air pressure. My Michelins on my J-20 have over 100,000 miles on em, rotated at 80,000 miles. Air pressure is key, you want about a quarter inch of the tread on outside not touching. Easy to see, use chalk or even driving off gravel driveway onto concrete like a shop floor, it'll show you. FWIW on said J-20 (Humpty) 48 lbs in front (4BT and big winch) and 35 lbs in rear is the sweet spot.

[Brynjminjones]

Thank you, I really did think these shocks might be a large part of the problem!

I'm sure my leaf springs aren't in the best of shape either, but I'm not in a position to replace those just yet.


I've been looking into shocks and I know it's a big topic of debate. I just want a nice soft ride and don't really care about body lean or handling.

I've found that I can get KYB Excel-G shocks for a really good price, and I remember a family member's WJ Grand Cherokee rode really nicely on KYBs.

Are KYBs decent soft/stock replacement shocks?

[rang-a-stang]

It's from driving on the wrong side of the road. OK, not that funny.

HAhAHAHAHA!!! Yes it was!!!

I have those same yellow Gas-magnums on mine and they ride like a Cadillac (soft). I have the 2 pack J20 springs in the front, too. Hm.

I would start with a free check:
Loosen (but don't remove) all 12 nuts/bolts on your springs and shackles. Take it for a short ride around the block, then come home and re-torque them to 100 foot pounds. Then go for another drive and see if that made a difference. (basically what wiley-moe and letank said). If those bolts were torqued while the suspension was hanging, that will make them a bit stiffer.

I also agree with bufurd about lub'ing your springs. If they are stuck together, they are not as much springs as they are beams. Again, this is an easy thing to do and will make a difference. Maybe you could use some spray graphite or lithtium. This is also almost free and should make a big difference. I would use a chisel rather than a screw driver, though.

[Brynjminjones]

It's from driving on the wrong side of the road. OK, not that funny.

Hahaha, sorry, I totally missed that first time round! That is pretty funny, also pretty accurate too - our roads over here are awful, and too narrow too so I always have to drive in the ditch!


Rang-a-stang, how strange that yours ride softly with the same shocks! I've just been for a long drive in the Wagoneer today and my girlfriend and I were both commenting how it makes smooth roads feel really rough.
I notice on RockAuto that they're listed as "heavy duty" so I would kind of expect them to be stiff too! (34958 is the part number)

I like the idea of re-torquing the bolts and lubricating. Maybe I'll try that this weekend when my girlfriend lets me have some garage time!

[jeepguzzi]

Check the shackles and bushings. Both for the condition of the bushings and the tightness of the shackles. They are meant to be able to move. If the bushings are shot, that may affect both.

When mine was stock, I had the yellow Monroe gas magnums on it. Ride was very nice.

[Mikel]

If you feel energetic, you might want to pull the shocks and see how she does, so you can tell if your problems come from that side of the equation.