Improving Chevy Silverado 3500HD camper

[DiploStrat]

Details, details!

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Very nice truck you have there. Thank you very much for sharing your experiences. Field experiences on nearly the same vehicle...that ist very helpfull. Can you tell me the dimensions of your truck?

7m long x 2.13m wide x 3m high - give or take a tiny bit. the length is bumper to bumper; shipping dimension. The width does not count the mirrors. The height is to the highest solar panel, not flex antenna.

-What improvements do you get from the A arm and pittman arm support?

The A arm replacement plus adjustment of the torsion bar keys gets more free wheel travel, especially in compression. Reduces bottoming. I know this works. If you look under the Isuzu/Chevrolet independent front suspension you will see that the A arms often rest directly on the compression bumpers. With the lift I have 2.5 cm of free travel. The steering stuff is claimed to reduce tire wear - can't prove it. See video: https://www.youtube.com/watch?v=JoCTj3BO5wM

-Adjustable Fox shocks: Would you go for the 2.0" or the 2.5" ones? Any idea what benefits the 2.5" compared to the 2" shocks would provide (for normal driving like we do, not racing)?

I have had Bilstein shocks fail in six months; Ranchos in two years - I always go for the biggest and baddest I can fit. With as much as the Tiger weighs, I want as much shock as I can find.

-900 kg rating for your tires...I think that is a bit low...should that maybe be 1900kg?

OOOPS! My feet got tied up in meters. You are correct.

-Any changes regarding oversteering or understeering after you added the rear sway bar? Did you change anything to the front sway bar? Can you tell me something about how much the max possible flexing has been reduced after you added the rear sway bar?

No change to the steering that I can notice. Never bothered to change the front anti-sway bar. By definition, an anti-sway bar should reduce total articulation. As a practical matter, for rough road travel, as opposed to rock crawling, the ride is much, much better due to reduced low speed sway. Again, I am designing for sustained travel on third world roads with minimum damage to the vehicle due to suspension bottoming or washboard vibration. The Tiger is much to big and heavy to be a rock crawler.

Hope this is helpful.

 

[chilliwak]

Pinkpanther many of the suggestions mentioned will help your truck. It is a combination of all of the improvements together that makes the final result. A rear sway bar will not hurt your flex, especially with all the weight you are carrying. Fox shocks are great and will not let you down. External resivours are good to have. It looks like you have room for some bigger tires if you want. Also, with all your weight I cant see any tire being too stiff unless you drive around a lot with an empty truck! Cheers, Chilli...

 

[DiploStrat]

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1. Especially while driving over speed bumps I get some rumbling noise from the rear end. Not sure, but I think that are the two upper leaves (helper spring?) hitting the stop. Probably normal operation. At normal ride high there is a small gap betwen the leaves and the stops:
View attachment 371941The picture shows the suspension at riding level, the weight of the vehicle is on the axle.

The rumbling noise is probably the sound of the overload springs slapping the stops. The general rule of thumb is that you want the overloads firmly on the stops at all time or you want the overload springs far enough from the stops that they only touch under the most extreme conditions. I take the second approach, using air bags to soften the impact. The air bags open up this gap, but do not fully level the vehicle.

2. Because of the additional weight, the rear hangs a little down. This is more an optical problem, but if it can be improved...

There are several things you can do. You can increase the spring rate by additional leaves or air bags, or, if the spring rate is about right, you can simply block the axle. As I mentioned, I used a combination. Using the air bags alone increased the spring rate too much, but in combination with blocks the vehicle is level and the ride is excellent.

3. Most important point. Think about the followoing situation: One wheel is driven over quite a big rock, then at one point the wheel slips down to the ground. This hit causes a side to side roll...so far normal...but unfortunately it takes up to 4 or 5 right-to-left cycles until it stops and in my opinion there is far to much roll.

An anti-sway bar will address this issue directly. Stiffer shocks won't hurt, but as these are low speed movements, shocks won't address the issue directly.

 

[Pinkpanther]

It looks like you have room for some bigger tires if you want.

Room would be there but our laws...if I have too much money and time I may start the project bigger tires But the room is quite nice to have...mounting snowchains or screwing in spikes last winter was quite easy.

Pinkpanther many of the suggestions mentioned will help your truck. It is a combination of all of the improvements together that makes the final result.

I think that is a good summary of this tread. I think I'll go on step by step, starting with new shocks see how the ride is improved (or degraded), then go on to the next step (Leaf spring, sway bar...)

Thanks all for your help.
Urs

 

[Pinkpanther]

Update...

Hi guys,

I wanted to give you an update on how things are going on...

While working on the truck I remarked that the front suspension was nearly resting on the bumper stops. I then set the front suspension slightly higher (by turning up the screws at the torsion bars). Now it is a little softer whithout any negative behaviour, on the contrary, now it is very nice and confortable to drive on paved roads.

Then I had the rear leaf springs changed. The 2 helper leaves where thrown out and 2 additional leaves where added to the main leaf package. One of the leaves was built as what whe call military wrap. The whole pack was then set up so the truck is level again (fully loaded) with the same spring rate as it ws before. The rumble noise at the rear end has gone. I'm very happy with that.

Last February (at minus 6 degres celsius) I then changed the shocks. I ordered 4 King shocks, non-adjustable, 2.5", with external reservoir, custom valved for my needs.




As per King specs they can be filled betwen 10 and 17 bar. I filled them to 17 bar and went out for a quick drive (around 10'000 km) to the north of Norway and Sweden :smiley_drive: :elkgrin:


Conclusion: I am very happy how it drives now. As far I could test, the side by side roll has gone, even whithout adding a rear sway bar. The suspension is now overall a little firmer whithout beeing to hard for most driving situations. Only on washboard roads the front suspension is a little harsh but this ist complaining at extremely high level. Anyway, I think I'll try to lower the front shocks pressure to 10 or 12 bar and see how it works out, but I think it has more to do with the torsion bars. I have the snow plow prep package with more payload on the front axle, so I think the torsion bars have also to be stiffer for that. The next thing is that I drive at 60psi on the front tires and 80 psi on the rear ones. The thread wear during the last 30'000km is quite even so these pressures seem to be quite ok for the normal onroad driving. Maybe, for the future I'll go 5 psi or so lower in the front for normal driving.

What pressures would you recommend me for dirt- or gravelroads, sand, soft sand and what is the absolute minimal pressure I should run in exeptional situations? On a Landcruiser I have the following good experiences. Onroad 45psi, gravel 35-40psi, sand 25-30psi, soft sand 15psi, in exeptional cases (for a few 100 metres) down to 8psi. The Chevy weights quite a bit more than a Landcruiser...around 4800kg, estimated 35/65% front/rear. Do you thing it could be a good starting point if I just double the abowe numbers for the Chevy?

Thanks

 

[chilliwak]

Looks like some really good upgrades Pinkpanther. King shocks are great so I am sure you will enjoy them for many years. As for the tire pressure you are just going to have to experiment a bit. Do avoid going too low a pressure for any long time as the tire will overheat and fail. I think double the pressure you mentioned wil be fine. Cheers, Chilli..

 

[Pinkpanther]

next improvements

Thanks Chilli.

Now I think about some more improvements. Background ist that I drive quite often on steep, curvy roads (Italy, France, Switzerland...). Sometimes I would wish to have a smaller first gear for this. Uphill it would probably keep the automatic fluid a little cooler but especially downhill it would help to keep the brakes cool (remember my truck is nearly fully loaded at 4600-4800 kg).
Of course I could switch to low range, but while switching to Low-Range I also switch to 4WD. So far not a problem. But, as probably most of you know, the switchable 4WD also acts like a closed middle differential. That said, it is fully out of consideration to switch to low 4 on paved roads. And even on gravel (dry) roads I can feel distortions and unhealthy forces in the drivetrain while driving on steep, tight 180-degres serpentines.

So I think the solution would be those hubs who disengage the front axle. Or are there any other solutions for that issue (payable and without changing the whole drivetrain)? Of course with such a solution, the driver needs to know what he is doing with a disengaged front axle and in 4-Low...

Now I was serching for these, but couldn't find anything specific for my truck. Maybe I just searched for the wrong words. In Australia I know they are called free wheel hubs. How are they called in the US? Or does anybody know companies offering such hubs, specific for my 2011 Silverado 3500HD. Some specs: 3.73 axles, GVWR 11700 lbs, increased front GAWR of 6000 lbs (snowplow package), SRW, bolt/stud pattern 8x180, drivetrain and suspension is OEM except for the King-shocks...

Btw. what axles did GM put into the 2011 3500HD Silverado? The rear differential has 14 bolts, is this the AAM 11.5"? I think the front diff (independent suspension) has 12 bolt.

Thanks a lot