Replacing Coil springs without air bags?

[Turbodime]

Looking to put new coil springs on the front of my HR. I don't want to run air bags and just go with a higher spring rate.  Has any one used the 6560sdm springs? 


When I look up the P30 chassis for replacement springs the 6560 and 6560sd come up but never the 6560sdm. I did find reference that the 6560sdm's are to be used on RV's longer then 28'



What I found on the net is the following.


Part#          Max load per spring         Rate per/in
6560             3289lbs                     1464lbs
6560sd         3789lbs                      1501lbs
6560sdm      4289lbs                        ?

[eXodus]

as far my knowledge goes the p30 was designed to be with airbags. So if you got no airbags you should get some. a former owner removed them probably.

[jeno]

when i wanted to replace mine the people that sold the higher rated springs told me i would have to wight my front end first thay said if i went with to heavy of a spring it could throw off my front end. hope this helps. air bages do help a lot.

[Rickf1985]

Springs are tailored to the actual weight of the vehicle. I am thinking you would not be happy with those springs since they would most likely ride like a buckboard. If they are too heavy for the weight on them then when you hit a dip and the front rebounds the control arms will slam down hard on the bump stops. It will not take long at all before damage is done. I would weigh the vehicle and see what is actually there first. Air bags are progressive, coil springs are not. At least not these.

[M & J]

http://www.classicwinnebagos.com/forum/index.php/topic,7759.msg36431.html#msg36431

Our good friend Stripe did the Full Monte on his springs and air bags. Sources/costs/part numbers are in the thread.

[Turbodime]

Called around this morning and found a place that recommended the 4560SDM spring since I don't want to run air bags.

Also talked with a long time RV suspension guy and he said air bags in P-30's were a fix when they started putting larger coaches on the chassis.   He also recommended going with stiffer springs and deleting the air bags. And suggested I weigh the rig first before throwing chance to the wind.

$190 out the door.  I have a 25 day vacation planned in June and will get back to this post on how the new springs worked out.

Thanks for the link to write-up, ive read thru it a couple times last year when I realized my front springs are sagging.

[eXodus]

get your rig weighed, and from side to side.

Why don't you want to run Airbags ? They are inside you have to refill the air every couple of months, not that big of a deal.  Coil springs only are always a compromise, you can not adjust for different weights and ride heights from side to side.

I'm quoting:
"The air bags are an integral part of the suspension system, they are necessary for proper ride height and front end alignment."

[Oz]

I tend to agree with the majority so far.  Indeed, they may have been added to beef up the suspension in consideration of longer, heavier coaches being placed on the chassis.  Anything which can provide beneficial enhancement is a good thing, for whatever reason it was added, so my advice would also be to keep them.

[bluebird]

At least with the air bags you can tailor the ride to your liking. They can be a bear to replace, but so can the springs.

[eXodus]

yeah the Suspension guy is probably wright just a short story:


There had been a car which had the tendency to flip over in sharp double turns (Mercedes A-Class) so they invented the electronic stability program (ESP)
It cured the problem with flip over of the car. Now it is in basically every car.  Is it now wrong to have a car with ESP just because the cause for it's invention is such an abstruse story ?

Why they added is just not an answer.
Keep us posted how the harder springs work out !

[GONMAD]

Gentlemen, I have been using a product from MOOG suspensions for about 35 years now with very good results. It's called a "variable rate spring". Here is the link.

http://www.moogproblemsolver.com/suspension/coil-springs/variable-rate-springs#.VTY6SaYqOq4 

I've used them on several of my work trucks for years with very good results thus far. They not only help stabilize a heavy load but they ride the same loaded as they do unloaded. They negate having to use extra devices for ride enhancement such as air bags etc. I increase my height with a 1" spacer ring underneath the bottom coil on my 'lifted' vehicles, but for an RV just the spring is enough. Here's the good part... The static spring height is such that you don't need any special tools to install them as they stand shorter than stock springs & go right in very easily. Your ride & ride height stays the same loaded or unloaded. I highly recommend using these as they DON"T need air bags to augment ride or ride height. They don't cost that mush considering the cost of replacing the bags every couple of years as I have had to do (3rd set of front bags). These chassis were designed to be a school bus van chassis & not an RV. They either cheaped out on the front suspension or the technology wasn't available at the time but my personal experience tells me to go to something that needs NO maintenance & these do the job. I recommend calling a MOOG rep for the proper part number as these things often change. I hope this helps someone out as it works for Me. C YA! GONMAD

[Rickf1985]

I used variable rate coils in off road racing 40 years ago and in many lifted trucks since then but I have never seen one as short as the ones in the P30. You need a fair amount of suspension travel for that to work and there is next to nothing on these vehicles. You wouldn't happen to have a picture of one installed would you?

[Rickf1985]

GONMAD, I just went to the link you gave and they only offer two springs for the P30, A regular and a superduty.

http://www.fme-cat.com/Application.aspx?year=1988&make=CHEVROLET&model=P30&cat=Suspension&subcat=Coil%20Spring%20Sets,%20Seats,%20and%20Insulators&brand=MOOG%20Steering%20%26%20Suspension&engbase=7.4L%208Cyl%20V%20%28-%29%28454%29&ga=Y&back=true

[Rickf1985]

Called around this morning and found a place that recommended the 4560SDM ...

I can't find a reference to that number on Federal Mogul or Moog or even on Google. Can you give us a little more info? My bags are shot and although I am leaning towards a new set of bags I do have an open mind. (my wife says it is empty?)

[Turbodime]

Going to Spectrac to pick up springs this week. http://www.spectrac.com/ $190

Here is another place that has them for a good deal on-line. http://www.stengelbros.net/350-6560SDM-P303500-MotorhomeFront-Coil-Springs-4289-lb-Spring-Rating_p_100.html

Shipping to AZ is $55 so I figured I keep the locals in business and buy from Spectrac:)

I called another local spring outfit and they bring all three springs in and he said he always suggests getting rid of the bags and going with a correct spring and ride height then an alignment.

I'll post more when I get the springs and take pics and mic the springs for wire size, coils, and length.

[shortbus]

I too would like some more info on these progressive replacement springs. I figured I would have to get airbags but if there is another solution I might would go for it. It was mentioned that the airbags were to help with the bigger bodies used on the p30. I only have a 23ft rig, would that make it less crucial to get airbags or move to an alternate spring?

[Rickf1985]

Man! That is a really heavy spring! 4300lbs. load each, 8,600 lbs lb. rating on the front alone. I am thinking it is going to be a really stiff ride, I hope I am wrong. If you are in fact loaded that heavy then you are over the spindle limits I believe.
I just looked at my sticker and mine is a GVWR of 15,000 lbs.. Front GAWR is 5,000 lbs, and rear GAWR is 10,000lbs.. This is on a 1988 WCN31RT.

[Froggy1936]

Also to strong a spring can knock the bottom out of an a frame then you will be in big trouble. Air bags do things springs cannot do  They can be used to adj for uneven temporary loads . and they will definatly help on corner lean, and buffeting from passing big rigs . They will correct ride height from a weakened spring . And alignment is not pushed out of specs by weaker or stronger springs The settings that are in the books are mid range settings There is allowable movement either way . Toe in is the big tire wear problem with camber being second and tire air pressure being third Tire balance will cause flat spots if excessive ,  Castor has no bearing on tire wear Only on stiffness of steering . And most tires on the average RV will need replaced due to age long before they are worn out ! Frank

[M & J]

I'm staying with bags. Matches whats under my eyes.

[Turbodime]

Springs are in and the rig is level:)  I took it out for a short ride it rode great.  Once I get back from my trip at the end of June I'll post a report on the springs.
When I picked up the springs I talked with a guy that worked there with 54yrs of working on motorhome suspensions and he said going with the heavier springs is the way to go when you don't want to run bags.

[Rickf1985]

So what was the final brand name and part number? You had listed several and I got confused on which you were getting.

[Turbodime]

I have Safe Steer on my rig and I didn't want to take all that off so I broke the top ball-joint loose.  Worked out well. Right side went on without a hitch but the left spring didn't want to go in and took an extra hour. 


I removed the shock, swaybar braket and outer tie-rods.


New springs had around .006-.008 paint so 0.925"+/- 0.005 would be a good number for the wire diameter.

[Turbodime]

Coming out.

[Turbodime]

Before and after ride height.

[Turbodime]

NEw and old springs. 
Old spring part number: 14854345
Box that the new springs were in.