Adding spring leafs to rear axle

marco10 · Post by **marco10** » Wed Jun 27, 2007 10:38 am

This may be a dumb question .... would adding a spring leaf on each side of the rear axle/suspension increase the load carrying capacity? For example the rear GAWR of my astro is 3100lbs. Would adding the spings increase this?

BLAZER · Post by **BLAZER** » Wed Jun 27, 2007 11:26 am

If you go by other vehicles, then yes i.e, my dad's 1/2 ton pickup has 4 leaves and a helper. A 1 ton of the similar year has 6-7 leaves plus the helper. You also have to factor in the thickness too though when looking at it that way.
I have a '95 that I added a leaf in from an '87 K5 blazer. It helped me reduce the sagginess I had in my factory leaves, plus the rear drops much less than before when a load is added. IMO though, your main top spring is what determines the max amount you can carry, it is the only spring with mounting points. Then on the other hand, they make add a leafs for extra carrying capacity that fit the same as the one I added and they work, but also give extra lift in process. I say if you can deal with 1-2" of lift in the rear, go for it. If not, then do like Dean and grab some air bags or some Timbrens.

marco10 · Post by **marco10** » Wed Jun 27, 2007 11:38 am

Thanks BLAZER. But do air bags or Timbrens increase the GAWR as well? I have a problem where I need to install a single bar weight distribution hitch to level out the weight of my trailer on the axles. The problem is I can't do that for reasons that are irrelavent on this topic. So what I would like to do is increase the capacity of the rear axle and at the same time lift the rear a bit. The van loaded with the trailer has a rear axle weight of 3060lbs. as you know the max is 3100lbs. I'm just 40lbs shy of the max which I am not comfortable with. Can you siggest any other form of doing this?

BLAZER · Post by **BLAZER** » Wed Jun 27, 2007 3:23 pm

I'm kind of lost with the 3100# rear axle weight number. I know our vans are rated from the factory to pull 5-5500# trailer weight with a 500# tongue weight. I have personally pulled a 16" trailer with a car on it, probably pushing 4500# with no WDH, but I did have the extra leaf. Still I didn't reach the max pull weight. I know others have pulled up to 6000# with no problems. You need to search for LiftedAWDastro's ( Dean) thread on his air bag install. He has an 03 and need the extra capacity for there camper and also flatbed trailer.
In my opinion, you can add the air bags or timbrens to keep the rear from saggin too much since you can't use your WDH, and just stick to the factory gross trailer weight which is usually 5000 for AWD and 5500 for RWD.
Here's Dean's thread ....
http://astrosafarivans.net/bb/viewtopic.php?t=595

The How TO
http://astrosafarivans.com/howto/main.p ... temId=1271

GEJ · Post by **GEJ** » Wed Jun 27, 2007 9:27 pm

Blazer-I posted a lot of things I want to do to Ole Yellar at one time.Here I'll deal with only the rear springs.Years ago I worked at a shop called Fry The Wheelman.It's main thing was building rear springs for large trucks and firetrucks.They did from time to time build special springs for other types.I guess my main question is what makes timbers special?.I'll check out Frey's to see what they are doing now and look at another spring shop I know of here in Roch NY too and let you know if they do any work on springs for Astro's/Safari's.Ole Yellar is a 1985 high top.

Gary

BTW:didn't mean to scare anyone off with my post before.Seems like a lot of work for one van,but I have waited along time to get to do what I wanted for a tow van for my Flea market business.This is the one.Now I am under the gun to get her done for a move down south I hope in Oct.

BLAZER · Post by **BLAZER** » Thu Jun 28, 2007 8:32 am

Gary, not sure about the Timbrens myself, just look like oversized bumpstops on Steriods.

Water Boy · Post by **Water Boy** » Thu Jun 28, 2007 7:30 pm

BLAZER wrote:...I have personally pulled a 16" trailer with a car on it, probably...

Yep, I could see that a 16 inch trailer would be no problem to tow.
#-o

2000AWD · Post by **2000AWD** » Thu Jun 28, 2007 10:32 pm

BLAZER · Post by **BLAZER** » Fri Jun 29, 2007 8:59 am

Water Boy wrote:
BLAZER wrote:...I have personally pulled a 16" trailer with a car on it, probably...
Yep, I could see that a 16 inch trailer would be no problem to tow.
#-o

Someone · Post by **Someone** » Fri Jun 29, 2007 1:05 pm

Again, I agree that you should not have a problem untill you are at 5000+ pounds. I used to install work packages in vans and trucks... I would say about 40% of the astros I saw over the last few years of prudction had timbrens added to help with heavy loads... about 5% got sent to a spring shop for an add a leaf.

I found for something you are going to drive with no waitregularly the timbren's are a great choice. It is basically a big rubber spring.. or an empty airbag... and they are tough. the purpose is to stop your axle from bottoming out.. as they compress they get stiffer causing a higher spring rate. A little expensive for rubber I agree but I have no complaints.

I have a set in my van (but they are cut in half because my van is lowered) because I carry a lot of semi-heavy loads in the back (500 - 1500Lbs)

since it is lowered it ran pretty hard with a full load, the bumpstops are not as soft as they sound.. the extra spring when the timbren contacts is definatlly nice.

tripplec · Post by **tripplec** » Thu Jul 12, 2007 7:52 am

Well I added a leaf to mine years ago. Why?
There was an ever so slight sag at the rear. When loaded modestly or carrying a number of passenger it would be a lot lower with the front up a bit. With the right arch in the addin spring it will be an inch to 2 higher than level and when load (whether trailer tongue or inside the van) it will ride much better. The posture will be normal and of couse you can carry more weight without bottoming out.

Capacity which I am sure is still based on OEM components and exceeding the GVW on the plate is not recommended. Axles, tranny, cooling could be strained to the point of failure. So make sure you address their needs and beef up cooling of the tranny if pushing to or over the limits. Top lubs should be used as well in the power train.

LiftedAWDAstro · Post by **LiftedAWDAstro** » Thu Jul 12, 2007 10:14 am

marco10 wrote:would adding a spring leaf on each side of the rear axle/suspension increase the load carrying capacity? For example the rear GAWR of my astro is 3100lbs. Would adding the spings increase this?

Adding an extra spring will increase the load carrying ability, but NOT the GAWR of the rear axle. The axle is spec'd by GM for 3100 pounds and if you continuously overload it, the axle will fail eventually. The weak point is the axle shafts and axle bearings.

Spike99 · Post by **Spike99** » Thu Nov 29, 2007 9:56 pm

Someone wrote: .... I would say about 40% of the astros I saw over the last few years of prudction had Timbrens added - to help with heavy loads... about 5% got sent to a spring shop for an add a leaf.
...

I have Timbrens in my 2001 AWD Safari. One of the best suspension upgrade products I bought / installed. Definately would buy them again - if I bought another Astro/Safari van.

For 2,000+ lbs of trailer pulling or rear cargo hauling in the Astro/Safari van, I'd install the Timbren SES units. Simple 10 minute install that 99% of people can do themselves. Install it and leave it. And being rubber based, there's NO air leaks to worry about. And, there's no upward rebound - like the +1 leaf or re-arch the van's existing 3 leaf system. Simply install and drive. And they only take effect when the rear of the van goes down 1/2" - 3/4" (or so).

To view the Timbren SES 2,000 units (with extra spacer due to 1.5" rear lift) on the rear of my 2001 Safari van, surf:

http://i178.photobucket.com/albums/w251 ... owords.jpg

.

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