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General Forums => The Mess Hall => Topic started by: neale_rs on August 02, 2010, 11:15:14 AM

Title: Extra load capacity
Post by: neale_rs on August 02, 2010, 11:15:14 AM

After the last trip, my rear springs seem to have sagged or settled about 0.5" due to the heavy load and hard use (the boomerang shackles actually hit the rear crossmenber on the inside of the frame rails). The Jeep (YJ) is still level (it used to be a bit higher in back than in front) and for most use this will be fine, more relative droop actually for rock crawling!

However, I'm looking for ideas for adding temporary load carrying capacity for heavily loaded trips.  Something that could be added just for the trip and then removed.

Could some sort of inexpensive overload shocks (those with springs around them) be used or maybe some sort of air shock?

What would be the chances of damaging the shock mounts (especially the top mounts at the frame)?

Thanks
Title: Re: Extra load capacity
Post by: Bounty Hunter on August 02, 2010, 11:35:53 AM
Airbags.  Can run with 0psi and have a smooth ride and articulation, pump them up for the occasional increase in payload capacity.
Title: Re: Extra load capacity
Post by: FourbangerYJ on August 02, 2010, 11:37:53 AM
Helper springs.
http://www.suspensionconnection.com/cgi-bin/suscon/scan/fi=products/st=db/co=1/sf=category/se=Helper%20Springs/op=eq/nu=0/sf=veh_make/se=Jeep/op=eq/nu=0/sf=model/se=CJ5%20%3A%3A%20CJ7/op=eq/nu=0/ml=25/tf=category/to=x/tf=veh_make/to=x/tf=model/to=x/tf=description/to=r.html

They list them for a CJ7 but it should work. Both springs are 2.5 inches wide.
Title: Re: Extra load capacity
Post by: sharpxmen on August 02, 2010, 12:46:14 PM
Airbags.  Can run with 0psi and have a smooth ride and articulation, pump them up for the occasional increase in payload capacity.

i was looking for a good writeup on that - do you know of one?
Title: Re: Extra load capacity
Post by: neale_rs on August 02, 2010, 12:57:23 PM
i was looking for a good writeup on that - do you know of one?

These instructions provide enough detail:  http://airlift.iwebcat.com/imgVD/AIL/MN-332_59503_59529.pdf
Title: Re: Extra load capacity
Post by: neale_rs on August 02, 2010, 12:59:06 PM
Thanks for the ideas.  The steel helper springs look like they could be the best alternative to avoid plumbing air hoses.
Title: Re: Extra load capacity
Post by: Jeffy on August 02, 2010, 01:01:36 PM
Thanks for the ideas.  The steel helper springs look like they could be the best alternative to avoid plumbing air hoses.
On the cheap you can use the main spring on a YJ leaf pack.  Just cut the ends off.  I have a set for my SOA but I've never used them.
Title: Re: Extra load capacity
Post by: neale_rs on August 02, 2010, 01:26:20 PM
I'm looking for something that can be taken on and off easily as needed.  But maybe something could be improvised using old leaves.
Title: Re: Extra load capacity
Post by: sharpxmen on August 02, 2010, 01:50:46 PM
These instructions provide enough detail:  http://airlift.iwebcat.com/imgVD/AIL/MN-332_59503_59529.pdf

i was looking more on the lines of a YJ writeup
Title: Re: Extra load capacity
Post by: Jeffy on August 02, 2010, 02:38:35 PM
It might just be easier to swap out the rear shocks for air shocks or maybe a shock/coil-over like the old 4way Shocks by Trailmaster.  http://www.trailmastersuspension.com/4way/4wayshocks.htm
Title: Re: Extra load capacity
Post by: neale_rs on August 02, 2010, 03:17:02 PM
Do you think the shock mounting studs would hold up with a shock like that?  That would be my main concern with those.
Title: Re: Extra load capacity
Post by: Jeffy on August 02, 2010, 03:43:51 PM
Well, the shocks aren't holding up all of the vehicles weight.  It's also not the first time it's been done.  They have done similar stuff back in the 50's and 60's.
Title: Re: Extra load capacity
Post by: Bounty Hunter on August 02, 2010, 08:28:53 PM
Thanks for the ideas.  The steel helper springs look like they could be the best alternative to avoid plumbing air hoses.
I've installed airbags on a few tow rigs, plumbing the air lines is the easiest part.
Title: Re: Extra load capacity
Post by: wolf on August 02, 2010, 11:11:11 PM
http://timbren.com/timbren-application-guides/application-pdfs/JRYJ1.pdf
Title: Re: Extra load capacity
Post by: neale_rs on August 03, 2010, 08:33:30 AM
I've installed airbags on a few tow rigs, plumbing the air lines is the easiest part.

I took another look at the intructions and it does seem pretty easy.  I was thinking it would require hooking it up to an on-board compressor.
Title: Re: Extra load capacity
Post by: neale_rs on August 03, 2010, 08:34:46 AM
http://timbren.com/timbren-application-guides/application-pdfs/JRYJ1.pdf

That one does look pretty simple to install.  The main complication would be to extend the mount to account for the lift.
Title: Re: Extra load capacity
Post by: neale_rs on August 03, 2010, 08:42:24 AM
Thanks for all the ideas.  The steel helper springs seem to be the cheapest alternative and are easy to put on and take off.  The downside is that the bolts hang down a bit and would get hit on rocks.  The airbag and timbren kits would be more out of the way but cost more and would be a more involved installation the first time they were to be used.  The overload shocks would also be a simple altenative but do place some load on the shock mounts.
Title: Re: Extra load capacity
Post by: neale_rs on August 06, 2010, 12:19:35 PM
After some pondering it seems the spring clamps/clips would interfere with the steel helper springs so that idea is now out (although maybe the cross bolts could be taken out so it could fit between the sides of the clip).  The shocks with springs around them, it turns out, capture the coils at both ends so the spring will tend to keep the suspension at a fixed point, it will pull up on the axle when the suspension droops and push down on the axle when the suspension compresses.  This seems like it would hinder droop too much.

So I've pretty much decided to get some air shocks that can be pumped up as needed or left unpressurized when no extra load capacity is needed.   After cross-referencing some part numbers and specs it looks like the Monroe Max-Air (part number MA728) shocks could work.  They would not limit suspension compression and would allow 9.125" of travel vs. the 10" with my present shocks, good enough given that my rear suspension doesn't seem to reach the end of the travel of the current shocks.  These are made for some Cadillacs and Isuzu Pickups.

It seems they come with mounting studs in the bushings which I would need to take out.  Also, the Monroe spec sheet shows that the bushings are  1 5/16" long with a 5/8" hole, the same as the upper bushing for a stock YJ.  So it seems it should work fine.