Uneven Air bag pressure - The 1947 - Present Chevrolet & GMC Truck Message Board Network

upon1 · 06-02-2018, 11:44 PM

I’m running a triangulated 4link on the back of my ‘55 with an accuair setup. For some reason I have way more pressure in one air bag than the other to keep truck level. Any ideas? Each side is set up exactly the same and am running the Firestone sleeve type bags.

BR3W CITY · 06-03-2018, 10:28 AM

Is there significantly more weight on that side? (relocated battery etc). A few more psi to compensate for weight isn't strange. How much pressure differential are you seeing?

**PGSigns** · 06-03-2018, 05:43 PM

Preload in the 4 link. Are the links adjustable?
Jimmy

upon1 · 06-03-2018, 05:50 PM

Weight is even, battery is actually on the side with less pressure.
What do you mean by preload in the four link?

tinydb84 · 06-03-2018, 11:32 PM

You can adjust the load on the suspension by lengthening or shortening links.

**PGSigns** · 06-05-2018, 07:47 AM

Here is a great video on preload. The entire series is good. Yes it is drag racing but it all applies in understanding how all this works.
Jimmy
https://www.youtube.com/watch?v=yMY-8_lBTZ4

SCOTI · 06-05-2018, 07:32 PM

It doesn't seem quite so simple in reality. What about if the front requires a different amount of air psi for each side??

I get adjusting preload, but it seems there would be WAY more to it on a street based 4-bar set-up vs. that race oriented 4-link. Typical street air suspension 4-bar set-ups w/poly type bushings @ each end aren't as adjustable (most only allow adjustment @ one end) & they're definitely not going to easily rotate to know if there's pre-load before making any adjustment.

When I did the 4-bar for my dually, I made jigs for the upper bars length (& lowers) to know each side/all 4 were equal/exact. I then installed everything & measured for square. I tweaked as necessary for getting things perfectly square. When they did the alignment, one thing I was worried about was the rear thrust angle & the 2 techs that did the alignment were impressed w/how tight/close the thrust angle was where I was afraid I might be off.

The alignment went w/o issue. But, my truck requires 10psi split up front & 20psi split out back. Also.... it's on opposing sides (pass front requires more psi; drivers rear requires more psi to be dead equal @ all 4 corners as measured @ the wheel opening lip (measurements validated pre suspension swap as well).

Thoughts?

tinydb84 · 06-06-2018, 12:47 AM

PG thanks for that link. I didnt know about all of his videos. Ive been watching non stop for an hour.

06-02-2018, 11:44 PM	#1
upon1 Registered User Join Date: Oct 2007 Location: Saskatoon Posts: 138	Uneven Air bag pressure I’m running a triangulated 4link on the back of my ‘55 with an accuair setup. For some reason I have way more pressure in one air bag than the other to keep truck level. Any ideas? Each side is set up exactly the same and am running the Firestone sleeve type bags. __________________ "Lifes to short to drive an ugly truck." Project 55 To Life http://67-72chevytrucks.com/vboard/s...d.php?t=432994

06-03-2018, 10:28 AM	#2
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Uneven Air bag pressure Is there significantly more weight on that side? (relocated battery etc). A few more psi to compensate for weight isn't strange. How much pressure differential are you seeing? __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

06-03-2018, 05:43 PM	#3
PGSigns Senior Member Join Date: Jan 2011 Location: Hayes Va Posts: 4,569	Re: Uneven Air bag pressure Preload in the 4 link. Are the links adjustable? Jimmy __________________ 60 to 66 Chevy and GMC window decals http://67-72chevytrucks.com/vboard/s...d.php?t=661131 Good friends, good food and a hotrod what else do you need? 1966 BBW long fleet Daily driver 1965 BBW short fleet Sold and going to a good home 1965 Suburban 2003 3500 Duramax 2005 Ultra Classic

06-03-2018, 05:50 PM	#4
upon1 Registered User Join Date: Oct 2007 Location: Saskatoon Posts: 138	Re: Uneven Air bag pressure Weight is even, battery is actually on the side with less pressure. What do you mean by preload in the four link? __________________ "Lifes to short to drive an ugly truck." Project 55 To Life http://67-72chevytrucks.com/vboard/s...d.php?t=432994

06-03-2018, 11:32 PM	#5
tinydb84 Registered User Join Date: Jul 2009 Location: San Jose Ca Posts: 2,871	Re: Uneven Air bag pressure You can adjust the load on the suspension by lengthening or shortening links. __________________ David Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991 My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985 Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557 Instagram: myfabguy

06-05-2018, 07:47 AM	#6
PGSigns Senior Member Join Date: Jan 2011 Location: Hayes Va Posts: 4,569	Re: Uneven Air bag pressure Here is a great video on preload. The entire series is good. Yes it is drag racing but it all applies in understanding how all this works. Jimmy https://www.youtube.com/watch?v=yMY-8_lBTZ4 __________________ 60 to 66 Chevy and GMC window decals http://67-72chevytrucks.com/vboard/s...d.php?t=661131 Good friends, good food and a hotrod what else do you need? 1966 BBW long fleet Daily driver 1965 BBW short fleet Sold and going to a good home 1965 Suburban 2003 3500 Duramax 2005 Ultra Classic

06-05-2018, 07:32 PM	#7
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 22,066	Re: Uneven Air bag pressure It doesn't seem quite so simple in reality. What about if the front requires a different amount of air psi for each side?? I get adjusting preload, but it seems there would be WAY more to it on a street based 4-bar set-up vs. that race oriented 4-link. Typical street air suspension 4-bar set-ups w/poly type bushings @ each end aren't as adjustable (most only allow adjustment @ one end) & they're definitely not going to easily rotate to know if there's pre-load before making any adjustment. When I did the 4-bar for my dually, I made jigs for the upper bars length (& lowers) to know each side/all 4 were equal/exact. I then installed everything & measured for square. I tweaked as necessary for getting things perfectly square. When they did the alignment, one thing I was worried about was the rear thrust angle & the 2 techs that did the alignment were impressed w/how tight/close the thrust angle was where I was afraid I might be off. The alignment went w/o issue. But, my truck requires 10psi split up front & 20psi split out back. Also.... it's on opposing sides (pass front requires more psi; drivers rear requires more psi to be dead equal @ all 4 corners as measured @ the wheel opening lip (measurements validated pre suspension swap as well). Thoughts? __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

06-06-2018, 12:47 AM	#8
tinydb84 Registered User Join Date: Jul 2009 Location: San Jose Ca Posts: 2,871	Re: Uneven Air bag pressure PG thanks for that link. I didnt know about all of his videos. Ive been watching non stop for an hour. __________________ David Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991 My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985 Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557 Instagram: myfabguy

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