Air Spring/bag replacement

[trimster]

On my 1998 international 4700 sport chassis both air bags are ready to die. I'd like to put lighter duty ones there in hopes of a softer ride. So, questions: which ones (model number)? and how about the Double Convoluted Air Spring designs? any advantage or disadvantage to those as a replacement for the stock bags? I typically see critical measurements listed like deflated and inflated height, bolt placements but rarely the weight rating. I think, not sure, that stock is like 12k lbs. Might be way off.

Thanks

Bob

[noteven]

http://firestoneip.com/commercial-truck-trailer-aftermarket

Hi Bob there is contact info for Firestone air suspension components info on this site.

[DieselHP]

Before you do anything try lowering the pressure in the bags.

[Ronbo]

Big truck bags don't work on pressure, they work on volume. If the pressure is lowered it lowers the frame closer to the differential, changing the angle of the universal joint. May turn out bad. I think a bag with larger diameter, more volume, would soften the ride. 

[trimster]

Noteven: I got in touch with them and they were helpful but could not help. I asked for a replacement bag rated for a lower load. They can only quote factory equivalents listed for the truck. I'm going to try the parts guy at the local International dealer.

Ronbo: Hmmm. Does not seem logical but some things about these trucks baffle me. Just talking out loud here, it would seem that if I find the point where the bag is inflated to proper height but not to rated 'full' pressure, it would ride softer and keep the frame off the tires (loPro chassis configuration).  Am I off target here?

Bob

[DieselHP]

Yes you can set the ride height at a lower pressure. You would have to install a regulator on the feed line to the valve. As far as the Navistar dealer giving you another part number I don't think that will ever happen. All "big trucks" are built to spec that is why when you need parts for it we need your vin number, Every truck can be different, all depends on what the customer wants. 

If your truck has a hard ride chances are the air pressure is to high in the bags and could be due to the rear suspension spec. If you want to give me the last 8 of your vin number I can look it up and let you know how it's built.

 

Rick

[trimster]

VH482547

[DieselHP]

Sorry this does not lay out here well but you should be able to see it. Any questions let me know If you look below down by 13 the truck has a 15,500 lb rear axle and look by 03 and you will see the air suspension is rated for 17,500 lbs.   Line Set Ticket
VIN Number	1HTSLAAK7VH482547	Model	4700 LO-PRO4X2	Build Date	1/31/1997
Eng Srl Number	001032185	Model Code	SH47540	Order Qty	2
Dealer Number	676601	Order Number/Suffix	277649B	Starting Job Number	482547
Sold To	ELLIS AND CAPP EQUIPME	Sales Region		Paint Code	9219
GVWR	18280	Ignition Key	K483	Wheel Base	188.0  in / 477.5 cm
AF Dimension	75.0  in / 190.5 cm	Gear Ratio	3.91	Recall Pending	No

Grp	Unit		Div	Variation	SE	Description	Cost Code

01	0001951		2007		SE	FRAME PRCNG S-SERIES	Yes
01	0001AHK		2001	CDGH		FRAME 9.125X3.062X.312 (80,000 PSI)
01	0001LLT		2000	BE		BUMPER-FULL WIDTH-CHROME PLTD ALUM-AERO
02	0002ADA		2001	C		INTERNATIONAL I-60S 6,000# FRONT AXLE
03	0003SAM		2016	ACZ		INTL 17500# AIR SUSPENSION
04	0004040		2090	ACLW	SE	BOSCH HYDRO-MAX II SPLIT BRAKE SYSTEM
04	0004144		2004			15X1.435 FRT DISC HYDRAULIC BRAKE
04	0004237		2002			15X1.435 REAR DISC HYDRAULIC BRAKES
04	0004GAB		2003	D		12X4 DCM PARKING BRAKE
04	0004RBE		2017	ACEM	SE	13.2 CFM AIR COMPRESSOR-BENDIX-550
05	0005710		2042	AFK	SE	STEERING COLUMN W/TILTING & TELESCOPING
05	0005PRG		2115	DFJVW		TAS-40 ROSS POWER STEERING
06	0006721		2193			ONE PROP CTR BRG BRKT
07	0007AAY		2098	FG		SGL EXH SYS(HORZ MFLR/TP)-SHORT TP(RSM)
08	0008000		0110	BCGHJLQSUZ		ELECTRICAL SYSTEM (12 VOLT)
08	0008518		2007			CIGAR LIGHTER
08	0008544		2010	B		DUAL AIR HORNS (GROVER) CHROME
08	0008585		2011	AB		TOGGLE SW/WIRING-CUSTMR MTD DR/FOG LGHT
08	0008GBN		2013	B		12V 90AMP DELCO CS-130 ALTERNATOR
08	0008MED		2068	AF	SE	BATTERY(2-FLTRITE)MAINT-FREE 12V 1100CC
08	0008RAK		2010			CB RADIO ACCOM PACKAGE
08	0008RAU		2006	ADF		ELEC TUNED AM/FM/CASS/CLOCK RADIO
08	0008RBK		2003			DUAL CB ANTENNAS
08	0008WAU		2001	AF		WINDSHIELD WIPER SWITCH (INTERMITTENT)
08	0008WCB		2003			WARNING LIGHT/BUZZER-ENG OIL PR/WTR TEM
08	0008WCG		2000			RADIO NOISE SUPPRESSION FILTER	Yes
08	0008WML		2000			HEADLIGHTS (2) LONG LIFE HALOGEN	Yes
09	0009107		2177	BDFMSUX		HOOD ASM, TILT
10	0010000		2002	BT		SPEEDO & MISC
10	0010210		2000			EMISSION LABEL (FUEL ECONOMY / NOISE)
10	0010761		2000			PAINT BASE COAT/CLEAR COAT 1-2 TONE	Yes
10	0040010		0001			MEDIUM DUTY STD WARRANTY	Yes
11	0011001		2000			OMIT CLUTCH & CONTROLS	Yes
12	0012959		2007			ENG BLOCK HEATER (PHILLIPS)120V-1250W
12	0012NHD		2061	BELMNVX		DT 466E HEUI INT DSL 230HP/2300RPM
12	0012TSJ		2016	A		FAN DRIVE(SCHWITZER DD-30)VISCOUS
12	0012UGM		2001			ELECTRONIC ROAD SPEED GOVERNOR	Yes
12	0012UGN		2006	BD		THROTTLE CONTROL ELECTRONIC
12	0012USC		2026	BDFGL		381 SQIN RADIATOR & 304 SQIN AIR COOLER
12	0012VVN		2006			ELECTRONIC CRUISE CONTROL	Yes
13	0013ABB		2105	ADFNQUWZ	SE	MD-3060/CR ALLISON 5-SPD AUTOMATIC TRAN
13	0013WBL		2000			ALLISON PUSH-BUTTON SHIFT CONTROL	Yes
13	0013WTA		2000			ALLISON SPARE INPUT/OUTPUT	Yes
14	0014ADP		2014	DTV		INTERNATIONAL S150S 15500# REAR AXLE
15	0015SAC		2106	CEGJ		SGL 50G FL TK W/STEP(RSM)(STL-RECT)U/CA
16	0016000		2373	BFHPT		TRANS COVER, FLOOR MATS, SEALS
16	0016196		2076	ADFHNS		CREW CAB
16	0016400		2001			OMIT PASSENGER SEAT	Yes
16	0016660		2000			TINTED GLASS, ALL WINDOWS	Yes
16	0016CCB		2000			COLOR - PEARL GRAY	Yes
16	0016GAU		2000		SE	DUAL RETRACTABLE MIRRORS
16	0016HAB		2003	A		ENGLISH GA CLUSTER W/ENGLISH SPEEDO/TAC
16	0016JAD		2001	BCN		FRONT BENCH SEAT VINYL W/VINYL
16	0016PZR		2000	BC		REAR BENCH SEAT - VINYL W/VINYL
16	0016WAK		2002			POWER WINDOWS (LT&RT DOORS)	Yes
16	0016WKB		2152	AEGNRS		HTR&A/C (INTERNATIONAL BLEND-AIR)
16	0016WMJ		2001		SE	DUAL CONVEX SS 8" MIRRORS
16	0016WSD		2004	CEKMQSTW		INTERIOR TRIM PREMIUM - CREW CAB
16	0016ZAA		2015	A	SE	CAB ACCESS PKG (DRIVER/PASS SIDES)
17	0027DNA		2000	AD		DISC FRT WHLS(19.5"PT-STL 8S)6.75DC RIMS
17	0028DNA		2000	AB		DISC RR WHL(19.5"PT-STL 8S) 6.75DC RIM
17	0029580		2000			INTERNATIONAL WHEEL SEALS (FRONT)	Yes

Explanation of Prop Shaft Locations

259DTA1402 *PROP SHAFT 1

259DTL1590 PROP SHAFT 1

UNISTEEL G133

AOTNMT01 TBLS N/M MT ASM 6

7309020179 *8R19.5-12PR 6

Prop Shaft Information

   

 

[trimster]

Great info. Thanks. Seems the truck was delivered to the builder who outfitted it as a toter. It was gray but was repainted white. Interesting.

That's some fairly heavy bags. Hmmm. Need to find lighter weight/load ones.

Bob

[DieselHP]

That is how all trucks leave the factory. Cab and chassis except in some cases a school bus will leave complete. 

Think of the air bags as a basketball. The more air pressure in it the harder it will bounce. 

Think about it your rear axle is made for 15,000 and your putting 1,500 to 3,000 pounds on it. I don't know your pin weight but it's nothing compared to want it's made for. 

If you had a bounce to your ride I would say you need shocks  if it's stiff the bags are too tight. You have to adjust because you have no weight to speak of on the truck