Improving the steering stability 1997 4X4 2 dr Tahoe

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drakon543

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The 4BT is about 750lbs (6BT is around 1100), the NV4500 about 220. I probably gained 350-450lbs. I have had it over the scales and I seem to remember 5800 but before I get it aligned next time I will weigh both axles.
Is the implication that I would have an unbalanced spring rate carrying the heavier load between the front and rear? I did also replace the drag link and idler (not sure of terminology) when I refurbed the front end before the swap. The OEM parts that I pulled off were somewhat worn and the rubber seals were going away but as I stated swapping out the front end parts made a minor improvement. I think that the steering box is probably more worn than I suspected. The feeling that I get from from the replies is that it should drive pretty well. This is encouraging! Since the chassis components are similar to a 1/2 ton PU my modest load increase seems like it should be within comfortable limits for the chassis.
(Editorial)......
Chinese tires are not necessarily bad tires. I am running load range F's on my ram. When I purchased them a few years ago load range F's in my size were very hard to find in any brand. I needed the load range F because my rear axle load was putting the load range E tires over their limit. I haul a slide in camper and pull a big enclosed trailer, typical CGVW is 22k it drives great and is not fussy at all. I have been running them 3 seasons and they still look nearly new. I am using them on my 3 axle equipment trailer that I haul a Case 580 on. Zero problems. Trailer duty is rough duty when you make a turn the loads that those tires endure are ugly. I am running them on my Monaco 36ft class A no issues at all. It drives just the same as with the previous Good Years. Any tire mfg can have issues. It takes a tough tire to survive at rated load full time. Check out the tire failures of name brand tires on class A motor homes. It is an epidemic. So bad that they recommend that you swap them out every 4 years regardless of mileage. When I spent a few weeks in the Shanghai area in 2012 the roads were full of all types of vehicles. Lots of trucks obviously loaded heavier than would be allowed in the US. The roads were not covered with tire carcasses or trucks with flat tires.
you only suggested chinese tires so i can only assume they were the cheapest thing you can find testing for fitment or something. with torsion bars its basically like having a single rate coil springs your basically riding around with them almost bottomed out with the keys cranked up. those bars only have so much spring twist in them. anyway as im still unsure of the capabilities of the tires im just going to assume they super squishy sidewalls with basically a super stiff suspension spring rate. the 4bt is about 750lbs with just the engine and oil. do you only have the alternator and ps on it for accessories? they don't weigh much just by themselves. so your definitely lighter up front than i thought maybe a bit heavier than you think tho according to what im reading. hmmm what are you running for shocks up front? the drag link is your steering cross bar the pitman arm is the z ish shaped arm off the steering gearbox to the passenger side there is another up there looks very similar called the idler arm. when i had my 97 i used to always run a mid load range tire dont remember exactly what load range it was but it could handle all the seats down fully loaded and a 16ft trailer fully loaded. my current assumption is your suspension is very stiff due to the extra weight and stiffness of the torsion bars paired with tires with very large sidewalls trying to flex and bounce and possible need for a firmer shocks to handle those points. maybe a mild lift and backing off on the torsion bars. sounds like your going all in anyway why not just go all the way and do a solid axle swap.
 
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Jim b

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I always liked the 4BT swap, NV4500 is a bonus as most use TH400. Long ago I had a short C40 with a 4-53 and it was fun to drive.
What year was the C40? Sounds nice. How did it perform?
On the highway the slightly cranked up 4B performs as good or better than the 350 did. I love pulling a 6% grade in 5th at 5000ft!
I am an old guy and still love manual transmissions. I should qualify that with overdrive manual transmissions! My first was in a 67 opel Kadet that I swapped a 225 buick V6 with a 3 speed with OD behind it. 3.08 gears. 3100 at 100. 35mpg if you kept it at 80 or less. Even though the 225 did not make huge power it did well in a 1800lb car. Surprised a few folks.
 
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Jim b

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you only suggested chinese tires so i can only assume they were the cheapest thing you can find testing for fitment or something. with torsion bars its basically like having a single rate coil springs your basically riding around with them almost bottomed out with the keys cranked up. those bars only have so much spring twist in them. anyway as im still unsure of the capabilities of the tires im just going to assume they super squishy sidewalls with basically a super stiff suspension spring rate. the 4bt is about 750lbs with just the engine and oil. do you only have the alternator and ps on it for accessories? they don't weigh much just by themselves. so your definitely lighter up front than i thought maybe a bit heavier than you think tho according to what im reading. hmmm what are you running for shocks up front? the drag link is your steering cross bar the pitman arm is the z ish shaped arm off the steering gearbox to the passenger side there is another up there looks very similar called the idler arm. when i had my 97 i used to always run a mid load range tire dont remember exactly what load range it was but it could handle all the seats down fully loaded and a 16ft trailer fully loaded. my current assumption is your suspension is very stiff due to the extra weight and stiffness of the torsion bars paired with tires with very large sidewalls trying to flex and bounce and possible need for a firmer shocks to handle those points. maybe a mild lift and backing off on the torsion bars. sounds like your going all in anyway why not just go all the way and do a solid axle swap.
The engine has a full compliment of functioning accessories. Actually the tires are load range D. Not the cheapest but had the profile that I wanted. THe load capacity is significantly greater than the load. No the sidewalls are not super squishy, It in no way rides harshly compared to my 2500 ram quad cab, nor does it wallow around like a 1972 LTD. The suspension is rather compliant and well behaved. The shocks are KYB's but not new. It does not have uncontrolled damping. Again the handling is better than when the vehicle was in stock form with 160K on it. I am pretty confident from other replies that replacing the steering box with a stiffer unit and getting the caster dialed in will make me happy. Contrary to what some true believers think you can successfully modify a vehicle from its "compromised to the maximum factory configuration" without causing issues. I have over 40k miles on the rig since the conversion and the only complaint is the wander issue. That is the only major complaint that carried over after the mods. Prior to that it was constantly shifting, unable to hold OD on minor grades, horrible fuel efficiency. I use this rig pretty hard. I pull my 27' pontoon boat up and down 8-9% grades many times a season. This is not on high speed roads. These roads are very crooked and require slow speeds and careful driving. It is equally happy running 65 with a utility trailer. While it is not a HD tow vehicle the short wheelbase and low range (with a switch on the xfer case lever to disable the front axle) make it ideal for maneuvering in tight spaces. It will pull the pontoon boat out of the lake at an idle. Just let the clutch out and it goes. So much more satisfying that the vortec. jim
 

exp500

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C40 was a 67 dump, small single axle 5x3 trans. Like a rowboat! Had a 427 powered truck around same time that had more power but was very thirsty!
 

drakon543

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The engine has a full compliment of functioning accessories. Actually the tires are load range D. Not the cheapest but had the profile that I wanted. THe load capacity is significantly greater than the load. No the sidewalls are not super squishy, It in no way rides harshly compared to my 2500 ram quad cab, nor does it wallow around like a 1972 LTD. The suspension is rather compliant and well behaved. The shocks are KYB's but not new. It does not have uncontrolled damping. Again the handling is better than when the vehicle was in stock form with 160K on it. I am pretty confident from other replies that replacing the steering box with a stiffer unit and getting the caster dialed in will make me happy. Contrary to what some true believers think you can successfully modify a vehicle from its "compromised to the maximum factory configuration" without causing issues. I have over 40k miles on the rig since the conversion and the only complaint is the wander issue. That is the only major complaint that carried over after the mods. Prior to that it was constantly shifting, unable to hold OD on minor grades, horrible fuel efficiency. I use this rig pretty hard. I pull my 27' pontoon boat up and down 8-9% grades many times a season. This is not on high speed roads. These roads are very crooked and require slow speeds and careful driving. It is equally happy running 65 with a utility trailer. While it is not a HD tow vehicle the short wheelbase and low range (with a switch on the xfer case lever to disable the front axle) make it ideal for maneuvering in tight spaces. It will pull the pontoon boat out of the lake at an idle. Just let the clutch out and it goes. So much more satisfying that the vortec. jim
ya i modify just about everything i own to fit my desire. wasn't trying to shoot any other suggestions down just going with what i know is a potential from the modifications you have already done. i haven't ridden in your truck so i cant really feel what you feel so my suggestions can definitely be contradictory to what your actually feeling. ive ridden in vehicles with extra weight upfront with a similar setup and my suggestions would have fit that vehicle. if the handling is there and its just not crisp enough for you then you would probably be heading in the correct direction with the other suggestions.
 
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Jim b

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Just wanted to update this thread. I finally had a chance to look into my wandering problem. Based on issues that I had with my desert buggy that I solved by adding positive caster I decided to try that on the Tahoe. I set it to nearly Max available with the common upper control arm cam system. I have not measured it. I then reset the toe in to slightly more than zero. WOW the thing drives like it's on rails. I am so happy with the improvement. It feels like I could get away with zero toe in but for now I will leave a bit in there. My coasting test indicates that it is rolling super easy as is.

So if you have wandering issues and you can't find any worn or bad components try more + caster.
Best Regards,
Jim
 

exp500

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Please edit the title of post, add "SOLVED" . Thanks, Makes finding a fix easier.
 
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Jim b

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Please edit the title of post, add "SOLVED" . Thanks, Makes finding a fix easier.
I would love to do that. Can I edit the original title of the post? If so how to access it? Thanks! Jim B
 

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