Torsion Bar Ride Quality

[25fabworks]

Hi All, did a bunch of searching and found the partial torsion bar thread and specs on all the bar torques, but still had a few questions. I'm trying to pick the right bar for my build and it's tough to select one without actually feeling how stiff it is, so was hoping for some butt dyno type opinions. They're going into a half ton that won't do a ton of hauling and is just a gas engine, so not a ton of front end weight like a diesel or plow truck would have, but I want the truck to handle well so don't want a soft bar.

That said I obviously can't go to stiff or the thing will skip over imperfections in the road and handle worse. Tried looking up all the different trucks that had the different code bars, but they pretty much all come up as HD bars, so it's hard to tell how they would ride. I'm sure some has to do with a arm legnth and actual leverate on the bar as well, but wondering what most guys with performamce handling in mind are running on their half ton. I know I will need the 54" bars but that's about it.

 

[stutaeng]

Handling and performance?

Have you looked doing a coil-over conversion? That system from Atomic Fabrication can be tailored to your truck prescisely. Not inexpensive though, so maybe not an option, but still worth a look:

99-06 Torsion Bar to Coilover Kit - Atomic Fabrication

This is a package that will include everything you need to do the coilover swap on GMT800 99-06 torsion bar equipped 1500 GM truck wanting from 5in of drop to 7in of lift. More details below.

atomicfabandperformance.com

 

[Tonimus]

First, welcome to the forum. Second, if I was looking for handling, I would assume GM's PPV package would be the best for that. At least as far as factory stuff.

 

[ORVietVet]

Welcome to the forum, from Oregon.

I see what you did there: " They're going into a half ton that won't do a ton of hauling".

IMO, there is no such thing as a "light duty" torsion bar. Just like no such thing as light duty shocks. It's just marketing words.


Also, IMO, Stick with as stock as you can and if you want handling, do the Hellwig Performance sway bar kits, front and rear. Then it will handle like you want. I have a 2005 Tahoe Z71 and I wanted handling instead of engine "performance". The Hellwig bars are the single biggest "seat of the pants" improvement, I have ever done.

 

[Marky Dissod]

First, welcome to the forum. Second, if I was looking for handling, I would assume GM's PPV package would be the best for that. At least as far as factory stuff.

GMT800 pickups use torsion bars that are MUCH stiffer than the Tahoe PPV / Suburban Z71 4WD torsion bars.
FYI, y'all:

Torsion Bar Reference

SuspensionMAXX GM Torsion Bar Reference Chart Use our calculator to convert your tire sizes from metric to inches The SuspensionMAXX GM Torsion Bar

suspensionmaxx.com

2000-2007
Part Numbers . . . . . . . . . RPO Codes . . . . . . . . . . . . . . . . . . Rate index, notes
15048307 & 15048308 . . 6XK&7XK . . . . . . . . . . . . . . . . . . . . 4553 . . . Tahoes, 2WD Suburbans
15048309 & 15048310 . . 6XL&7XL . . . . . . . . . . . . . . . . . . . . 4626 . . . Z71?
15058265 & 15058266 . . 6YF&7YF . . . . . . . . . . . . . . . . . . . . 4863 . . .
---------------------------------------------------------------------------------------------------------------
15048311 & 15048312 . . 6XM&7XM . . . . . . . . . . . . . . . . . . . 5638 . . . PPV / SSV / Avalanche
15712407 & 15712408 . . 6WX&7WX . . . . . . . . . . . . . . . . . . . 5826 . . .
15528955 & 15528956 . . 6GF&7GF . . . . . . . . . . . . . . . . . . . . 5826 . . .
15058267 & 15058268 . . 6WY/6YH&7WY/7YH . . . . . . . . . . . . . 5913 . . . K1500PU?
---------------------------------------------------------------------------------------------------------------
15528957 & 15528958 . . 6GG&7GG . . . . . . . . . . . . . . . . . . . . 6707? or 6790? . . .H2
15528959 & 15528960 . . 6GH&7GH . . . . . . . . . . . . . . . . . . . . 7161 . . .
15072933 & 15072934 . . 6WZ/6YK/6YT&7WZ/7YK/7YT . . . . . . 7267 . . . Z85 / Z60
---------------------------------------------------------------------------------------------------------------
15528963 & 15528964 . . 6GK&7GK . . . . . . . . . . . . . . . . . . . . 8615 . . . bubba 2500
15528965 & 15518966 . . 6GL&7GL . . . . . . . . . . . . . . . . . . . . 8782 . . . Z85 6.0L / 8.1L
15732338 & 15732339 . . 6XG&7XG . . . . . . . . . . . . . . . . . . . . 9054 . . . snowplow?
----------------------------------------------------------------------------------------------------------------

HEARD / READ that SUV torsion bars and pickup truck torsion bars are different lengths, and thus not interchangeable ... bad-sad news for me ...
ANYWAY
Since you did not bother to mention what kind of pickup truck you have, put your VIN in here

Free GM Vin Decoder | GMPartsGiant

Free GM VIN Decoder - Do a VIN lookup to acquire specific car information. Ordering exact-fit parts has never been this smooth and hassle-free on GMPartsGiant!

www.gmpartsgiant.com

to learn which bars you already have, and go with stiffer bars ... how much stiffer is up to you ...

 

[25fabworks]

GMT800 pickups use torsion bars that are MUCH stiffer than the Tahoe PPV / Suburban Z71 4WD torsion bars.
FYI, y'all:

Torsion Bar Reference

SuspensionMAXX GM Torsion Bar Reference Chart Use our calculator to convert your tire sizes from metric to inches The SuspensionMAXX GM Torsion Bar

suspensionmaxx.com

2000-2007
Part Numbers . . . . . . . . . RPO Codes . . . . . . . . . . . . . . . . . . Rate index, notes
15048307 & 15048308 . . 6XK&7XK . . . . . . . . . . . . . . . . . . . . 4553 . . . Tahoes, 2WD Suburbans
15048309 & 15048310 . . 6XL&7XL . . . . . . . . . . . . . . . . . . . . 4626 . . . Z71?
15058265 & 15058266 . . 6YF&7YF . . . . . . . . . . . . . . . . . . . . 4863 . . .
---------------------------------------------------------------------------------------------------------------
15048311 & 15048312 . . 6XM&7XM . . . . . . . . . . . . . . . . . . . 5638 . . . PPV / SSV / Avalanche
15712407 & 15712408 . . 6WX&7WX . . . . . . . . . . . . . . . . . . . 5826 . . .
15528955 & 15528956 . . 6GF&7GF . . . . . . . . . . . . . . . . . . . . 5826 . . .
15058267 & 15058268 . . 6WY/6YH&7WY/7YH . . . . . . . . . . . . . 5913 . . . K1500PU?
---------------------------------------------------------------------------------------------------------------
15528957 & 15528958 . . 6GG&7GG . . . . . . . . . . . . . . . . . . . . 6707? or 6790? . . .H2
15528959 & 15528960 . . 6GH&7GH . . . . . . . . . . . . . . . . . . . . 7161 . . .
15072933 & 15072934 . . 6WZ/6YK/6YT&7WZ/7YK/7YT . . . . . . 7267 . . . Z85 / Z60
---------------------------------------------------------------------------------------------------------------
15528963 & 15528964 . . 6GK&7GK . . . . . . . . . . . . . . . . . . . . 8615 . . . bubba 2500
15528965 & 15518966 . . 6GL&7GL . . . . . . . . . . . . . . . . . . . . 8782 . . . Z85 6.0L / 8.1L
15732338 & 15732339 . . 6XG&7XG . . . . . . . . . . . . . . . . . . . . 9054 . . . snowplow?
----------------------------------------------------------------------------------------------------------------

HEARD / READ that SUV torsion bars and pickup truck torsion bars are different lengths, and thus not interchangeable ... bad-sad news for me ...
ANYWAY
Since you did not bother to mention what kind of pickup truck you have, put your VIN in here

Free GM Vin Decoder | GMPartsGiant

Free GM VIN Decoder - Do a VIN lookup to acquire specific car information. Ordering exact-fit parts has never been this smooth and hassle-free on GMPartsGiant!

www.gmpartsgiant.com

to learn which bars you already have, and go with stiffer bars ... how much stiffer is up to you ...

Yeah suppose I should had added that. Truck is actually an F-150. That's the problem. Ford in their infinate wisdom didn't publish the spring rates. So I'm trying to find out what GM bars would work with it and ride similar to the Ford number 8 and or 7 bars. I know we can use our 54" bars in the Fords, just like the Ford keys will lift the 800s, I'm just trying to put it all together. My GMC is just a V6 std cab, so I'm sure has the softest bars possible and I do want it stiffer than that truck. That said I'll go grab the vin and see what bars it has. I'm not sure it even has 54" bars in it since it's not an HD. Probably just the 52's.

 

[25fabworks]

Welcome to the forum, from Oregon.

I see what you did there: " They're going into a half ton that won't do a ton of hauling".

IMO, there is no such thing as a "light duty" torsion bar. Just like no such thing as light duty shocks. It's just marketing words.


Also, IMO, Stick with as stock as you can and if you want handling, do the Hellwig Performance sway bar kits, front and rear. Then it will handle like you want. I have a 2005 Tahoe Z71 and I wanted handling instead of engine "performance". The Hellwig bars are the single biggest "seat of the pants" improvement, I have ever done.

I did upgrade the front swaybar, debating adding a rear too since my truck didn't come with one. Just have to solve my torsion bar issue first to see how this thing will handle. Probably should have put it in the original post, it's an F-150. Ford doesn't sell the bars anymore and my bars are junk. So I'm going to upgrade to the GM bars since I can get them new still most likley. Just have to figure out which ones are similar to my bars which is going to be near impossible I think. So tyring to get some seat of the pants opinions to sort of guess where I should be.

 

[25fabworks]

Handling and performance?

Have you looked doing a coil-over conversion? That system from Atomic Fabrication can be tailored to your truck prescisely. Not inexpensive though, so maybe not an option, but still worth a look:

99-06 Torsion Bar to Coilover Kit - Atomic Fabrication

This is a package that will include everything you need to do the coilover swap on GMT800 99-06 torsion bar equipped 1500 GM truck wanting from 5in of drop to 7in of lift. More details below.

atomicfabandperformance.com

I actually did look into coilovers but decided to stick with torsion bars, but appreciate the input. Maybe one day I'll switch it up, but for now torsion makes the most sense for me.

 

[25fabworks]

Well ran the VIN and I'm kind of shocked, but my 03 has the 6YH and 7YH bars in it. Is that because it's a 4x4? I'm kind of shocked to see it have that heavy of a bar. I mean the thing rides pretty solid, but I'm a little surprised a 6 cylinder that doesn't even have a hitch on it got those bars. Just a lil old standard cab long bed.

Have to get out there tomorrow and measure the bar length to see if it has the 54" bars. Then I'll measure the center of the bar to the center of the lower ball joint to see how different it is on my GM vs the Ford, so I know the actual torque being applied to the bar. The F-150 is a V8 extended cab, so has some more weight up front too, so I'll have to take that into consideration too. Maybe the GG bar is the way to go.

 

[stutaeng]

Well ran the VIN and I'm kind of shocked, but my 03 has the 6YH and 7YH bars in it. Is that because it's a 4x4? I'm kind of shocked to see it have that heavy of a bar. I mean the thing rides pretty solid, but I'm a little surprised a 6 cylinder that doesn't even have a hitch on it got those bars. Just a lil old standard cab long bed.

Have to get out there tomorrow and measure the bar length to see if it has the 54" bars. Then I'll measure the center of the bar to the center of the lower ball joint to see how different it is on my GM vs the Ford, so I know the actual torque being applied to the bar. The F-150 is a V8 extended cab, so has some more weight up front too, so I'll have to take that into consideration too. Maybe the GG bar is the way to go.

That's probably because the torsion bar stiffness/rate is a function of the GVWR of the truck (and is a 4x4), not based on the engine size.

On my 99 (2wd, so coil spring) when I did a V6 to V8 swap, I didn't even think about the "added weight sagging the front more," or anything like that. AFAIK, the coil springs are the same. There's actually not a lot of weight difference between the 4.3 and the 4.8/5.3/6.0, maybe 50 lbs-ish?

 

[Marky Dissod]

That's probably because the torsion bar stiffness/rate is a function of the GVWR of the truck (and is a 4x4), not based on the engine size.

Not trying to make an unpleasant argument, trying to understand - this actually seems like a good hypothesis to test.

What's the difference in GVWR of a civilian 3.73 Tahoe, vs a Tahoe-PPV?
Why do Z60 Silverados get such stiffer torsion bars (instead of, say, much stiffer swaybars)?

I think it's more about acceptable ranges of stiffness, which is why my list above groups them ... ?

Still have lots to learn about how GM (conservatively) calibrated these suspensions;
was hoping it might be possible for my Tahoe to use H2 torsion bars ...

 

[25fabworks]

Well what's going to be interesting too is when I measure the torsion bar and a arm on the Ford vs GM. The longer a arm will severely effect the leverage on the bar. My F-150 had one of the stiffest bars available but I have no way of knowing what the torque rating is. It's quite annoying actually. Ford really doesn't support their vehicles after 10 years.

I could do the math I suppose to calculate the bars strength but without knowing the exact kind of steel it is, it would throw everything off. My factory bars are hollow also vs the number 7 Ford bars that aren't. Hollow bars actually respond faster which is awesome but they tend to sag sooner, and without available replacements. Well.... Lol

 

[Marky Dissod]

GM also typically resorts to aftermarket support for parts over 10yrs old (including what passes for 'GM OE').

Still need length measurements for GM torsion bars, because I want/need to know if I can use any of the torsion bars I typically find belonging to GMT800 pickups under my Tahoe.

 

[25fabworks]

Well went to a couple yards and documented the below of what I found. Hopefully it helps someone out. Measurments are approximate as it was kind of hard to measure under the truck in the yard with the bar mounted and concrete blocks in the way but they should be close.

WY – 54.5"

XL – 51/52"

XK – 49/50"

YH – 54"

XM – 52"



2500HD – GK

Suburban – 6XL/7XL

Tahoe – XK

X2 Z71 – 6WY/7WY

Yukon XL – 6XL/7XL

Z71 1500 – 6YH/7YH

X2 X1 Z71 Avalanche – 6XM/7XM

Non Z71 1500 – 6YH/7YH

Yukon Denali – 6XK/7XK

1500 SLE – 6WY/7WY

1500 4x4 – 6YH/7YH

Half ton – YT

3500 – GL

1500 ext cab 1SE - 6YT/7YT

 

[Marky Dissod]

Well went to a couple yards and documented the below of what I found. Hopefully it helps someone out.
Measurements are approximate as it was kind of hard to measure under the truck in the yard with the bar mounted and concrete blocks in the way but they should be close.

WY – 54.5"
YH – 54"
XM – 52"
XL – 51/52"
XK – 49/50"

Tahoe & Yukon Denali – 6XK/7XK

Suburban & Yukon XL – 6XL/7XL
X2 X1 Z71 Avalanche – 6XM/7XM

X2 Z71 – 6WY/7WY
1500 SLE – 6WY/7WY

Z71 1500 – 6YH/7YH
Non Z71 1500 – 6YH/7YH
1500 4x4 – 6YH/7YH

Half ton – YT
1500 ext cab 1SE - 6YT/7YT

2500HD – GK
3500 – GL

Combining your notes with mine above, it LOOKS like the suvs were 'meant' by GM OE to use 'XK', 'XL', or 'XM' torsion bars.
If that's truly the case, I've learned something sad - 'cause I'd hoped to consider the 'WX', 'GF', or 'YH' bars - but at least I've learned something.

 

[JorgeS]

As other have said...if you want a decent ride, but reduce leaning in turns (sway) for better handling, keep the torsion bars small and add stiffer (anti-)sway bars, and good shocks .
When you go over a bump on only one side, you'll feel it because sway bar will affect both sides (right & left), but no worse that stiff torsion bars. When you go over pavement joints or other pavemet defects that affect both sides, the ride will be much
better than with larger torsion bars.

 

[25fabworks]

As other have said...if you want a decent ride, but reduce leaning in turns (sway) for better handling, keep the torsion bars small and add stiffer (anti-)sway bars, and good shocks .
When you go over a bump on only one side, you'll feel it because sway bar will affect both sides (right & left), but no worse that stiff torsion bars. When you go over pavement joints or other pavemet defects that affect both sides, the ride will be much
better than with larger torsion bars.

Yeah I did upgrade the sway bar but that will only get me so far. I'm going to get to the yard this week and pull some bars and see how it rides. Then start swapping bars out like an idiot until I get what I want. I have at least narrowed it down to 4 different bars. Realistically probably 2.

 

[Marky Dissod]

Yeah I did upgrade the sway bar but that will only get me so far. I'm going to get to the yard this week and pull some bars and see how it rides.
Then start swapping bars out like an idiot until I get what I want. I have at least narrowed it down to 4 different bars. Realistically probably 2.

When you do this, would you PLEASE measure the LENGTH of those other bars? I THINK I MIGHT be able to get away with using a 53" torsion bar ... maybe ...
Thanks in advance.

 

[25fabworks]

When you do this, would you PLEASE measure the LENGTH of those other bars? I THINK I MIGHT be able to get away with using a 53" torsion bar ... maybe ...
Thanks in advance.

See above. I posted bar measurements. What exactly are you trying to do and what are too looking for exactly?

 

[Marky Dissod]

What exactly are you trying to do? What are you looking for exactly?

Can my Tahoe use torsion bars STIFFER than 'XM'? Looks like XM were the stiffest GM OE torsion bars for GMT800 suvs, including PPVs / SSVs,
as well as 4WD Suburbans & Avalanches 1500.

If GMT800 1500 pickup trucks came with OE Z85 / Z60 handling package using WZ / YK / YT bars,
why can't I 'get away with' using at least WY / YH bars?

(Hummer H2 bars look like they'd be WAY too stiff for any Tahoe ...)

My 'phantasy' is a Tahoe that can 'intercept' GMT821 PPV, using parts loosely interpreted as 'GM OE':
6.0L, 4.10s, and a suspension built from OTHER GM OE parts where possible, especially for the suspension, I.E: a GMT921 PPV rear sway bar.