So your considering upgrading your H3 Suspension System...

[Talljeeper]

Seems Tim and I have a little difference in opinion when it comes to the currently available Rancho system. There also seems to be a vast chasm of knowledge an expectations regarding what to expect if your considering modifying your suspension.

Here are some pretty basic facts about things to consider before you lay your money down and start turning a wrench.

Begin by becoming famliar with fourwheel drive systems. Having written for Four Wheeler, Four Wheel Drive, Off-Road and 4-Wheel & Off Road, over the years these publications will help familiarize you with some great information. There are common laws of physics that apply to ALL altered four wheel drives. These publications will help you make informed decisions and more importantly ASK informed questions.

If you increase overall tire diameter ( say from 33" to 35", you impact;
Braking performance (by increasing overall rotational mass weight.) Imagine the physics of trying to stop a 30# kid swinging on a swing set vs. a 70# kid. It takes more force to stop the inertia of the 70# kid. The same thing applies to rolling tire AND wheel combo. One vehicle I bogged had rice cane combos that were over 400# each. Not only did I have to upgrade the axle brakes but also custom build a driveline brake to compensate for the weight and stop the beast. The point is you cannot change the laws of physics.

Gear Ratio - improperly geared you will turn your poor little 5 cylinder into a four popper...well almost.
By adding the additional tire diameter you're essentially turning your 4:56 gears into a 3:73 ratio, or there abouts (I haven't done the math but would be happy to if requested). The I-5 is supposed to operate within a very specific range of operating conditions. By altering overall gear ratio you WILL impact negatively, acceleration, off the line torque, transmission cooling and operation,fuel mileage, speedo (can be recalibrated) and cooling efficiency. The only way to correct this is to perform a ring and pinion replacement. Period. No amount of engine add-ons can compensate for a poor power curve grenaded by tall tires. There is a point of no return when it come to oversizing tires.

Tires and wheels...the mystical beyond... LOL
I have seen some pretty curious questions....
"can I run a 12.50 on a 7.5" wheel...."
Confusion over the term backspace and offset...
How rim width impacts the overall stance of backspace at the axle.....
Choosing design because they look cool and without regard to proper fitment.

Anytime you are considering a tire and wheel combo decide upfront what your are trying to achieve; traction, clearance, mud performance, snow/ice performance, street, etc... No tire performs well in every scenario. Thats a fact, but there are many good choices that provide a balance to perform well in "most" fourwheel drive environments. Large aggressive tires have many drawbacks that the novice should be aware of. They are hard to balance (this can be a BEAR to chase with shimmy problems and a lot of tire shops are not real friendly when it comes to rebalancing large tires check your area for GOOD 4WD tire shops)(many times a lift system will be blamed for poor performacne when in actuallity its the tires), wear fast, produce noise, and can impact ride comfort. So if your considering a TSL Swamper style tire be ready for dynamics not present in your OEM tires.
When it comes to wheels the only way to know for sure what fits and what hits is to try them on. When picking wheels choose three designs that you like EQUALLY well. Wheel mfg.'s often limit the wheel width, diameter, badckspace, centricity, and lug configurations within a specific wheel design. Never settle on ONE wheel design when getting ready to purchase. If its not in stock...WAIT till it comes in! The proper wheel for your H3 may or may not be available within a mfg product line or the one you like the best. Look at multiple mfg.'s.

Warranty issues - Some dealers are extremely averse to alerations made to vehicles, particularly suspension mods. just be forewarned. I have in many instances consulted with service managers outlining what I would like to do. This helps me gauge their reaction, and also get a a feel of what to expect in the event of a warranty claim.

Shocks - There are only two or three major players mfg'ing shocks, even though there any MANY companies offering proprietary or "signature" shocks. Hydraulic shocks, while cheaper are not usually the best choice. Gas shocks have MUCH better characteristics particularly for those that live in extreme hot/cold climates.

Lift Design - Any time you alter OEM suspension systems you are MODIFYING componentry. I have literally gutted ( cut, grinded, welded, bent, pounded, well you get it) Chevy's front ends to "install" lift systems....not fun. All systems have negatives limited to overall design. The more you go up the more modification is required. The more modification that is required the more areas for potential problems there are. If you are not capable of installing your own lift you will be pretty much at the mercy of retailers that sell and install specific product lines, unless you can find custom builders. Both have there drawbacks, but the key here is experience with not only the product but also your vehicle. Ask the question about problems that could arise related to the install and how well the installer will stand behind their service.

Altered center of gravity - Anytime you go up, you are impacting the overall center of gravity of the vehicle. You can compensate that by increasing the overall width related to the vehicle track width. Many prefer more narrow "look" but if your going up, go out as well to maintain stability, particularly in off camber 'wheeling situations. The H3 was designed with incredible center of gravity coefficients remember to try and maintain that balance.

Alignment - ALWAYS have you vehicle aligned after the initial install. Always re-tighten after 500 miles. In the case of any handling problems take the vehicle to an independant alignment shop. I prefer shops that have the high end Hunter digital alignment machines.



Hope this helps....

[timgco]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Talljeeper:
Having written for Four Wheeler, Four Wheel Drive, Off-Road and 4-Wheel & Off Road, over the years these publications will help familiarize you with some great information.
Hope this helps.... </div></BLOCKQUOTE>

Well I don't know if you have writen for these publications or copied this from somewhere....either way it is very informative for anyone that is going to make descision on lifting their rig.

I'm glad your Rancho kit worked out for you. I honestly do. (I saw the pic of the red H3 in the other post). Anymore pics.. esp. where your tires are close to that nuckle in front? What are the specs on your rim/ tire package? and maybee a pic where it shows your track width against the width of your fender flares?

I agree with your post on everything mentioned here. but you forgot the one MOST IMPORTANT thing for those that are looking into the lifting of their rig: Let someone else do it first and drive theirs to make sure you like how it will look, handle, stop, and accelerate.

BTW- you have this lifted H3 on a HUMMER forum with the name TallJeeper? WTH?

[Talljeeper]

Tim, I've been customizing fourwheelers and street rods for gosh over 25 years...yikes!

A lot of my comfort level comes from experience. The TJ I have now I completely removed the suspension with 12 miles on the odometer and installed a prototype system. This was when the TJ was first released. At the time it was the third TJ to have the system. It was virtually bug free but it allowed me to provide feedback to the supplier for future production modifications.

My moniker comes from an extensive Jeep history having owned somewhere around 35 Jeeps and many many other performance 4wd's (tractor puller, mud boggers, monster truck, show vehicles, etc.) over the years. Several of my Jeeps have been feature vehicles published in various well known rags. I have also been on Truckin USA with one of my rides on TNN...but that was quite a while back. One of my rides was a highly customized 51 Chevy Sedan Delivery 4WD wholly sponsored by Hasbro toy and registered as the only DOT approved Tonka in the world.

I ran out of patience with Daimler and their feet dragging on the Rescue, hence my purchase of a H3.

Ill get some pics up for ya and more specifics on my setup

The stuff I have submitted for readers here is all mine.....

I would agree that modifiers should research the heck out of what they plan on doing, unfortunately there aren't many H3 customizations completed yet.

[HummBebe]

Beautifully written! Excellent advice! Would you care to elaborate on the effects of larger tires and their relationship to gear ratios? 4:88's vs 5:13's?


Thanks!

[Ted]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Talljeeper:


Warranty issues - Some dealers are extremely averse to alerations made to vehicles, particularly suspension mods. just be forewarned. I have in many instances consulted with service managers outlining what I would like to do. This helps me gauge their reaction, and also get a a feel of what to expect in the event of a warranty claim. </div></BLOCKQUOTE>


The dealer can get averse as they want. If you modify your suspension, they don't have to fix any issues with the suspension. If your AC dies, they still have to fix that if it's convered under warranty.

You are protected by the Magnuson-Moss Warranty Act. A lot of service managers don't understand things like Federal Law.

[Talljeeper]

Sure HB...bear with me here cuz this can get confusin quick
lets use your 4:88/5:13 example

First the 5:13 is the lower of the two gears
(if this is to basic please forgive me)
When you install larger tires you raise the overall gear ratio (higher). To compensate for a higher gear ratio you install a lower gear (ring & pinion...Front AND Rear).

So if your running 33" tires with a stock 4:56 gear and you change to 35" tires, you RAISE the gear ratio (I'm gonna guess around 4:10).
What this translates to in the real world is at say 60MPH you will have gone from, as an example, 2000 RPM to 1750. Now while this does'nt sound like much, it can make a huge difference for us mountain drivers, highway cruisers, or heavy load carriers. Combine that with a torque sensing transmission or air conditioning (HP sucker) and you have now possibly created a gear hunting pig. The anemic (sp) 5 cylinder likes to gear hunt anyway due to the H3 weight.

Someone alluded that the gear calculators are inaccurate...actually they are pretty dog gone close for determining RPM. The poster then began to talk about weight, load etc...the gear calculator estimates RPM...not horspower to weight ratios..something completely different.

I have found my best friend when determining the sweet spot for gearing is an accurate speedo and a tach. Start noting what the readings are of your tach and speedo. Also note how your tranny shifts (in an auto) or what gear you seek (if manual). In the case of an auto the final gear 4speed auto is a 1:1 ratio. In other words for every rotation of the crankshaft, the driveshaft, connected to the R&P turn the same revolution...one to one, so highway speeds are typically used as the gearing vs. rpm benchmark. Why I bring this up is that tranny gearing can be important in choosing a gear set. Where do you need to develop the maximum torque. Are you a trail rider or streeter. It has been my experience to error on the side of being to tall(higher gear) than to be to steep (low gear). To steep of a gear on the road equates to a high revving motor....conversely, its no fun to have to high a gear...a gutless wonder. If you want all out balls to wall performance then the lower gear will bring a motor "in" fast. In a manual tranny you will do whats known as sawing the gear shift if your too tall....think about it LOL
In an auto it will constantly be looking for the right gear.

I have actually installed larger tire s to bring down the RPM 400 or 500 rpms for high way driving! Screaming down the road at 65 at 3500RPM SUX!!

Another consideration is ring gear thickness and tooth number. In the H3 differentials it not as big of deal as say in a Dana 30. But the steeper you go on a gear set the weaker it becomes. The reason for this is that you reduce the "contact" area of the R&P. You also have to compensate on the ring gear thickness. This is only a real issue ih high torque, high HP, heavy tired, or small differentialed setups.

Does this explanation help you any!

Also remember that even though a tire says 35" ALWAYS check the REAL diameter. Most 35" are in the neighborhood of 34". What that means is that you need to be CERTAIN what numbers you plug in to any ratio calculator.

I cannot imagine even considering 37" tires for the H3 without a gear change.

The 37" SSR I am running on my TJ are almost 100# EACH!@*$)&@*($
Combine that added weight with a tall gear, an underpowered 5 cylinder and you have built a four wheel drive underpowered slug LOL

Let me know how else I can help

[timgco]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ted:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Talljeeper:


Warranty issues - Some dealers are extremely averse to alerations made to vehicles, particularly suspension mods. just be forewarned. I have in many instances consulted with service managers outlining what I would like to do. This helps me gauge their reaction, and also get a a feel of what to expect in the event of a warranty claim. </div></BLOCKQUOTE>


The dealer can get averse as they want. If you modify your suspension, they don't have to fix any issues with the suspension. If your AC dies, they still have to fix that if it's convered under warranty.

You are protected by the Magnuson-Moss Warranty Act. A lot of service managers don't understand things like Federal Law. </div></BLOCKQUOTE>

For those that are concerned about warranty, you can pruchase a warranty as I did when I bought the lift. It covers everything GM may choose to void due to the mods you have installed. I did this through 4 Wheel Parts for about $750.00. Anyone can do the warranty work after an authorization is given.

[Talljeeper]

Ted, your sort of right. Magnusson primarily deals with excessive warranty claims and lemon issues.

I have seen service managers fail to warranty stuff like brakes issues, transmissions, drivetrain, and other NON RELATED suspension warranty claims due to "lift kits". What I am pointing out is buyer beware. I had a super service manager that arranged to cover ANY OEM part. In one case I had blown an axle and the SM covered it. On this vehicle I was lifted running larger tires an obviously far from stock, but there was never a question or raised eyebrow.

Tim be sure and read the fine print, they maybe farming you out to a third party for warranty work. Its getting the authorization that may be sticky....

[Operator24]

TallJeeper,

Well done. Nice thread. Compreshensive.

[f5fstop]

First, very good information.
Second, let's get one thing straight...a dealer CANNOT void a warranty that is issued by General Motors. They can notify GM, and GM through their warranty department, void the warranty on certain parts, that are affected by accident, misuse, aftermarket additions, etc.
If the dealer issues the warranty like for a sale of a used car, then the dealer can void that warranty or parts of that warranty. However, a factory warranty is just that, it is issued by the factory, in the case of a H3, General Motors Corp.
Third, a vehicle manufacturer cannot void the warranty on a vehicle due to an aftermarket part unless they can prove that the aftermarket part caused or contributed to the failure in the vehicle. That is part of the Magnuson Moss Warranty Act. However, this can be misleading, since under most circumstances that a manufacturer voids items in a warranty, they have substantial proof, the aftermarket modification can cause problems. Good example is a SC, add one, blow the engine, and I will bet you will pay the cost yourself. (Unless you have one hell of a relationship with the service manager, or photos of the manager in a very compromising position.)
GM as well as all other manufacturers know how far to push the Magnuson Moss act, and they are pretty good at winning in arbitration and/or the courts.
Now, everyone can forget this post, and get back to the great information and discussion on lifting, larger tires, gear ratios, and all that great stuff.

[HummBebe]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Talljeeper:
Sure HB...bear with me here cuz this can get confusin quick
lets use your 4:88/5:13 example

First the 5:13 is the lower of the two gears
(if this is to basic please forgive me)
When you install larger tires you raise the overall gear ratio (higher). To compensate for a higher gear ratio you install a lower gear (ring & pinion...Front AND Rear).

So if your running 33" tires with a stock 4:56 gear and you change to 35" tires, you RAISE the gear ratio (I'm gonna guess around 4:10).
What this translates to in the real world is at say 60MPH you will have gone from, as an example, 2000 RPM to 1750. Now while this does'nt sound like much, it can make a huge difference for us mountain drivers, highway cruisers, or heavy load carriers. Combine that with a torque sensing transmission or air conditioning (HP sucker) and you have now possibly created a gear hunting pig. The anemic (sp) 5 cylinder likes to gear hunt anyway due to the H3 weight.

Someone alluded that the gear calculators are inaccurate...actually they are pretty dog gone close for determining RPM. The poster then began to talk about weight, load etc...the gear calculator estimates RPM...not horspower to weight ratios..something completely different.

I have found my best friend when determining the sweet spot for gearing is an accurate speedo and a tach. Start noting what the readings are of your tach and speedo. Also note how your tranny shifts (in an auto) or what gear you seek (if manual). In the case of an auto the final gear 4speed auto is a 1:1 ratio. In other words for every rotation of the crankshaft, the driveshaft, connected to the R&P turn the same revolution...one to one, so highway speeds are typically used as the gearing vs. rpm benchmark. Why I bring this up is that tranny gearing can be important in choosing a gear set. Where do you need to develop the maximum torque. Are you a trail rider or streeter. It has been my experience to error on the side of being to tall(higher gear) than to be to steep (low gear). To steep of a gear on the road equates to a high revving motor....conversely, its no fun to have to high a gear...a gutless wonder. If you want all out balls to wall performance then the lower gear will bring a motor "in" fast. In a manual tranny you will do whats known as sawing the gear shift if your too tall....think about it LOL
In an auto it will constantly be looking for the right gear.

I have actually installed larger tire s to bring down the RPM 400 or 500 rpms for high way driving! Screaming down the road at 65 at 3500RPM SUX!!

Another consideration is ring gear thickness and tooth number. In the H3 differentials it not as big of deal as say in a Dana 30. But the steeper you go on a gear set the weaker it becomes. The reason for this is that you reduce the "contact" area of the R&P. You also have to compensate on the ring gear thickness. This is only a real issue ih high torque, high HP, heavy tired, or small differentialed setups.

Does this explanation help you any!

Also remember that even though a tire says 35" ALWAYS check the REAL diameter. Most 35" are in the neighborhood of 34". What that means is that you need to be CERTAIN what numbers you plug in to any ratio calculator.

I cannot imagine even considering 37" tires for the H3 without a gear change.

The 37" SSR I am running on my TJ are almost 100# EACH!@*$)&@*($
Combine that added weight with a tall gear, an underpowered 5 cylinder and you have built a four wheel drive underpowered slug LOL

Let me know how else I can help </div></BLOCKQUOTE>

Thank you SOOO much! For a second there, I thought you were my Dad f'n with me.

See, I understand gear ratio's and transmissions from a street rod/racing perspective. This whole going slow thing is what is new to me. Also adding the larger tires and how that affected HP/Torque is what had my thinking skewed. Just could not get my arms wrapped around that one

Not anymore! Thank you!

I'm thinking for the trails that I like, more torque (lowend) is what I need. yes? (5-7 rated)

Yea a nice discussion on gearing effect resulting from different tire sizes. Or to make it simple I wonder how 0-60 mph times would be impacted.

If 0-60 with 33" tires = 10 seconds at best
then maybe 35" tires = 12 seconds
then maybe 37" tires = 14 seconds

In short we are talking Yugo acceleration on the street. And you thought your stock H3 was barely adequate.

S.

[Killer]

I just did some calculations and if any of you have the H3 with the adventure package you get 33" tires and a 4.56:1 rear end. If you were to upgrade to a 35" tire you actually reduce your rear end ratio to approximately 4.31:1. Not bad considering and not that noticeable in regards to power. I recently drove a friend of mines H3 with an upgrade to 35's and the feel or should I say performance feels very close to my rig which still has 33's.

Not bad, but with 35"'s 0-60mph would be lucky to be better than 12 seconds. For those that are complaining about marginal power in stock form on the street, this might take them over the edge.

Pop it into low range offroad and the difference should be less noticable.

S.

[timgco]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Steve-SanJose-H3:
Not bad, but with 35"'s 0-60mph would be lucky to be better than 12 seconds. For those that are complaining about marginal power in stock form on the street, this might take them over the edge.

Pop it into low range offroad and the difference should be less noticable.

S. </div></BLOCKQUOTE>

We have two H3's: One with 33's and one with 35's and SMA exhaust. They feel the same to me. 4LO, I notice no difference whatsoever.

[NEOCON1]

im thinking that 4 low may be better with the 35's . how is it tim & op ? and i dont care about 0-60 times didant get it for runnin the 1/4 mile 35 " tires are at the shop BFG AT's wheels on b.o. couple weeks to go

Yea feels similar in hi range for 2 reasons:

1. 35" tires are probably closer to 34" in diameter.
2. And the feel of comparing 2 relatively slow vehicles is very similar. Only a stop watch would show a measurable difference. Slow versus slow essentially.

The gearing in low range, especially with the adventure package should mask any difference at all.

I assume that the offroad benefits of the 35" tires are significant, not just a style thing.


S.

[NEOCON1]

the larger tires give more ground clearance but you need the lift for clearing bigger tires so it becomes a vicious circle . the 315 70's are 34.5" and our so called 33's are just over 32" . i guess we just want to make our trucks go over stuff that a stock h2 cant

And none of want to leave our H3's box stock, including me. The mods are part of the fun.

S.