strange vibration only down steep hill 75+ mph

[joe diffy]

hi eric and members. i had a question. I have a 2009 honda fit (manul trans) with about 57000 miles on it. since i’ve owned it i’ve never changed the tires. I recently changed JUST the front tires with brand new tires and some used rims i bought. I mounted them myself and balanced them with a bubble balancer. I took it out on the road and drove up to 80 mph and didn’t notice any vibrations other than the engine and road surface. however i noticed under a particular circumstance there was a vibration. when i drove down a very steep hill at about 75 mph i noticed a vibration in the steering wheel. i found this very odd because on level roads and uphill i can go up to 80 mph with no vibrations. i put the old wheels and tires back on the front and did not notice the vibrations when driving down the same steep hill at 75 mph. what could this be? could it be the fact that i have old tires on the back and new tires on the front? could it have something to do with the used rims i bought and put on the front? I probably will eventually change the rear tires as well and hopefully the vibration goes away but i’m afraid it might not. if it helps the old tires are 175/65 -R15 84s and the new tires are 175/65 -R15 84t. really confused on what this could be. i also realize that getting it professionally balanced would probably be a good thing to try but i am a hard core do it yourselfer and would prefer not to. plus if it were a balancing issue wouldn’t it vibrate under all conditions and not just down hill? also what’s even weirder is the down hill it vibrated on was VERY steep. other downhills that weren’t so steep it did not vibrate.

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[Lorrin Barth]

Years ago when rims and tires were narrow a bubble balance worked pretty good. With the wider rims and tires on modern cars a bubble balance is not sufficient. You can have a heavy place on the inside of the rim counter balanced by a heavy place on the opposite outside of the rim and the bubble balance will say perfect balance but you will have vibration.

[Dwayne]

this may help..http://www.aa1car.com/library/vibrations.htm

[joe diffy]

thanks for the replies guys.

I really am hesitant to think it’s a balance issue since it only does it under that one specific condition.

keep in mind i was able to get up to 80 mph on level, uphill, and moderately downhill roads with NO vibrations. I could have probably gone even faster with no vibrations but it seemed unimportant since the fastest road in america has a speed limit of 85 mph.

the only condition was down a VERY steep hill at 75+ mph. another odd thing was that i think the vibrations were worse when i went down the hill with the clutch pushed in (coasting) as opposed to going down the hill in 5th gear.

Could it be a tire tread issue? since i am going down a very steep hill and all the weight is on the front tires.

[Bryan Carter]

[quote=”joediffy345″ post=112609]
keep in mind i was able to get up to 80 mph on level, uphill, and moderately downhill roads with NO vibrations. I could have probably gone even faster with no vibrations but it seemed unimportant since the fastest road in america has a speed limit of 85 mph.

the only condition was down a VERY steep hill at 75+ mph. another odd thing was that i think the vibrations were worse when i went down the hill with the clutch pushed in (coasting) as opposed to going down the hill in 5th gear.

Could it be a tire tread issue? since i am going down a very steep hill and all the weight is on the front tires.[/quote]

Being able to accelerate up to 80mph in a Honda Fit while going up a hill seems like a rather dubious claim…

Anyway, it is quite possible for a car to vibrate while going downhill, but not uphill… and vice versa. The vehicle’s orientation and drivetrain loading create changes in suspension geometry that may either dampen or amply vibrations.

But let’s zoom out and take a “big picture” view. Since this only occurs with your new tires, we can tentatively eliminate the rest of your car from the equation. So that would leave us with the following possibilities:

1. Tires have a defective tread design that only manifests on steep downhill grades at speeds in excess of 75 mph.
2. The tire design is fine, but this specific set of tires has a defect creating the described symptoms.
3. The bubble balancing performed on the new tires is inadequate.

Nothing against you (or whomever balanced the tires), but I’m leaning towards #3.

[joe diffy]

thank you for the reply.

could tire pressure have something to do with it since when going down a VERY steep hill there is probably a lot more weight on the front than the back?

my rear tires are at 38 psi and my front are at 37 psi.

i was thinking of tinkering with the front tire pressure to see if anything changes.

i was also thinking of putting the old tires on the front and the new on the back to see what that did.

any chance it could be defective rims? I put different rims on when i changed the front tires.

[Ingvar]

1. your tires are over inflated. 32 is about top margin for HF.
2. IS THIS THE SAME STIP HILL EVERY TIME? As if it is, it’s not tires, but road condition. I knaow quite a few “shakers” along my usual routes.

[Ingvar]

Btw, Hondas are KNOWN for being SUPER sinsitive to lug nuts torque and rotor/hub mating surfaces HAVE to be perfectly clean, or rotors will set crooked pulling wheel out of kilter.

[Bryan Carter]

[quote=”joediffy345″ post=112614]thank you for the reply.

could tire pressure have something to do with it since when going down a VERY steep hill there is probably a lot more weight on the front than the back?

my rear tires are at 38 psi and my front are at 37 psi.

i was thinking of tinkering with the front tire pressure to see if anything changes.

i was also thinking of putting the old tires on the front and the new on the back to see what that did.

any chance it could be defective rims? I put different rims on when i changed the front tires.[/quote]

Tire inflation typically will minimize or exaggerate an existent vibration, but it’s usually not the root cause. Your idea about swapping the front and rear tires is definitely a worthwhile experiment to try. As for your other theory… it’s possible, that the rims are defective but It’s unlikely.

[joe diffy]

yes it is the same steep hill (it’s the only hill around here that’s that steep). i would blame it on the road but like i said my old tires and rims handled it just fine.

on a weird side note the vibrations changed depending on if i went down the hill in 5th or neutral(with the clutch pushed in/coasting)

i will try lowering the psi to see if that makes a difference and i will try rotating the front to the back.

however my old rear tires have been at 38 psi forever so would it be bad to lower it to 32 psi at this point.

it just seems like such a shame if it’s a balance issue because i got sooooo close to making it work with a bubble balancer.

PS: yeah i was really only able to get up to 70-75 mph on an uphill road in 4th gear (these fits are weak) but still there was no vibrations.

[Dwayne]

[quote=”joediffy345″ post=112561]hi eric and members. i had a question. I have a 2009 honda fit (manul trans) with about 57000 miles on it. since i’ve owned it i’ve never changed the tires. I recently changed JUST the front tires with brand new tires and some used rims i bought.I would suggest you get a professional to take you for a drive in your car, get him to drive it like you do, no radio on, and maybe they can look over at you within a few minutes with a huge GRIN and say ” I know what the problem is” and you may not ever figure it out for months, if at all
if your like me “I LOVE TO WRENCH IT” and don’t want help, but I know my limits, and tuck my tail between my legs, and go ask for help, but I always learn something new, and next time I come across the same issue I had problem with…I will know how to repair it:)

[joe diffy]

for the record when i feel the vibrations i am not braking at all. I am either coasting or accelerating down a very steep hill. I’m pretty sure it has nothing to do with the brakes.

one possibility i was considering is that since the front tires are new maybe they are gripping the road better/differently than the rear and causing the rear to skid a little which could cause the vibration.

another thing i think might be worth mentioning is that my old tires had sufficient tread left on them. The only reason why i was trying to change them is because they felt very spongy. like if i went around a corner the car would lean to one side slightly and if i shut the car door with a little force the car seemed to wobble back and forth a little.

i was also thinking of having both the new tires on the same side, one on the front and one on the back. if the vibration goes away then i would think this would tell me that it’s just a matter of replacing all the tires.

also the new rims i used are original ones. they look exactly like the ones that came on my car.

[Erin]

Two things here –
First –
Just take it to a tire shop and spring the few bucks they will charge to properly set the tires. Tire problem can cause all kinds of strange handling problems like “it only does it at this speed on this road when it is 82 degrees and raining”. They may also recommend putting the “good” tires on the back axle.

Second –
Flying down a “very steep” hill at 75+ mph in a top-heavy vehicle is a good way to ensure your next car ride will be in a hearse. On a flat road if something lets loose (ball joint or tire blow-out), you are at the mercy of only inertia. But down a steep hill, gravity AND inertia will be playing ping-pong with your ride.

If that second part gets me a butt chewing, I will take it with pride.

[joe diffy]

thanx for the reply

First –
by set the tire you mean balance? i’m pretty sure i mounted and inflated the tires correctly on the rims so it’s hard to think what else could be wrong other than the balance.

Second –
for the second point this whole problem may never even come up in my daily driving seeing as how i probably won’t be driving down steep hills at 75+ mph any way. i think the speed limit on the hill was about 65 mph so i may have been speeding a little to test it out. luckily no cops were around. is the speed limit for most very steep downhills in america below 75 mph? this vibrating condition may not ever occur without speeding.

[Lorrin Barth]

Sorry, but I’m really not interested in trying to figure out what may be wrong with your car when I know your wheels are not properly balanced. So, have the wheels computer balanced and see if the problem still occurs.

Some years ago an auto repair shop was going out of business and their equipment was sold at auction. I was looking at their tire mounting and balancing machines and was sorely tempted. But the machines were too big for my little shop. So, DIY hardcore, and I am, I still have to pay to have my wheels balanced.

[Dwayne]

[quote=”joediffy345″ post=112673]thanx for the reply

First –
by set the tire you mean balance? i’m pretty sure i mounted and inflated the tires correctly on the rims so it’s hard to think what else could be wrong other than the balance.

Second –
for the second point this whole problem may never even come up in my daily driving seeing as how i probably won’t be driving down steep hills at 75+ mph any way. i think the speed limit on the hill was about 65 mph so i may have been speeding a little to test it out. luckily no cops were around. is the speed limit for most very steep downhills in america below 75 mph? this vibrating condition may not ever occur without speeding.[/quote]
stay under 65 and don’t worry about it:)I also pasted a really good link for you to read…

[Author]

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