Full Load - Heavy Floor Rotational Vibration

[Fuzz]

Hi everyone. Alright... As some people might know, I track my car.. a LOT.

At the end of last year, I visited Mosport, and in Turn 2 (Downhill, 90 degree left hand -70ish mph), I got a nasty vibration in the FLOOR Only.. I almost thought it was grinding, I actually DID think it was grinding at the time (15" Wheels, low center, high speeds). It doesn't shake in the steering wheel... JUST the passenger floor. I am clueless and need some help.

This weekend we are having the AISA School in St Eustache. At lunch, the instructors are allowed to take their cars out on track for some fun... so I go out. We have a caroussel turn, (double apex'd horse shoe), and I quickly noticed that that same vibration is there.

It was the very first time the car has been on the track since blowing the engine in october, right after Mosport. I ran last year St Eustache every week with the Monday Night Lapping program, and never had any problems.

There has only been 4 changes to the car since Sept 25th 2009 (Last ASE Date), and Oct 12th (Mosport, first noticed noise) and Today (After new Engine re-install). That was the Engine, the Transmission, new Axles, and Exhaust.

I am at a complete loss. The car makes no noise in any other turns... I can put the car on 3 wheels trail bracking and have no issues what so ever, it drives smooth, no wheel bearing noise... NOTHING. There are 2 other Left Hand Turns @ Mosport with High Speeds, and 2 other fast, and 2 slower left handers at ASE and niether make noise. Its never done it going right.

CV Joint Issue maybe?? Maybe the DriveShaft isn't long enough (H23 Engine and Trans in a 98 Accord, with 98 Accord Driveshafts). It HAS to be something drive train related, it is the ONLY change. The suspension has been taken off, checked, re-installed, checked, torqued, checked again... NOTHING.

Any takers on this one???

I have another school in 2 weeks and I want the car to be tip top for it.

 

[finch13]

So does it do it under load or no load? Left turns only?

I think you might be on track with the CV joint... but I think it might be too long instead of too short. That inner CV joint is the one that allows the axle to change length as the suspension moves, so if it were too long you may not be able to pull the axle out far enough. In left hand turns with the RF suspension fully compressed going downhill, that could make the axle shaft rub the joint cup and the 3 bearing grooves in the cup.

Do you have a CV boot clamp crimping tool? I would take the axle out and spread the crimp on the inner CV boot clamps and slide the boot down the axle. Wipe the grease off the axle and look for wear. Makes sense in my head... that rubbing would go into the tranny, into the mounts, into the subframe and into the passenger floor pan... It's free to check s long as you don't **** up the clamps or boot.

CV Boot Clamp Tool: http://buy1.snapon.com/catalog/item.asp?P65=&tool=hand&item_ID=10746&group_ID=1333&store=snapon-store&dir=catalog

Another guess I had was old tires and sidewall hard spots since you probably roll onto the sidewall a bit on 15s, but you would definitely feel that in the steering wheel.

 

[Drift]

How do the wheel bearings feel?

 

[Fuzz]

Wheel Bearing feels good, no play, no noise.

The vibration comes all the way from when I enter the corner.. off throttle, trail braking, neutral throttle past the fist apex, and then starting to apply power through to the second apex when I start to open up the wheels. (3, maybe 4 seconds). It is a left handed, 15 degree banked double 90 degree turn "Caroussell"

Today was the second day of our two day school, and I got to beat on the car a bit more during the lunch break. No noise, it didn't happen, however it was in the wet, so less speed is carried (I forgot to NOT Trail brake and nearly looped the car lol).

For anyone who has ever had a car sliding in the wet because of understeer has felt this nasty chatter vibration in the chassis as your front wheels are getting grip / loosing grip. (eg full lock left while car is sliding forward).

I'll check the CV joints and i'll grab a set of axles just in case I don't like what I see.

Thanks guys!

 

[Fuzz]

I found a nice left hander off ramp up north, a HUGE swooping 160 degree corner that cuts right and then a long left.

As you enter the corner, if you dial in a lot of steering to close to the inside of the corner, the vibration starts..... then you ease up, it goes away, dial in, comes back... I managed to make it come and go 4 times in the corner like an on-off switch depending on the steering input... yet no vibrations IN the steering.

I'm picking up both right side tables, axle, and I will see what needs to get changed!

 

[Fuzz]

I solved the problem. It was a defective axle that I had picked up during my swap.

I did Tech Inspection before my School at Calabogie and I managed to detect some play with the axle. The CV at the wheel end would up being loose. Saturday was a wet day and didn't pose any problem. I did an axle swap at the end of the day

Thanks for the suggestions!!