Ran at the track tonight,problem on the drive home,insight would be appreciated

[Paulyworld1432]

Ran at the local track tonight, all runs were done with a 4.5k launch... one a little closer to 5.
My problem is, while driving home upon light acceleration I felt a slight "bouncing" or bucking. The headlights showed the movement so it was quite harsh. I only experience the bucking at partial throttle maybe 50 percent of the time. Under boost there is no bucking surging feeling.

While on the drive home I realized the bucking happened 100 percent of the time was if i was approaching a stop with the car in 2nd, no braking, from 3.5k down to 2k rpm's the car would shake in a back and forth motion.

My motor mounts were just replaced 4k miles ago with the install of KO4's 034 street density. This leaves me with the only other assumption that it may be the Rear Diff mount? Does anyone else have any ideas?

On a better note the car ran wonderfully with the less than mediocre track conditions! :)

[Sleeeper X]

well, it sounds like your having some missfire issues. vag your car, and check for missfires. Have you changed your plugs recently?

[Paulyworld1432]

Unfortunately I do not think the problem is related to the motor/fueling. The RPM's and vacuum stay constant and do not seem to be the cause of the jerkiness. vag shows 0 misfires. Literally every sensor, Hose, part (plugs) were replaced about 3k miles ago, the only part I did not, and have not upgraded is the rear diff mount. That is why I thought it might be the culprit, I am going to take a look at all of my mounts tomorrow and see what I find.

But as for the track 12.2 @ 116 was very pleasing for my first track experience!

[Sleeeper X]

Unfortunately I do not think the problem is related to the motor/fueling. The RPM's and vacuum stay constant and do not seem to be the cause of the jerkiness. vag shows 0 misfires. Literally every sensor, Hose, part (plugs) were replaced about 3k miles ago, the only part I did not, and have not upgraded is the rear diff mount. That is why I thought it might be the culprit, I am going to take a look at all of my mounts tomorrow and see what I find.

But as for the track 12.2 @ 116 was very pleasing for my first track experience!

Congrats, what do you have done to the car.

[Paulyworld1432]

KO4's, Vast Kevlar clutch, ASP Downpipes and a Vibrant Catback, 60lb Injectors, 85mm maf, marc's tune, a bunch of miscellaneous drivetrain mods (DTS, Mounts ETC), and RS4 intercoolers.

Had my MBC set at 19, 93oct, nothing taken out of the car (spare and toolbox included), and 19in wheels with halfway decent tires, falken 452's. Next weekend if this problem is sorted I'll be running with the MBC set at 22.5 and hope to be in 11's on pump :)

Edit: forgot to mention, with the sun going down the sudden drop in temperatures cause a large amount of condensation on the track, eventually closed down to one lane due to it. Even experienced tire spin shifting to 2nd, so hopefully conditions will be better next weekend also.

[Sleeeper X]

KO4's, Vast Kevlar clutch, ASP Downpipes and a Vibrant Catback, 60lb Injectors, 85mm maf, marc's tune, a bunch of miscellaneous drivetrain mods (DTS, Mounts ETC), and RS4 intercoolers.

Had my MBC set at 19, 93oct, nothing taken out of the car (spare and toolbox included), and 19in wheels with halfway decent tires, falken 452's. Next weekend if this problem is sorted I'll be running with the MBC set at 22.5 and hope to be in 11's on pump :)

Edit: forgot to mention, with the sun going down the sudden drop in temperatures cause a large amount of condensation on the track, eventually closed down to one lane due to it. Even experienced tire spin shifting to 2nd, so hopefully conditions will be better next weekend also.

Not bad, You should see 11's with 22/23lbs of boost. Your currently running my 18lb stage3- times. Either way, its still impressive none the less. Btw, were you nervous on your first run. I was soo ansy.

[Paulyworld1432]

Thanks I'm sure I could have run closer to flat 12 with better conditions and some more practice alone! But yeah pretty nerve racking the first time, got a terrible launch and still beat the piss out of a cobra mustang :) by the end of the night my last three runs were all sub 1.8 60ft's so I was happy with that!

[2k1.5blacks4]

Check condition of tranny mounts while your looking over everything, too.

[Sleeeper X]

Thanks I'm sure I could have run closer to flat 12 with better conditions and some more practice alone! But yeah pretty nerve racking the first time, got a terrible launch and still beat the piss out of a cobra mustang :) by the end of the night my last three runs were all sub 1.8 60ft's so I was happy with that!

how did you launch your car, and yeah, my first 3 runs at the track were soo nerve racking. I was soo nervous I launched when my nerves gave out and i happened to get a .3 reaction time lol

[BITRBO]

Unfortunately I do not think the problem is related to the motor/fueling. The RPM's and vacuum stay constant and do not seem to be the cause of the jerkiness. vag shows 0 misfires. Literally every sensor, Hose, part (plugs) were replaced about 3k miles ago, the only part I did not, and have not upgraded is the rear diff mount. That is why I thought it might be the culprit, I am going to take a look at all of my mounts tomorrow and see what I find.

But as for the track 12.2 @ 116 was very pleasing for my first track experience!

nice times indeed. I say you'll def. be in the high-to-mid 11's with some more practice, boost, and a little race gazzz

as for your problem: if the car is still running smoothly, and everything checks out in VAG, then there must be something loose/broke in the drivetrain and/or suspension.

btw, what were the track temps on those 1.7X 60ft's?

[Paulyworld1432]

Tranny mounts are brand new 034 street density But I definitely am going to check everything out. The First post says it was pretty much a dump at 4.5k, slipped a tiny bit just to tighten up the drivetrain components and then let loose. Ambient temp was 49, I believe the track temp was 65-68 degrees.

[JDM EJ1 95]

where from chicago?

and what track did you go to GLD?

[BITRBO]

Tranny mounts are brand new 034 street density But I definitely am going to check everything out. The First post says it was pretty much a dump at 4.5k, slipped a tiny bit just to tighten up the drivetrain components and then let loose. Ambient temp was 49, I believe the track temp was 65-68 degrees.

Very nice... that's roughly 18-20 deg. C by my calculations. Sounds like the 452's did alright with cool ambient & track temps

[Paulyworld1432]

I live in Wrigleyville, on the Northside of the city. but I made the trip to GLD to see what the car would run. Where are you from JDM? And yeah I was overall quite satisfied with the tires performance especially for what I paid for them!

[Paulyworld1432]

BREAKING NEWS PROBLEM FOUND!!! problem was not a mount.... Who can guess it?













Drivers side axel is twisted almost 180 degrees Not good at all I am going to take a pic and post it up. Where is the best place to get a new axle from?

[Videlov]

BREAKING NEWS PROBLEM FOUND!!! problem was not a mount.... Who can guess it?













Drivers side axel is twisted almost 180 degrees Not good at all I am going to take a pic and post it up. Where is the best place to get a new axle from?

http://www.jhmotorsports.com/shop/ca...roducts_id=111

This is what I recently purchased, waiting for them to arrive. Heard good things about the product and the I think it's a good price.

[JDM EJ1 95]

I live in Wrigleyville, on the Northside of the city. but I made the trip to GLD to see what the car would run. Where are you from JDM? And yeah I was overall quite satisfied with the tires performance especially for what I paid for them!

Im from the NW burbs and work in the northshore.


these cars dont need much tire to get goin. mine scoots out consistant 1.68-1.75 60ft on bald michelins

[Paulyworld1432]

Looks like that is what I'll order, How long ago did you order?



Here is a picture of the axle

[Paulyworld1432]

BTW I'm originally from the NW burbs, I used to live in Lake Zurich, which suburb do you live in?

[Sleeeper X]

Looks like that is what I'll order, How long ago did you order?



Here is a picture of the axle

How the F does that happen.

[JDM EJ1 95]

BTW I'm originally from the NW burbs, I used to live in Lake Zurich, which suburb do you live in?

arlington heights

[NOVAS4]

good thing you found the problem... i cant wait to get my car in shape for the track... anyway for replacement axles i recomend r-axles... raxles.com

[Videlov]

Looks like that is what I'll order, How long ago did you order?



Here is a picture of the axle

Order went in on Wednesday and estimated date of arrival is on Tuesday the 7th with the cheapest method of delivery.

Holy shit how did that thing twist like that?

[JDM EJ1 95]

its not uncommon to twist an axle.


think about it.. 5k launches with 400+ awtq in a 3800lb boat is goin to put some stress on things.. and if an axle has a weak point in it.. you bet your ass its going to show over time

[Paulyworld1432]

Yeah I wasn't really surprised that it happened... only disappointed haha. So what is the consensus? R-axles or JHM "solid" axles?

[Paulyworld1432]

PureMS also has axles for sale for 108. Any thoughts on these? are they OEM or higher quality?

[ThirdStrike]

Yeah I wasn't really surprised that it happened... only disappointed haha. So what is the consensus? R-axles or JHM "solid" axles?

pm sent

[BITRBO]

I guess I don't understand how that is going to make the car buck or surge, esp. over 50% throttle... I'd think it would just shake the car like crazy no matter what speed or throttle input. IDK

[Paulyworld1432]

Well It felt a little rougher at all speeds but I guess the vibrations had enough distance in between them when the axle was rotating slower. to where it became blatantly apparent there was a problem. I guess I probably just did a bad job explaining oops but I'm sure It is the problem

[2ndEngineS4]

I've been driving on a twisted axle very similar to that for 5 months. I've never experienced any jerking or bumping. You should replace the axle, sure, but that's probably not the cause of your problem, look deeper. Have you checked your diff mounts, driveshaft mount/bushing, rear CV axles and joints? Just a thought.

[Matt@JHM]

This is exactly why we run (and supply) our solid axles.



I think Jason has sheared 3 or 4 of them.

[JDM EJ1 95]

I've been driving on a twisted axle very similar to that for 5 months. I've never experienced any jerking or bumping. You should replace the axle, sure, but that's probably not the cause of your problem, look deeper. Have you checked your diff mounts, driveshaft mount/bushing, rear CV axles and joints? Just a thought.

its a very good possibility that its the problem. i would bet money that thats the issue.

an axle out of balance like that can cause some bad vibration

[Paulyworld1432]

I am 99 percent sure that it is the problem I described the problem poorly, but after realizing the axle was bent, the way the car drove/felt seemed to make perfect sense. It is more than a slight twist the inner CV boot is stretched because it is so out of balance. But... if I replace it and the problem doesn't go away I will obviously look other possibilities. But I did already check all the other mounts and driveshaft, and everything else seemed to be in check.


To JHM I posted over on audiworld and a member said something about the possibility of an even beefier shaft being in the works? is this true?

[Matt@JHM]

To JHM I posted over on audiworld and a member said something about the possibility of an even beefier shaft being in the works? is this true?

We are pretty damn sure that our new/current solid axles are going to withstand a major beating.



We are now pre-greasing everything before shipment. So you don't even have to get your hands dirty.

[black99.5a4]

this is a stupid question but do s4 axles fit an a4?

[Matt@JHM]

this is a stupid question but do s4 axles fit an a4?

No, but we have everything for the B5 A4 listed here: http://www.jhmotorsports.com/shop/ca..._62_63_125_213

Good question

[MacDaddy]

awsome price on the axles, but i can't help but think audi made them hollow for a reason.

if you upgrade the axles, then the next weakest link in the chain will break, and who knows what that is.
hub splines?
front diff?
shaft running from center to front diff?
center diff?

something i would keep in mind.