New rental program comming!

[Logan]

The 4 month old J 42069 Timing belt tool rental has been very positive. Loved by Saab and Saturn owners. We need to buy more kits..The site can be seen here:

<a href="http://www.ledfix.com/timingbelttoolrental.html" target="_blank">http://www.ledfix.com/timingbelttoolrental.html</a>

Anyway, working on a new rental program. *Wiggly 1998 and newer Seville and Deville owners take note.

The expensive Kent Moore J 38792 EVA tool...more to come.

[Logan]

Ok...The EVA came in today. Like a new scan tool, having a crash course on how to make it work..

Some interesting data so far.

Tool is the Kent Moore J 38792 electronic vibration analyzer. It has the 'good' blue cartridge EVA2 software.

Couple of different ways to make this equipment work. Speed based calculations, or RPM based calculations. Hz or RPM.

You can run instant feeback or average. Both are helpful, but in instant mode a bridge joist or bump in the road will give some scrambled feedback. Averaging slows down that issue.

So far, the best readings I get are to use the magnetic sensor on the strut tower. Only got to play with it 1 or 2 hours today..

Technically, you get scrambled data from road harshness etc. What you are looking for over 10 miles or so is repeat flags at a preprogrammed speed. You can 'tune' the vehicle speed on the tool as you get close to that speed. Easy up or down buttons.

In the case of the Deville/ Seville. I think 70 mph is the target.

There is some math involved.

First, you have to find out how far your tire moves at 5 mph. GM has some tables for this. In my case, my 235-55-17 tire turns 1.06 times at 5 mph. Enter that into the tool.

Then you do the math, using the number above calculated to the speed where the vibration happens. In this case 70 mph. So in this case, the 5 mph number x 14 (=70 mph) would be equal to 14.84 (hz).

When I drive the car at 70 mph. I have 14-18 hz showing up all the time mixed in with the road/ bridge/bump/false data.

This tool also nails it. The display will show '14hz TIRE 1'. The 1 shows first order vibrations.

Be sure to see this site too:

You can download a 15 day trial version. http://www.vibratesoftware.com

On the vibrate software you need your build codes. My 2001 has this..

Axle 'FV3' = 3.11 ratio

Trans 'MH1' = 1st: 2.960 2nd: 1.626 3rd: 1 4th: .681

This software is used along with a EVA. I did enter my Deville tonight using a 15 day trial version. It then creates a chart. You can choose either RPM or Hz.

I added a scan of the Hz chart generated from vibrationsoftware.com. The yellow hightlight shows where I think the analyzer is trying to tell me where the issue is. 14-18Hz at 2000 rpm. That area is T1 which is 1st order tire vibration.

That being said. My car is a bunch better then when I bought it. Last RF balance came in at about 15 lbs road force. Still, it should flow like a Jag.

But, Tennessee black tops are screwed up from all the trucks. I expect some scanner trash and ride harshness from that.

This make me think...maybe something else is going on. Yes, it points at the major rotating assemby on the car. But GM did release new control arms. I think the front control arm bushing may be it...

More to come..going to play with it this afternoon.

[Logan]

Here is a picture of the Hz data.

Note '16 Tire 1' @ 70 mph.

That means a 16 hz vibration, 1st order, at 70 mph. .03g issue. Measured at the top right front strut tower.

[Logan]

You can also use RPM to find this issue.

The RPM chart from vibrationsoftware.com puts 1st order tire vibration @70 mph in the 925-1000 RPM range...

.07g issue. The 360 seems to be internal noise on the EVA (you can hear it on the radio buzzing away...) the 1800 is road hash.

[Bruce Nunnally]

Thanks for posting this info; I enjoy discussions/investigations like this.