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Off the wall question

Frogman
October 24th, 2005, 06:40 PM
I jacked up the rear of my 98, (turned off Air Ride), and started the car. Turned off the traction control, and slowly started accelerating in Drive. Once the speedo got to about 40MPH, the motor started acting funny, and would not easily go past 45, IIRc.

Is this normal, aka: the computer is trying to figure out why the rear wheels are turning, and the fronts are not, so it derates the motor, or did I forget to turn something else off?

I did this little experiment in an attempt to find the elusive shudder I'm dealing with.

JC1994
October 24th, 2005, 07:55 PM
dunno'...

MrWilson
October 24th, 2005, 07:58 PM
i would think that wouldnt be a problem, or else how would you be able to use a dyno? just make sure ur not just jacking it up, get some stands under there too.

Frogman
October 24th, 2005, 08:27 PM
Yeah. Thank you for that safety advice, Mr. Wilson. I had two midgets holding the rear end of the car up. :p

94m5
October 24th, 2005, 08:52 PM
I'm not really sure man.




Could it be the awkward angles of the CV joints in the rear? Like wilson said.....they run these cars on dynos all the time, so this IS wierd.


Mike

Psychostang
October 24th, 2005, 09:34 PM
I saw on the MKVIII message board, that a shudder during initial acceleration is due to a defective 1-2 shift accumulator piston.

Here is a link: http://www.markviii.org/LOD2/part_numbers.htm#Spring

MrWilson
October 24th, 2005, 09:54 PM
just makin sure, lol.

Joeychgo
October 24th, 2005, 09:58 PM
Yeah. Thank you for that safety advice, Mr. Wilson. I had two midgets holding the rear end of the car up. :p



ROFL!!!!!!

Frogman
October 24th, 2005, 10:16 PM
I saw on the MKVIII message board, that a shudder during initial acceleration is due to a defective 1-2 shift accumulator piston.

Here is a link: http://www.markviii.org/LOD2/part_numbers.htm#Spring


Yes sir. I have a 98, and I have the J-Mod done.

Come on people! The person who gets this right gets a one year membership donation to LvC! :D

MarkOfDeath
October 24th, 2005, 10:35 PM
when you do it, keep the car in first till 30 then upshift in to 2nd, turn off overdrive as well

buddylee
October 24th, 2005, 10:35 PM
can't rember why .... but what you did is not good for the rear-end or trany.
I just rember being yelled at from shop teacher for doing the same thing.
something about no presure on the rear-end.

MarkOfDeath
October 24th, 2005, 10:40 PM
WARNING: IF ONLY ONE DRIVE WHEEL IS ALLOWED TO ROTATE, THE SPEED MUST BE LIMITED TO A MAXIMUM SPEEDOMETER READING OF 55 KM/H (34 MPH) SINCE THE ACTUAL WHEEL SPEED WILL BE TWICE THAT INDICATED ON THE SPEEDOMETER. EXCEEDING A SPEED OF 55 KM/H (34 MPH) OR ALLOWING THE DRIVE WHEEL TO HANG UNSUPPORTED CAN RESULT IN TIRE DISINTEGRATION/DIFFERENTIAL FAILURE, WHICH CAN CAUSE SERIOUS PERSONAL INJURY/EXTENSIVE VEHICLE DAMAGE.

After a road test, it is sometimes useful to do a similar test on a hoist. (Use an axle hoist, not a frame hoist. An axle hoist will not change the driveline angles. If only a frame hoist is available, axle stands must be used.)



Elevate the rear wheels slightly. Check to make sure both wheels will turn. WARNING: THE ELECTRICAL POWER TO THE AIR SUSPENSION SYSTEM MUST BE SHUT OFF PRIOR TO HOISTING, JACKING OR TOWING AN AIR SUSPENSION VEHICLE. THIS CAN BE ACCOMPLISHED BY TURNING OFF THE AIR SUSPENSION SWITCH. FAILURE TO DO SO CAN RESULT IN UNEXPECTED INFLATION OR DEFLATION OF THE AIR SPRINGS, WHICH CAN RESULT IN SHIFTING OF THE VEHICLE DURING THESE OPERATIONS. CAUTION: The suspension must not be allowed to hang free. When the Constant Velocity (CV) joint is at a high angle, extra vibrations as well as damage to seals and joints can occur.
Start the engine and place the transmission selector lever in DRIVE (D). Explore the speed range of interest using the drive/cruise/float tests.
A coast down in NEUTRAL must also be conducted. If the vehicle is free of vibration when operating at a steady indicated speed and behaves very differently in DRIVE and coast, an axle concern is likely.

MarkOfDeath
October 24th, 2005, 10:43 PM
so by u letting the suspension hang you might of caused damage hope this helps

JC1994
October 24th, 2005, 10:57 PM
I guess he let it all hang out! LOL!

MarkOfDeath
October 24th, 2005, 11:00 PM
man your silly, hey did your headers make that much of an improvement, you should get a 3500 stall, it wakes these cars up

JC1994
October 24th, 2005, 11:05 PM
I know! a little. yeah a stall would be cool.

Frogman
October 24th, 2005, 11:43 PM
I don't understand the whole "Only one wheel rotating" bit.

I ran the car for max of 10 seconds. As soon as I noticed the motor acting up, I shut it down. Granted, I did use the brakes, I did not slam them, but gradually applied them.

Thanks MOD. Will update as soon as I get home, and get a chance to look around some more.

mespock
October 25th, 2005, 07:21 AM
I'm going with the Midgets

MarkOfDeath
October 25th, 2005, 07:59 AM
if only one wheel is moving, the speed is doubled, i guess

Frogman
October 25th, 2005, 08:45 AM
That'd be hard to do on a posi unit, me thinks.

MarkOfDeath
October 25th, 2005, 11:50 AM
well i dont know what mods you have, im just saying what needs to be done, or checked

Frogman
October 25th, 2005, 04:12 PM
Aye. 3.73's with Trak-loc.

MarkOfDeath
October 25th, 2005, 04:25 PM
let me know if leveling the suspension works, so i can look into other possible problems

phreakness
October 25th, 2005, 05:15 PM
has your chip been programed with the 3.73 gear set? How extream was the angle of the car when you started the car?

Frogman
October 25th, 2005, 07:02 PM
MOD, I reset the suspension height to stock. Haven't had a chance to test it out though. Will know Thursday. Thank you sir.

phreak = What Chip?

What was the Angle of the car? umm.. I think the midgets had the rear raised to about 1.4degrees off center. I dont know what the angle was... enough for the tires to clear the cement.

Brozly
October 25th, 2005, 07:35 PM
Were Both midgets the same height???

Frogman
October 25th, 2005, 08:29 PM
Yes sir....

94m5
October 25th, 2005, 08:33 PM
Don't laugh....


I've seen some pretty stout midgets.


Mike


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