Author Topic: big knock (Read 577 times)

eZ65 · « **on:** September, 07, 2008, 04:15:14 PM »

Well I took the stang for a drive today...i was very nervous...it actually drove very well but when the transmission would shift into OD under very little load something in the rear would slam. could not yet tell if it was coming from the tranny or the rear. felt like the rear.

I have an AOD into a detroit locker 9'' with 4.10 or 4.11's whichever. lol

any ideas or how i go about tracking down the problem?

daveSanborn · « **Reply #1 on:** September, 07, 2008, 05:24:08 PM »

Quote

could not yet tell if it was coming from the tranny or the rear. felt like the rear.

Personally, I'd look at the transmission first. The rearend shouldn't know what gear you're in..... whether it be 1st, 2nd, 3rd or OD, the rearend should behave the same in any gear.

Could it have something to do with the Detroit Locker? Hmmm... I dunno.....

daveSanborn · « **Reply #2 on:** September, 07, 2008, 05:27:15 PM »

Crap, this ones going to be tough to troubleshoot....

Jackup the rearend, place some quality jackstands underneath it, start up the car and run her through the gears..... See if you can duplicate the issue without a load on the Detroit Locker.

blue65coupe · « **Reply #3 on:** September, 07, 2008, 05:47:09 PM »

Like Dave said, it's gonna be tough. I would lean toward the tranny being the issue since the rear should act the same. A hard change in the tranny will send the "shift" to the rear and could cause it to sound like it is coming from the rear. Did that make sense to anyone but me? When it shifts into OD, does it act like a tranny with a shift kit? Very quick with no "lag"?

eZ65 · « **Reply #4 on:** September, 07, 2008, 07:09:21 PM »

The tranny does have a shift kit. I could lighten the tv cable but then when i go WOT the car shifts too soon.

blue65coupe · « **Reply #5 on:** September, 08, 2008, 07:58:13 AM »

It has a shift kit but only "slams" when you're going into OD? Is this correct? Is it a newly rebuilt tranny?

eZ65 · « **Reply #6 on:** September, 08, 2008, 02:19:17 PM »

new tranny...first drive in the car...does not do it all the time

daveSanborn · « **Reply #7 on:** September, 08, 2008, 04:18:59 PM »

Other than reading about Detroit Lockers, I have no firsthand knowledge of them. I know that they have some weird operating characteristics... could it be something to do with the locker?

Try my jackstand test and see if anything changes.

blue65coupe · « **Reply #8 on:** September, 08, 2008, 05:25:27 PM »

Yep, do what he said first.

eZ65 · « **Reply #9 on:** September, 08, 2008, 09:44:51 PM »

why does the jack stand thing seem dangerous?

blue65coupe · « **Reply #10 on:** September, 09, 2008, 04:48:29 AM »

It's not if you raise the rear and not the front!!! It's fine though. Just set them under the rear axle, chock the front tires, and hook a cable from your car to the biggest tree you can find. You'll be ok. Seriously, we've all done this at one time or another.

daveSanborn · « **Reply #11 on:** September, 09, 2008, 06:20:42 AM »

Quote

why does the jack stand thing seem dangerous?

.... because you've seen "Farris Buellers Day Off" too many times?

If you put a couple quality jackstands under the rearend housing... and then chock the front tires..... the chance of the car "falling" off of the jackstands with the engine running and the tires spinning are the same as if the engine was off.

If this really makes you nervous, bring the car down to a local garage and have them put it on a professional lift, but now you're paying a $60+/hr labor rate.