Had this issue, disappeared when I junked my 8.8...

 

That little hopping is a break down in the Modifier and/or the breather is getting plugged.

 

KLITCH- i have the 9.75 in this truck. same problem. it bounces when unlaiden and when i have over 400pounds in the back.

i have no idea what you are talking about.

 

No? Most of you will, well maybe ? It's mainly a Ford LS Rear Gear prob. Also after awhile their EP (extreme pressure) additives go flat or loose viscosity.

So -

#1.) The Friction modifier begins to go south/break down, - sooner, once you get over 100,000 miles.

#2.) The EP additives break down as well and won't stick.

The Hop is your clue that she needs some maintenance. You may think that over-sized tires might easier on your rear end fluid. Unfortunately, that's not so, not with a LS rear end. The oil and modifier gets spent that much quicker.

 

ive had this truck since it was stock with 28,000 miles on it and it has done it. it now has 65K and still does it. my 97 had 120K on it and it did it also, i think it is a problem with the trucks in general.

 

jbrew your a freaking life saver.. or truck saver lol im 17 and i have mechanical abilitys in changing stuff out (spark plugs o2s oil and all that stuff) and also can do more but im also still learning. im going to college to be a mechanical engineer in hopes to get on with ford or someone cause my passion is vehicles .. so thanks for adding to my knowledge multiple times and im selling some 4 wheeler ramps and thatll give me half the money for a mag hytec diff cover and im gonna put some rp and the recommended amount of friction additive that ford recommends.. hopefully anyways beens now that i know its my differential im gonna try to get my dad to chip in the other half and just let me pay him back cause im VERY picky about maintnence and i cracked a diff on christmas night (spun out hit ice then a guard rail :/ ) and i got a new one and had a local shop to put it on and i told them to change out the fluids cause the one i had put under it had been sitting for a while and i also told them to paint the axle black while they had it out and it never got painted black and im guessing now that it never got the fluids changed either.. thankyou and for future reference with the over sized tires and all how often should i change it out? every 3k when i change the oil??

 

Think what you want, -personally, I think your not listening.

 

No problem, yea those Mag-Hytecs are awesome. I go a little heavier with the modifier myself and I don't get that hopping anymore. I think just keeping it all fresh makes a biggest difference.

 

alright thank you again my trucks in the process of having lt headers installed and new o2s igh flow cats and all the good stuff lol so as you can probably guess ive spent alot lately and i think i have a hundred dollars left from the 4 wheeler sale and when i sale the ramps ill have another hundred so then ill have my differential cover

 

im just saying there is no way diff fluid has broken down after only 28K miles.

 

well i think there was less than 100k on the differential i have under mine right now ... whether or not fluids where ever changed i dunno. it sounds reasonable because before i got my lift it did it a lil then after the lift i guess i just felt it more. at least if its NOT the diff fluid ill know its my tires and whether or not my warranty covers that i dont know but if it did itd be nice

 

That diff cover is expensive, that's why I don't have one yet lol. If your installing LT headers and still haven't purchased O2's, Oriely's/Murrays usually stock the correct O2's w/12-14" harnesses. That will save you some $$$ since you won't need extensions. They're part numbered for downstream, but the sensor itself is the same as the upstreams. Different part numbers with O2's only designate harness length. In case you weren't aware.

 

i ordered some bosch o2s and they hzve some with 18 inch harnesses unfortunately i was guessing at which one was them cause summit racing doesnt list the length and i got the short ones so i bought two 14 inch extensions and they are gonna fit no problem depending on if i get a cel ill either do the gotts o2 mod or get a custom tune when i get my programmer.. if i dont ill just leave it as is.

 

What sucks the most about ordering, you don't get much of a choice. While at Murrays getting other supplies I decided to check and see if they stocked Bosch or Motorcraft O2 sensors. They had them all in stock, two different sized harness for the front and 3 different sized harnesses for the rear, the largest being a 17". In the parts book, they also had length, BUT, the length is measured and figured for the entire part. Yea, that means the connector and sensor length included

So, that can screw you up. Specially if anyone measures what they need before hand. Because the sensor and connector is at least 3.5 - 4". Yea, definitely enough to have you coming up short...

 

thats why i ordered the extensions.. not only for that but i dont see how on a stock exhaust the front (if your going from the manifolds back ) reaches without a extension but the rear o2s in the cats go very short distance in my eyes anyways