I have a 92 formula 350 with almost 200,000 miles on it. Lately when I accelerate from a stop with about half throttle I hear a slight thump from the rear end and I get a very brief hesitation going foward. I will admit I am "transmission stupid." The thump is almost the same as when my tanny mount went bad but this time it seems to be coming from the rear end. The hesitation leads me to believe that maybe I broke a tooth on one of the rear end gears. Does that sound right?

Could it be the tranny mount again?
Is there any other mount in the rear that could be worn?
Does the rear end just need maintnence i.e. fluid change?
If so, can I do that myself with just jackstands?

I love my car and this annoyance is riding very heavy on my concience (sp). Can someone please offer some suggestions or shed some light on the subject? (I already tried doing a search)

Thanks, Jon.

 

check your u joints, tranny mount, torque arm mount, do you hear any grinding or whining noises? do you hear the thump in reverse? or just in drive? do you hear it thump right when you put it in gear or just on acceleration?

 

Thanks for replying. Isn't a little gear whine normal? Other than that no other grinding or whining noises to speak of. As for the thump, I only hear it when I accelerate more than half throttle. I don't hear it when I "smoothly" leave a stop. With that said, it sounds to me like a mount of somesort. My problem is that Ive only owned the car for a couple of months and I really dont know where to start.

Not sure if it happens in reverse...

Jon

 

if you can hear gear whine inside the car over wind, road and engine noise....thats not good. I would check those things I mentioned previously and while your under there check the rear sway bar links and the conditon of the bushings for the LCA's and panhard bar. Doing a fluid change of the rear wouldnt be a bad idea, it will also let you look for signs of wear or damage to the differential. Do you have a posi? I'm not sure if a broken posi could cause those symptoms.

 

Thanks for the suggestions! Like I said before I have no experience with any aspect of transmissions or tranny maintnence. Is it pretty easy? Is there any resources I could use to walk me through it. I havn't checked the tech articles yet...

Thanks again...

 

the search button is your friend

changing the rear fluid isnt hard, but can be messy. do searches on differential or rear end or something similar, cruise around the suspension board for more info on the rear suspension.

 

Plus the rear fluid smells really bad... like cat ****... just a warning! Get a new rear gasket while you're at it. I usually slap some "Permatex High-Tack Gasket Sealant", in a metal can with a brush inside the cap, on the gasket. Fill the rear by snipping a little bit off the gear lube container's tip- just enough to slide an old piece of fuel line over the pointed tip. Then remove the fill plug using just a 3/8" ratchet (the square hole in the fill plug is the same size as a 3/8" drive ratchet), put the fuel line (with bottle attached) into the hole, and squeeze the snot out of the bottle. Just make sure the hose doesn't slip off the bottle tip, or you'll cover yourself in foul smelling gear lube. (gag) The rear's full when you can put your finger "flat" (horizontal) inside the fill hole, and your finger touches gear lube- the axle should be filled so the gear lube is right below the fill hole.

Easy way to check if your trans mount is busted; crawl under the car, and try to push the tailshaft (rear most part of the trans) up towards the floor. If the trans mount is busted, you'll be able to move the tailshaft upwards very easily (it all pivots on the front motor mounts). If you can't move the trans at all, the mount is good- or you're too weak to pick up a can of soda

 

Thanks alot guys... you rule. I swear if I didn't have thirdgen.org I would have set my car on fire now.

Jon