Any thoughts on this shakin' problem '94 GT

[donjohn]

Anybody have suggestions on how to fix a shaking problem with my '94 GT vert. Here's the symptoms: Sometimes it runs great and other times it shakes like hell when you get it up to ~4500RPM. At first we (me and my dad are fixing it, he's a mechanic) thought it was the EGR valve, then we found the distributor cap had a crack in it so we replaced that, and also found a vaccuum leak, now we don't know what to think- maybe it's the fuel regulator or maf. Any Ideas??? I just bought this car and we've been fixin' it, we'll probably find the problem but any help would be cool. Thanks.

 

[FedRich]

Balancer

From what I have been told, the harmonic balancer on the 5.0s are notorious for going bad. I would guess that could be the problem. I plan on replacing mine very soon.

 

[donjohn]

Thanks but the shaking isn't constant and the timing marks line up so the harmonic balancer is probably not the problem. I'll take a look at it anyways- thanks.

 

[iluvstangz]

i had a 94 that did the same thing you should check in to the harmonic balancer but other than that dunno

 

[donkey_punch]

if its not the harmonic balancer, then check your fuel pump or your fuel filter. your fuel pump could be going bad and not be able to hadle the feeding at high RPMs. or you fuel filter could be clogged to the point where it's restricting fule flow at RPMs.
but most likely it the harmonic balancer. and you better hope you change it before it goes. i've seen a crank snap in half cause the harmonic balancer went bad.
oh another thing if you haven't change your spark plugs wires, it could be that too. not to long ago my work van was shaking like crazy. all becuase of one of the wires was bad. but doudle check that harmonic balancer thou, its very important.

 

[cb18201]

does your car shake in neutral when you rev it up to 4500 rpm? if it doesnt shake and only shakes while your moving at 4500rpm chances are its your U-joints. did you replace your gears because that is a common problem when you replaces gears.

 

[jacob9]

DO NOT BUY FROM D&D MORTORSPORTS IN CA. THEY'RE A BUNCH OF *******S, WHO CAN'T PRODUCE WHAT THEY PROMISE TO DO. THEY'RE COSTOMER SERVICE BLOWS . ANY ONE WHO BUYS A PRODUCT THAT D&D CARRIES BUT GETS IT FROM ANOTHER COMPANY., AND INSTALLS IT AT VALLEY PERFORMANCE IN BELLVILLE NJ. I WILL PAY YOU THE DIFFERENCE IN CASH!!! AND NO I DON'T WORK AT VALLEY I'M JUST A CUSTOMER. DETAILS TO COME

i thought that i was the only one that had problems with those *******s. i guess they lie to all of their customers.

the owner of the company, Dave is a prick on wheels and one of the sales guys doesn't know anything about cars. i used to buy parts from them locally but i would get into arguments with all the employees everytime i went there.

the ads in Muscle Mustangs and Fast Fords make them look like a big operation when actually its 3 guys in a small wharehouse on a sidestreet. the owner always has a huge pile of bills on his desk but not enough money to pay them. he's always trying to make a big sale to keep from going out of business, so he blows alot of smoke up your ass to motivate you to buy from him and he badmouths all of the other local mustang shops.

They don't keep anything in stock and tell alot of lies about how they supply all of the other mustang speed shops in southern california. I've been to 4 different mustang speed shops locally and everyone knows they are a joke

i found a local mustang speed shop that dislikes them as well and gives me prices that always beats D&D Motorsports in Valencia, Ca. (not to be confused with D&D Performance in Wixom, Michigan who sells trans and drivetrain parts.)

i've had dealings with these fools for the last 2 years. if anyone has questions, i've got answers.

 

[donjohn]

sorry i didn't specify... The car shakes in neutral as well. When the rpm gets up to about 4500 it starts shakin again but the car does shake other times just not consistently.

Sometimes it will start, idle and shift almost perfectly then other times i start it and it shakes really bad, then i start goin and it stops shaking and then starts up again when i either get it up to about 4500rpm or go to stop.

 

[cb18201]

harmonic balencer is the only other thing i can think of, i would get that checked out even if you dont think that is it. its worth a try

 

[donjohn]

I didn't even think that would be the problem but i'm going to check it out tomorrow. Thanks Alot everybody (<- wow, first useage of the smiley)

 

[clang5oh]

when my harmonic balancer went out, it was never a consistent shaking. at idle it would shake. at driving speeds it would be fine, but when i revved it for a downshift it would shake, at first i thought i blew my clutch apart.

 

[Slow5.0]

I have same problem after I rebuild trannt , balancer is going bad , I gonna replace this friday with street/race SFI balancer

 

[aaamoranto]

Is vibration in the car at high RPM(5000 up) also a sign of harmonic balancer failing?

 

[donjohn]

does your car shake in neutral when you rev it up to 4500 rpm? if it doesnt shake and only shakes while your moving at 4500rpm chances are its your U-joints. did you replace your gears because that is a common problem when you replaces gears.

So I gather my problem is the harmonic balancer but this post might apply to your prob

 

[Slow5.0]

Is vibration in the car at high RPM(5000 up) also a sign of harmonic balancer failing?

I have vibration over 5000rpms and balancer is very bad

 

[Rootus]

If it's the harmonic balancer, that's something you want to fix. Internal engine damage awaits you if you don't fix it.

Dave

 

[donjohn]

Hey guys thanks alot- With a new Harmonic Balancer about $100 later installed today, the car runs great. Good thing everybody suggested that was the problem or i'd be switchin out parts right now.

Thanks!

 

[Slow5.0]

How about this a few months ago I had vibration 5K rpms and up and I replace balancer with aftermarket one from 50resto http://secure.50resto.com/product1.cfm?SID=1&Product_ID=1733&Category_ID=571 after installed balancer vibration are gone BUT last night I installed after market upper and lower control arms and laste when I start car I find out vibration is back but this time 4500rpms and up
Tomorrow I gonna check balancer and see whats wrong now

 

[Venom351R]

From what I have been told, the harmonic balancer on the 5.0s are notorious for going bad..

luckly mine has lasted 116,000 miles so far. Although that dosent change the fact that I have Romac ballancers waiting to be installed next month

 

[InWhatGear]

What exactly goes wrong with the balancer that makes it vibrate?
Does it start to loosen itself from the crankshaft, or something? What should I be looking for when I check it.