TWRViper

Hey guys,

I am new to the forum and I have a question for all you manual transmission GT owners.

I am considering getting a 87 GT from a local. He wants $7000 for it, but he did put a lot of work into it.

I took it for a test drive and noticed at low RPM (and low speeds) between 1500-2000 RPM in a high gear there was a vibration/clunk that seemed to be coming from the rear every once in a while if i were to slightly depress the gas. The owner didn't know what is was and said that all Mustangs he drove had that feeling. He simply said he drove in 2nd or 3rd @ 3000 RPM rather than 4rd or 5th @ 1700 RPM around 40-45 MPH.

I have a tendency to drive in high gears (5th @ 30 MPH) if I am not trying to get anywhere fast and trying to conserve fuel (in my Mazda MX6 V6). Is that a bad habit in MTX Mustangs?

Here are the mods on that car that are relevent:

GT40 - 1000 miles
Racing tranny? lower 1st gear - 1000 miles
King Cobra clutch
New tranny mounts
Aluminum driveshaft
Control arms
3.73 cobra rear end

Any thoughts on what this vibration/clunk could be? I would be considering an aluminum flywheel if I were to get the car.

Thanks

Tom

92hatchLX

What's an MTX mustang?

TWRViper

I ment manul transmission. sorry

92hatchLX

Oh that's okay, sorry bout the problem I have an automatic... Check U-joints though especially the rear one, there should be no play there if you move the drive shaft around.

Trannyman

Check those u-joints, and make sure all of your mounts are Ok. Like, motor mounts, tranny mount, and the bushings in the crossmember. You may need a pry bar to check the mounts as it's hard to tell if a mount is good or not unless you try to lift up the engine or tranny.

TWRViper

Thanks for the input!

So it sounds like the u-bolts and the bushing on these mustangs are common problems. I guess that is normal for old cars.

mustang8719

Also check the sway bar mountings and the shocks.
Also find out if the control arms have Urethane bushings in them.That might not be the problem but might transfer some vibration into the body.

P.S.I.cho

check the rockers/lifters but i dont think it would be that bad so

86HOGT

My u0joint in the rear is a bit loose and vibrates like a **** at higher speeds. Honestly, that's not that much into the car or anything special for $7000.

TWRViper

Those aren't all the mods.

I will try to list all the modifications:
87 GT Convertible garage kept)
Cobra motor GT40 heads - 1000 miles
Somesort of aftermarket transmission 1000 miles (feels solid)
aluminum driveshaft
carbon fiber ram air hood - functional
CAI
shorty headers
larger alternator
underdrive pulleys
cobra posi trac rear 3.73 with rear disks
offroad H pipes
92 interior (seat belts don't seem to line up)
Viper alarm
crossdrilled rotors - front
lowering springs - front
coilovers - rear
tokico shocks and struts
17x9 cobra rims
subframe connectors
three point front strut tower brace
removed AC
carbon fiber tail lights
projector headlights
aftermarket rear spoiler
custom interior and trunk interior for 1-12 sub box (doesn't look all that nice)
dynomatted trunk
4 point bolton roll bar
king cobra clutch
larger MAF
larger throttle body
Paint looks good but not perfect
Top looks good but will eventually need to be replaced
200 MPH white face guages
190 warbro fuel pump
adjustable FPR
24lb injectors