73 Mach 1 didn't make it out to "Ford vs Chevy" Night

[BigPinoyHunk]

well the last friday before last i drove the mustang to work and leaving the base onto CA-20 i hit my newly found USABLE 1st gear hard and powershifted into 2nd gear really hard. shortly afterwards i felt a rear vibration of the car, the vibration isnt in my steering wheel and its definately in my rear and it will shake my rearview mirror when it travels.

it took me a while to check it out but, i've made sure it isn't my u-joints by pressing on them really hard to see if they'll move. i removed my driveshaft and did however find my old transmission mount was super separated from the metal and etc so i replaced it. i also made sure it wasn't my wheels/tires, i put my wife's 07 mutang gt wheels on there which i know are balanced for sure and the vibration is still there.

i have aftermarket tom's 31 spline axles and i strongly believe i don't have enough power to twist or bend 31 spline axles with my current 460 and especialy with only drag radials.

my driveshaft is NEW when i did the tko600 swap and no weights look to be fallen off.

i didn't however, replaced the axle bearings when i had the change when i did my cobra brakes. but can they really cause a vibration after a super hard 2nd gear shift?

and i do however know i have a OEM cased 9 inch with a OEM differential which i hear i have enough power to break because of the case not being a notdular case (thats being fixed shortly)

what do you guys think it is? i was quite angry not to be able to race her tonight and to only watch the wife race her 07 ft today.

 

[marks73]

Sounds like it may be a broken tooth on your ring gear:s Probably time to pull it and inspect before you do further damage. Man I hate spectating.

 

[BigPinoyHunk]

i did forget to mention that it only does it at 60mph+ and it seems to be ok at lower speeds.

this would automatically assume wheels/tires but i've put two different sets that i know for a fact that are balanced well and no dice.

and when i was under there, i can turn the pinion on the 3rd member about 1/2 inch in both directions before the wheels start to spin. is this excessive play?

 

[downwardspiral]

i did forget to mention that it only does it at 60mph+ and it seems to be ok at lower speeds.

this would automatically assume wheels/tires but i've put two different sets that i know for a fact that are balanced well and no dice.

and when i was under there, i can turn the pinion on the 3rd member about 1/2 inch in both directions before the wheels start to spin. is this excessive play?

I'm no rear expert but I think the play is acceptable, mine does the same since it was rebuilt.. has survived numerous holeshots and burnouts. I would double check the u-joints though, they should be the weakest link the in drivetrain.. The same thing happened to me a couple times and it was the u-joints.. Hold the pinion still and wiggle the driveshaft while its in neutral, there should be no play at all, no clicking noises. I'd also check your pinion angle while you are down there, that's what was killing u-joints for me. Last time, the first thing I did was check the u-joint and I deemed it ok on the side of the road. When I got it home I checked it again before I panicked and it was actually bad. I guess it could be a wheel bearing, but I would think it would make noise mostly around turns and whatnot.

 

[c9zx]

Since the vibration was not noticed before the really hard 2nd gear shift it probably isn't anything like pinion angle or a freaky damper problem. It sounds like something bent, twisted, or broke on the shift, it is a high torque engine with sticky tires. You might try putting it on a lift that allows the rear tire to rotate, be careful, run it in gear to look for non-circular motion at both ends of the driveshaft and the tires. years ago the standard TKOs were bad about bending the main shaft, don't know if Tremec solved that in the 500/600 series transmissions. You could pull the axles to see if you have twisted the splines enough to change center to center alignment from one end to the other (read split and about to part). I hope you get it sorted out. Chuck

 

[Tnfastbk]

Since the vibration was not noticed before the really hard 2nd gear shift it probably isn't anything like pinion angle or a freaky damper problem. It sounds like something bent, twisted, or broke on the shift, it is a high torque engine with sticky tires. You might try putting it on a lift that allows the rear tire to rotate, be careful, run it in gear to look for non-circular motion at both ends of the driveshaft and the tires. years ago the standard TKOs were bad about bending the main shaft, don't know if Tremec solved that in the 500/600 series transmissions. You could pull the axles to see if you have twisted the splines enough to change center to center alignment from one end to the other (read split and about to part). I hope you get it sorted out. Chuck

+1 :goodpost:

 

[BigPinoyHunk]

alright guys, today i got my good old trusty ford buddy at work to help me today before my daycare hours ended.

i put the entire car on jack stands and ran her. we shifted all the way to 5th gear to about 70 mph (pinoin angle right with the jacks on the axle tube) and i couldn't find anything spinning out of the normal. the wheels spin true along with the driveline. i did however see the pinoin wobble when we started stopping completely and then taking off in 1st gear. we couldn't quite figure it out. we took off the driveshaft and trying to inspect the pinoin rotation or something for some kind of damge to the 3rd member. we didn't really find much. however..............i went to take the driveshaft out of the botom of the car to possibly take it to have the balance check again (even though its brand new and built). i said, lets check the u-joints again and take off the caps. the first one was brand spanking new, the second one had a broken piece broken off and all the needles went to the same side of the cap. i could almost tell right away when i looked at the ujoint when the rubber was lifted up a tad one the inside part.

with the ujoint installed on the pinoin, i was praying on every angle of both ujoints and found no play on any cap so i automatically thought it was ok.

its time to go with the best dam u joints out there instead of the normal auto parts ujoints you can buy anywhere. any suggestions?

a 1330 ujoint is suppose to be good up to 700hp (internet and driveline builders specs) and i'm nowhere near there so i'm assuming i should be ok still.

 

[downwardspiral]

its time to go with the best dam u joints out there instead of the normal auto parts ujoints you can buy anywhere. any suggestions?

Spicer U-joints are supposed to be the best around, I'd get them. My buddy off-roads his jeep with disgusting pinion angles and swears by them.

 

[c9zx]

Glad you found something! Almost anything not made in China or India WITHOUT a grease fitting. Spicer seems to float to the top. Chuck

 

[droptop73]

One weak link found __ more to go. Running a car hard with a manual transmission will find ANY weakness or flaw in the driveline.

I've been crew member on several manual transmission drag cars over the last few years. We have them pretty well bullet proof but there is always something that needs attention.

 

[BigPinoyHunk]

One weak link found __ more to go. Running a car hard with a manual transmission will find ANY weakness or flaw in the driveline.

I've been crew member on several manual transmission drag cars over the last few years. We have them pretty well bullet proof but there is always something that needs attention.

i had to downgrade with the gears because of my tire size and the super fast reving didn't do too much with my 6k max powerband. i went to a 3.50 gear in a nodular case and a 4 pin posi. what i had before was a standard case with a kitted open track diff that had the kit in it to make it a 75% of the time posi.

so now i'll have the HUGE 1350 all the way back to the diff and having the nodular case and aftermarket 31 spline axles should hold up really well. i'm planning on launching at 4000rpms at the track with the drag radials and see how that works out. then going to go FULL SLICKS.

i just couldn't believe i had 1310 u joints in the car. i believe they were original because my car is a OEM c6 car and the 31 spline slip yoke too is a 1310 u joint. i couldn't believe my ears when i heard i had a 1310 u joints on a 460 and a manual car.

its better to overbuild my driveline now along with my diff and axles so its a no worrysome area.

 

[69 Rustang]

Many years ago I replaced a U-joint only to have the new one fail after some hard driving. It had a vibration at speed just as you describe.

 

[BigPinoyHunk]

well my friend's dad built me a nodular cased 3.50 geared posi unit from a 71 mach 1. he told me it has 1350 u joints because i had a 1330 u joint that felt loose in the yoke.

i get a fully new 1350 u joint driveshaft with the reconditioned spicer slipyoke with new driveshaft end yokes using the same 3 inch tube i had. then i go in there to bolt up my new driveshaft and the end caps are too big. i placed my spare 1330 u joint in there and its too small. i am thinking to myself WTF!!!!

i called the driveline shop and told him the situation and told me there is another cap thats called a "cleveland" u joint. i have my original pinion yoke and neither will fit either. i am livid about now and i start thinking about changing the pinion yoke out to a full 1350 but i don't know if i have a solid crush sleeve in there or not.

to make things easiers just for now, i went ahead and got the more expensive conversion yoke that went from 1350 to a cleveland size. it sucks that its a greasable u joint that it'll have to work for now. i guess there are people out there using the 1350 and 1330 u joints out there that are holding up great. but a 3rd member builder told me i'll probably break my factory nodular case before i break a 1350 to cleveland conversion u joint.

however, after all this and got the new 19 tooth speedo gear in. i now cruise at 60mph in 5th gear at 1550rpms (not sure if its running efficiently at that rpm) and at 70mph in 5th gear is at 2000rpms (bottom of efficient and barely 200rpms into my powerband).

my first 2 gears are more usable now and more enjoyable without having to shift thru all the gears before hitting 50mph. or not have to spin to almost 4k just go shift into 2nd gear at 20mph.