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73 Mach 1 didn't make it out to "Ford vs Chevy" Night
#1
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.
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#2
Sounds like it may be a broken tooth on your ring gearConfused Probably time to pull it and inspect before you do further damage. Man I hate spectating.

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#3
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?
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#4
xoliex;31869 Wrote: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.
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#5
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
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#6
c9zx;31942 Wrote: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
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#7
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.
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#8
xoliex;31960 Wrote: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.
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#9
Glad you found something! Almost anything not made in China or India WITHOUT a grease fitting. Spicer seems to float to the top. Chuck
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#10
One weak link found __ more to go. Big Grin 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. Big Grin

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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