Aligning the drive train
Thread Starter
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Aligning the drive train (fireball)
fireball I went with the steel because aluminum is hard to weld. Our local shops will not do it. It still costs me about $256 and $265 for the last two shafts. I go with the 3 inch tubing and new ends for this price. The stock 2 inch tubing is pretty small and hopefully the 3 inch will solve that problem.
Instructor
Joined: Apr 2002
Posts: 229
Likes: 3
From: Highland MI
Re: Aligning the drive train (norvalwilhelm)
I just did not want you to do alot of work that is not needed. I see race teams chasing problems all the time with out them looking at the obvious.
By using a shorter drive shaft, it does increase the angle of the shaft. I just wonder if it is bad enough to be an issue. Didn't the 1982 vette have a 700R4?
What about your engine. Is it the same as before you changed to the overdrive.
There are a lot of corvettforum members that have installed overdrive transmisions. I wonder if everyone is having this vibration. I installed a T-56 but have not put it on the road yet.
By using a shorter drive shaft, it does increase the angle of the shaft. I just wonder if it is bad enough to be an issue. Didn't the 1982 vette have a 700R4?
What about your engine. Is it the same as before you changed to the overdrive.
There are a lot of corvettforum members that have installed overdrive transmisions. I wonder if everyone is having this vibration. I installed a T-56 but have not put it on the road yet.
Thread Starter
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Aligning the drive train (69schemers)
69schemers The motor is the same but this is not rpm related. You can go to 80 , push in the clutch and coast down from 70 to 62 and it is still there. It comes back at 90 alot harder. If it was the motor rpm would affect it not speed?
I appreciate you making me think about it.
Instructor
Joined: Apr 2002
Posts: 229
Likes: 3
From: Highland MI
Re: Aligning the drive train (norvalwilhelm)
Did youhave your half shafts balanced? Did you remove you rrear rotors for any reason? Both could cause a vibration. But, doesn't explain the twisted drive shaft.
:crazy:
:crazy:
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Re: Aligning the drive train (norvalwilhelm)
So Norval, are you saying the vibration is there even when the clutch is in?
mine vibrated only under load in neutral is was fine...
Aparently ujoints complain a lot more when under load...
mine vibrated only under load in neutral is was fine...
Aparently ujoints complain a lot more when under load...
Thread Starter
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Aligning the drive train (69schemers)
69schemers. This is my 8-71 blown 460 with 12 pounds of boost, twin 850 double pumpers, wild set of heads, full roller and 940 desk top dyno horsepower.
I did break 3 700-R4's in one summer with 12.50 ET street slicks. I also twisted the axles
I did break 3 700-R4's in one summer with 12.50 ET street slicks. I also twisted the axles
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Burning Brakes
Joined: Oct 2001
Posts: 860
Likes: 40
From: Woodforest
Re: Aligning the drive train (norvalwilhelm)
I had the same issue with mine. At around 68, the vibration started, got worse until around 78 or so, then decreased slightly. I had my tires balanced, still there. Started checking u-joints, driveshaft, etc and noticed the same issue with misalignment of the trans to diff. I corrected this by slotting the back transmission mount, bringing the alignment closer to true. This did not solve the problem. Started considering having the half shafts and drive shafts balanced, but went to another tire store and asked them to check the tires one more time.
This guy came back and said the rear tires were out of balance and he couldn't balance them properly due to a slipped belt. The tires were a little worn so I went ahead and got two new ones. Problem solved. My lesson learned was sometimes doublecheck the simple stuff because the first idiot may not know how to do his job properly! Would have saved me about 6 hours of fooling around with this issue. :yesnod:
This guy came back and said the rear tires were out of balance and he couldn't balance them properly due to a slipped belt. The tires were a little worn so I went ahead and got two new ones. Problem solved. My lesson learned was sometimes doublecheck the simple stuff because the first idiot may not know how to do his job properly! Would have saved me about 6 hours of fooling around with this issue. :yesnod:
Drifting
Joined: Sep 2000
Posts: 1,355
Likes: 0
From: Germantown Maryland
Re: Aligning the drive train (norvalwilhelm)
Norval,
My vibration was, I think, accountalbe to a bent Diff mount. In my case I think the drive shaft was straight aligned but due to the bent top mount on the Diff , the Shaft rear Ujoint was slightly kinked. In other words the diff yoke was pointed slight to the ground instead of parallel. I had vibration at 55-65 MPH that I noticed a lot. Just something to check..
Chris
:flag
My vibration was, I think, accountalbe to a bent Diff mount. In my case I think the drive shaft was straight aligned but due to the bent top mount on the Diff , the Shaft rear Ujoint was slightly kinked. In other words the diff yoke was pointed slight to the ground instead of parallel. I had vibration at 55-65 MPH that I noticed a lot. Just something to check..
Chris
:flag
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: Aligning the drive train (69schemers)
Norval, one thing concerns me, and perhaps you have thought it through.
Essentially, you are rotating the differentiaql assembly, making the pinion
point towards the tranny yoke. This helps to decrease the angular
difference between the two stafts. I agree. However, by rotating the
differential assembly by X degrees, aren;t the halfshaft yoke to spindle
angles increasing by the same angular value (X degrees) ?
It seems to me that you may be pushing the "knot in the noodle" so-to-
speak. Perhaps the optimum situation would consider the halfshaft yoke
angles - and settle on a differential rotation that is somewhat less than "X".
Reasoning that the halfshafts are slightly shorter than your new driveshaft,
I would say that 2 degrees of compensation would be more than the
mathematical ideal. Of course, once your motor is figured into the equation,
the whole thing goes non-linear and is not easily calculated.
Do you have poly mounts all-around ? The flex in the mounts could make
the issue worse.
:seeya
Essentially, you are rotating the differentiaql assembly, making the pinion
point towards the tranny yoke. This helps to decrease the angular
difference between the two stafts. I agree. However, by rotating the
differential assembly by X degrees, aren;t the halfshaft yoke to spindle
angles increasing by the same angular value (X degrees) ?
It seems to me that you may be pushing the "knot in the noodle" so-to-
speak. Perhaps the optimum situation would consider the halfshaft yoke
angles - and settle on a differential rotation that is somewhat less than "X".
Reasoning that the halfshafts are slightly shorter than your new driveshaft,
I would say that 2 degrees of compensation would be more than the
mathematical ideal. Of course, once your motor is figured into the equation,
the whole thing goes non-linear and is not easily calculated.
Do you have poly mounts all-around ? The flex in the mounts could make
the issue worse.
:seeya
Instructor
Joined: Feb 2002
Posts: 154
Likes: 0
From: hersey mi
Re: Aligning the drive train (norvalwilhelm)
Norval,
Hi, love your car. No, love your motor :D someday..... Anyway, I stuck a 700r4 into my 69' and have been chasing down a vibration problem as well. I have mine narrowed down to the drive shaft angle. I did the same type of hanging strings and measuring as you. At first I thought, man this thing is waaay off center, but have since found most of it is supposed to be that way :rolleyes: However, the one thing I did find was the angle at the trans to driveshaft was off approx. 2 degrees more than the shaft to axle. I fab'd an adjustable trans mounting plate so I can test the trans to drive shaft at different angles. The vib comes on at about 70 mph and progressively gets worse as mph increase.
I am very interested to see what you find out with your problem. As soon as the weather clears up here I'm taking my car out for a test ride to see if this adjustment helped. As you know tracking down this kind of vibration is a major pain and can be very frustrating. Talk to you later.
Rick :cheers:
Hi, love your car. No, love your motor :D someday..... Anyway, I stuck a 700r4 into my 69' and have been chasing down a vibration problem as well. I have mine narrowed down to the drive shaft angle. I did the same type of hanging strings and measuring as you. At first I thought, man this thing is waaay off center, but have since found most of it is supposed to be that way :rolleyes: However, the one thing I did find was the angle at the trans to driveshaft was off approx. 2 degrees more than the shaft to axle. I fab'd an adjustable trans mounting plate so I can test the trans to drive shaft at different angles. The vib comes on at about 70 mph and progressively gets worse as mph increase.
I am very interested to see what you find out with your problem. As soon as the weather clears up here I'm taking my car out for a test ride to see if this adjustment helped. As you know tracking down this kind of vibration is a major pain and can be very frustrating. Talk to you later.
Rick :cheers:
