This comes under the "I know it's wrong, but how do you fix it" heading. I bought an unused TKO 600 kit from NHVette for my '69. Upon install with the stock rear transmission mount, the transmission tailshaft appears to be low. The differential yoke is pointed down slightly as well, with the stock (or poly) mount bushings. It looks like the driveshaft is pinched at both ends. I know the two yokes should be parallel, but I'd have to raise up the rear transmission mount about 1/2" (will it still fit in the tunnel?), and the differential yoke the same (which would make it hit the frame mount) to get them parallel. The longitudinal axis seems to be OK if I pry the rear of the transmission towards the driver side. A couple of pics to illustrate. Any help or advise would be greatly appreciated.

Jim

 

From what I can see it looks good to me the way it is. Not sure what you mean by the driveshaft being pinched.

There is very little clearance between the tunnel and the top of the transmission access plate. In fact, just enough to accomodate the tunnel insulation that comes with the automatic, so I wouldn't try to raise the tail. The driveshaft needs to be off center because the engine is mounted off center towards the passenger side in the chassis.

 

Shafrs,
I'm not too worried about the long axis (left and right), but I'm worried about the verticle where the transmission tail shaft points down, and the differential yoke points down as well (that's what I meant by pinch). I guess that's what U-joints are meant to fix...

Jim

 

I agree with shafrs3, I think your assembly looks fine. Your first picture looks as if the driveshaft is parallel with the frame rails which is good. The engine/trans should be inclined at about 4 or 5 degrees to the tailhousing. U-joints need axial misalignment to work properly.

Edit: After looking at the diff joint, it does appear too high. That angle will change depending on how tight the front bolt is on the lower mounting bracket (the one with the rubber isolators).

 

BBShark,
Thanks for the input. When you say you think the diff joint is too high, do you mean the yoke is pointed too far up? With both of the front and rear u-joints tighter at the top and wider at the bottom, I thought that was bad.

Jim

 

I have a 68 with a 2.50 inch driveshaft and a Tremec, same setup as yours. The bottom of my driveshaft is about 1 inch away from the top of the crossmember. I have about 1 inch of clearance between the tunnel and the rear of the driveshaft. It's very tight in there but looks to be about 1 inch clearance all around.

Now you have me thinking. I just went to the garage and checked the installed angles. The diff is up (in the front) 1 degree. The driveshaft is level. The engine is 4.5 degrees down (at the tailhousing). You are right, I think you want about a 5 degree difference to get the needle bearings in the u-joint caps to turn. Perhaps the side to side driveshaft misalignment added to the 1 degree alignment is enough.

You do nice work, that frame looks better than new.

 

BBShark,
Have you had any vibration problems? If not, I'm gonna press with my existing angles. I may shim the rear transmission mount up just a bit if you say you have an inch clearance. I just don't want to put the body on it and have the transmission hit the tunnel. Thanks for the replys.

Jim

Gotta love the '68 Here's mine...

 

Did you send the photos to Kiesler? Even if you bought it from another user, it is their kit. As much as they monitor the posts here on their products, they probably would like to help you have the right angles so you will be satisfied and recommend their products to others.

 

Mark,
I was kinda hopin' they'd weigh in. No sign yet. I've got a week before I can get back to work. Maybe a revalation will hit me over the noggin.

Jim

 

You need 3 degrees of angle to make the U-joints work. A perfectly straight driveshaft creates a whipping motion and certain vibration. It doesn't matter how you acheive the three degrees trans up or down right or left as long as you have the three degrees. We have used a large washer or two under the differential pinion mount as was posted earlier by another forum member to bring the nose of the diff down to bring the angles in the correct area. As far loosening the diff pinion mount nut to lower the nose of the diff is concerned it's a no-no it must be spaced down. The diff mount willl have play and will clunk on decel and acccel if the nut and bolt are loosened. The diff pinion mount has a sleeve that allows the bolt and nut to be tightened and allow movement. As was also mentioned earlier the trans is very close to the tunnel and in some cases too close. You may be surprised when the body goes on just how tight things are. The other thing to consider is the trans yoke to emergency brake cable. The trans needs to be close to the tunnel on the passenger side to clear the cable.
We've put in quite a few and the tunnel can be very tight on the top of the trans on pre-75 cars because the fiberglass floor sags in the center. We've installed rubber biscuits between the center crossmember and the floor with a steel plate to spread the load. This brings the floor back level over time and the Tremec transmission has sufficient clearance.

 

Jim -

I just got back in from vacation and only have sporadically popped in on forum since 3/12.

When in doubt, give Keisler tech support a shout! I'll also send them a link to this thread.
865-609-8187 Ext 2

 

hawgn68:
Please give me a call at your earliest convienence and we can discuss this driveline angle issue. In a perfect situation, the tailhousing should be at 0 degrees or not more than 5 degrees positive, while the pumpkin should be the exact opposite angle of the tailhousing. In other words, if you have 3 degrees positive at the tailhousing, you should have 3 degrees negative at the pumpkin. This can be acvhieved several different ways and I will be glad to discuss this with you when you call. You can reach me at customerservice@keislerauto.com or at 865-609-8187 ext. 201

Richard
Tech support/Customer service
Keisler Engineering

 

You do understand that Vettes have their motors offset to the passenger side?

 

Good info, guys. I'll call you Richard to see what the options are. I know that ideally, the two yokes (differential and trans) should be parallel (one pos and one same degree neg). But right now they are both negative. Gkull, the offset left and right is easy, it's the vericle I'm worried about.

Jim

 

I don't like the looks or your alignment. I agree the transmission is too low. It needs to come up.
You are NOT trying to get the transmission in a straight line with the pinion but you are trying to get the transmission output shaft as high as possbile. It will always point down but at the same time as little as possible.
You then have to get the pinion pointing UP at the same angle as the transmission points down.
Equal but opposite angles cancel each other.
Raising the pinion is strictly a matter of the donut/spacer thickness.
I have done a number of these swaps but with the body on.
I push the transmission as high as possible, cut the floor to clear the tower , if you cut carefully the tower just passes through the floor but using a jack I push the transmission as high as possible until it is touching the tunnel but again the tower passes through the floor. In this possition I make the mount on the crossmember and then use a poly mount and count of the slight sag to pull the tranny off the tunel once the weight is taken by the mount.
I then use a protactor to measure the output shaft on the transmission. Say it is 1 degree down.
I then set the pinion using the same protactor to 1 degree UP by playing with the donut.
As for side to side I string the car with a string down the centerline from the rearend to the harmonic balancer and then make sure everything falls along this string.
I could go into this more if you want.

 

Norval, Is your driveshaft parallel with the side frame rails (horizontally not side to side)?

 

I don't know. I ran a string from the centerline of the harmonic balancer and the centerline of the rearend and then aligned the transmission, drivesaft and pinion along this string and yes it takes work but I did whatever it took and ended up with a totally vibration free setup. Up to 130 mph where I quit the shift handle is rock steady.
I hang around a race car shop and they string all their drive trains.
Originally I found the pinion pointing off badly towards the front passengers wheel.
I ended up modifying the crossmember to align the pinion with the crank centerline.
Yes it takes work but the end result is worth it.
As for the drivetrain aligning with the frame rails this wasn't a concern of mine.
A vibration free drivetrain was.

 

Norval, I am looking for installed angle information about the driveshaft because I would like to do this right also. I just don't see how a big block with a Tremec could be mounted in a C3 at 0 degrees (from the post above). The balancer is right on top of the cross member so the front of the engine cannot rotate down and the length of the engine/trans (from balancer to U-joint) is probably 60 inches. In order to change the engines installed angle 1 degree, you have to move the tailhousing UP 1 inch. My engine is in at about 4 degrees from horizontal with the Tremec crushed up in the tunnel (with a hole cut for the shift tower) and there is no way I could move the tail up 4 inches to get it level.

I guess I am skeptical that the engine in any big block C3 is installed level. Surely someone knows this.

 

You are reading this wrong. The drivetrain can be checked in two different planes. Vertical and horizontal.
When I string the car I am checking that everything is in a straight line, not up and down but side to side.
What if the back of the transmission is actually pointing off to the passengers rear wheel and believe me most do. Wouldn't you like to straight this alignment? Shouldn't the centerline of the crankshaft, the transmission , driveshaft and pinion form a straight line side to side?
I am not talking about up and down but a straight line side to side.
I moved the back of the transmission towards the drivers side and moved the pinon/ A stock pinion points more towards the passengers front wheel. I moved mine to the left rotation or more towards the centerline of the car.
So to align side to side I moved the back of the transmission towards the drivers side and the pinion also towards the drivers side. This has nothing to do with up and down.

For up and down agian I raise the transmission on a jack until it is resting against the tunnel but not the tower. I cut the floor to fit the tower through the floor and into the consol. I then mount the transmission with a poly mount and the amount of sag in the mount gives me the clearance.
Next I measure this down angle and then adjust the pinion angle equal but opposite. I raise the nose of the pinion to equal the down angle of the transmission.
The harmonic balancer is just a point I use at the front to center the string. You can not use the frame rails. When you remove the rear spring there is a hole in the cover. I made a plug with a plumb bob to fine the center of this.
After work everything else using plumb bobs aligned. When I started nothing aligned. The tailstock was off to the right of the line and so was the pinion.
Please don't tell me about motor offset. I understand this more then most because of the blower sticking out of the hood.

 

The engine should sit straight back and the driveshaft is angled inboard because the pinion is almost centered (I think it's 3/4 off center)..either way the pinion is closer to the center than the engine. If you line it all up you will have an angle at the pinion but not at the trans and your engine will sit angled in the car. It's not supposed to be like that. the top view posted there looks good, that's how it's supposed to be.

the side view looks like the trans needs some shimming to get similar but opposite angles there and on the pinion.