Ah -- yeah that won't work....


Tunnel issues with the new bigger transmissions --- and combine that with our low stances --- yeah --- that's usually a tranny hump mod and driveline tunnel raise....

Those are easy mods even in a done car..... it's a carpet issue --- and back seat tunnel modification...

I've already cut my tunnel once for the trans and don't mind doing it again. I'd like to do an integrated chassis brace and trans mount like DSE does while I'm there. I also don't mind doing the tunnel for the shaft as I have no interior now. It's the fact that many other people are running SBC/T56 combos in 2nd gens and aren't having these issues at all that concern me. Maybe I am just that low compared to them, but I'm concerned I'm doing a lot more than other's have had to do. That makes me questions what I've done wrong.

Thanks Greg. I appreciate the reply.

Ah -- gotcha Trey.

Your motor only need be down 2* - and assume you have a degree / angle indicator.... The car needs to be on it's own 4 -- so jackstands under the axle so the weight in on it.... and place the angle indicator on the face of the pinion... if it's up 1 to 2*....

Then it's a matter of suspension travel.... and that's probably UP 2" and down 2" or in there.... and of course there should be a "bump stop" of some kind to prevent the stuff from hitting...

Trey, my driveshaft is same way, higher at the rear than the front. A lot of guys with lowered vehicles are in the same boat...with no vibrations.
Driveshaft angle is irrelevant. You should see the angle of my brothers rear shaft on his 87’ truck. 17” of lift. It’s steep, and there’s no vibrations with 44” Boggers.
Engine/trans combo should be 2-3 degrees down. Even 4 is ok, I’ve done it. The trick is your rear must be up the same, whatever it is. These angles are also irrelevant of frame/chassis angle. Measure against shop floor, not chassis.
Are you using shims under the rear end to adjust angle? I’ve seen these shims not be exactly the same, and cause binding on the rear end housing when the u-bolts were torqued down tight. Angled lowering blocks can be the same way.
I know you’ve been all over this for too long now. Let’s hope the driveshaft change fixes it. DONT TORCH THE CAR!!!!

The problem with the rear end being higher than the trans output shaft is that the working angles increase when the suspension compresses. So if you start out with a working angle of 3.5, under full compression it may go to 5.5.

This is exactly why you see people on here cutting their tunnel to get the tailshaft of the trans up higher. That will allow for more conventional and smaller working angles. The more severe the working angle, the more they tend to vibrate as speed increases.

This is what I'm thinking will end up happening. I'm just not sure I can raise the engine due to how close I built the headers to the floor.

I know a CV shaft has greater working angle capacity but I'm not sure it would be right for my application. I'll see what the information they come back with. I didn't hear from Lucas today. Maybe tomorrow.

Thanks everyone.

Have you determined your actual working angles? I can't imagine a vibration around 60 mph unless your angles are very severe. Not in the 3-5 range. Normally is would get worse with speed with this scenario. Start to feel it around highway speed and increases as you speed up.

About 5.5 to 6 degrees, Todd. Unless, of course, I'm doing it wrong again.

With the whole car sitting on cribbing, I get 2.5 degrees nose up on the pinion, 3 degrees front down on the driveshaft, and 3 to 3.5 degrees down on the tail shaft.

Vibration doesn't get worse as I speed up, but it's still very obvious. The frequency may increase a little with speed though. Intensity does not.

Thank you

So your rear working angle is 5.5*

Your front working angle is 6 to 6.5*

It looks like this exaggerated drawing of passenger side view

pinion / \ / engine

You need to roll the pinion down.....a lot.

You will find if you set it up like

pinion \ _ / engine

you will be able to get working angles under 3* and then get them to match.

AH --- actual real numbers to work with!! LOL


Donny is correct..... your working angles are a total mess.


I'm glad I got you to look at them. LOL