First of all, I'm glad to be part of the community. I purchased a 2005 V with 112,000 miles a few weeks ago for a steal and I've been enjoying reading all the existing resources out there in learning about the car.

The motor mounts and transmission mount were shot on the car. I replaced the motor mounts with Creative Steel Stage 2 Poly's and added a Revshift block to the trans mount, which raised the transmission up about an inch!

Unfortunately, I now have three new symptoms as a result of this work:

1. Parade clunk - I have already purchased a 3.2125 Chevy Bushing Kit to modify to replace the pinion bushing. This isn't a surprise given how widespread this issue is and the new driveline geometry.
2. Some whining - I believe this is from the driveshaft carrier bearing/support, which I intend to replace - not surprising.

And the one I'm worried about:

3. I am noticing some dragging in the driveline, especially upon deceleration. I am also noticing a burdened feeling when accelerating - the car just doesn't feel as quick as it used to be.

With regard to #3, I am concerned that a drivetrain alignment problem could be causing this. I have been reading information from Tremec and others (https://www.4crawler.com/4x4/CheapTr...line-101.shtml) about drivetrain alignment techniques - I want to make sure I am thinking about this the right way:

• The transmission angle is adjustable by the support which now has the very firm revshift support (and about an inch higher).
• The rear differential pinion has more vertical deflection now that it will in the future when I install a polyeurethane pinion bushing.
• I could have a bad guibo or the wrong thickness guibo (although mine doesn't look too bad and it is not distorted as if the bolt center was the wrong spacing.
• The previous owner could have done something funny (he says it has a Generation 3 rear end and the rear end doesn't have a guibo, which I have heard some cars do.

In my reading, with a CV setup like we have, I am looking for the rear propshaft section to take up nearly all the angle. The first section should run parallel (between the transmission and the driveshaft support.

When I receive my angle gauge, I need to measure my angles to see what I am currently set at - and really the only things I can control are: l

• lowering the transmission position by trimming or removing the Revshift bushing.
• shimming the center support - although the angle of the support is not adjustable as it mounts only by two bolts on an axis perpendicular to the driveshaft.
• following the correct torque spec and sequence on all bolts

If anyone can chime in here and let me know if I am missing anything here or thinking about this the wrong way, please let me know. My understanding is that with a CV setup, I shoudn't have to worry about this, but I can't get over how sluggish the car feels since installing the motor mounts and transmission insert.

 

The V6 cars had giubos at both ends of the driveshaft, but Vs only had a front giubo.

As you said, you want a straight shot from the output of the transmission to the drivetrain center support, because the giubo really can't take too much misalignment. The height of the engine mounts and transmission mount will determine the angle of the engine/tranny combo, which thus determines whether the front half of the driveshaft is pointing where it needs to. My guess is with the rear of the tranny raised ~1", that you're aimed too high. I believe others have had that issue with the Revshift bushing insert.

 

I have been playing with this as well after adding the voodoo chicken center bearing i noticed a vibration, I believe in my case due to the UMI motor mounts being shorter than stock, I currently have the transmission cross member spaced down, i got some big washers under the 6 mounting bolts. I have yet to get it up to 70 mph to see if it is better though. but that is an option to lower the back of the transmission as well.

 

Interesting. The Creative Steel matched up height wise to the OE ones I took out.

 

The whining could be from the diff. The clunking can be the driveshaft carrier bearing or the rear end slapping the mounting hole where the forward rear diff bushing gets abused to all heck.
The sub-frame has weak rubber inserts that have begun to degrade by now if they are stock. All the other soft rubber bits allow more deflection thus, cause the rear end to feel sloppy and loose. If the rear end and drivetrain is OEM, the answer is probably not shims. But I think worn out stock bits that need upgraded vs replaced with OEM parts that will only fail again. The transmission mount being higher can cause the problems but the 2 piece driveshaft splined with a CV joint should take that height into account.

The Gen 3 refers to the diff unit itself. GM had to redesign the diff multiple times to avoid class action lawsuits and I dunno how, but they did avoid a class action lawsuit.

 

Parade clunk: driveshaft coupler is the primary source, differential bushings are the secondary source, excessive differential backlash is the tertiary source. Whining: differential oil or bushings.

Vibration that gets worse with speed (but not RPM): worn tires or failure to torque wheels in a star pattern with a torque wrench. Failure to properly torque flywheel and clutch is the secondary source. Driveline misalignment angles is the tertiary source. Quaternary source is failure to torque the driveshaft rubber coupler in a star pattern.

Excessive drag: differential oil is the primary source. I replaced mine at around 15k miles (w/1 gal Redline 75W140) and it felt like someone took 200 lbs off the back of the car. Transmission oil is the secondary source. 3 quarts Redline D4 ATF and 1 quart Redline MTL 70W80 GL-4 is still my recommendation--it will add drag but the shifting improvements are worth it.