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What we need are these black washers shown here....
I used the cradle shims because that's what I had and I also wasn't sure how firmly the rear diff bracket located the diff itself in the cradle. I had to take the front diff mount off to put the damper on and quickly realized that the rear bracket doesn't hold the diff firmly at all. We should have no issues adjusting pinion angle off the front bracket and leave the cradle where it is as long as the bolts will thread. I'd be concerned that if we used more than one washer, the bolt would be at enough of an angle to where it wouldn't thread but we'll see.
I also guess we could use different length bushings to do this as well.
I'm about to install my 8.8 in the coming weeks and I was thinking about replacing the 2 rubber bushings with the revshift poly bushings (for where the big bracket mounts to the cradle). Based on this it sounds like the stock rubber moves quite a bit, but that may be a good thing to allow for alignment? Do you think the harder bushings back there would hinder movement needed for alignment?
I'm about to install my 8.8 in the coming weeks and I was thinking about replacing the 2 rubber bushings with the revshift poly bushings (for where the big bracket mounts to the cradle). Based on this it sounds like the stock rubber moves quite a bit, but that may be a good thing to allow for alignment? Do you think the harder bushings back there would hinder movement needed for alignment?
I doubt it. The diff fell so far after I removed the front mount that I had to jack it back up to get the bolts in it. It dropped a couple of inches on the stock bushings and you would probably never need more than a total of 1/4 or 3/8 of an inch pinion adjustment which you should be able to get no problem.
I can tell you from experience that if you tip the front of the diff down too far the driver side inner CV bolts will contact the subframe. This was figured out by having my bushings (small tops and thick bottoms) installed reversed.
I can tell you from experience that if you tip the front of the diff down too far the driver side inner CV bolts will contact the subframe. This was figured out by having my bushings (small tops and thick bottoms) installed reversed.
That figures....well I'll take it as far as I can and then go back to the cradle. Puzzles me how some cars are fine and others aren't.
I think what I said is kind of hard to read. The poly bushings I have are two different thicknesses. In the correct orientation the thin ones go on top and the thick on the bottom.
What I was saying is that if you inadvertently reverse them and put the thicker ones on top, it will cause the pinion angle to be pushed down. Down far enough that the driver side inner CV bolts ever so slightly come in contact with the cradle. I drove about 65 miles with it like that before I took the time to figure out what the f-ing noise was.
It had CS stumped too since they had never had that problem arise before me. So woot! for being the first idiot to have done that on the record.
I think what I said is kind of hard to read. The poly bushings I have are two different thicknesses. In the correct orientation the thin ones go on top and the thick on the bottom.
What I was saying is that if you inadvertently reverse them and put the thicker ones on top, it will cause the pinion angle to be pushed down. Down far enough that the driver side inner CV bolts ever so slightly come in contact with the cradle. I drove about 65 miles with it like that before I took the time to figure out what the f-ing noise was.
It had CS stumped too since they had never had that problem arise before me. So woot! for being the first idiot to have done that on the record.
So when you swapped bushings, it changed your pinion angle. Could you tell a difference in the car before and after the bushing swap?
Honestly, I can't say. I didn't have enough seat time when they were switched. Plus I was more more focused on the new noise I had.
And this wasn't a bushing change. I had already had these bushings, this was a complete new 8.8 rear I put back in when I didn't like the 3.55's. I just didn't remember which way the bushings went and I guessed wrong when installing them.
To make things even more confusing my bushings are the same height...
Yeah. They are both the same thickness as my tops which are the thinner ones. So they are correct. The bottom bushing doesn't need t be a different size. No idea why some manufacturers made different sizes. Only thing it changes on our cars is how far the front bolts thread into to mount. But that's all.
I emailed CS about getting a few of those washers. Jordan said they were simply 12mm fender washers so I guess I'll dig some of those up.
Thanks for the heads up on this one. I might try some washers there this weekend, as I still have a vibration in the low/mid 40s. I would think installing those washers would be quicker/easier than doing the big cradle washers on the front cradle mounts.
Thanks for the heads up on this one. I might try some washers there this weekend, as I still have a vibration in the low/mid 40s. I would think installing those washers would be quicker/easier than doing the big cradle washers on the front cradle mounts.
Working around the exhaust is a little bit of a PITA and although you'll have to loosen both bolts at the same time to get it to drop some, you only want to take one bolt out at a time or you'll have to jack it back up far enough to thread the bolts.
After Nik reminded me of his axle clearance issues, I figure I'll probably be using a combination of cradle and diff mount washers.
Added a single 12mm fender washer on top of the front bushings today. The driver side bolt was clear of the exhaust, so I was able to drop that one straight down with no issue. The passenger side bolt is almost directly above the exhaust, and there's wasn't quite enough room to drop it down enough to slip the washer in there. I have V-bands upstream of the mufflers, so I undid the passenger one, and that gave enough flex in the exhaust to drop the passenger side bolt to get the washer in there.
I have the Revshift rear diff bushings (the ones at the rear of the diff in the cradle) and that didn't seem to create any issue at all in getting the washers in there. I didn't have to pull down on the nose of the diff - just loosened the bolts and the gap created itself.
Unfortunately, no real detectable change in the vibrations. Actually, it might be a little bit worse. Damn. I had additional washers, and was initially thinking I would put 2 washers in, but decided to just do 1. Based on what I felt on the drive home I don't think putting in 2 would've made it any better.
I got the laser alignment tool from Creative Steel on Friday, but didn't have time to drop the exhaust and pull the driveshaft today to try the tool out. Hopefully I can try that next weekend.
Edit: Went and ran some more errands, I'd say it's definitely worse with the washers installed. Not massively worse, but it seems to have spread the speed range a bit.
For aligning the drivetrain, I told the shop to use the technique that Matt from VoodooChikin recommended (bolt the driveshaft in without the flex disk to see where that puts the carrier bearing, adjust things as necessary). I wasn't there to see it done, but the tech said the driveline was definitely not straight, that the carrier bearing was offset to one side. He loosened the tranny crossmember bolts and was able to shift that a little to get the carrier bearing to line up with the mounting holes.
I know this is a hair pulling experience after spendng 5k plus buying this conversion and getting it installed...the only reason I've spent so much time dicking with this is because vibes like this are a make or break for this car to me. I'd sell it if I couldn't smooth it out but fortunately, I got mine right enough so I'll be keeping it for now.
The challenge I have AAIIIC is continuing to verify what I think is the right way to align the drivetrain in this car. There is a complete lack of information on aligning multi piece driveshafts that use a flex disc so in a sense, we're winging it here. It isn't hard to develop theory on how to align the rear part of the shaft and another theory to align the front part of the shaft but no written confirmation that putting these 2 theories together will work other than the positive results I've personally had climbing under the car and doing it.
While Fuzzylogic was gracious enough to dump a bunch of theory on us in this thread....https://ls1tech.com/forums/cadillac-...pgrades-2.html....translating theory into reality with the equipment we have to work with is the hard part.
Fuzzy's theory that the net "misalignment" needs to be zero is easily confirmed if you're working with u-joints, but the evidence suggest this isn't true if you're working with dual CVs. Based on the link I posted in the thread above (along with Frank's opinion at DSS), "Constant Velocity" joints can work at angular totals that aren't net zero which, simply stated, if you're driveshaft uses 2 CVs, you shouldn't have to worry so much about how they're aligned. U-joints, yes, CVs, no.
So, based on this, shimming the diff to change the pinion angle on you're factory 2 piece is fairly pointless from all I can tell because the rear portion of the 2 piece uses CVs at either end and should compensate for any misalignment you have.
I've been successfully changing the pinion angle on mine to accommodate the U-joint that is at the rear of the one piece DSS provides. The u-joint isn't' as forgiving as a CV and it has certain angular requirements for operation and changing the pinion angle is simply a way to accomplish this optimal U-joint operating angle. You shouldn't have to do this with your dual CV shaft from all the evidence I've seen. So why did they use a u-joint on one end and a CV on the other? Because its affordable and the one CV should be enough to compensate for any misalignment once you get the U-joint operating in the right angular range.
As much of a struggle as this is, I'd reconfirm the alignment of the carrier bearing before going much further with the pinion angle. Mark where the carrier is located now and make changes to it to see how the car reacts to confirm this. This is even easier to do than shimming the diff just make one adjustment at a time.
From what little direct evidence there is about aligning this shaft (that I've been able to find anyway) combined with the one instance of positive results I've had, this should be where you're vibes are coming from. Keep us posted.
EDIT: to make this even more of a pain in the *** is the known vibrations that the T56 has in 5th and 6th gears. Is it possible that what may not have been noticeable when you're drivetrain was stock could be noticeable now because you've change the harmonics/dampening rates of all this crap. I have no idea but I've seen stranger things....
Double Edit: How hard was your driveshaft to install with the shorter adapter? Is it possible to that the adapter is too long or short? Again, I don't know but the easiest adjustment to make at this point is the carrier bearing position so that's where I'd start....
Based on the link I posted in the thread above (along with Frank's opinion at DSS), "Constant Velocity" joints can work at angular totals that aren't net zero which, simply stated, if you're driveshaft uses 2 CVs, you shouldn't have to worry so much about how they're aligned. U-joints, yes, CVs, no.
So, based on this, shimming the diff to change the pinion angle on you're factory 2 piece is fairly pointless from all I can tell because the rear portion of the 2 piece uses CVs at either end and should compensate for any misalignment you have.
I've been successfully changing the pinion angle on mine to accommodate the U-joint that is at the rear of the one piece DSS provides. The u-joint isn't' as forgiving as a CV and it has certain angular requirements for operation and changing the pinion angle is simply a way to accomplish this optimal U-joint operating angle. You shouldn't have to do this with your dual CV shaft from all the evidence I've seen.
Funny you say all that, because that's exactly what I was thinking as I was doing it! I had the car up on a lift at a military auto hobby shop, and one of the other guys was taking a look at what I was doing. I said to him, "There's a CV here, and a CV here, so it really shouldn't matter what the pinion angle is, but I've read other guys say that pointing the pinion down helped reduce vibration." In amongst these various threads and discussions I missed/forgot that your driveshaft has a U-joint. Ah well... I'll take the washers back out Thursday after work.
Originally Posted by ls1247
As much of a struggle as this is, I'd reconfirm the alignment of the carrier bearing before going much further with the pinion angle. Mark where the carrier is located now and make changes to it to see how the car reacts to confirm this. This is even easier to do than shimming the diff just make one adjustment at a time.
Yeah, that's the plan. Well, that and I do want to try the CS laser alignment tool. I want to recruit one of my buddies to come work with me, as it's a pain in the *** trying to manhandle the exhaust and driveshaft off and on by myself with the car up in the air. Hopefully I can do that this weekend.
Originally Posted by ls1247
Double Edit: How hard was your driveshaft to install with the shorter adapter? Is it possible to that the adapter is too long or short? Again, I don't know but the easiest adjustment to make at this point is the carrier bearing position so that's where I'd start....
The tech at the shop that did the 8.8" rebuild (at which point the shorter adapter was installed) said it went right in with no issues. Of course, he also said the driveshaft came right out with no issues with the taller adapter installed, which made no sense to me at all. There was no ******* way that driveshaft was coming out when I had the car up a lift, and others here confirmed that with the taller adapter they had to lower the cradle or the pinion a bit to get enough room to work with.
Man, I installed my CS diff block (for the 8.8) and now my upper bushings aren't squeezed on at all and there is a gap Bolts are wow tight. I have to call CS on this.
Man, I installed my CS diff block (for the 8.8) and now my upper bushings aren't squeezed on at all and there is a gap Bolts are wow tight. I have to call CS on this.
Their block works with the diff that they provide.
Their block did not fit perfectly with the Aluminum 8.8 housing I sourced myself, but was easy to modify for the different clearance needed.
04-01-2016, 10:40 AM
I had additional washers, and was initially thinking I would put 2 washers in, but decided to just do 1. Based on what I felt on the drive home I don't think putting in 2 would've made it any better.
I had the car up on a lift at a military auto hobby shop, and one of the other guys was taking a look at what I was doing. I said to him, "There's a CV here, and a CV here, so it really shouldn't matter what the pinion angle is, but I've read other guys say that pointing the pinion down helped reduce vibration." In amongst these various threads and discussions I missed/forgot that your driveshaft has a U-joint. Ah well... I'll take the washers back out Thursday after work.
Bolts are wow tight. I have to call CS on this. 