JohnnyBs98WS6Rag

iTrader: (1)

I've recently replaced my stock 10-bolt w/ an S60 and am attempting to get the driveline angles setup. I have an adjustable TA that allows me to adjust the rear pinion angle to whatever I want. I've got the factory springs/shocks, but my ride height as measured right in front of the rear wheels increased by ~1/2-3/4" (I think this is due to the spring perches on the S60 being higher relative to the axle centerline due to the tube being slightly larger than the 10-bolt). The guidance I got and found was to set the angle of the rear pinion to the same angle as the engine/trans output shaft. On my rack w/ ~1.1 deg downward slope towards the rear, I was measuring ~6.0 deg down from horz (F-to-R) on the engine/trans (measuring on the front of the engine vibration damper), so I set the rear pinion (measured on the yoke flats) to the same 6.0 deg down from horz. (F-to-R). This is where I made the length measurements to order my custom driveshaft from MWC/Strange. I installed the shaft and found that the driveshaft was about 0.0 deg (level), resulting in a 6.0 deg operating angle for both front and rear U-joints (the engine/trans and pinion are parallel as is recommended)

During break-in, I noticed that I'm getting a vibration when I got much over 85 MPH. So, based on some other info I found that recommended the max U-joint operating angle of 4 deg, I went to install some shims under the trans mount to raise the tail-shaft up (to reduce the front U-joint operating angle) and discovered that the T56 trans is basically clamped between the trans crossmember and the trans tunnel: There is no way to raise the trans tail shaft since there is a rubber bumper on the top of the trans that is right against the peak of the tunnel (a few inches forward of the shifter), thus I'm stuck w/ the ~6.0 deg down (F-R) of the engine/trans angle.

So then I attempted to reduce the rear U-joint operating angle and got it down to 0.9 deg down (F-R), which lowered the rear of the driveshaft (now at 2.1 deg down F-R) which reduced the front U-joint operating angle to 3.9 deg and resulted in the rear operating angle of 1.2 deg. (the engine/trans and pinion are no longer parallel w/ a net angle of 5.1 deg) Took it for another spin and now the vibration doesn't start until ~90 MPH.

I'm working on another adjustment to attempt to get the U-joint operating angles closer to each other, however any attempt to do this will result in an increased angle between the engine/trans and pinion which seems to be a bad thing to do. It seems the only way to get the engine/trans and pinion angles parallel w/ U-joint angles < 3-4 deg is to raise the tailshaft of the trans, which seems to be impossible w/ how the T56 is clamped between the crossmember and tunnel.

Any advice on how to rectify this situation? I didn't think to make any measurements of the factory driveline before I pulled it to see what those angles are for comparison. Does anyone have measurements of a factory driveline? I've never had driveline vibration issues w/ the 10-bolt up to 120 MPH, so the factory was doing something different. I suppose it would be possible to raise the rear of the car with lift springs to lower the pinion WRT the engine/trans, but I don't want to look like old-school muscle car w/ slicks and skinnies. A higher CG is not the direction I want to go.

LLLosingit

iTrader: (4)

6 degrees down on the engine and trans doesn't seem right. Most stock configurations at 1.5 to 3, I assume you had the car level and suspension at normal ride height (compressed not drooping) before measuring anything?

440_Stroker

This is what I thought, too. If the rear is not lower than the back of the tranny with the degree slope angle down you can't have the rear with the same angle.

JohnnyBs98WS6Rag

iTrader: (1)

On a level surface, the engine/trans would be ~4.9 deg down (F-R). All measurements were made using an app on my phone using the same edge of the phone to make all measurements.

When I installed the S60, I also installed a MWC TA which came w/ a new trans cross-member. When I installed that, I jacked under the trans to hold it up while I swapped the factory cross-member out w/ the new one. I wasn't really paying attention to the engine/trans angles at that time, and kept the same trans mount (rubber), which is bolted to the new trans cross-member without any shims. Everything seemed to line up the same way as w/ the original trans cross-member (no gaps between the cross-member and the floor-pan). It wasn't until I attempted to jack up the trans to install shims under the trans mount at the cross-member that I discovered the rubber bumper on the top of the trans being right up against the tunnel / floor-pan, leaving no room to install shims to raise the rear of the trans.

Is it possible that back in '99 when "grey-haired granny" in MI smacked me in the driver's door resulting in me jumping a curb could've buckled the floor-pan (F-R) such that the engine/trans is now pointed downward more than originally? I had the Pontiac dealership do the repairs (new door skin, front fender and rear quarter, new front LCA and a new rim or two) and as far as I know and can tell they got everything aligned back up (all panel and door gaps are as good as when it left the factory). Shortly after that I installed the KBDDSFCs which was welded in place w/ the car's weight on the suspension. I've never had any drive-line vibrations following that (although I've never gone faster than ~120 MPH in the car).

JohnnyBs98WS6Rag

iTrader: (1)

I was able to get the pinion and engine/trans angles to be the same (parallel), however to achieve that the driveshaft tilts up WRT the engine/trans and the resulting UJ operating angles at both ends are around 6 deg. This was my initial setup, which I think is good for getting the pinion and engine/trans parallel, but the UJ angles are too large. Indeed, I was surprised at this situation as most car's I've seen (not to mention nearly every generic diagram on the web) shows the driveshaft tilting downward from the trans, not up like mine. That's why I'd be interested to see what angles a stock setup has.

In the meantime, I've entered all my data I've collected over ~13 different adjustments into a spreadsheet and plotted the UJ operating angles vs. pinion angle to see where to go. I think what I'm going to do is to use a SPL meter that I have to measure the vibration noise level at 5 MPH increments from 70-90 MPH as the pinion angle is adjusted in 0.5 deg increments to see if I can determine an optimum pinion angle that gives me minimum noise/vibration. Seems the pinion angle is the only adjustment I have at my disposal (dropping the trans to BFH the tunnel to allow me to jack up the rear of the trans is not in the cards..........at least not yet).

Thanks for the feedback!

jimmyg

U joint angle is not supposed to be more than 3
Both u joint angles need to be within .5 degree of each other . You can use the TREMEC app
Or the spicer angle calc . I'm going thru the same **** . There is a place called driveshaftshop.com that makes a cv joint driveshaft . Supposed to fix .

JohnnyBs98WS6Rag

iTrader: (1)

Thanks. Yes, that is what I was shooting for. However, not being able to adjust the tail-shaft of the trans upward makes achieving that impossible.

I just dropped $500 on this driveshaft, dropping another grand for a CV-driveshaft is going to make me regret swapping to an S60 (or any other rear) instead of fixing my 10-bolt and pissing away any dreams of more power.

WTF is wrong with my car? Why is my engine/trans angled downward so much? Why is there no room in the tunnel to allow me to shim it up? NONE of that has anything to do w/ the S60. While I can't rule out the possibility, I can't believe my chassis/floor pan buckled from my '99 collision and my doors / top / seals are all still lined up perfectly. Can someone please measure their stock engine-trans / driveshaft / pinion / ground angles so I can determine if my car is whacked? Much appreciated.

jimmyg

What car is this ? Year etc...

JohnnyBs98WS6Rag

iTrader: (1)

Its in my sig and username ('98 WS6 'vert M6).

merim123

iTrader: (11)

https://www.spohn.net/support/questi...shaft%20angle.

440_Stroker

Your S60 has nothing to do with your issues. The extra inch or so towards the front that the pinion is pushed is of little consequence.

Are your engine/tranny mounts new? Even so they could have buckled.

JohnnyBs98WS6Rag

iTrader: (1)

Thanks. I do question the validity of this though:

Seems like a pretty bold statement to me. In any case, as they define "true pinion angle" being the difference between the pinion and driveshaft angle, a 0 deg true pinion angle would result in a front UJ operating angle of ~4 deg. I'll try that next and then vary each direction to see if that's the sweet spot.

Agreed 100%. The engine and trans mounts are original (only have 21K mi on the car). However I doubt that's my issue, if the engine mounts had collapsed, the trans would be tilting less downward (F-R) and would help, not aggravate my situation. And if the trans mount collapsed, I'd have room to lift the tail of the trans up.

Thanks for the feedback all, keep the ideas percolating. Sorry if my frustration is showing through in my earlier post. I do appreciate having this community for bouncing ideas off of. This blind squirrel will find a nut eventually.

merim123

iTrader: (11)

I went through something similar. I would recommend you use a real gauge and not your phone for the measurements. get an angle gauge for $5. take the driveshaft out. Here's my own thread where I got it resolved. see post #26. https://ls1tech.com/forums/gears-axl...ion-45mph.html

440_Stroker

OP, don't worry about how you come across. This is the internet. Everyone is a cage fighting Scientist who dates super models and has a 13 incher.

JohnnyBs98WS6Rag

iTrader: (1)

I do have a $5 angle gauge, but not only is the dial hard to read when I'm measuring certain points, at best the resolution is 0.25 deg when I can see the dial really well. A phone app has a resolution of 0.1 deg and is much easier to read. The accelerometers used by the phone apps are pretty good, their default "calibration" may not be dead-nuts on, but that's irrelevant when making relative measurements.

Thanks for the link, however the pinion yoke on my S60 has pockets for the UJ caps to sit in, eliminating the possibility of mounting the driveshaft off-center WRT the pinion yoke.

Since I'm locked into a fixed engine/trans angle, I'm left to trial-and-error. I'm in the process of collecting SPL data at 5 MPH increments from 70-100 MPH as I adjust the pinion angle every 2-flats of the adjustment hex (~0.5 deg). Once I complete this, I should know what pinion angle gives me the minimum vibration and will set it to that and live with it. I'll share the data here in case its helpful to someone.

Darth_V8r

iTrader: (4)

Maybe I missed it in the thread - are you measuring trans angle off the tail shaft housing or off the U joint? I find variability on the housing. I use a socket on the u joint cap to get the trans angle.

My TA from the factory had the DS is a broke-back configuration. Both angles matched but were on the same side of the DS. Trans was at 6, pinion at 2, 2 degree interior angles. That was years ago lol.

I shimmed under the trans to get to 4 degrees when I installed nine inch. Raised pinion to 3.5. DS angles at 2 and 1.5. Under load, pinion raises just a smidge and it is perfect.

JohnnyBs98WS6Rag

iTrader: (1)

I'm measuring the trans angle off the harmonic balancer at the front of the engine. There's not much of a flat on my slip yoke to get a good measurement there, and the trans housing is also quite small when avoiding the dust seal.

So you were able to shim up the trans at the trans mount / cross-member? Do you have a T56 or 4L60?

Here's my data summary from my multiple measurements. After making the first 4 measurements, it was clear that I had passed through the sweet spot, so I backed off 2.5 flats of adjustment at the TA to get my final setting. At the starting point (-0.8 deg), it seems I had a vibration mode occurring around 80 MPH and another mode coming on at 100 MPH. Increasing the pinion angle made that lower mode disappear and further increases made the higher mode disappear, but overall vibration / noise started increasing. I dialed it back to a 1/2-flat past the prior adjustment and the result had the higher mode coming back but overall less noise < 100 MPH. I measured the driveline angles both after adjustment and after the test drive (some settling shows up in the data). Of course, in order to get the post-drive measurements, I had to unload the suspension to rotate the driveshaft and then sat it back down to get a decent pinion angle measurement, so that probably invalidated some of the settling of the suspension during the drive.

Darth_V8r

iTrader: (4)

T56.

You are not using a poly trans mount are you?

Also, long or short torque arm?

I found on the long torque arm, the car like about a two degree drop transmission vs rear. Short, it just liked then to be within a half degree.

I do not worry about the working angles of the DS. Just make them match

JohnnyBs98WS6Rag

iTrader: (1)

Thanks for the feedback. The trans mount is the factory piece. My TA is the MWC long one that connects to a replacement cross-member that also holds the tail shaft of the trans. As I mentioned above, with the new cross-member in place, once I remove the bolt from the trans mount, jacking up on the trans just lifts the whole car because there is a rubber bumper on top of the T56 (a few inches in front of the shifter) that is up against the tunnel which prevents me from shimming up the trans tail shaft. I've not looked into what it takes to remove that bumper, but I'm sure there's a good reason its there.

98cherrySS

iTrader: (2)

Following along. Keep digging OP! The more people I meet with S60 and Fab 9" rears, the more I discover that many of them have vibration issues similar to ours.