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I keep plugging away - This bump steer stuff is taking a lot of time!

Front spindles are drilled/tapped for 5/8-18 Tie Rod ends, the 16" sleeves were 1" too long so had to cut 1/2" off each of those (and then likely replace with 15" ones later). Finally got it all assembled and started taking some measurements and playing with the new adjustments. I was a bit too excited (and maybe hopeful) that I could just dial this in quick and move on to other things - I spent a few hours not documenting what I did/didn't change and ended up getting lost in the data so I put this job aside and put the gas tank in with the new straps as a distraction.




Ok - Now back to bump steer. One of the things I was hoping to accomplish with the new fancy adjustable parts was the ability to lower the inner tie rods so they'll clear the oil pan. They clear - barely - this is at the physical limits of the steering box. I can lower them about 0.050-0.075" more with more shims and a bit more with some careful filing on the oil pan.


Since this is where I wanted the inners to be, I left it here (centered the steering), set the toe to 0 at ride height and then went through a more methodical process, documenting what I did, and what each result was. I ran out out of time today to continue, but feel that I can get it figured out with this process and more time. The first side will take a long time, the 2nd side should go quickly :). I might have to go back to the purple "baseline" setup and take baby steps to keep the target in my sights while I make adjustments. Right now it's so far off I'm literally guessing what direction and how far to move things and documenting what it did/didn't change. I think this is called the hard way :).

Below is a quick summary of the day's work. The Baseline might have had the signs reversed (so the curve would go the other way), but it looks promising if I can get back there with the lowered inner tie rod position. I don't know how good I can get it, but will report back with what I find. If anyone has done this on a B/D body, I'd love to see what the results were. So much more to learn!




Otherwise not much this weeek - Tires showed up, no rims yet. I took the hitch and bumper to the galvanizer last week - should have them back in a few weeks so I can install those. Probably need to drop the fuel tank to do it though (doh!). Once I get this bump steer stuff figured out, that'll be a big weight off my shoulders.
 

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With mine, with all the geometry production, I did nothing more pull the nose down to the snubbers on the alignment rack and then lifted a couple inches above ride height.
Jammed the steering box up as high as it could go, adjusted the idler so the center link was level.
I remember pulling some caster to lower the outer tie rods.
This while watching total toe on screen.

I do not remember a toe arc suggesting a tie rod length issue though.
Is your inner to inner tie rod measurement different than original?

When you are playing with toe length are you moving the center link to rezero toe to effectively move inner pivot to "test" inner position ? Or am i misunderstanding.

If I understanding, the blue line is the only one with a decent tie rod length as it doesnt arc
 

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The inner tie rod location is production, except I have the ability to raise/lower it. I'm taking a home run swing and choosing to lower it 0.500" to clear the oil pan and hoping I can achieve decent bump steer by adjusting the outers accordingly. This might not work.

With the coilovers removed, I've a floor jack under each control arm set to ride height with the wheels in free air - Steering wheel centered, toe was set to zero on both tie rod ends (and square to the rear end). The wheel was removed, bumpsteer measurement setup installed and then the suspension articulated +/- 3" from ride height (6" total travel) while recording bump steer measurements at 0.5" increments. No movement of the center link either side to side or up/down so far. Up/down is a variable, but as mentioned before, would like to keep it down as far as possible for full steering travel/oilpan clearance.

Hopefully I've answered your questions - let me know if not.
 

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Ok - Finally have a handle on the bump steer situation, have both sides more/less equal and (think) I have an understanding of what variables do what in terms of adjustments. I'll post more details when I get the data presentable, but ended up with as good as it can be with the hardware I have. It's not the 0.010"/" of vertical travel that the race cars target over the full suspension travel, but in most normal suspension travel it's close. It's always toe in which I read isn't as good for stability, but as noted above, it's not something I can change with the hardware I have. It's going to be good enough for now. Feedback welcomed on the below.

Vertical TravelRight Left
Compression-3.0-0.078-0.058
-2.5-0.058-0.041
-2.0-0.040-0.025
-1.5-0.023-0.012
-1.0-0.010-0.003
-0.50.0000.000
Ride Height00.0000.000
+0.5-0.008-0.006
+1.0-0.022-0.025
+1.5-0.046-0.057
+2.0-0.093-0.104
+2.5-0.157-0.182
Extension+3.0-0.243-0.274

With the front steering/suspension more/less solidified, I did a final check on wheel/tire clearance and it's much better than I anticipated it would be. On the left side at full right steering box travel and full compression, the inner tie rod is just shy of the oil pan (see pictures above from last week), the tire just barely touches the inner fender in the middle and the inside of the rim touches the swaybar. At ~1/2 suspension travel, the tire hits the swaybar which will ultimately limit steering travel in that scenerio, but not by very much (less than 1/8 turn of the steering wheel). Full left turn has no issues on the left side.

Right side has much more room on the inside - only issue is same as above at mid suspension travel the tire hits the swaybar at full lock to the left, but otherwise clears everywhere else. However there is much more interference on the outside, specifically on the fender lip. Enough that it will catch an edge which is bad. I did roll the left fender a bit, so maybe that helped more than I thought? Interesting how much difference there is from side to side as well.

With that more/less sorted, I was able to work on a few other things...I found a rear sway bar in the yard that looked like it would fit, and it does surprisingly well!


If I rotate the mounts forward about 30 degrees, I'll clear the gas tank and the rear end cover. Just need to cut off the 1st bend and figure out how to attach it to the frame. It's 1.5" diameter

But, until I get that far, I decided to mount the "limp noodle" that came with the SpeedTech kit instead. As mentioned before, this kit is designed for the sedans and the wagon's are just enough different to make things not quite bolt right in...

Had to weld tabs on the bolts so they could be installed since there is room for the bolt head only, no socket. Easy enough, but still takes time.




It's close with the exhaust but should clear. Might have to grind part of the exhaust locating bracket just in case. I should (and probably will) drill a hole farther to the left in the below picture and move the bracket out so the link is more vertical.


The other side mounts the same way, same location, just has a lot more room without a 4" tube running through there...The sway bar will make adjusting the rear height a bit of a PITA, but shouldn't have to do that often (hopefully).


Otherwise, just a lot of little things. Painted a few areas that were sandblasted, but not painted. Bled the rear brakes. Started thinking about all the little things to do before it's road worthy again.

Wheels should be in this coming week. Paint should be dry too so I can install the front coil overs. Another couple weeks before the hitch and rear bumper are back from galvanizing. Will need to drop the gas tank again to install the hitch so probably won't hook up the hoses yet. Really need to get back to the wipers one of these days too, and install the battery, and figure out a parking/emergency brake, and, and, and, and...
 

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Another good weekend's work...I think the mechanicals are pretty much ready to go. I put a wrench on everything since it last drove. All the ball joints, tie rod ends, shocks, etc.

I found a neat little trick for cotter keys. One thing that is frustrating about cotter keys is that they always rust and then break off, need to get pounded out with a little punch, and it's always on the side you can't get the punch/hammer into etc. When I reamed out the lower ball joint holes on the spindles for the 5/8 ball joints, I only went deep enough to get them in and the nut threaded on. This became a minor issue when I went to put the cotter keys in because the hole was partially covered by the nut since the taper could (should) have been just a bit bigger. It turns out that a 0.045" piece of stainless filler wire fit in just fine, and after thinking about it a bit, I figured that this would make a good cotter key in general (likely in 1/16" for most of them). No rust and they should come out easily enough when necessary, and I always have stainless TIG filler around whereas usually not new cotter keys.



Otherwise just a lot of little things. Finished welding on the rear coilover mounts, installed the brake dust shields, ABS sensors, routed the rear fuel lines, tightened the body mount bolts, installed the new battery, cleaned a bunch of junk out from on/in/under the car, etc.

The remaining 3 wheels showed up last week - all from different locations as supposedly they're the last ones available due to being discontinued. One of them was a 6 bolt pattern :( , fortunately I found this before mounting them, so we'll see what happens with this. I did get a couple pictures of the tires side by side for comparison.





Bumper and hitch should be done mid week so hopefully I can pick those up in time for the weekend and get them installed.

Mechanically it's pretty much ready to run. The interior needs some love, but it's functional. If the wheels show up this week we'll try to drive it this coming weekend, if not, we'll work on the interior.

Had some help with some body work finishing touches...its been bothering him that there was a Duramax label on the drivers door, but not the passenger door so we put this one on this morning.
 

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Had to make an unwanted and sudden repair yesterday. Was sitting in the drive thru when the wagon started to run rough. Since it was my lunch break I decided to roll the dice and hope the car stayed running while I got my food. So I sat there with the car in neutral since it wanted to die in gear or anytime I touched the throttle. I figured a plug wire was shorted or something since the CEL was not on. Got food and headed back to the shop and to my surprise the car drove perfectly once it got moving.

Parked it and ate before checking things out. Car was very hard to start, had to put pedal to floor (clear flood) to start the car and it would die if I tried to power brake it. I figured it a fuel issue but went over everything under hood anyways and that's when I noticed the strong fuel smell. Pulled the vac line from FPR and gas poured out letting me know it was bad.

Finding a new one was a difficult task because NO ONE had any in stock except for a cheap adjustable one from O'reilly auto and a part that NAPA said was correct. The part from NAPA ended up being wrong so I bit the bullet and got the adjustable. Putting it on was also fun because the tiny torx head screw holding the lines in place stripped out when I tried to remove it. After some cursing and careful bending I got it swapped out and the car runs perfectly again.
 

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Took Friday off and the weather was beautiful (especially for October!). Was able to get a lot done too! The new wheels didn't come in and the hitch/bumper isn't done at Galvanizing yet, so on to the interior...

There were a lot of loose paint spots and a little bit of rust on the passenger floor. Guessing poor prep from the factory, so started cleaning those up...The little rusty spot that was about 1.5" in diameter turned into a lot bigger/more than I thought so it got cut out.



A new patch panel cut out and bent/beat to match the floor


Holes drilled to plug weld it to the body and body mount underneath


Floor scuffed for welding and glue


Generous beads of "The Right Stuff" laid down


Then plug welded after it had time to setup. Also put a perimeter coat of sealant down after welding to insure no leaks


With that done, a layer of sound deadening material went down, then the carpet and seats went back in


Since the interior went in so well/easy, I decided enough was enough and it was time to drive it. This is no small task as about 8 pallets of "stuff" and 30+ semi tires had to move out of the way, then a 3 person guidance crew to help make the 8 point turn to get out of the room it's in. I didn't get a before picture, but here's what it looks like after. Still grateful to be able to work on this project here!


First voyage with all new suspension, steering, etc. No major problems to report. Still a lot of work to do though! Put about 100 miles on it, venturing farther and farther each time, but never too far in case something happened. Still very happy at 1300 RPM at 60 MPH and will hold 6th gear down to ~50 MPH (~1100 RPM) even with moderate throttle. If you stand on it the transmission downshifts ~3 gears, the exhaust and turbo create a nice rumbly whistle and away you go :). Still stock power tune - inside of the tailpipe is bare, no soot at all after 100 miles. The dash indicated ~24 MPG over the 100 miles which may or may not be accurate, but is encouraging none the less.


There's a driveline vibration to get figured out yet. I need to do the trig on the below picture and figure out my pinion angle. It "looks" too much, but should be easily fixable if it is.


And while I love the turbo whistle and exhaust note, it will be too loud for daily use/long trips so will need to find somewhere to put a 2nd muffler - Probably by the transmission somewhere/somehow.

I was also able to drive it across the scale and see what I've actually done to this thing :)

Stock (with me, 100lb of stuff in the car and 1/2 tank of gas)
Front: 2360
Total: 4940
Rear: 2560

With Duramax/6L90E swap (with me, my 7 year old son, 200lb of stuff in the car and 1/4 tank of gas)
Front: 3000
Total: 5360
Rear: 2360 - Missing rear bumper and hitch which is easily 100lb at the very back of the car

Still added more front weight than I expected, but overall I guessed 500 additional pounds and wasn't too far off. Once I clear out all the junk in the back, get the bumper/hitch on, back to 1/2 tank of fuel, different wheels/tires, etc I'll re-weigh.

I adjusted the ride heights and have the front where it should be for the bump steer to be centered and the rear adjusted to make it look right. I didn't get a distance shot while out and about, but below is what we'll start with - It's actually sitting on its own for once :). There is just over 6" ground clearance at the front cross member.


I was also able to get the center dash panel modified and installed this morning. It's not perfect, but came out pretty good in my opinion. There's a little gap (~1") on each side of the instrument cluster, but it otherwise really fits well. The headlight controls are almost identical in size (but turned 90 degrees). The shifter clears, the tilt doesn't move things around, etc.






All in all a really good weekend. I've a list of 20+ items to take care of yet, but most are pretty minor and can easily be done as small little projects.

It felt really good to drive it again :)
 

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I don't know off hand other than to say "it's pretty straight" - The u-joint coming off the back of the transmission is not visibly angled like the one at the rear end shown above. Next time I'm under there with the rear suspension compressed, I'll remove the driveshaft loop and look closer at it.

Given the above, I'd guess the crankshaft angle is pretty much in line with the driveshaft. I'll do the trig on the picture tonight
 

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The drive shaft angle relative to the pinion is ~6.5 degrees. According to the internet, it looks like I should be targeting 2 degrees or less and equal angles between transmission output shaft and driveshaft as well as drive shaft to pinion while at ride height. I'm pretty sure I checked phasing when I received the driveshaft, but will check it again when it's up on the hoist.

Wheels came in today, so hopefully I can see if they will fit this weekend. They're 0.6" more negative offset which will likely be ok 99% of the time, but will probably hit the outside of the front inner fender at full compression.
 

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My two bits is, crank on your rear arms, ,make the pinion and the crank parallel and the ujoint angles will be "magically" o_O the same as each other.

If you have good bushings in the back you dont need some big angle allowance

If the ujoint angles turn out to be excessive, then you would have to reposition the engine then realign the diff to it
 

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Agreed - I adjusted the new rear control arms to be the same length as the old ones, but didn't think about that the engine may not be at the same angle as the original one.

The only rubber bushings are the two in the top of the rear end housing and they looked brand new (the car recently had new control arms, springs, etc before I bought it). The other 6 are hard rubber/plastic so minimal torque induced deflection to change pinion angle.

I can tilt the rear end up/down easily enough since both upper and lower control arms are adjustable, but any kind of engine repositioning is...ugh, I don't want to think about it :).
 

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Because your diff to frame relationship is different than mine , this likely does not apply.
My engine is in about the same as a stock LT1 auto.
Little more than 4.0 degrees relative to the frame.
My pinion , and other B cars I have worked on near always needed the nose of the pinion to come way up.
 

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Hitch, bumper and tins were completed at the galvanizing shop so I picked those up - They came out really good! As expected, a bit of work needed to be done to clean up the tapped holes, but all in all I'm pretty happy with how it turned out. Best of all, it was $120 - really difficult to get this kind of coverage on interior parts any other way. The bumper cover is ~1/2" high so the tailgate won't open so need to look at that and figure out if the metal part below it needs to drop or if there's something else holding it up. It all worked before I had it galvanized?.







Wheels also came in so was able to get the tires mounted and get them put on and checked for clearance. Sound simple, but had to remove both front coil overs, disconnect the sway bar, install rim/tire, articulate through the movement, find where it hits and fix that, etc - none of it particularly hard, but tedious work. The wheels have an additional 15mm offset (0.6" farther out) which doesn't sound like much but caused a lot of issues where there was room before. They fit and clear but not by much - 1/8" at the most. I'm expecting some rubbing at some point as things flex around.

I really do like how the wheel/tire package looks - maybe better than what I had picked out before :)






Need to get longer rear springs as well - To get the ride height down where it is with 10" springs, they would go free by ~1.5" when the rear suspension was extended, so I lowered the lower mounting point so the spring wouldn't go free, but forgot that now the axle doesn't hang down as far and you can't get the wheel out from under the skirt...So to change a rear wheel you need to jack the car up, and remove the lower shock mounts and let the axle fall the rest of the way down. Again, not a big deal, but takes time and obviously not a solution to live with on the road. Will get longer springs on order from Vi-King. There are 750 lb/in springs in front and 450 lb/in in back. I'm considering going softer in back (maybe 300 lb/in) since there will be airbags back there to help out when there's hitch weight or whatever. Shocks are set to full soft on both compression and rebound and it still feels a bit "solid" in the back over bumps. I recall reading something about this a year ago, but don't remember what it was anymore.

Found the major source of my engine related vibration - when the body mount bolts were tightened down, it pulled the body down into the transmission. I was able to push the floor out of the way with a prybar for now and it has taken care of the worst of the vibrations (especially the idle vibration). If/when the transmission is out again, we'll make sure to clearance the floor in that area.

Pinion angles were also checked more accurately than last time. Came out with a 2 degree difference between the transmission output shaft and the pinion angle. I was able to extend the lower control arms 1.5 turns each side to get it down to 1 degree difference at ride height. I was able to drive it up to 75 MPH while up on jackstands and on the brakes and everything seemed quieter/smoother, but the wheels/tires are not balanced and a bunch of other things so a bit hard to tell until it's on the road. Will try to do this again on the hoist while someone looks around for any other issues. There's another vibration (or two) somewhere - maybe I'll just loosen all the body mount bolts again :).

Found a spot for a 2nd muffler - right under the passengers feet - so will get that installed one of these weekends to help quiet things down a bit more.

Lots more details to work out, but it's coming together - Getting lights and wipers working will be key to getting it safely on the road.

I should probably also get a horn - Any suggestions?
 

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Nothing in particular on the above, but I did buy another Roadmaster wagon today.

1994, 163k miles, pretty rusty underneath, but solid enough. Everything works except the rear air leveling suspension and the interior is practically perfect. Tailgate only swings open, not fold down the drivers door panel is cracked and the right rear window won't roll down (the 96 above has the same issue?). Otherwise it's really clean inside. Scanner shows left front wheel speed sensor reads zero all the time so it's probably in need of replacement which is turning the ABS light on. Otherwise, no codes, fuel trims look good, cross counts are good, etc.

It didn't have much/any heat, if I revved it up it would get warmer, but luke warm at best. Once I got home I disconnected the heater core hoses - it was tempting to drill out the plastic restrictor, but I left it alone. Flushed water through the heater core both ways a few times, then used an air hose to blast the remaining water through which broke a bunch more stuff loose. Hooked it all back up and now it heats much better! Cooling system looks pretty muddy so should probably do a full flush someday, but for now it's good enough.

It's rusty like I mentioned - the spare tire fell out one day on the previous owner! He's got some HVAC sheet metal and spray foam in place of the lower part of the spare wheel well. It isn't deep enough so the tire sticks up too high and the interior panel doesn't fit.

It's nothing worth putting any significant time/effort/$$ into, but still has a good amount of life left in it until the rust gets really bad. I'll get it up on the hoist one of these weekends and check out the brake lines and such that might be at risk. He was going to donate it to Rawhide or something like that so it would have likely ended up in the crusher. Too many good parts in it to let that happen.

 
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