Eric's '90 80QT: rustic bits

[elaw]

Yeah I was wondering the same thing! I couldn't find any numbers at all on the new bearing. I'll try to clean up the OE one tonight and see what markings I can find.

FWIW I went to McMaster and they don't have a bearing with the same dimensions as the one that came out of the 80 (30mm ID, 55mm OD, 15mm thick).

[DE80q]

Interesting, I will have to do a search in the parts catalogs tonite. One of the perks of working with bearings so offten, is being able to find strange sized bearings I wonder if having a 2mm spacer would help the 6006 bearing from failing. That would pinch the bearing, and keep the yoke in the proper location.

[elaw]

So... I installed the new support bearing on the driveshaft, and today I put the unit back into the car.

Result? JOY! :woowoo: No funny noises at all, at any speed, no vibration, nothing. It just works.

And here's something that may seem shocking: a support bearing designed to fit an Audi fits an Audi better than one designed to fit a BMW! Who knew?

As I related before, I installed the BMW bearing (the one multiple Internet writeups say fits) onto this DS when it was used in my 4KQ and I don't recall any fitment issues. But when I moved the driveshaft to this car, initially the bearing barely fit - in order to get the mounting bolts into the holes it had to be jammed up against the driver's side of the tunnel. And as you can read a few pages back in this thread, that resulted in a major driveshaft misalignment issue - only fixed when I filed the mounting holes so the bearing could move farther to the right.

Although I did preemptively file the holes in this mount too because I expected it to have the same problem, my expectations were wrong - it fits beautifully and can adjust over a wide range side-to-side. So the bottom line is, based on experience of installing it and about 10 minutes of driving, this bearing is way better than the other.

[DE80q]

Thats great! I'm glad it fit properly. Sounds like the BMW units will work, but not quite right. Interesting that so many others have used that bearing and never complained about issues lime the ones you had.

[elaw]

Well folks, here's today's goofy-question-du-jour, and it's a long one.

I'm sure most of you are familiar with B2/B3 quattro transmission mounts which look like this:


Notice the rubber "fingers" on the mount pointing downward. Notice the cone-shaped sheet metal thingy that's set up such that if it lifts up too far, it'll hit those "fingers" and prevent (or reduce) further upward motion.

Now here's the thing. When you accelerate, reaction torque from the transmission driving the front axles causes the front of the engine/transmission assembly to rise up (hence the snubber in the front), and the rear to move downward. In the case of my car, it's moving downward so much it hits the heat shield that's below the center driveshaft.

I find it odd that the mount is apparently designed with a feature to limit upward movement, even though in most situations (unless you tend to floor it in reverse) the rear of the tranny is trying to move downward. So what I'm curious about, is whether anyone's ever tried installing the mounts upside-down? Obviously proper spacers would have to be found/made to go between the tranny mount arms and the sheet metal cone but that doesn't seem too hard. It seems like doing that would limit downward travel of the back of the tranny which IMHO is more useful than limiting upward travel.

And yes I know 034 sells stiffer mounts... but it seems to me if my goofy plan worked, it would allow a soft mounting to reduce engine vibration while still limiting travel when necessary, as opposed to being rigid all the time which would increase vibration.

[elaw]

Well this isn't going to be the most exciting progress report, but it's nice to have one more thing checked off the "to-do" list: the cruise control now works!

I'd already been through rebuilding the pedal switches, replacing vacuum lines, and relocating the throttle actuator as described earlier in this thread. But the switch on the stalk was junk so the system still didn't work. Well thanks to Dave (DE80q, a great seller by the way) I have a brandy-new switch and a cruise control that works like a champ. Yay! :-)

[DE80q]

Glad I could help! I love this project.

[elaw]

So... it looks like I need to qualify that last post a little. The CC works, but does not work perfectly.

The actuation of the throttle is a little "spastic" - it holds speed well, but if you watch the boost gauge it's all over the place. Not a huge big deal, but I know it's not going to get very good fuel economy that way. I suspect the issue is that the CC "brain" is tuned for the non-turbo engine which of course makes a lot less power than the current one, and thus needs more throttle motion to hold speed.

So I'm wondering... could I maybe plug in a control module from a turbo car of the same era? Does anyone know if the pinouts are the same? Or, is there somewhere online I can view a wiring diagram from, say a UrS4 or turbo 5000 or 200 to see if they're the same?

[savagerocco]

I dont think there us a difference between them. They use the same pump and actuator..... pretty sure the same control unit as well.

[ur20v]

About the trans mounts - do you have a snub mount? Is it adjusted correctly? If so, then it seems your trans mounts have seen better days.

[ur20v]

I dont think there us a difference between them. They use the same pump and actuator..... pretty sure the same control unit as well.

Yep, the cruise system for pretty much all the drive-by-cable cars, from 1980's CIS cars to the 1999 A8, are all the same. They just monitor the VSS signal and adjust the bellows accordingly.

[oil_me]

Glad to hear your CC success. I started following your thread a while back as I needed the same rear axles for the urq diff(thanks Hank) This inspires me to pursue getting the CC operational for my mTDI swap as well. I appreciate the details.
Rich

[elaw]

About the trans mounts - do you have a snub mount? Is it adjusted correctly? If so, then it seems your trans mounts have seen better days.

Yeah, I do have a snub mount and I think the adjustment is pretty good. Although the bracket that used to attach to the front crossmember is now attached to a frame I made that might be a little less stiff than the OE setup. The tranny mounts are essentially new, as are the motor mounts.

[oil_me]

Is there too little /too much leverage on the pedal arm; as in where the chain attaches could or should it be further from the pivot point? Having more travel might make it more responsive. I know you have space constraints though.
Rich

[elaw]

Yeah I thought about that, but you're right... where I've got it attached is about the only usable place. I did hook it as far from the pivot as possible. I think the "ratio" (for lack of a better term) is pretty close to that of the OE setup... full deflection of the vacuum thingy-dingy gives about 3/4 throttle.

Way back when, I took apart an old Saab cruise ECU, made by VDO and looking an awful lot like the Audi one. It had a specialized Motorola chip in it that would be easy to change the gain on. But the ECU from the 80 actually has a microprocessor in it (that's not reprogrammable)! And I cracked open another old Saab box I had lying around and it was a completely different design. So it seems that these VDO control modules that all look the same on the outside have vastly different stuff inside.

Oh well, I guess if worse comes to worst I can build my own... in my copious spare time.

[savagerocco]

One other thought is that the actuator is having a hard time pulling the pedal and the drag of the cable rather than just the throttle like it was originally designed. What about mounting one on the throttle and seeing how that reacts?

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[elaw]

Hmmm... you may have a point there - there is a bit of "stiction" in the cable.

Unfortunately there really isn't a good place to mount the actuator and connect it directly to the throttle with my setup. The TB is moved forward from its normal position, and to put the actuator in the same relative position it would have to be in the same place as the thermostat housing. :tard:

Maybe I'll try lubricating the cable and see if that helps.

Actually I just had a cool idea.... I've got a spare pressure/vacuum sensor under the hood that's wired to the Megasquirt. I could use that to log the vacuum in the cruise system and compare that to throttle position. If the vacuum changes without a corresponding change in TP, that would indicate it's sticking.

Gee, I'm beginning to think I may be some sort of a geek...

[savagerocco]

What about a flex cable, say from the local bike shop and remote mount the vacuum actuator somewhere else in the engine compartment?

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[elaw]

I thought about something like that but there's a problem. The thingy the cruise linkage attaches to on the TB moves when you press the gas pedal. So when the cruise is not active and the pedal is pressed, it would basically be pushing against the cable which is kind of a no-no. It can cause the cable to kink, or catch on something, or become detached depending on how the ends are set up. Kind of like a bicycle brake cable - they're happy when pulled but not when pushed.

At one point I'd actually considered using a cruise unit from a Saab 9000 because it's a neat little self-contained module - just hook up +12, ground, speed signal, brake/clutch switches, and control switches and you're set. But it has a cable output so it would have the same problem. On the Saab the arm on the TB that the cruise actuator connects to has a separate spring so it doesn't move when you press the pedal.

I also tried using it this morning at a lower speed and it worked much better. So I'm more inclined to think it's a sensitivity problem, as the problem seems worst at highway speeds when the engine is right in the turbo's spooling range (2500-3000 RPM).

[savagerocco]

There are a lot of oe stuff out there like a long slotted slider, let's throttle move on its own and only pulls the throttle when cruise is engaged can find those of Chevy carbed trucks all thru the 80's

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[elaw]

Well here's an interesting one for you... I think my clock has Alzheimer's disease! It seems to forget the time at random. Actually not entirely at random... I've never seen it change while the car was running. But several times recently I've noticed the clock being off, reset it, then a few trips later it's off again. Sometimes by just a few minutes but sometimes by hours. I know a dead battery could cause this but the battery in the car is almost new and in excellent condition and fully charged.

Is this a known issue with the clocks in these cars? I know all about the displays "bleeding" but have never seen anything about losing the time setting.

[AudiSport4000]

Never heard of it forgetting the time. Have any spares to swap in?

[savagerocco]

Mine does it all the time, now it is off half the time as In not working at all. Seen it before, bad cold solder joints bust out the iron....

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[oil_me]

The clock in the current 80q resets itself to 1:00 every time I start the car; so I always show up to work at 1:30 in the morning. Weird.

[elaw]

The clock in the current 80q resets itself to 1:00 every time I start the car; so I always show up to work at 1:30 in the morning. Weird.

The real question is, when that happens do you get overtime pay?