Window regulator Warp Drive

[markb]

I did this fix over ten years ago when my front window quit with the familiar "clicking" sound of the gear teeth failing to engage... the usual warpage of the regulator casting, misaligning the drive gears. After pulling the regulator, I found the casting had actually cracked (from memory, it was towards the motor end; I think they also crack around the arm pivot point). This was a temporary(?!) fix that seems to have held up (some might call it a hack):

I GENTLY flattened the warpage in a wood vise as much as I dared (it was already cracked, so what the hell). I fashioned two pieces of 1/4" square steel bar (any hardware store carries it) to provide some backbone to the casting; you can see the ends of the bars in the pic. I attached them by drilling holes in the casting and running screws into tapped holes in the bars. It drew the casting flat(ter), and has kept the gears re-meshed. In hindsight, there was probably room to add another bar spanning the other two to backbone the pivot point, which is still (or since?) badly warped. That would be a little more complicated but at least this partial fix has been working for 10+ years. The point is that there's room to reinforce the casting, and it doesn't take much. Did I say a temporary fix?

A related problem: the white nylon insert that bushes the lift arm has worn to the point of popping out.. which underscores the need for lubrication of the window channels. The glass needs to move without binding!

I have a hard time paying the kind of money we're seeing for something that is just going to fail again. I'd rather try to improvise (ok, I don't have that kind of money). I like another poster's suggestion of a 1/4" steel plate behind the entire casting (even a 1/8" plate might work?). That might elevate it above the hack status. Anyone have a CNC plasma cutter?!

[floyd111]

That was pretty much what I thought this was about, and I had the same idea of fixing it this way.
Actually, I have bought new ones, and planned to attach a properly cut re-enforcement plate, in the same fashion you speak of.

If this could be a flat plate without relief, but simply needs to be the right thickness, the right shape, with pre-drilled holes in the right spots, that sounds like a Taiwan pattern-part candidate.
It should be very affordable to have such plates designed and made here.
Am I correct to assume that 7076 aluminium should work well?

-How many MM space is there between the door and the regulator, still allowing a functional operation?
-Would fronts and rears allow for the same plate?

I would take 8 of them myself, and I can have jobs like this done here, cheaply starting at 25 pieces.
In general, 100 pieces allows for 95% rock bottom pricing

Any people in here that would be interested?

[beagle2022]

Definitely interested.  I am sick of doing this job and would love a permanent solution that doesn't need a second mortgage.

[Benzman53]

Count me in as well. I've replaced all regulators over past 9 years on my 1980 300SD.

[floyd111]

That would be 25 units already, if we can get confirmation on whether fronts and backs can have the same plate installed.
Can anyone confirm this?

[Alec300SD]

I'm also interested in 4 units for my 1978 300SD.
My used spare PS rear window regulator is ready to install.
Great idea to mount a supporting plate to strengthen the part.

[ptashek]

Fronts and backs have different shape.
While all of my regulators are new, I don't expect them to work well for long.

I'll measure one of the fronts today and will try to make a rough 3D model of a plate.
Don't expect this to work the first time without a few prototypes being put through their paces

[markb]

I'm in for all 4... that would be awesome if it could be made to work. A big cost savings if the left/rights were interchangeable, kept to just 2-d plates. I don't have a spare to look at but their MIGHT be an issue with some of the ribbing slightly higher than the datum that I used.. I don't recall how "strategically" I placed the steel bars. I may have even ground off a few ribs in favor of seating the bars flat on the casting. The trade-off: using a thinner plate and nylon stand-offs at the attachment points. That would not be nearly as good as sitting flat (on the plane of the perimeter casting).

I've never had the rears out. They still work, but I'm guessing they're about to say "hello"...

RE material selection.. Floyd, your knowledge already sounds better than mine. I'm pretty sure I used .250" square stock, and there's a gnat's-ass clearance remaining.

Does anyone have experience with the aftermarket regulators; do they fail in the same way? Are there any problems with the gears and/or bushing quality etc?

[floyd111]

Just to scare the good folks at home.. I just had a good look at the 2 new front regulators I bought, NOS. One of them is warped to a point that there is a 1.5CM gap on 1 side, if installed. No re-enforcement plate can re-shape such a warp without breaking the alu.
WTH? Does aluminium warp over time, even in the box? These plates are cast, so how can there be tension in the metal?
Anyone else ever seen NEW ones warped?

[orientrot]

I would be interested in a set.

Just to scare the good folks at home.. I just had a good look at the 2 new front regulators I bought, NOS. One of them is warped to a point that there is a 1.5CM gap on 1 side, if installed. No re-enforcement plate can re-shape such a warp without breaking the alu.
WTH? Does aluminium warp over time, even in the box? These plates are cast, so how can there be tension in the metal?
Anyone else ever seen NEW ones warped?

I've got an NOS drivers front I picked up for cheap on craigslist and a set of rears that I pulled from a nice well maintained (but crushed by a tree) 300TD that looked as if they had been very recently replaced (very clean, no corrosion/dirt on main body or the arm, perfect teeth, shiny new non-corroded bolts). All three of them are slightly warped already, though I don't have them on hand to measure the extent of how warped they are.

The driver's side in my main car is one of the cheap aftermarket replacements and has worked well for a couple of years. As it has already been mentioned, the biggest issue for them warping and failing is lack of lubrication/improper maintenance of the window system. I think a lot of people just keep on replacing units rather without addressing the system in terms of it not binding or whatever and get frustrated when the replacement fails.

I have access to waterjets and cnc machines through the things I am involved with at school so I might try some things on my own. I have thought of designing a more modern cable style regulator or trying to adapt an existing design but between school, home renovations, and everything else I haven't gotten around to it.

[ptashek]

Anyone else ever seen NEW ones warped?

I got new ones from the dealer, not NOS ones. All four were in perfect order.

[ptashek]

While measuring the plate today, and looking at how the mechanism works exactly, it became quite obvious why it warps the way it does:

- it's made of cast aluminium, instead of forged and heat treated aluminium; it's simply not as strong as it could have been
- there's a 45mm hole in the very centre of the weakest point of the plate, which is right between the two gears; const savings gone wrong, or deliberate design choice?

Judging by its gearing the servo motor can deliver a ridiculous amount of torque, and when there's extra friction in the mechanism the gears will buckle outwards on their axes, bending the base plate out of alignment along the center line of that hole between them. Maybe that was done by choice, so that in case of servo failure, the regulator would break before the motor would catch fire?

Either way, apart from careful and regular maintenance, reinforcing that section should take care of the buckling issue.

[beagle2022]

Great analysis.  Hopefully the bracing solution will address this one before replacements become unobtanium.

[floyd111]

Been trying to upload another pic, but the site won't let me.
What I'd suggest is to extend the plate further to the left, as well as to the right.
The cost diff is next to 0, but would there be another issue with that idea?

[markb]

Dang.. I changed my forum email address last Thursday, trying to solve my image upload problem..then I couldn't get an activation email.. then I couldn't even login to the forum! And sorry, I don't know your names!

Here's my take.. I recall the plane of the window is offset from the plane of the gearing and lift arm pivot point by a good amount, and I think that off-center load creates a lot of the torque that warps the drive. Certainly then, when the gears are in different planes, their loads add to the problem, going lord knows in what direction (hereinafter referred to as TWERKING?). I agree the central hole is a weak spot (my guess it's an inspection hole?); that's where mine was cracked, on either side of that hole.

Anyway, if you look at my photo (first post), the lift arm pivot point is way-warped now. Also, see this picture: http://s616.photobucket.com/user/chrisp_album/media/15112010005.jpg.html, which confirms the load on that point. I would even say the plate needs to extend beyond and SURROUND the pivot point. For that matter, as Floyd says, how much material used is a minor issue. Perhaps surround all the mounting bosses?

On the other hand, if we make it too big... we run the risk of not being able to get it thru the door opening (Murphy's Law)! Ptashek, if/when you have a CAD model and can post a dxf or step or some kind of file that I can print 1:1, I'd like to make a cardboard mock-up and make sure it can be installed. I happen to have my right-rear door opened up and am in a door-opening mode. EEK!.. the rear regulator looks like a pretzel; I can't believe it still works.

Don't forget we would need a large clearance hole for the spring, right? It isn't mounted in your photo, Ptashek. I agree with Floyd, the plate could extend to the right (or not.. do we need that clearance to get to the motor screws?) and quite a ways to the left (or do the rib heights change there?). And if you factor in the spring clearance, we could use more meat top and bottom as well? Anyway, good start.. the pivot point is my main concern.

Orientrot.. small world.. we're in the same hood! And I also went to GA Tech, uh.. 35 years ago, in the industrial design program. While recently pondering my rusted-out sunroof tray, I was tempted to look up an old buddy who went on to run the prototype shop there. I remember they had an enormous vacuum-forming rig.. I had delirious visions of punching out a plastic liner for the sunroof tray. We should talk! (I'm also knee-deep in home renovations..)