I found 2 e28 rear regulators for my ‘74 e9 front windows. One was inoperative. My mechanic said he matched the Porsche motor to the e28 motor and it worked. Or did it. The drivers window with the Porsche motor broke the window. He’s ordered a new one from Wallothnesch and will be here soon. Does anyone know if it was his installation, or if it is the Porsche motor that caused the breakage?
E9 front window regulator.
- Thread starter Pflyer
- Start date
Difficult to say, as from a pile of glass scraps you can't really do any detective work. It could be both, or a combination.
I've never heard of e9 windows breaking, so i'd say it has to do with at least some part of the work.
Did it break when it reached fully down? or fully up? or during the travel up/down?
The motor could be too powerfull, pushing to hard on the glass. But as Porsche windows aren't exactly thick guage (i expect; too heavy) and i think smaller in size vs the E9, I expect the posibilty of the porsche motor having too much power wasn't the culprit.
Now installing the bolts incorrectly may just do the trick. I know for sure there are a few different length bolts in the whole door. At least 20mm and 12 mm M6 ones are used in the bottom window guide bracket), and swapping those could possibly create an obstruction. Other bolts holding the door opener, armrest and/or ashtray could also be problematic.
Third, the window slide mechanism has at least one rubber end stopper on the bottom as a defined end point. I do not know the motor-to-gear-to-glass setup of E-windows (i have manual), but i expect that there are 2 rubber buffers as well mounted on the large gear wheel as end stops. If any of those 3 are missing / incorrectly installed or adjusted I do not know what would happen ( I never tried ofcourse), but they are there for a good reason. Our E9's are quite well engineered (apart from the rust thingy).
all in all, there are a few things to check before pushing that button again.
I've never heard of e9 windows breaking, so i'd say it has to do with at least some part of the work.
Did it break when it reached fully down? or fully up? or during the travel up/down?
The motor could be too powerfull, pushing to hard on the glass. But as Porsche windows aren't exactly thick guage (i expect; too heavy) and i think smaller in size vs the E9, I expect the posibilty of the porsche motor having too much power wasn't the culprit.
Now installing the bolts incorrectly may just do the trick. I know for sure there are a few different length bolts in the whole door. At least 20mm and 12 mm M6 ones are used in the bottom window guide bracket), and swapping those could possibly create an obstruction. Other bolts holding the door opener, armrest and/or ashtray could also be problematic.
Third, the window slide mechanism has at least one rubber end stopper on the bottom as a defined end point. I do not know the motor-to-gear-to-glass setup of E-windows (i have manual), but i expect that there are 2 rubber buffers as well mounted on the large gear wheel as end stops. If any of those 3 are missing / incorrectly installed or adjusted I do not know what would happen ( I never tried ofcourse), but they are there for a good reason. Our E9's are quite well engineered (apart from the rust thingy).
all in all, there are a few things to check before pushing that button again.
Last edited:
While comparing to MB motors some time ago, I noted three different offsets available between gear height and the three mounting points.
Using incorrect "shorter" one caused interference. Also wallowed out mount holes on regulator and corresponding pot metal shoulders on motor/gearbox played havoc with smooth operation. Presume bolts loosen up over time from torque. Check motor gear to regulator gear alignment and for parallel engagement. I haven't looked at Porsche motor; post some side view pictures when you get it. I'll try to dig mine up.
Using incorrect "shorter" one caused interference. Also wallowed out mount holes on regulator and corresponding pot metal shoulders on motor/gearbox played havoc with smooth operation. Presume bolts loosen up over time from torque. Check motor gear to regulator gear alignment and for parallel engagement. I haven't looked at Porsche motor; post some side view pictures when you get it. I'll try to dig mine up.
I do not think you can break a window by applying a larger compression force using a more powerful motor...
A larger pulling force, even less. Did it break while lowering or raising the window?
Or perhaps when slamming the door?
My glass damages were:
1) Cold water hose on a very hot day.
2) Flying debris on the windshield.
3) Vandals broke driver's window to steal things from give box.
A larger pulling force, even less. Did it break while lowering or raising the window?
Or perhaps when slamming the door?
My glass damages were:
1) Cold water hose on a very hot day.
2) Flying debris on the windshield.
3) Vandals broke driver's window to steal things from give box.
Sure, you can board it with plywood for now
.Attachments
OK, need the table level view (vs. overhead) - if put a ruler flat across gear top and another across the two mount surfaces, what is difference? Are both units same?
If you mount each motor in position on regulator and look from the side (regulator gear as horizon) how does the motor gear sit? Centered, at top, at bottom
On one MB I tried the regulator hit solidly a few inches from the top of travel and twisted the arm out of whack. I didn't have glass on but could have easily done damage.
If you mount each motor in position on regulator and look from the side (regulator gear as horizon) how does the motor gear sit? Centered, at top, at bottom
On one MB I tried the regulator hit solidly a few inches from the top of travel and twisted the arm out of whack. I didn't have glass on but could have easily done damage.
Attachments
I am quite sure the E28 rear regulators are not the same as an E9.
jmackro
Well-Known Member
Right! E28 rear motors will substitute for e9 motors pretty easily (and are faster/more powerful, though not "window breaking" powerful). But I doubt the E28 rear regulators are similar to E9 front's; I suspect that Pflyer's mechanic just substituted motors and not regulators.
Pflyer said:
Define "worked". E9 and E28 BMW window motors have an 8-toothed gear, while later-model Porsche 928 motors have 10-toothed gears. Otherwise, the motors look identical. The large, driven gear on E9 regulators are designed to work with 8-tooth drive gears, so substituting a motor with 10 teeth might mung up the driven gear. But I can't see how using an improper gear would cause a window to break.
eriknetherlands said:
Yes, that's right. The large gear that is driven by the motor has two blocks mounted to it which contact rubber stops at the upper and lower window limits. When properly adjusted, those stops - not the glass - should take up the force from the motor at the limits. If the stops are improperly adjusted, the glass would be subject to compressive force at the top of its travel. But again, I doubt the motors are powerful enough to shatter the glass.
Last edited:
I'm confused. Why not use the original E9 regulators that were in the car to begin with.
You are not confused; everyone is still using original regulators. Using "regulator" as shorthand for regulator drive units (motor and gearbox). The 12mm shaft motors are beefier than the 10mm shaft motors, although not as classically elegant as non-unitary early drive system with rubber coupling
Still hoping for offset dimensions on the Porsche ones.
Still hoping for offset dimensions on the Porsche ones.