I have a 1975 Corvette that I bought off a guy pretty cheap but has a host of minor problems. One was the driver side window did not work. It is an electric window (despite everything else being manual) and he told me the motor was no good. I ran across a deal on a used regulator and motor for $40 so I went ahead and bought it thinking that was the problem.

When I got into it I found that the back plate on the motor that holds the gear into place, was missing two bolts and the third was loose. When I went to take it out the spring sprung, luckily I didn't have my hand in there. I had no idea what had happened and since my new used regulator and motor looked better I decided to put it in. After a lot of struggling (I didn't have anything to judge where the spring should be set so I took off my other door panel to see where it was positioned and found out the spring was broke on that door), I finally got it in and ended up with two problems. 1) The switch is now reversed, when you push up it goes down and when you push down it goes up. 2) I see why this broke in the first place. The window is 3 inches or so from going down all the way when it stops, I looked inside to find that the track is hitting on the top bolt of the motor. Not sure why this isn't clearing... anyone ever have this problem? Am I missing a part? This had to be the reason why this broke before, it eventually knocked two of the bolts out. Other than the two problems the window works perfectly, goes up really fast, but I need to fix this clearance problem for it to go down all the way.

Also, since my regulator was okay, would it be possible for me to take the spring out and put it on the passenger side to fix that one? It goes up and down but you have to help it when it goes up.

Any ideas or help would be appreciated.

Last item, both of my manual mirrors are very loose, you can set them but the wind is pretty much going to move them where it wants. Any easy what to tighten these?

 

This may help.

Is this an after market installation?

 

I'm a bit confused. You say everything is manual but the driverside window is power. Then you say the passenger side window is slow going up suggesting its also power.

If the window is not clearing the motor it could be you have the regulator in wrong or the wrong regulator or the window tracks at the bottom do not have the spacers on them. The biggest mistake is usually using bolts too long to hold the regulator in place, is it hitting the motor or is it hitting the bolts.

As for the spring. It has to be installed when the regulator is in the full up position. The spring compresses as the window goes down to help push it back up.

The switch problem sounds like the wiring is reversed or the switch is upside down. See if there is evidence of splicing. Best fix is to find the problem. Easiest fix is to remove the wires from the connector and switching them.

 

Everything is manual except for the windows... both windows.

I thought all c3 regulators were the same. The regulator rides behind the motor, the track is hitting on the head of the top bolt that holds the plate over the gear so the length of the bolt wouldn't be the issue.

You talk about spacers, are there spacers anywhere on the track for the window? I don't remember there being any spacers at the top or bottom of the tracks. This is probably the problem. There isn't enough clearance to move past the head of the bolts. The passenger side goes up and down without any clearance issues, I guess I need to pull that apart again and look at the setup to see what I am missing on the driver side.

When you say switch the wires, do I switch them on the motor itself?

 

I don't think it is aftermarket. It looks just like the picture.

 

The tracks are spaced away at the bottom by a piece welded onto them. Check the good side, I'm sure you will see the reason.

As for the wiring. I can't understand how it's reversed unless the plug was forced one backwards or the switch is backwards. Or it was previously wired wrong. Once again check the passengers side for wire colors

 

I believe the two wires were attached to some sort of plug in at one time, now they are all taped up and each wire is slipped on individually. There is a possibility they are on the wrong ones, I just put them back the way they were, but it didn't work at all before I took it apart, so it may have been wrong before. So if I switch them it may reverse the process? I just don't want to screw something up electrical. But I guess neither wire is a ground wire because it is grounded by the bolts.

 

There should be two wires to each motor. One is up and one is down. Simple reverse them.

Based in the 82 manual and I assume yours is the same, brown is up and blue is down on the driver side. On the passenger side tan is up and light blue is down.

Jim

 

Finally had the weekend to work on the car. The spacers were on the track but it was still bumping the bolt heads. I ended up spacing them a little more and it worked fine, no other issues. I also swapped the wires and it is now going in the right directions when you hit the switch!

I went to fix the passenger side and really didn't want to have to take the regulator out, couldn't find any information on how tight the spring needed to be when it was in the up position, so I simply took the spring off the regulator I didn't need, stuck my hand in the hole and put the spring on doing everything by feel. I lubricated the joints and greased the tracks and it now works like a charm... both windows work great!

Thanks for the idea of switching those wires... I should of thought of that. I just assumed they were on right when I took them off... I should not assume anything with this car - this guy seemed to have a field day of rigging stuff up.

On my grocery list of things to fix I accomplished, both windows, seat belts, fixed headlights (was relays, cost me $70 for new ones), speedometer, gas leak... pretty productive weekend!

 

Nice work! Sounds like you did the spring correctly. It has to be installed when the regulator is in the up position, spring compresses on the way down and helps with the up.

Something is not right on the driver side, factory spacer should have been enough but if it works now so be it.

Jim