Tried replacing the gear in my 2000 C5 Driver's Side headlight motor. Didn't know about the needed "T" brace so the motor blew apart.

So, just bought a brand new motor and tried to install it (with a "T" support). The three bolts are just fine but the headlight lever won't fit onto the new motor shaft at the "flats". The motor shaft is just a tad too large in diameter. Took the motor back off and double checked the fitting. Nope, the headlight lever won't go on.

There was a change in the headlight motors from 1999 to 2000 and I am wondering if maybe my car, a 2000 C5 purchased in December, 1999, maybe had the prior design 1999 headlight motor.

The BIG question here, as obscure as it is, is whether the 2000+ headlight motors had a slightly larger in diameter motor shaft, compared to the 1999 and prior motors.

I can send the purchased one back but I don't want to be in the same boat if the 1999 (and prior) headlight motors have the same larger motor shaft.

So, did GM make the motor shafts larger in diameter when they did the 2000 design change?

Thanks, Bob

 

If you have the three bolt lid "metal" headlight assembly you're not supposed to use the T bar. The T bar is meant to reinforce the plastic "glued" headlight assemblies, as the force of the lever against the plastic housing can damage it. You probably cannot install the lever because the T brace isn't giving you enough room for it to slip over onto the key way of the throw lever. You can discard the T or hang onto it.

Despite there being two distinctive designs of headlight for the C5 they are completely interchangeable, and I've come across cars that actually have each style installed from side to side, typically because a replacement was sourced cheaper or easier that possibly didn't match. Some people actually prefer the earlier "metal" lid style because it's believed to be stronger. The plastic style was utilized by GM to help reduce costs.

 

Hi Velocity Vette ,

Thanks for your reply. This BB is amazing for knowledge.

I don't think that the T-Brace was causing the problem since I removed the entire motor and tried, repeatedly, to match it up with the lever slot. It just won't go in. Tried turning the motor **** all around and the shaft is just too big for the lever slot. I'll poke around with it again later this afternoon.

After I installed the new gear to the old motor, the lever slipped on just fine. I did install the lever up side down the first time (knuckle up instead of down) and the headlight came up while the other went down, but I changed that and the new-gear motor worked fine until the glued cap fell off. (No T-Brace!).

I got back to the motor vendor and asked him to do a caliper measurement of the 1999 and the 2000 motor shafts to see if there is any difference but as you indicated, there should be no difference in shaft/flat diameter between the two different designs.

The original headlight motor had a metal casing. The new one (too large shaft/flats) also had a metal casing. (Made in China so that might explain something, but the vendor says that he has never had a problem with them).

I'll remount the new motor this afternoon without the T-Brace and see what happens. I'll report in...Thanks, Bob

 

There's some confusion here. Yes, there are 2 headlight motor versions: "97 to early 2000" and "late 2000 to 2004", but they are 100% interchangeable.

The only difference, as mentioned above by Velocity_Vette, is that the 1st version has an aluminum gearbox, while the 2nd version has a plastic gearbox. Both of them have a metal motor casing.

They are easily identifiably because in addition to the different gearbox material, the 1st version has a removable gearbox cover held in place by 3 little screws, while the 2nd version cover is glued in place.

Because of these differences, their gear replacement kits are different: the 1st version doesn't require the T-Brace nor the glue, but needs a new gasket, while the 2nd version is the other way around.

1st version on the left, 2nd version on the right:




Since yours was glued and it failed because it didn't have the T-Brace, your headlight motor is a 2nd version unit with a plastic gearbox.

By the way, a factory new 2nd version motor doesn't need a T-Brace.

It seems the motor you purchased is not 100% compatible. Personally, I would have gone for a new internal rubber isolator, a T-Brace with plastic bushing and a pouch of glue and properly do it again for just a few dollars. As I mentioned in your other thread, these items can be separately bought through this link.

 

Fixed...

There was a small internal raised edge to the internal lever slot. Worked just fine with the original Headlight Motor but this new one apparently had a shaft and flats that were just a tad larger than the original GM part. (Chinese measurements?). So I just knocked the edge off with a Dremil and the lever arm slid on perfectly with a bit of spray oil lube. I could have used the nut to force the lever on but I'd never be able to get it off again.

So, thanks for the comments/assistance. Bob...