E36 convertible automatic to manual top conversion

By Mike Reily

I love my 1999 328i. It is my first ragtop and there is nothing like putting the top down on a nice day and going for a ride. However, ever since I bought the car in 2009, the motor that raises and lowers the top cover has failed several times each season. The failure was always the same. It would start grinding the drive gears at the end of a up or down cycle. I must have had the motor out half a dozen times re-align the gears or modify it so that the gears would stay aligned. Over the course of the last year, I collected all of the components I would need to convert it to a completely manual operation and finally, when the motor failed for the second time this spring, I decided that I had enough. Below is my description of the process of making the switch, which I publish in the hopes that it will save someone else the headaches that I experienced in the process.

Parts Required

Below are diagrams that show the parts (circled in red) necessary for this conversion. For the top flap cover, I got the Bowden cables (11 and 13), the lever deflector (14) and latches (1) as a used assembly and the other small parts I ordered online. Clicking on the following diagrams will take you to the vendor that I bought some of the parts from. There you can find individual part descriptions and prices.

For the front of the car, I bought the manual folding to lock assembly (8, 12 & 25) as a used assembly.

Summary of parts I purchased to do this replacement:

quantity	Part number	Description	Price ea	Price
The following refers to Figure 1:
1	Used eBay	Cable and latch assembly (1, 10[x4], 11[x2], 13, 14)	80.00	80.00
1	51211977540	Door Handle Inner Right (6-1)	14.97	14.97
1	51228219024	Covering, Right (7-1)	4.00	4.00
1	07119907925	Fillister head self tapping screw (8)	.36	.36
1	07129904227	Body nut (9)	.47	.47
1	51258191461	Bracket (25)	2.54	2.54
2	07119907925	Fillister head self-tapping screw (16)	.83	1.66
2	63171367868	Expanding nut (17)	.28	.56
1	51258165488	Cover (15)	12.95	12.95
1	51258183280	Clip (order number needed to organize the cables)	2.54	2.54
The following refers to Figure 2:
1	Used eBay	’94-99 318i Front top lock assembly (8, 12, 25)	149.99	149.99

Total cost of parts was ~$270

Start at the Rear of the Car

Replacement of the hardware in the rear of the car was very straightforward and roughly goes like this:

.

Completely disconnect and remove the rear top cover motor from in front of the left rear tail light. Lower the top and prop up the top cover then remove the rear seat and side panel. The seat bottom just pops up in the front and the back pops out after the headrests are removed. The side panel is removed by just sliding forward. This panel will be modified later.

Remove the two latches on the left and right that connect via Bowden cable to the top flap motor that you removed above. This only involves removing 2 T30 torx bolts.

In the trunk, disconnect 2 wire harness that goes to the trunk interlock microswitch that is mounted to the right side latch. Fish the wires and cable through the rear panel and remove both Bowden cable and latch assemblies.

Now you can install the manual cables and latches shown above. The photo on the right shows the connections inside the lever deflector box.

Fish the long cable with white ends thorough the side panel and attached to the release lever and mount the lever with the bracket, J-nut and screw as shown. While you are here, you can remove the electronic top controller, which is located to the rear and below the release handle – you don’t need that anymore!

Raise the roof to get it out of the way and route the cables in the folding top compartment. Using the screws and expanding nuts mount the lever deflector to the existing square holes in the back panel.

Now remove the connecting rods and levers that operate the folding top. You will need allen socket and assorted torx sockets to disconnect all of the components. Take time to soak the connection of the large lever to the motor shaft (the large hex socket screw) with penetrating oil. This was very tough to get out and eventually the socket stripped. Luckily, I had backed it out enough so that I could finish removing it with a vice grip. After the rods are out of the way and with the the main lever still installed in the motor, you can remove the smaller lever using a 15 mm socket from inside the trunk. Then you can remove the main lever and drop the motor by removing the 4 torx bolts exposed in the folding top storage compartment.

Now for the Front of the Car

Next, moving to the front of the car, the primary thing is to swap the motor and two power locking mechanisms for the one-piece manual latch assembly. This is where things got a bit more complicated. Unfortunately, I was fighting the clock to get car buttoned up for my commute in the morning, so I stopped taking pictures. In hindsight, I could do this again in an hour, but it took me almost 5 to figure everything out. Most of this was trying to remove the motor-driven locking latches. Hopefully, the description below will save folks some time. To begin, remove the header trim panel: Remove the single screw in the “emergency release” panel and the two clips that hold the trim to the top frame on each side. There are six Phillips head screws that need to be removed next to release the headliner from the trim. The trim can now be removed from the car for later modification (see below).

This is a picture of the left side locking latch, but the description on its removal is the same for both sides. First, there are 3 T3 torx bolts (arrows #2 & 3) and a 13 mm nut (arrow #4) that hold the assembly to the top frame. The problem is that you cannot remove #2 without first removing the slider pin indicated by arrow #1. Fortunately, this is easily accomplished by removing the c-clip (near the arrow) and sliding the pin out to provide access to the bolt head located at arrow #2. Once you have removed all three fasteners, then the socket indicated by arrow #5 is simply pried off the ball that it attaches to on the top frame member. I took one of these apart 7 ways from Sunday before I figured all this out. It is then obvious and easy to remove the center-mounted motor that drives these devices. After the motor is out, remove the two rubberized motor mounts with a vice-grip or similar. Installation of the manually operated locking mechanism is straightforward with the same fasteners and mounting holes being used. As you will see, the metal tab that the “emergency release” panel screwed into needs to be bent back flat and parallel with the roof line to make room for the handle to lay flat.

At this point the top should operate completely manually. Now, the only thing remaining is to modify the header some of the trim you removed above. First, the door panel needs to be cut to allow access to the top cover release lever. Fortunately, this necessary hole is already laid out on the inside of the panel (thank you BMW).

To finish off the door panel, reinstall it and slide the trim piece in place:

Next, you need to attend to the headliner and header trim piece. Apparently, the factory trim and headliner is different for manual and semi-automatic tops than it was for fully automatic ones like mine. The header trim piece for the former is much narrower and has no accommodation for attaching the headliner.

So, you can either buy the correct factory trim and headliner, or do what I did and modify my existing head trim as shown above. This allows for re-attachment of the original headliner and proper operation of the locking handle. This is what the final installation looks like: