Wiring harness firewall hole diameter for grommet

[mike87]

Does anyone have a digital caliper handy (and an E30 shell lying around) that can kindly measure the hole diameter where the wiring harness grommet goes through on the E30 firewall (red circle below)?



Thanks,
Mike

[mjweimer]

Mike - I don't have a shell to measure but in my swap notes I have 52mm written down. I ended up using the stock M20 DME grommet so I did not go much further in my search for an alternative.

If you search Ebay for "Lucas black rubber bulkhead grommet" you will see some options.


MJ

[mike87]

Mike - I don't have a shell to measure but in my swap notes I have 52mm written down. I ended up using the stock M20 DME grommet so I did not go much further in my search for an alternative.

If you search Ebay for "Lucas black rubber bulkhead grommet" you will see some options.


MJ

Thanks for the note and I did actually see the Lucas bulkhead grommet on eBay but haven't bought it yet. If you re-used your M20 DME grommet, did you have to cut it to get it on the E36 harness, and does it leak?

[mjweimer]

Thanks for the note and I did actually see the Lucas bulkhead grommet on eBay but haven't bought it yet. If you re-used your M20 DME grommet, did you have to cut it to get it on the E36 harness, and does it leak?

I cut the M20 grommet and fit it to the Z3 harness. I glued it back together using 3M weatherstrip adhesive and held it in place with a couple of zip ties until it dried. I also rotated the cut in the harness to the 9 o'clock position in hopes it would be shielded from direct water contact. Small note, my Z3 harness was slightly thinner than the M20 harness so I increased the diameter a bit with a couple of wraps of 3M electrical tape until it was nice and snug. After I pushed everything through the firewall I put a zip tie around the outermost portion of the grommet as insurance against the adhesive coming apart...you can see a pic in this post about 9 pics down:

https://www.r3vlimited.com/board/forum/general-forums/members-rides/the-project-forum/375198-project-rolling-wreck-24v-swap?p=9937460#post9937460

I found that Lucas grommet after I had my stuff back together. Can't speak to leaks since I have only had the car on the road for a short time but I'm really confident it won't be an issue.


MJ