Brake fluid reservoir cap, does it match another vehicle's format?

[SammichLover]

I'm trying to use a Motive brake bleeder tank and having a hard time getting a seal to be able to pressurize. Besides a threaded cap and huge two-hole block adaptor, the Motive kit comes with a "universal" cap, which is basically a cap over a thick rubber stopper with a hole in the middle that you clamp down by tightening up on a chain you run underneath the reservoir. Unfortunately the universal adaptor is about 1/2" too wide and there isn't enough room as the gutter at the bottom of the windshield gets in the way of getting it centered enough.

So I'm left with either pulling apart enough under the hood to remove that whole gutter assembly or finding a correctly fitting cap. Motive has a number of cap designs but nothing labeled "Tesla". Does anyone know if Tesla reused someone else's cap design?

P.S. Motive has the option of me mailing them my reservoir cap and they'd send me back a custom built cap. However being without a cap for weeks(?) doesn't seem feasible. Also wasn't clear if I'd get my cap back or if they planned to just drill a hole in the top and affix an air hose into it.

 

[rtanov]

I had the same problem last year. Since I couldn't find a standard attachment to fit I decided to make one - I bought several caps that looked similar and one of them seemed to fit very well. I made the attachment but when I pressurized the system it was leaking a lot and quickly depressurizing. I wasn't able to get a tight enough for to flush the system. I ended up using a vacuum bleeder at the callipers. I would rather use the pressure pump in the future and would also like to know if someone has come up with a solution to this.

 

[SSedan]

Far as I know the S uses a standard GM cap, not saying the 3 does but worth comparing.

 

[RayK]

Wouldn't ordering a replacement cap from Tesla solve any problems? OP could send the extra cap to Motive and have them do their magic on it, all the while being able to drive the car. Buying several caps which may look like they will fit doesn't guarantee that one of them actually will fit.

Note: This advice comes from somebody who just spent +$400 on a pair of triangular rear windows in the hopes of being able to use them as design guides so TAP Plastics can determine if it's possible to bond a sheet of polycarbonate to them.

Yes I know that lead times for getting parts directly from Tesla or their service centers can be long at times. Not to mention the price paid. My window purchase may have been an anomaly as I expected (and the service guy I dealt with also thought) that these windows would be in very short supply as the number of break-ins around the Bay Area seems to be very high. But he had them in stock.

 

[SD_Engnr]

Motive is currently working on a solution for the 3, and might be done with it soon. I was going to buy a used cap and send it to Motive but it wasn't cost effective, so I opted to wait.

 

[SammichLover]

Wouldn't ordering a replacement cap from Tesla solve any problems? OP could send the extra cap to Motive and have them do their magic on it, all the while being able to drive the car.

This had occurred to me. I wasn't sure about timing, getting a part from Tesla and then sending it off for an unknown duration sounds pretty sketchy.

I was both behind schedule and also trying to get ahead of the panic of today. Fortunately I didn't boil the fluid yesterday. I'd swapped the pads for the MPP Street ones. That appeared to be enough for what I was doing to stave off issues. Also working in my favour; I was a total chickensugar on the braking most of the time.

As well I struggled with SOC, will need to work that process out better, and had only mentally prepared for normal CW and the F4 team in the other session of the rotation got up yesterday morning and decided we were running CCW. Only had a couple laps I was reaching 115 on the fastest straights, for example, once I'd gotten used to the track and then skipped a session to make a SC run. That SOC fall-off is really noticeable like that.

Motive is currently working on a solution for the 3, and might be done with it soon. I was going to buy a used cap and send it to Motive but it wasn't cost effective, so I opted to wait.

Good news. I'll contact them directly and then try wait it out.

 

[SammichLover]

Motive is currently working on a solution for the 3, and might be done with it soon. I was going to buy a used cap and send it to Motive but it wasn't cost effective, so I opted to wait.

FYI, they now have the solution but don't advertise it on their site yet. Use part number 1118, "BLACK LABEL GM / LATE MUSTANG 3-TAB CAP", but only direct from them for now because the older stock version of the same part number won't work. I'm going to order mine now.

<edit> Ordered, two day USPS shipping was the the cheapest option for me so basically whenever I have a solid 3 hour block with no chance of rain.