Z4 E89 / 3er E93 / 4er F33/F34 -Urgent recommendation to replace the hardtop relais

[RobbiZ4]

Just to push this important topic up:

Link to Spool Street Com with a detailled explanation:
https://bit.ly/3rU2SRA

[BugsBunny]

I just changed my salmon relays. My car production date is March 2009, so probably one of the first. Absolutely no issue with the roof until now, or the car in general, apart from the usual wear and tear.
The salmon relay change is preventative. I changed one manufactured on week 5 of 2009 with one manufactured on week 28 of 2021.
I observed the Amps is quite different: 22A vs. 62A. In my book that would mean that the new relay can support more cycles. Am I reading this correctly?

[RobbiZ4]

Well done.

The following assumption is wrong:

Originally Posted by BugsBunny

...the Amps is quite different: 22A vs. 62A. In my book that would mean that the new relay can support more cycles. Am I reading this correctly?

This information is only manufacturer information and does not correlate with possible amps. All relays with this BMW part number are of the same type and quality.

[surfwooder]

I recently changed both salmon relays in my E89 Z4. Upon inspection, I noticed pitting on the contacts of both relays. These pits indicate to me that when the relays are moving from open to closed a degree of arcing is taking place. Please note the wiring of both relays indicate full direct point to point from the main buss bar to the salmon relays. Internal to the buss bar is a fuse to protect the motor. I also own a 2008 BMW 328IC, which has the same relay set up on its top system. I replaced both relays on the 328, and opened both and found pitting on the contacts, but more severe than on the relays from the Z4. I think the difference is because the weight of the top in 328 makes the motor draw more amps to move the pump in the heavier 328 I top, so when the CTM fires the relay the load draw causes a hotter arc within the relay. The arcing would take place on the surface of the contacts and displace material from one contact to the other. Actually, I'm sure BMW engineers looked closely at the quiescent distance between both + and - contacts, and the material of each contact. It would be of some advantage to know this to predict the longevity of the relay, and number of expected cycles under load. The motor, and the pump is a factor also. The motor is designed to operate at a specific RPM, and power, by the winding. As the motor is run, the bearings begin to wear, placing a drag on the motor. This causes the motor to draw more current through the buss bar through the relay contacts. The pump as it wears increases the drag, dirt or debris from failed parts within the pump could cause the pump to fail or freeze. This will cause the current to spike, above the buss bar fused connection. The results would be a stuck top in either a up or down movement.

[bigendbob]

Also as the battery becomes less efficient more amps drawn as volts drop.
When possible i only operate roof with the engine running.

[RobbiZ4]

Originally Posted by bigendbob

When possible i only operate roof with the engine running.

I don't care about this. The power consumption of the roof process is lower than an engine start.