S65/S85 throttle actuators - electrical failure SOLVED

[marksae]

Hmmm.. I wonder if it'd be worthwhile for those of us who haven't experienced a failure yet to go in a clean the gears. My idle has been on the fritz as of late. Once in a while, the idle will start fluctuating.

[thekurgan]

Originally Posted by alpina-527

That small reduction gear carries a very high torque loading to open the 8 throttles (10 on S85)

It's hard to see the wear in this pic but it's mainly one 3 or 4 teeth and transfers the wear pattern onto the output gear

It certainly appears that once the gears start snagging, the electrics suffer which results in the burnt Mosfet

I think each actuator opens 4(s65) and 5(s85). You are right though, the gears take a beating. I just did mine today and removed the covers for some photos tomorrow, that small gear shows the "teeth" far sharper than other areas.

[M33too]

where can we get gear upgrades????

[Sean1933]

Originally Posted by binh513

where can we get gear upgrades????

Alpina527 has supplied various replacement sets of gears to members on the M3Cutters forum which I believe have been well received. He has however also been helping with trying to diagnose a trend with these electrical faults by providing me with a faulty m3 and m5 boards, so I can vouch for his assistive/determined character!

I cannot speak from first hand experienced re his gears as I sourced from another supplier - but I am yet to receive or test them so holding judgement before disclosing details.

[thekurgan]

I replaced my actuators yesterday, and snapped some quick photos of the half gear, ptfe gear and board. I can take other pics if anyone likes.

Both actuators operate smoothly. I lubed up the rail and ball with some anti-seize. There was not much of any lube on them previously. The squeaking is gone now, however.


I'll place these in the following order:

Bank1 (No faults)

1. half gear
2. ptfe gear
3. board

Bank2 (failed bank, you can see a lot of ptfe gear shavings)

1. half gear
2. ptfe gear
3. board

[tkearns119]

Any way to tell other than an eye test if it the gears alone causing the codes or both the gears and the mosfets? Multimeter on the board?

[MMAJNKE]

Nice

[Richbot]

So why is this in the "M3 vs." Forum and not in the mechanical or engine forum?

[e92zero]

good info. sub'ed

[Flea7]

Originally Posted by Sean1933

Alpina527 has supplied various replacement sets of gears to members on the M3Cutters forum which I believe have been well received. He has however also been helping with trying to diagnose a trend with these electrical faults by providing me with a faulty m3 and m5 boards, so I can vouch for his assistive/determined character!

I cannot speak from first hand experienced re his gears as I sourced from another supplier - but I am yet to receive or test them so holding judgement before disclosing details.

Are there any kind of update on your actuators Sean? Are they functioning ok with the replacement of Fet and gears?? Any issues??? Luck on sourcing the replacement gears??

Any tips and instructions on replacing the semiconductor??

Much thanks Sean!

[Flea7]

Originally Posted by Beemdog

I found the Fairchild MOSFETs at Digi-key.com (search on "HUFA76429D3ST_F085T-ND") on the Digi-key site. They are $1.44 each in single unit quantities.

Thanks Beemdog....ordered up 6. It's cheaper to go with Digi-key for those in the states.

[SYT_Shadow]

This looks incredible

OP, you should find a way to source the entire fix and sell it as a package. Make sure to leave some margin for yourself for pioneering this awesomeness

[Sean1933]

Hi all.

I'm sorry to say (read as 'I'm very frustrated') it looks like I jumped the gun in considering this issue as fixed. After multiple times of replacing the blown Fets, and indeed the motor (which had play in the shaft). It seems the Fets have blown again. Sadly due to the need to have my car on the road (my significant other is very heavily pregnant) I have had to bite the bullet and buy a new actuator from the stealers . It is quite clear they are being overloaded but what exactly is causing that isn't clear at this time.

When time allows me, and I get some enthusiasm back, it will be my intention to further dissect and test both the motor and electric board. However I am by no means an electrical expert so don't really know what I'm looking for. Luckily, my dad is an electrical engineer but he lives in California...he's hoping to visit in April/May so I'll try and get him to assist with the diagnosis, but until then I don't expect to make much progress.

[Gbyleveldt]

^^^ I'm assuming you've not replaced gears yet? If so, that would explain why the Mosfets has burnt again I'd imagine

[bmwlover0725]

This thread is epic. I've been posting about this (similar issue, but definitely the same part). I picked up a couple of transistors today, but they are SLIGHTLY different on the data sheet. I'm going to give them a shot and see how they are. This will also tell us if the transistors used (assuming the ones you used are identical to factory spec) are not properly rated. I know this could go on for a while and fail on me if it even works, but I'll let you guys know how it goes. Sub'd for sure on this one

[Flea7]

Please keep us updated. I got the digikey fairchild ones but I haven't done anything with it.

Good Luck.

[gimmethemuumuu]

I have an actuator for sale which was replaced after it threw a code. If anyone's interested in performing the rebuild, let me know. Thanks!

[bmwlover0725]

Just posed with pics in my other thread. Unfortunately my boards look completely fine and the gears completely worn. It's not permanently in limp mode after screwing with them.

http://www.m3post.com/forums/showthr...1#post18047761

Update to those who read this already: it is **NOW** in permanent limp mode.

[code7rpd]

Very insightful post...

[omniphil]

It would seem like some good preventative maintenance would be to replace the gears early considering what the actuators cost.

I don't suppose there's a source to just get the stock plastic gears themselves?

[thekurgan]

Originally Posted by omniphil

It would seem like some good preventative maintenance would be to replace the gears early considering what the actuators cost.

I don't suppose there's a source to just get the stock plastic gears themselves?

Or just lubricate externally once in a while.

[omniphil]

Originally Posted by thekurgan

Or just lubricate externally once in a while.

Do you mean internally?

I have some race grease for my bike, I assume that would probably work good. It's used for clutch and brake levers and stuff like that.