S4 Starter motor in S3

[Victorsanders]

Hi all

Just thought I’d let you know of my latest upgrades

My starter motor was on the fritz.. sometimes worked sometimes didn’t sometimes stuck on .. was planning on just replacing the solenoid but after some reading, found the S4 manual non turbo starter was supposed to be a straight swap.

I took the plunge and bought part number M1T70781 from Amazon for £100.14.. I thought if it doesn’t fit then it’s easy enough to send it back through Amazon

Well. It fits. Perfectly in fact. The only change is that the top hole on the S3 starter is threaded .. and the S4 is just a hole. The original stud is long enough to add a nut on the end so that solves that problem immediately.

It now starts perfectly every time. On the button.. and the starter even sounds smoother engaging.

I also took the opportunity to tidy up some wiring , relocate some relays and add a small 4 way fuse box to neaten up the bits iv added (alarm/immobiliser, headlight relays, fog light relay, under seat subwoofer, remote number plate)

I also upgraded the Live and Ground cables to 0 Gauge and replaced the cable from battery to engine bay fuses to 4 Gauge.

In doing this it seems to run smoother, the windows are so much quicker, and the lights are substantially brighter.

All in all spent less than £200 and it seems well worth it !


Eventually il upgrade the alternator and wiring .. but that’s another weekends plan .. maybe after finally plumbing in the Aircon unit

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[Hobbawobba]

Nice job. Changing those old OEM cables does make a nice difference aye! Have you added relays for the windows? They help a lot also!

[Victorsanders]

Thank you kindly !

I haven’t fitted relays for the windows just yet.. I’m undecided where to fit them .. at the moment I’m thinking of extending the wires like Malcolm did and having the relays in the dash behind the clock

They’re currently sitting in my centre console waiting to be fitted

[gt_james]

Some nice upgrades there, I like the battery cable upgrades. I am going to be doing similar for mine at some point soon.

Also is your s4 starter a gear reduction one? As far as I know the S1,2,3 and S5 is a direct drive, the s4 is a geared one. Also the geared ones can be upgraded from the original 1.2Kw motor to a higher output motor, which should have upgraded battery cable but could be nice to have if you want a more powerful starter.

[Victorsanders]

Some nice upgrades there, I like the battery cable upgrades. I am going to be doing similar for mine at some point soon.

Also is your s4 starter a gear reduction one? As far as I know the S1,2,3 and S5 is a direct drive, the s4 is a geared one. Also the geared ones can be upgraded from the original 1.2Kw motor to a higher output motor, which should have upgraded battery cable but could be nice to have if you want a more powerful starter.

Thank you !

I couldn’t tell you if it was a gear reduction one unfortunately! I hadn’t delved that deep into the research and the part number doesn’t really give much info.. the motor housing is probably 2/3 the size of the original.. and quite a bit lighter .. it also sounds like a turbine spooling up as opposed to a mechanic whir. If that makes sense .. I do know it’s a 1.2kw motor. I had seen 2kw motors online but they started at something like £300.. which if it didn’t fit, was potentially a large waste of money.. I’d only found the 1.2kw on Amazon and I know I can trust them to take returns with no dramas. That being said, The 1.2kw seems more than sufficient as the engine starts in like a second with this motor. so I wouldn’t think a 2kw would be on my future upgrades list ! .. if you go down that route, please do let me know what it’s like though

[gt_james]

could you post the link please?

If it sounds like a turbine its geared. If its lighter I'd be interested as I'm all about shedding weight off my race car. I'm not bothered by 2KW motor which is usually the reason for running a geared s4 starter, bigger motor and upgraded cable means more weight!

[gt_james]

Oh and I wouldn't be changing a starter purely for weight, I'm not that keen! But my current S3 starter is intermittent and sometimes the motor spins without engaging the flywheel, and I'm nervous it'll stop engaging altogether at the worst time, so keen on a new starter, and if a lighter option exists will be fitting that if I can!

[Victorsanders]

Of course !

https://amzn.eu/d/24hBCM5

It says currently unavailable so I’m guessing they’re out of stock .. il have a look and see if I can find another using the part number.

Yea that sounds like how mine went… easy enough to change the solenoid but for the sake of £100 it’s well worth the swap to a newer version in my opinion.

I am keeping the original for originality sake though !

[Hobbawobba]

Thank you kindly !

I haven’t fitted relays for the windows just yet.. I’m undecided where to fit them .. at the moment I’m thinking of extending the wires like Malcolm did and having the relays in the dash behind the clock

They’re currently sitting in my centre console waiting to be fitted

I put mine under the passengers seat carpet

[Casey]

Very nice work Vic, your car just gets better and better, so clean too