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Now I'm aware that this title is an open invitation to ridicule and hate, I'm aware that "it can't be done". Other than rumors of a factory built awd 944 prototype it seems it may never have been done. So I'm going to try, by upgrading my Electric 944 to dual motor AWD. Yes I'll admit, doing this with electric motors will be far easier than any form factor of gas engine.
Let me set the scene, back in 2009 I designed an electric vehicle conversion. In 2010 I settled on the 944 as the perfect EV conversion candidate, it was rolling in 2011 with 300+hp and 300+ ft-lbs and daily driving in 2012, revised and rebuilt in 2012/2013 after I blew up the first electric motor, and was again a daily driver till 2020. Sadly this time it had as much HP as a stock NA, but with 220ft-lbs from 0 rpm so it was a zippy little run about, but it was definitely not fast.
A few photo's and info about the car from 2020 when I started down the path I'm on today. (slight pause for 'vid19) Porsche 944EV Now the small front Tesla drive unit that I've had for the past few years is nice (nearly 300hp) it's not quite what I'm looking to build today. Kia (KIA!!!) makes a reasonably priced car that will do 0-60mph in sub 3.5 seconds, I must do better...
Today's plan:
Install the Tesla small front drive unit in the front of the 944. VW golf/jetta VR6 front suspension/steering parts are quite similar to the 944. So much so that the lower ball joint lines up with 2 out of 3 holes on the steel 944 lower control arms (the 3rd hole is measure and drill, no problem) allowing me to use the VW passenger side spindle on the drivers side (they have the steering rack behind the axle) the Tie rod bolts right up (upside down, but more on that later)
I need to build a custom cross member to mount the Tesla drive unit anyway so it will have clearance for the CV and allow me to raise the steering rack about an inch to re-align the tie rod with suspension travel.
VW front brakes are a slight concern, however I will have variable 4 wheel regen to go along with the 4 wheel mechanical brakes, still I will try to get the biggest VW brakes that fit.
Please ignore the rusty control arms, all of these parts will be replaced with new ones in the final assembly (tie rod ends, control arms, bushings, ball joints, bearings etc)
So all this talk about the front motor makes the first FWD Porsche 944 (I contemplated starting the thread that way). Sadly the control system that I'm going to use won't allow just the front motor, though I should be able to disable the front motor and run the rear only if desired. How much hate would a FWD burnout in a 944 get on youtube?!?! So to make the system work I need another Tesla drive unit, this time a rear. Choices are: small rear at nearly 300hp giving me an awd 944 at just shy of 600hp and instant torque. For context a Telsa model S 100D (which is the same drive train, but weighing 4883lbs) does 0-60 in 4.3 Seconds. Next up is a large normal rear motor at 450hp this would give me almost 750hp (there is no Tesla with this small front/base rear configuration), next up is the Sport Large drive unit at 536hp giving me a solid 830hp (Tesla P100D, 4941lbs, 0-60 in 2.6 or 2.7 seconds) final choice is a Tesla Large Sport Plus drive unit at 636hp or 930hp total (Tesla P100D Ludicrous, 4941lbs 0-60 in 2.3 seconds) My previous curb weight was 2850lbs, I expect to stay around 3000-3200lbs. Now these last two motor combinations become hard to power on the battery side given the limited space for a large pack without having it higher in the car than I would like, and probably more $$$ than I can swing with the extra cost of the higher performance Tesla drive units so those two are out.
So in reality it comes down to two small drive units and almost 600hp, or a small and a large base drive unit at 750hp (100lb extra on the large, plus some extra battery to power it). On the plus side the mounting of small and rear drive units are the same so if I built the car around a small I could upgrade in the future if desired (provided I build the battery to be capable of 750hp).
The hardest part is going to be to redesign the cross member to hold the Tesla drive unit and steering rack, and clear everything while locating the lower control arm exactly where it's supposed to be with a cutout for the CV. Anyone with an existing drawing of the cross member or its mounting points deserves a beer.
So why am I posting here instead of just waiting till it's done? Maybe one of you know better parts for the front steering knuckle, brakes, has drawings or CAD of the engine bay etc. I looked at Audi and it seems that the Audi 80/90 have similar geometry, but the VW parts are cheap and easy to find.
I've seen some threads on radically updated front suspension from a Lexus and others, but I have enough on my plate already no need to make the project even more complicated. This is going to be a capable street car, (daily driver) not a race car, and the suspension should be reasonably compliant. Will the steel lower control arm be strong enough? It has to take significant braking force but zero "drive" force. The front drive unit is 294hp, and 243ft-lbs with a fixed 9.34:1 open diff gear reduction. There is an available LSD for this drive unit but I will likely skip it unless front wheel traction or torque steer becomes too big of an issue. So even if the car doesn't hook up I should be able to get a 3.xx second 0-60 time. If it does hook up, it could be low/mid/high 2.xx seconds, who knows? The control system has basic traction control but I'm sure it's nothing like what Tesla has.
Now before anyone says I should use Tesla Plaid parts, I am on a budget here, and Plaid drive units are going to command crazy $$, plus I didn't need 830hp, or 930hp from one of the older Teslas so I definitely don't need 1020hp (Plaid). I'm pretty sure I'm already overboard with the lowest option at 600hp considering it should be around 1600-1800lbs lighter than the Tesla it came in.
I have some more VW parts on order to prove out the mounting and see what kind of strut I need to make this work, the first being a 5 bolt hub. Now as far as offset mine is an early 944, so the vw parts are 20-25mm further inset (basic measurements without a strut so far) than the Porsche, so it should allow me to run a 20-25mm spacer/adapter to get back to 5x130 and run all of my existing wheels.
So can I make this work? Who knows. Will it be fun trying? I think so!
For further info on the EV side of things I've done numerous EV conversions and my day job is designing and building batteries for Bowhead Corp I'm also the Power Specialist at LyteHorse Labs. I have a new battery design in mind to support the 600-750hp (360v @ 1600A) power target of the car.
So, wish me luck, or tell me the wheels are going to fall off, but let's keep it civil!
If you are not familiar with the early 924's and the 931, it may be worth taking a look at the different engine mounting system used.
Instead of mounting to the crossmember, the engine in those models is supported by the longitudinal frame sections.
That type of system may reduce the design demands on the cross member.
"Can't be done."
If a transplant will physically fit within the recipient envelope, it can be done.
It just comes down to time, money, and determination.
Good luck, keep us posted!
If you are not familiar with the early 924's and the 931, it may be worth taking a look at the different engine mounting system used.
Instead of mounting to the crossmember, the engine in those models is supported by the longitudinal frame sections.
That type of system may reduce the design demands on the cross member.
Thank you for the tip, I'll look into those a little deeper.
I will need a minimum of 2 or more points further forward to tie into beyond the cross member as the rotational torque load (same axis as the wheels) will be very high and the cross member only had to deal with rotational torque loads in the axis of engine rotation.
if your spindle ears are 94mm apart which i suspect they are on that generation of VW you can use the early 90s "G60" caliper from some VW and Audi models, it's a twin-piston caliper with a 40/45mm pistons and should bolt on.
...or you can use 944 turbo calipers if you can find some for any kind of decent $..
what year is the donor VW you got the spindles from? I am actually looking for a set of front calipers for an 88-98 Jetta/MK3 golf/90+ Passat. it's a Girling caliper with single 54mm piston. i can get them relatively cheap refurbed but really only need the bracket by itself.
if your spindle ears are 94mm apart which i suspect they are on that generation of VW you can use the early 90s "G60" caliper from some VW and Audi models, it's a twin-piston caliper with a 40/45mm pistons and should bolt on.
...or you can use 944 turbo calipers if you can find some for any kind of decent $..
what year is the donor VW you got the spindles from? I am actually looking for a set of front calipers for an 88-98 Jetta/MK3 golf/90+ Passat. it's a Girling caliper with single 54mm piston. i can get them relatively cheap refurbed but really only need the bracket by itself.
The spindle is from a '98 cabrio, (ebay) but it appears to be the same part in a very wide range of cars. The mounting ears are 94mm, I'll look into the options you mentioned. I'm new to replacing brakes, I'm switching to a 5 bolt hub, so I was going to start searching there for a compatible caliper. I saw the caliper bracket on Rockauto when I was cross-referencing what parts what years use. I definitely have more to learn about the braking system!!
Very interested in how you do the rear tesla drive unit as I have always dreamed of doing this myself. Would love to see how you accomplish mating it up to the rear.
Very interested in how you do the rear tesla drive unit as I have always dreamed of doing this myself. Would love to see how you accomplish mating it up to the rear.
There are a few people who have already done small Tesla drive units in the rear of a 944. I haven't seen the episode yet but vintage voltage season two did a 944 S2
Love this! Will be following. I'm exploring EV conversion of a 944 NA, right now trying to figure out options for mounting a tesla model S/X small drive unit, or maybe a Model 3 / Y rear drive unit (they seem to be more plentiful in the aftermarket, and that trend may continue with so many new Model 3's and Model Y's being sold today). Aside from the transmission mount's mounting points to the frame, I'm not seeing any obvious bolt-on points in the rear subframe / gas tank / rear suspension region of the 944 NA. Ideas welcome! I'd love to hear how you mounted yours.
haha thank you! Yes great video, which I've watched many times now I'm thinking of using their basic design too (battery & motor placement). I think its a great template for me to follow. They do a deeper dive (I think) in the Vintage Voltage TV series. Trouble is, its only available on Discovery+ UK version. If I can get my hands on that full episode, I'm hoping to find some more detail about the mounting points they used in the back.
09-07-2022, 01:39 AM
DIY AWD '86 Porsche 944
AWD/4 Wheel Drive 944
I'm thinking of using their basic design too (battery & motor placement). I think its a great template for me to follow. They do a deeper dive (I think) in the Vintage Voltage TV series. Trouble is, its only available on Discovery+ UK version. If I can get my hands on that full episode, I'm hoping to find some more detail about the mounting points they used in the back.