My Bumblebee Electric, upgrading from DC to AC |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
My Bumblebee Electric, upgrading from DC to AC |
palmer_md |
Dec 5 2013, 03:17 PM
Post
#1
|
Member Group: Members Posts: 106 Joined: 15-November 10 From: Hermosa Beach, CA Member No.: 12,389 Region Association: Northern California |
Hello all,
I'm a long time lurker here, and I've posted a few times, but I'm starting this thread to discuss the upgrade I'm doing to my 74 bumblebee LE. I converted the car to electric drive starting in 1995. I purchased the car in 1994 with the intention of putting in a chevy v8 or something, but after looking at what that would take I opted to put in an electric drive train. The car was sitting in a field with weeds all around and no interior, engine, transmission or anything. It took a few years to just get the car restored before I could put in the electric drive. I got the car on the road as an electric in 1997. It has been a fantastic car for commuting and it is a lot of fun to drive, but with all the lead in the car it was a bit heavy. I decided last year that I was going to upgrade the car to lithium power which will remove about 700lbs of battery and give me more power and more range at the same time. I purchased a gearbox (BorgWarner 31-03) that is the same as a Tesla Roadster, and I got a Siemens induction motor and inverter that will give me almost as much power as the Roadster. I should end up with a little less weight than the Roadster which should allow me to have similar performance numbers...assuming I can get enough grip from the tires. In order to fit this motor and gearbox under the hood, I'm going to have to remove the firewall between the trunk and the motor bay. The gearbox sits between the axles (obviously) and the motor will sit above it (hence the space time conflict with the firewall). This is not a problem since I've seen posts with this firewall and trunk floor removed and then triangulating by putting a bar between the strut towers and then two more from the towers down to the rear trans cross bar in the trunk. This part of the build is all pretty clear in my mind. The connection between the strut towers works perfect as an upper mounting point for the motor and gearbox. Existing motor and trans mounting locations work for the lower support. The area where I have a question is with regard to the gearbox location. In order to put the gearbox and electric motor in the car, it installs like a transverse motor in a FWD vehicle. The gearbox is mounted slightly to the driver side of the vehicle and the motor is to the passenger side. So instead of the existing 901 getting installed exactly in the center between the two wheels, I'll have to mount the eGearDrive about 5" toward the driver side of the car comparatively, and then I'll have to put in an intermediate half shaft on the passenger side to allow for the articulating portion of the axles to both be equal length (about 5" shorter than stock). Anyhow, this is my question, and one that I thought I'd ask for help here first before heading to a drive shaft shop to get opinions. Will the suspension work well with 5" shorter drive axles. It means probably steeper angles as the suspension articulates, but I think it should work. I just don't have any experience in this area and I'm going to have to get some help with this decision before I start cutting the trunk apart to install all of it. If it does not look like it is going to work I'll have to come up with a plan "B". I'll post some pictures in a later post, but I wanted to get the question about the drive shafts out there since I need that answered. Thanks, Michael |
palmer_md |
Dec 27 2013, 01:07 AM
Post
#2
|
Member Group: Members Posts: 106 Joined: 15-November 10 From: Hermosa Beach, CA Member No.: 12,389 Region Association: Northern California |
I'm still looking for some information about suspension travel. My question in post #6 was not answered. How much suspension travel does a 914 have?
My car is sitting without any motor or transmission, and just for the sake of documenting some numbers I found that the distance from the edge of the fender to the center of the wheel is about 14" when sitting like this. When I jack up the car and let the wheel "hang" it extends to 15". When I loaded all my batteries into the car is dropped to 12". I'll have another 250lbs to add with the motor and gearbox, so I assume it will drop another 0.5 inches. to put it at about 11.5 inches. That makes the downward travel about 3.5 inches. How much upward travel can I expect. Is there a suspension wiki somewhere? I have not found anything so far regarding how much travel to expect on the rear suspension (nor the front). |
Lo-Fi Version | Time is now: 10th June 2024 - 06:27 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |