924Board.org

Fuzzbeaner · Joined: 03 Dec 2003 Posts: 236 Location: Central MA

Hello boys!

I'm doing some battery work, and I found a real steal. Some used 8 Volt batteries for just 10 bucks a pop! Only problem is, I'd need a hefty 15 of these beasts to get to the 120 volts I need for my electric 924.

Now, I'm probably going to be looking at adding some weight. Did I say some? I meant a LOT.

For all of these batteries, I'm looking at around 1000 lbs of weight. Even the most generous people think shedding all the internal combusion stuff is around 550 lbs. Add on to that 200 lbs of electric motor, controller, charger, wiring, and...well....you get the point.

In a worst case senario, I might be slapping 700 lbs of batteries in the rear of the two-four. (Shudder) This would, of course, make it look like an elephant taking a dump. Do you guys know of any heavier duty shocks that would be able to work with the rear and front axles of it? I know people usually end up looking for things to lower the car but...well...this is different! I'm wondering if maybe the stock 924S shocks from the heaviest year would do the trick. After all, some lowering is acceptable, and cool!

Thanks a ton! Or at least 1/2 of one...

-Jeff
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A Ravaged '77 924 (Electric Conversion in Progress)

Smoothie · Posted: Tue Jul 20, 2004 8:26 am Post subject:

http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/storeId-10101/p-2125/c-10101/catalogId-10101

Pretty sure what I have is the 750 lb. pair listed at the bottom in the above link. They're sized perfectly to fit in the existing rear shock mounts using very little of the hardware that came with them - only used either one or both of the supplied spring end "cups" for each spring. My guess would be that the middle listed 1250 lb. pair would be the same diameter and fit just as well, while the upper one for HD shocks would be too large diameter-wise.

one of my JCWhitney coilovers

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http://f2.pg.photos.yahoo.com/ph/smoothies931pics/detail?.dir=/7a86&.dnm=722d.jpg
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

Smoothie, do you use these as well as or instead of the torsion bars?
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

Smoothie · Posted: Tue Jul 20, 2004 8:50 am Post subject:

The torsion bars are still there and were never touched (not even adjusted). I put the helpers on because when I started using a set of 911 Fuchs wheels, the difference in their offset left them sitting something like 17mm further out than the stock wheels and they rubbed the fender lip on sharp turns, bumps, or with a heavy load. The helpers took care of the problem with I'd imagine way less work than replacing or adjusting the torsion bars.

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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Fuzzbeaner · Joined: 03 Dec 2003 Posts: 236 Location: Central MA

Hey, thanks, those look perfect!

-Jeff
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A Ravaged '77 924 (Electric Conversion in Progress)

Paul · Posted: Tue Jul 20, 2004 10:25 am Post subject:

Did you factor into the mix that you won't need 100 pounds of gasoline?

Smoothie · Posted: Tue Jul 20, 2004 1:21 pm Post subject:

Jeff - Of course you asked a shock question and I gave you a spring answer, but you still need the shock question answered because they'll need to be able to dampen the greater up-down momentum generated by the extra weight.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

jpab924 · Posted: Tue Jul 20, 2004 1:53 pm Post subject:

This guy has 20 12v deep cycle lead acid batteries = 240v in his setup. And by the look of things, they all don`t sit in one location.

some in the trunk....

and some in the engine bay....

Sleykin · Posted: Tue Jul 20, 2004 4:17 pm Post subject:

I can't believe somebody turned a 928 into an EV! Now steam ... that would be a worthy task

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Glenn Neff
Medford, OR
87' 924S

Fuzzbeaner · Joined: 03 Dec 2003 Posts: 236 Location: Central MA

Paul: I haven't factored in gasoline, but once I couldn't get within 100 lbs of exact IC weight, I gave up trying to find out the real weight! I just know it's 500-600 lbish.

Smoothie, ok, but you've got me 1/2 way there! Anyone know where to find big ol' shocks?

JPab, I know that putting them all in one location would be counter productive. In a worst case senario, I will have to put 700 lbs of the 1050 pounds of batteries into the back of the car, but I hope that number to be more along the lines of 300-450 lbs. After all, to maintain weight ratio, since there used to be an engine in the front, I'm probably looking at a 8:4 ratio between front and rear batts, if possible.

-Jeff
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A Ravaged '77 924 (Electric Conversion in Progress)

wdb · Joined: 02 Nov 2002 Posts: 2024

I would think you could fit six on the floor in the back seat , then weld in a shelf over the top of them , across the whole back seat should hold a least a dozen . 18 total , then and if needed go to the engine bay and hatch area . trying to keep the ends of the car light for handling .

Fuzzbeaner · Joined: 03 Dec 2003 Posts: 236 Location: Central MA

WDB, I'm intrigued by your idea! Do the back seats really reside at an even distance between the front and rear axles? Since they're pretty useless anyways, that might be cool, and leave me with some cargo space. I had always been thinking that putting weight directly over the axles would be best, but you're probably right!

Five Batteries in the engine bay and ten where the back seats were would probably come close to maintaining a 50/50 weight ratio, and distribute the extra load evenly between both axles!!!

-Jeff
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A Ravaged '77 924 (Electric Conversion in Progress)

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Are you upgrading to the 5 bolt brakes to deal with the additional weight? How do you address the vacuum booster for the brakes given you no longer have an internal comustion engine?
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1987 951 - M193 Version for Japan

Fuzzbeaner · Joined: 03 Dec 2003 Posts: 236 Location: Central MA

I'm considering the 5 bolt brakes, but I'm hoping that I'll get suitable braking from the current 4 bolts. Once again, it's all about the money...

And you're right, without an intake manifold, I will not have power brakes. I'm going to use a 12 VDC vacuum pump with a PVC pipe and a vacuum sensor to act as a vacuum source. I actually got a sponsorship from SurplusCenter.com for the pump!

Also, for those who aren't sure of their own craftsmanship, premade brake pumps can be bought, but they cost a pretty penny. Usually made for diesals, or heavily modded engines that can no longer make suitable vacuum. Unfortunately, they ring up at 300$ or more...

-Jeff
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A Ravaged '77 924 (Electric Conversion in Progress)

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

It will be interesting to see if you get sufficient braking from the disc/drum setup...
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1987 951 - M193 Version for Japan