9sixty4

Has anyone used an optima battery in a C4? I was wondering if the positive battery post will interfere with the brake booster pump. Or any other fitment problems?

Strabo

I tried to put my Optima battery into my 1993 RS America. However, the positive post is too far from the edge of the battery. The positive cable has a sharp angle that allows it to fit close to the vertical edge of the battery, but it is designed to fit a battery with the post closer to the edge. Hope this makes sense.

Strabo

Randall G.

Hey Strabo,

What's the model of your Optima? It's my understanding that the red-top 75/35 is a direct bolt-on for a 993, and the 964 and 993 Porsche battery part numbers are the same (999-611-070-20). Of course, if it's a direct bolt-on for a 993, it ought to fit the 964, as well.

Some reference links:

<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic&f=3&t=006932#000011" target="_blank">Optima Link1</a>

<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=3;t=006937" target="_blank">Optima Link2</a>

Bob Krantz

The red-top posts are a problem: too far from the side for the factory positive clamp (quite a large metal casting inside the rubber) to grip. I wrote a Running Report for 911 & Porsche World (June 2002) that described how I made a brass extension to create a new post nearer to the side. John Miles has that report but has not yet added it to his 964 web. Let me know if you want more info or want to see photos.
Bob K
1989 C4

Strabo

Bob,

I would like to see your adaptor for the Optima battery. I am a big fan of these batteries and would like to put it in my RSA. I had an optima in my SC for 10 years and it is still going strong in another vehicle.

Strabo

Randall G.

Bob/Strabo,

Which red-top did you try fitting? If you read Link2 in my post above, the guy first tried to fit the 34/78, but it didn't work. The 75/35 was a direct fit.

Pics of the batteries:

<a href="http://www.optimabatteries.com/products/pdf/75_35.pdf" target="_blank">75/35</a>

<a href="http://www.optimabatteries.com/products/pdf/34_78.pdf" target="_blank">34/78</a>

Not certain (as I haven't personally installed a 75/35 in my car--yet), but you may have been trying to install the wrong model Optima.

Bob Krantz

Randall:
I checked out the Optima web site pics, and the 75/34 looks better (bit not perfect compared to the stock battery I had). When I went shopping for Optima, still in Alaska, the best I could find was a 34-800s. If anyone want to see pics of my post extension, email me. Since I am not a Rennlist member, I cannot upload photos.
Bob K
1989 C4

Randall G.

Hey guys,

I just took this picture of the battery in my car:

<img src="http://members.rennlist.com/rgranaas/Battery1.JPG" alt=" - " />

Here's a pic of the 75/35:

<img src="http://www.batteryweb.com/productpics/optimapics/7535-925.jpg" alt=" - " />

Looks to me like the 75/35 should fit directly on our cars--even when considering the 90 degree connection on the positive terminal--though Bob's extension might come in handy for someone that already has a different model Optima.

Strabo

Randall,

Good Work! Your information is a valuable service for everyone.

I have never seen a 75/35 and did not know that they exist. But I do know that my 34/78 has been providing flawless service for well over a decade. It is a great battery.

Strabo