Fitting JRZ Front Struts on '73 911 RSR Clone
 

I have a set of JRZ raised spindle adjustable front stiuts that I am planning on installing in my '73 911T to RSR Clone project car. Today I was comparing the JRZ's to my original Koni struts and I have several questions that I am hoping one of you experts might be able to help me with.

1. Can I use my original front hubs and replacement wheel bearings for a '73 911 with the JRZ's? I ask this question because the theaded end of the spindle on the JRZ's seems to be about 2mm larger than the threads on my Koni struts.

2. Since the threaded spindle diameter on the JRZ's is about 2mm larger, I must need a different clamping nut and outer bearing washer than the original '73 Koni strut?? Also the original '73 strut/washer combination has a keyed slot. The JRZ's do not have the key slot on the threaded end of the spindle. What clamping nut nut and outer bearing washer do I need to make this combo work?

3. The locating holes for the brake calipers on the JRZ's are about 1-2 mm closer to the centerline of the spindle than on the Koni struts. Will I have a problem fitting my original '73 S calipers to the strut? I am planning on using Zimmerman crossed drilled rotors.

3. The original Konis have a bracket on the strut body to hold the brake lines. The JRZ's do not have this bracket. How do I deal with this?

4. The JRZ's came without the upper strut dust cover. Can I use the strut dust covers from my Koni struts on the JRZ's

5. Lastley ( Thanks for your patience if you've gotten this far), I want to paint the struts Bilstein green as I want this car to look like a factory RSR as close as possible. I am planning to bead blast the plating off the JRZ's and have them painted Bilstien green. Is this a good idea??

Finally I want to say that the Pelican Parts 911 Tech Forum is great. I am in the middle of my dream 911 project. (see the post "Another RSR Clone Project" for more details) and the information on the website has helped more than anyone could imagine. I really appreciate the advice and experience of all of you who have gone done this path before me.

Since no one else has stepped up to the plate, here goes.

I don't know what size bearings you will need, however the normal bearing on your koni is a BCA5. This btw, is the same as used on the 53-54 Chevrolet and Corvettes up to '63. I can't remember what the outer bearing is however, your local bearing house could tell you from the number on a standard set of outer front wheel bearings.

You could go to your nut and bolt house, look for the guy with the grey hair, and tell them you need a locking nut for the front spindle. They may have a couple of choices. You may even cross drill the thread and use a castilated nut, like early american iron. Some early Chryslers used a castilated washer that held the nut in place along with a cotter key. This is a very positive method of holding your axel nuts in place. They probably have a bucket full of washers that will work under the nut to hold the bearing in place.

Using your original calipers? The first thing will be getting the rotors on there and then you will know pretty well what your options could be. You will probably get to know the guys at the machine shop pretty well by now.

I would probably make a custom bracket to hold the brake line. You might use something like 16 guage sheet metal strap with a nut and small bolt holding it together. I really don't like welding on struts.

The dust cover problem will only be known by direct comparison. There are many dust covers available. Very often the motorcycle guys know this area. They have to put up with all sorts of compromises when they work on their front ends.

Don't bother blasting off any plating. The plating keeps things from rusting better than paint. Find a good paint or rust proofing type primer and paint it. After all, this isn't exactly original anyway.

Good luck, sounds like you got some neat parts to play with!

David Duffield

Dave

Thanks for your insight. I did a little research and found that the clamping nut and outer bearing washer changed in 1974, while the hubs and wheel bearings stayed the same from from '65 to '89. I am guessing that I need the newer ('74 to '89) clamping nut and bearing washer.

i can see your point (old porsche) about welding struts. I certainly wouldnt like to lay a fat one up the side of a bit of 4mm plate or anything like that but i reckon a couple of tiny blobs with a mig to attatch a bracket would be ok.


Andy