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Old 07-29-2009, 07:57 AM
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Default 944 brakes ona bug link

I found this this morning, while sipping on my morning coffee.

Porsche 944 Brake Conversion
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Old 07-30-2009, 08:11 PM
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Every time I am at the junk yard, and I find a 944, I always look the the rear suspension and brakes. The really do look like VW bug rear suspension. I can see how a little welding could make this happen.
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Old 10-18-2009, 02:24 PM
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Hi. I'm new to the forum, but I've got a touch of experience with Porsche suspensions swaps.

The first 944's actually borrowed its original suspension design from the superbeetle, and therefore it will actually bolt straight in without any real modifications. In order to use the front brakes from the 944 there are a few modifications that to the Porsche hub and the VW spindle that are needed but you can call Lanner at VW Engineering in Canada and he can hook you up on those.

As for the rear suspension, the earliest 944 trailing arms are dimensionally the same as an type 1 IRS trailing arm, but Porsche added an additional piece of steel inside the arm for strength. Also, the 944 used a cast aluminum backing plate that mounted the parking drum brake and the caliper to the arm. The rear disc just slid onto the porsche hub from there. In about '85.5 or '86 Porsche changed out the stamped steel trailing arm for a cast aluminum one on the 944 Turbo. These whole trailing arms still bolt in place of the original ones adding about 24mm of track to each side. From '87 on, all 944's used a different cast aluminum trailing arm, with a hub set up for ABS that adds about 72mm per side. From '85.5 on all 944 Turbo's used fixed 4 piston brembo calipers while the naturally aspirated 944 used single piston sliding calipers (ATE I think, but I'm not positive).

In pace Domini

Damon
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Old 10-18-2009, 09:52 PM
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Thanks for that post, Damon. You have some good details and information that I was missing.

I first learned that it was possible to use 944 rear suspension on a Bug from an article in a book I found a Carlisle a few years ago. (I remember being incredibly surprised that Porsche was still using essentially the exact same suspension geometry as VW had been using for more than a decade. Must have been a good design!)

I never got around to doing the installation on my car...yet...but I did go as far as to pick up a pair of complete 944 trailing arms with hubs, brakes, etc.

Below are some old photos from my archive that I took the weekend the trailing arms were delivered. You can see how similar they are to the Bug trailing arms. And you can also see the differences: The brake rotor are MASSIVE compared to the Bug's, and the whole arm is much beefier and stronger.

I've been told that you have to alter at least one of the bolt points where the spring arm attaches, and you have to machine the urethane donut where the arm attaches, both of which are relatively minor modifications. It still blows my mind that these two cars -- a little beetle-shaped passenger car from the '60s and '70s versus a front engine, rear drive sports car from the '80s -- can share these parts. Pretty cool.

I didn't know that it increased the track a little. Thanks for that information.

For those of you who don't already know, an inch = 25.4 mm. So according to Damon's info, the conversion ads about an inch to the track, overall. (Or three inches in the later models of 944s).

Here are the photos of 944 turbo trailing arms sitting next to the stock Bug trailing arms on my blue Sterling:

944 brakes ona bug link-944_brakes-1.jpg 944 brakes ona bug link-944_brakes-2.jpg 944 brakes ona bug link-944_brakes-3.jpg
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Old 10-19-2009, 01:11 AM
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Hi. As far as modifying the attachment points, there shouldn't be any machine work involved. It's the inner pivot bolt that needs to be changed, but all you have to do is pop out the rubber bushing and push in a Beelt bushing. The only difference between the Beetle bushing and the 944 Turbo bushing is the bolt size. Oddly enough, the Porsche uses something like a 1/2 inch bolt, but the Volkswagen uses a monster bolt that's closer to 3/4 inch.

One thing I forgot to mention is that in order to use the Porsche trailing arms, you have to also use the Porsche axles and 100mm CV joint output flanges on the transaxle.

Pax Christi

Damon
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Old 10-19-2009, 01:57 PM
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Yes, thanks for the clarification. I know from reading that there isn't any metal that needs to be machined differently at the hinge point. But I remember that something had to be subtly changed about the rubber/urethane donut. I guess it was simply that difference in bolt size. I've been told that most of the (small handful of) people who've done this swap usually "upgrade" to urethane bushings in part because they can machine the urethane more ealisy than the stock rubber to make these small alterations.

(I've been told you can machine rubber, but you have to do something odd like freeze it in dry ice first. Never tried it.)

And yep, you need at least the Porsche outer CV joints. Damon, do you know whether the Porsche half-axles mate directly up with the Bug trans? I was going to use Bug half-axles that were modified to accept the Porsche outer CV joint. Do you know what other people have done to solve that? I know I've seen Bug-to-Porsche axles in magazines, but I don't know which parts were borrowed from which cars.
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Old 10-19-2009, 02:07 PM
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If you take a look at the Porsche trailing arms you'll see that the stub axle is tucked way back inside of it. It turns out the you need to use the 944 Turbo axle because it is about 5 inches longer than the bug axle. You can still get away without having to use any crazy or custom parts though, since the 944 just used 100mm type 4 CV joints. This means that you can swap out the type 1 gearbox output flanges for Thing flanges, or if you want to use a type 2 gearbox you're golden since it already uses 100mm flanges.



If anyone is interested in doing the conversion I'm selling a basically complete "kit" for it. I've gathered everything and had all the front spindle machine work done, but have just run out of time and money to finish the conversion.
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Old 10-19-2009, 02:53 PM
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That sounds great, but how would one get 944 brakes all the way around, since most of the braking power comes from the front.

Also, how would one adapt the axles when using the scooby motor and trans?

I mean, the inner half shafts would have to be scooby right? then the axle, and Im guessing 944 turbo or type 4 bits after that?

Where does one go to get such a frankenstein part made like that?
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Old 10-19-2009, 03:16 PM
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In order to make the front brakes big and impressive Porsche bits, you have to machine the Porsche hubs (I used '86 parts because they are narrower on the front too) to use type 1 bearing and to fit on standard beetle spindles. Once the hubs are fit and the disc is on you can fit the caliper using a custom adapter. I had all that work done by VW Engineering in Canada. Lanner (of VW Engineering) does his modifications in such a way that he only changes parts that don't get replaced. That way the caliper, rotor, and the bearings are unmodified stock items that can be sourced from any parts house. Take a look at the pictures below.


As far as connecting everything to a Scooby trans, I think you're out of my league. Do you know how big the CV joint on the output flange is? Or does it use one of the big tripod joints where you have to replace the whole halfshaft? If it's conveniently 100mm then you might be able to get away with using the Porsche/VW joints. Also, do you know how the width of the gearbox across the CV joints compares to the same dimension on a type 1 gearbox? If it's narrower than the VW gearbox you might be able to use adapter plates so that all of the parts that might need replacement over time are production parts.

Peace!
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944 brakes ona bug link-img_0044.jpg   944 brakes ona bug link-img_0045.jpg   944 brakes ona bug link-img_0046.jpg  

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Old 10-20-2009, 01:52 AM
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Very nice,
Thanks that good info. Id be nice if we had a common teh section for common questions like this.

I do wonder if the red 9 guys selling those front ends would offer a 944, or 911 setup on their products?
Id be nice to have it already done and ready to go on the unit once installed.
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