Porsche 944T brakes on VW 1303S

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TZepeSH
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Porsche 944T brakes on VW 1303S

Post by TZepeSH » Wed Nov 22, 2017 7:18 am

As I have been writing on the Euro Look forum, I purchased a complete 944T rear axle and front brakes. The ones with 4 pot Brembo calipers. I already have Porsche brakes on my car, but the NA 944 version, with ATE sliding calipers. I just needed the rear arms and stabilizer bar and was convinced I would easily sell the 944T brakes which I did not want. But, when I laid my hands on them, I changed my mind instantly. They are so much nicer than the NA brakes... So, now I will have to find a way to install them.
I will post updates as I do modifications. At a first glance, the strut mounts are thinner by 2mm so I will have to make a shim to compensate, and the strut mounting holes are closer by 5mm than the NA version.
Next on the list, I want to use my Cookie Cutters which do not clear the front calipers. I want to use 21mm spacers on front, so longer studs are on order. I could use 15" Phone Dials PN 95136210400 which clear the calipers, but I do not like them; I have two, maybe I will make a set to be used as winter wheels. Technically, it seems better to use spacers on front, because the rear is widened by 7cm/side by the aluminum arms and normally the Bug has a wider front track than rear, for stability due to the heavy rear. Hopefully the wheels will still fit under the 4cm flared fenders. If not, I will have to use the 15" Phonies without spacers.
One idea that came to my mind is to install also the ABS. Pump, ECU, sensors and harness are ~300 bucks. But I found some comments on another forum from Vaughan Scott, a guy working with ABS systems daily at work, not recommending to install ABS systems on cars that did not have them from factory. His reason is that algorithm is tuned to the specific car, based on weight distribution and on dynamic distribution change during braking. I do not fully agree to that, but I am no expert. 944 ABS, as I know, just reads the wheels speed, and if one has significantly lower speed, it removes pressure for a defined amount of time. So it should work in any conditions on any car. I do think it might be a problem that the 944 system is for a front engine/rear traction car, and the Beetle is rear engine/rear traction, so light front. But in the end, the system shall do the same: remove pressure from the low speed wheel. Wheel diameter is the same for Porsche 944T and beetle, 25", so wheel speed is the same, no problem there. If the ABS was to be used in conjunction with ESP like in modern cars, I would agree that it might not work properly.
Any opinions on this, has anybody considered ABS systems?
Sorry no pics now, I will upload later when I get to my home computer.

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Re: Porsche 944T brakes on VW 1303S

Post by H2OSB » Wed Nov 22, 2017 9:10 am

Though I agree the cookie cutters are nice looking wheels, phonies don't look bad if you get them powder coated all black. I think 21mm spacers are pretty wide and would be inclined to use the phone dials...or get something else. Cookie cutters are ET23, so if your phone dials fit, I'll assume they're the ET52.3 flavor.

It's tough to find 15 inch wheels in a 5x130 PCD. I too have n/a 944 brakes (Well, Porsche M caliper on the front). I'm running 15x5.5 steels with 912 hubcaps. I will probably get a set of phonies for autocross tires, as they're plentiful and cheap. Ultimately, I'd like to find a set of the 15x5.5 ET30 alloy space saver spares (the bright red ones), as my car theme is a sort of pseudo outlaw look.

Good luck
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TZepeSH
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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Wed Nov 22, 2017 9:58 am

The 15" Phonies that fit the 944T brakes (actually the only 15" wheels that do fit without spacers!) are also ET23.3. I would end up with ET2.3 on front in the end. The ET52 Phonies do NOT fit over 944T brakes.

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Re: Porsche 944T brakes on VW 1303S

Post by H2OSB » Wed Nov 22, 2017 10:48 am

Ah. I've never looked at those calipers.

If i go away from my heavy calipers, I'll probably go with Wilwood calipers, for the weight savings, not for improved performance. The 48mm piston front, 36mm piston rear calipers I have now are more than enough for the driving I do.

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TZepeSH
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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Thu Nov 23, 2017 8:13 am

Well, NA sliding calipers are also enough for my driving needs. As I said, I just bought the 944T brakes because the seller did not want to sell just the rear aluminum arms... And now, love at first sight with the 4 pot calipers. Also it is not good for my budget, because I only had planned 500 bucks for the arms and stabilizer, I am now 500 more deep with the brakes. All looks like it would be better to just sell them and get back to my budget, but I so much like them!
And don't think it is braking overkill. Due to the design with different sizes of pistons (36/40mm fronts and 28/30mm rears), the braking force is not necessarily higher (at least not at full brake application), but more smooth, gradual and controllable.
What about ABS?

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Re: Porsche 944T brakes on VW 1303S

Post by Jadewombat » Thu Nov 23, 2017 11:46 pm

Aside from the extensive plumbing and fabrication involved to mount everything, I wouldn't bother with the ABS. For a heavier car, maybe. But a 1303 which is maybe 2000lbs I think would create more problems than solve them. I got my car weight down to about 1500lbs. for auto-X and it was fairly easy to lock up the brakes with 944 N/A brakes on that car and dual M/Cs and a good jab on the brake pedal. With four pots and not much effort it would be even easier to lock up all four wheels and would confuse the heck out of the ABS unit.

I almost went ABS on my old Golf with a set from a Corrado because the cars were arguably similar and I wanted something as safe as could be.

TZepeSH
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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Fri Nov 24, 2017 2:40 am

Isn't that the whole purpose of the ABS, to avoid wheel lockup?
I believe that during normal braking the 944T brakes will be more controllable. At hard braking, yes, they might be locking easier. Or, get used to the brakes and learn how to brake properly. I was more concerned about winter time, when losing grip on one wheel happens more often, and lockup is more dangerous. Vaughan's point was that the worst case that could happen is to lose brakes completely due to ABS algorithm, but I do not understand under what conditions this would happen. Normally on fault ABS shall be de-activated and rely only on normal braking. His concern was about witing harness done wring, but using original harness this should be avoided.
Anyway, ABS is more of "what if it can be done" topic, I was just considering it because I have the provision for it in the brakes. I would listen to an expert in this field, as I am not so savvy, but I also want to learn about it.

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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Fri Nov 24, 2017 9:25 am

My beauties.
142922257_2_1000x700_frane-porsche-944-turbo-fotografii.jpg
142922257_6_1000x700_frane-porsche-944-turbo-.jpg
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Re: Porsche 944T brakes on VW 1303S

Post by H2OSB » Fri Nov 24, 2017 10:14 am

nice!

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Re: Porsche 944T brakes on VW 1303S

Post by Piledriver » Fri Nov 24, 2017 11:42 am

Aircooled VWs (and old Porsches) are an outlier on brake setup if you want max performance.

I'm running the fronts on the back to get the brake balance right at max braking, with a Wilwood proportioning adjuster, and 1.25"x4 Wilwoods up front.
On a low CG vehicle with 30/70 weight distribution, same piston area front and rear is just about right for 1G braking, you need enough rear area to turn down, so equal to slightly larger rear is workable.

Even without the bias adjuster, my fronts still lock first.
(probably down to brake pads, PF 12s front Pagid blues rear)

Play with this:
http://brakepower.com/

The 944T or 928 had 50/50 weight distribution (and shared brake parts), so needed much larger front brakes.

The only practical stand alone ABS setup I know of is the old BMW system, which needs very expensive reprogramming dependent on the target vehicle and components used.
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Re: Porsche 944T brakes on VW 1303S

Post by Jadewombat » Sun Nov 26, 2017 12:09 am

If you have the time and the means, go for it with the ABS if you can convert back to without it easy enough. I'm just skeptical because the cars are so light (1) I don't think much would be gained going that route and (2) the system may try to overcorrect when it's not really needed.

In my 2012 Chevy Colorado, which tips the scales just under 4000lb. F disk R drums, I've hit enough bumps and potholes with one or both wheels front or rear at low speeds to where the ABS kicks in it's just annoying, doesn't help braking, and jerks the steering wheel momentarily if it's on the front end. In the wet, it's a different story and I wouldn't live without it though.

TZepeSH
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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Fri Dec 08, 2017 8:20 am

I have a question on driveshafts. For the 944T trailing arms (late, wide), what "long driveshafts" shall I use?
I have read that early 944 and 924 had the same length as the IRS Bug (somewhere around 16", or 402 or 412mm, not clear).
For 944 driveshaft length seem to be 21" (531mm) either in NA or Turbo, after '85. However, there are two PNs for NA and Turbo (951).
I have read that I could use Vanagon driveshafts, but also for this one I did not find the length, there are many opinions: 20 1/2" (520mm, Vanagon automatic, Left), 21 1/4" (540mm), 21 1/2" (547mm), 22 1/2" (571.5mm Vanagon automatic, Right).

According to PET, for 944 manual transmission cars:

Steel trailing arms use:
477 501 103 (401.5mm) http://www.design911.co.uk/fu/prod3490/ ... nual-Cars/

Early alu trailing arms (1985.5-1986 944 / 1986-1988 924S) use:
944 332 038 01 (531.5mm) http://www.design911.co.uk/fu/prod3491/ ... ange-Unit/

Late alu trailing arms (1987-onward 944) use:
951 332 038 02 (531.5mm) https://www.buycarparts.co.uk/lobro/1385586

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Re: Porsche 944T brakes on VW 1303S

Post by H2OSB » Fri Dec 08, 2017 9:03 am

Someone should create a sticky with the various driveshaft lengths (hint hint)

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Re: Porsche 944T brakes on VW 1303S

Post by Piledriver » Fri Dec 08, 2017 11:38 am

Off road forum has that IIRC, although the usual reference is http://www.blindchickenracing.com/how_t ... es_101.htm there is a lot of good info on their website re: fabrication.

I have early Turbo arms and they took the manual Vanagon axles.

AFAIK the only difference between the early and late 944 Turbo arm axles was the part number.

The main difference between early/late arms was the stub axle/hub was longer on the late units to make room for an abs ring (so are wider track).

Late arms also lack the bump stop boss, early arms boss mostly lines up with the t1/t3 bump stop.
...but the bump stop must be mounted, I used late Ford Mustang foam stops and glued them on with Plastic Welder.
The modern foam stops work much better than either urethane or the stock bumps, esp on a lowered car.
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TZepeSH
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Re: Porsche 944T brakes on VW 1303S

Post by TZepeSH » Sat Dec 09, 2017 1:29 am

Pile, that is the site i used to get the vanagon axle lengths. But it does not clarify what axles work with the 944 alu arms. It is not clear for me if 944 axles (531mm) will work, or if vanagon manual axles are needed (540mm, it seems thay are a bit longer).

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