GL 1303S project from Romania

[Xellex]

yes, that's what I thought. Still, there are a few people on this forums that plumbed it the other way around. I think Wally did it too. Am I right?

[Wally]

Yeah, but I plumbed it back and actually removed the 944 MC all together and used a bug 19/19 MC again
My thinking is that larger diameter MC brakes with less force and if you don't realy need the lesser pedal travel, you better use the smallest piston for the most pressure inside the MC. More pressure= lesser brakepedal effort= harder braking.

[Xellex]

I think that would only be true if the calipers were the same size front/rear, and if the 19mm would push enough fluid to succesfully move the big NA 944 front caliper pistons.
Your thinking makes perfect sense, but imho the total volume of the pistons inside the calipers at full braking (expanded the most / brakes locked) has to be equal or lower to the volume of the piston inside the MC when pedal is released. If it's bigger then there's a big problem.
So yes, the lowest volume MC piston is the best, but there's a lower limit, and there's also a higher limit, to the point where brake effort is too high, and pedal travel is extremely small.
The question is: does the 19mm MC fit somewhere above that lower limit? Ofcourse on the street/track you could get great results, and good braking because the bug is so light.
And the second question is: what does that do to the rear, lower volume calipers? Probably locking them too early.

That's just my late night thinking, and the only fluid dynamics classes I took were in college, so I could be very wrong.

Anyway I'll just do the extra plumbing and mount the MC the normal way.
Thank you for your response, I apreciate it.

[flat]

I've tried to stock 19mm dual circuit MC with 944NA brakes, and it doesn't work well. Not enough volume. You need the 944MC for the NA brakes. With aluminum brembo's, the stock 19mm works extremely well.

Lanner

[evilC]

The original standard m/c for the 944 was a 19/19 unit that was later changed to 23/19 and that is the one that most people refer to as the 944 m/c. Fluid volume is not really the issue with a fully working system with good lines and fresh fluid (well bled). The basics of hydraulic advantage is that the pedal effort is multiplied by the area of caliper pistons (2No.) / area of mc piston. The stand off of the pad from the disc is very small so as minimise pedal travel. The main effects on pedal travel are hose bulge and water/air in the system that then compresses.
On a bug with a larger caliper piston area at the front than on the rear the stepped m/c can be of some advantage as the desireable brake bias is unity i.e. the braking effort front and rear should be about the same. The larger m/c piston is around 45% larger in area than the smaller piston and therefore gives 2/3rds the fluid pressure than the rear line.

evilC

[Wally]

Yeah, that too

[flat]

I've just speaking from my experience. The 19mm stocker didn't feel right with the 944NA brakes, the pedal travel was too deep. Everything on the car was new/rebuilt, with fresh fluid in the system. It would brake, but you felt the need to pump the pedal to get the required volume. Swapped it over for a 23/19 MC and it was amazing. Tall pedal + great clamping = driver confidence. The 19mm MC worked, but the 23/19 worked MUCH better.

So, the question boils down to this: Has anyone used a 19mm stock MC on a 944 NA brake system with good success?

Lanner

[ricola]

stock 944 NA front brakes and standard 19mm m/c I found I didn't get enough travel (pedal was bottoming out), maybe if they were all fully bedded in they would get borderline acceptable?

[Xellex]

thanks for all the input guys, I really apreciate it.

@ $aint: thank you, I really hope I can bring something back to this great comunity.
About the headlights, yes they are the same as those on Cip1, but mine have clar glass all the way. So the light output is awesome.. much better than a new car, but not disturbing the incoming traffic.
They are made all out of plastic and the overall quality is not that good, but acceptable for now.
There is that problem about having to remove them if a light bulb gets blown, but Xenon headlights should hold much much longer than halogen ones. (at least in theory).
About incorporating the turn signal bulbs in them, I wanted to do it too, but now I think it's not a very good idea. The radius from where they can be seen would be too small. Instead of that, I want to incorporate fog/city lights in them, and place the turn signals in the bumper.

[yellow73]

You have a really clean car. I am enjoying your reading about your progress.

[Xellex]

thank you, I'm happy to hear that
I made some more progress last week. I decided to make the custom brackets for the rear Porsche stabilizer bar, and I copied the Kerscher design. They didn't come out as nice as the german ones, but they worked ok.
The lower part, where the bushing stays is actually the original piece that I removed from the Porsche torsion bar housing.



I assembled the Porsche drive axles, with Beetle CV joints to one side and Porsche CV joints to the other.

[Xellex]

And the Kerscher ball-joints came with the mail, so I went to a shop to replace the original ones. I also drilled the hole in the spindle, for the speedometer cable. It came out very nice. And I installed the urethane bushings into the A-arms.

[Xellex]

This goes to Wally and the other guys living in the Netherlands: I just got tickets and I'm gonna spend Christmas (23Dec-27Dec) with my girlfriend and brother in Hague and Amsterdam.
I've checked the keversite website, but I can't understand much of it. (other than the fact that there's alot of activity in the netherland's aircooled world) I want to know if there's something bug/aircooled related that's worth visiting in that area.
The Paruzzi store seems close... maybe it's worth going there. Anything else interesting? (kieft&klok maybe?)
Oh, and I'd love to meet you and see the white bug and the 411.
Thanks

[Xellex]

Haven't done much to the bug lately... Master brake cylinder is in now, so are the drive axles. I had to shorten that pedal push rod that goes into the MBC about 1cm.

And I changed the gear coupler bushings. I'm extremely happy with the results, but I will have to change that bushing in the tunnel too, to get everything perfect.

I will have to order the custom struts soon, but it's not on my priority list with christmas/new year and all.
I've ordered a full braking hard lines kit, after I tried to re-route one of them and it broke in my hand.
Oh, and I cleaned the Porsche R&P steering, to be able to handle it without getting my hands dirty. It's a challenge but I really want to try and make it work... we'll see if I'm gonna get anything good of it. If not, then I'll probably settle for a stock post '75 1303 R&P.


Still waiting for a response to my previous post, if any1 in knows anything and is willing to share

[evilC]

Xellex, are you convinced about using the porsche rack? i have a couple of queries:
1) The porsche rack looks as though it will give a huge amount of bump steer as the pivot point is too far outboard for the pivot point of the lower suspension arm.
2) I would have thought that utilising a power steering unit will be overkill for such a light front end and you will lose all feel.

A standard steering rack would be the way to go and it should be quick enough for most circumstances.

evilC