GL 1303S project from Romania

[Xellex]

well I'm not 100% convinced, but if I have it, why not give it a try... If the results are not gonna be ok, then I switch back to the stock steering and try to source a late 1303 rack.
Yes, I've read about the bump-steer problem alot all over the aircooled forums, but I've never actually heard it/read it from someone who has really done it.
The pivot point is actually not that far out, compared to the stock 1303 pivot point (not r&p version). I'm gonna get exact measurements, and yes, I realise only a few mm could matter for a good or bad setup.
Right now, it looks like everybody is saying "don't do it, yo're gonna get bump-steer!" based on calculations, maybe engineering studies or experience, or just a hunch (did I spell that right?) ....At least I'm gonna be the one to say "Don't do it, I've already tried that and it sucks!"
There's a subaru powered bug featured in the 2008 Kaefer Revue Magazine that has this conversion, and it looks like it's working.
And yes, mine is the power steering unit, but w/o a pump, it should be just like the normal one. I'm not planning on using a pump for the start at least.
I've read everything I could find on steering setups and the bump-steer effect, but it's not much. If you guys can point me to some more info, I would be grateful.
I'll take into consideration everything you guys might have to add, pros or cons. The first thing for me too is safety.. That's for sure!
The only other porsche rack setup, I found, besides the one in that magazine would be in these 2 pictures, but I can't remember where they are from:

[Xellex]

I could be very wrong, but I think bump-steer has more to do with the position of the rack (height, forward/rearward pos. and perfect paralelism to the ground axis) than it has to do with the length of the tie-rods, compared to the length of the a-arms. Of course, as long as the tie-rods are the same length left-to-right, not like the older beetle steering systems.

[evilC]

Your first photo is an excellent example of what I am commenting on. You will see that the rack pivot point is much closer to the wheel than the track arm pivot point. When the suspension compresses the rack tie rod and the track arm move through different arcs therefore the 'king pin' moves much less to the centreline of the car than the steering arm end, thus it will pull the steering arm inwards causing the wheel to toe-in. If the bump is on one side only the vehicle will turn away from the bump (bump steer).

The position of the rack is influential and difficult to assess without extensive 3-D modelling either by CAD or a physical 3-D model

I suggest you read Allan Staniforths book on the subject for a better and more detailed overview:-
http://www.amazon.co.uk/Competition-.../dp/185960644X

[Xellex]

Man, I can't believe it's been so long since the site went down! Take an average of 20 times a day checking if it's back up, and multiply it to the days passed, and you get a mad man :mad2:

I've made some progress on my bug too. I gave up on the idea of using the Porsche rack, but still, I decided to try someting just a little bit different. More on that later.

I mounted some small stuff on the bug, like a 3rd brake light, some mounts for the front licence plate, that move it under the bumper, I replaced all the brake plumbing, I also replaced that bushing inside the tunnel, for the shifter linkage, I installed the flip-it bushings. Pics in my album, link is in my signature.

And most importantly, my front suspension came, and it's awesome! It's the LA Performance set, for late 944 spindles.




And after a long time, the bug can sit on all it's 4 wheels again!



If you look closely in the suspension pics, you can see the rack mounts that I'm trying to make, using the original pre '75 steering box mounts. Right now it's only a mock-up.
The rack it's self is from the Audi 100 / Audi A6 Typ 44. It's almost the same as the late 1303 one, but the mounting points are different and the splined shaft has the same diameter, but more splines. The model that I chose also has power steering, but I'm probably not gonna use it.
There are a few little problems that I have to solve somehow but I'm confident it's gonna work.

[jmd]

I am way into this thread. I can't wait to see what comes of the Rack and Pinion setup...

[typ4boy]

Originally Posted by Xellex

Man, I can't believe it's been so long since the site went down! Take an average of 20 times a day checking if it's back up, and multiply it to the days passed, and you get a mad man :mad2:

I've made some progress on my bug too. I gave up on the idea of using the Porsche rack, but still, I decided to try someting just a little bit different. More on that later.

I mounted some small stuff on the bug, like a 3rd brake light, some mounts for the front licence plate, that move it under the bumper, I replaced all the brake plumbing, I also replaced that bushing inside the tunnel, for the shifter linkage, I installed the flip-it bushings. Pics in my album, link is in my signature.

And most importantly, my front suspension came, and it's awesome! It's the LA Performance set, for late 944 spindles.




And after a long time, the bug can sit on all it's 4 wheels again!



If you look closely in the suspension pics, you can see the rack mounts that I'm trying to make, using the original pre '75 steering box mounts. Right now it's only a mock-up.
The rack it's self is from the Audi 100 / Audi A6 Typ 44. It's almost the same as the late 1303 one, but the mounting points are different and the splined shaft has the same diameter, but more splines. The model that I chose also has power steering, but I'm probably not gonna use it.
There are a few little problems that I have to solve somehow but I'm confident it's gonna work.

Nice struts .

[Xellex]

hehe thanks!
Actually Lee, I have a small question for you. I just noticed something in a picture of the white bug that you're currently building (which is awesome by the way). It seems like half the bottom of the trunk is raised by a few centimeters. Am I right? Is that something normal for the r&p bugs? I'm asking because looking at my bug, it's impossible to fit a r&p without cutting exactly the part that seems to be raised in your pic.

And another question for everyone that lowered their bugs: what's the maximum suspension travel (when it's compressed) before the lower arms hit the r&p or something else? Do we need to prevent that by using some bump stops on the struts, or it's not gonna happen?

[Wally]

Originally Posted by Xellex

And another question for everyone that lowered their bugs: what's the maximum suspension travel (when it's compressed) before the lower arms hit the r&p or something else? Do we need to prevent that by using some bump stops on the struts, or it's not gonna happen?

With a lot of lowering, it eventually WILL hit the mounting ends of the rack & pinion... Don't know what the exact amount of lowering is, but somewhere near 10cm and using type 1 Golf struts (which have a lower casing on the bottom) and shorter bump stops and you'll get there. Not likely for most of us I think Just using normal full length bump stops helped for me.
Thats all I know about this.

[Xellex]

Hi guys! I made some more progress since the last update. Now the steering rack brackets are ready, and the rack is on. The brackets are a little thin, so maybe I'll copy them in a thicker material if needed.


I used the u-joint shaft from a VW Golf, but I changed it's rack-end with the Audi one. In the second pic, starting up to down, late Porsche 944 shaft (and I think it's the same for the late post '75 VW1303), then Golf2, pre '75 1303, and Audi 100.


The tie-rod assemblies are Audi 100 C4. The length is perfect.
I didnt manage to drive it yet because I can't get it out on the street... a mountain of construction sand is blocking my way out, so I have to wait a few weeks.

And I'm in the process of making the power steering work too
I mounted an electrical power steering pump, from the Vw Polo/lupo or Skoda Fabia or Seat Ibiza/Cordoba. The pressure lines are in too, I didnt manage to start it yet, it needs some wiring, a sensor mounted on the steering column and a good electrician to sort it all out.



Don't start asking me why I needed power steering.... its a challenge... I just want to see if I can do it :d

[Xellex]

and another quick update: I split them like this because the forum says there are too much pics in the same post or something.
I got a few parts from the "Maikaefertreffen" in Hannover:
An original key, and a VW1303 keychain, 4cm widened front fenders from Kerscher Tuning, a front bumper with holes for the turn signals, and some clearglass turn signals, and for the first time since I have the car, Running boards!
Everything is already on the car





"Too many pics" message again haha

[Ganjalf]

Good luck with the power steering. I hope it works out

ABS next?

[Wally]

It looks twice a good already with that stance. Well done!

[evilC]

Hi Xellex,
It occured to me this morning that if you had power steering then there was no real limitation on the amount of caster that you could run. Have you thought about setting it up with say 9-10deg caster? That would provide very stable straight line running together with better loading of the outsde wheel in the turns? Also, I would be expecting better feel to be generated compared with the normal caster setting.
With the weight to the rear and the centre of aerodynamic pressure too close to the centre of the wheelbase, the bug needs all the help it can get to track straight at speed. The higher the speed the worse it gets so with the limitations on the amount of caster that would be acceptable on a manual steering the compromise is in favour of poor high speed stability. With power steering there will be no real practical limitation on how much caster you can dial in.

[Wally]

So, does anyone know what the 911's run caster-wise? They later ones are quite stable at speeds and might have power steering as well?

[Xellex]

Well that's an interesting idea, and I think it might work, but what are the bug's possibilities of caster/camber setting?
I haven't seen too many custom stuff either, designed for this thing. Other than those flanges somebody was selling at the Hannover meeting this year.
I wonder if those are adjustable, or they only have a (higher) preset angle?