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  #16  
Old March 18th 2005, 11:55
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Mathematically, the Akerman angle has more to do with the width of the front track. There would be a difference, for example, if the vehicle had a 61-inch front track versus a 69-inch front track.

When it comes to driving conditions, it gets even more complicated, albeit on a more subtle level, when tire characteristics such as sidewall flex and tackiness of the tread to pavement as well as the speed of the vehicle are factored in.

I mention this because it is possible one may not want a complete adherence to the Akerman angle given the unequal stress taken on by all four tires when cornering. (I'll leave it the racers to opin on what's desireable because I just plain don't know.)

Keep in mind, the rear tires aren't piveting at all (unless someone has instituted four-wheel steering at which point, someone owes us a tech article ).

Even if not perfect, a r&p system allows for the compensation necessary better than a steering box can.

I would think the amount of turning radius per steering wheel turn would be of greater concern. I read on some forum the stock VW r&p system (1975-79) is not as good as the steering box (1971-74) in that regard. If true -- and I have not yet confirmed this -- this might be a stronger point of contention when converting and upgrading. (Again, I'll leave this to the racers who would know about desireability.)
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  #17  
Old March 20th 2005, 06:35
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Quote:
Originally Posted by Jeza
Thanks Steve

I hope you don't mind, that is your new project I have linked to above
Hi Jezza no worries, thats what looked like after sitting in shed for 19 years.

The guy who owned my 1303 before me spent a couple of days on his wheel alignment machine to get the rack in the correct place so that there was no bump steer.

The Ackerman problem showed up when I 1st fitted the rack, going hard on highways the inside front wheel would give a little chirp if I crossed the centre line, this was chased back to a slightly bent strut and too much caster.

Steve
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  #18  
Old March 20th 2005, 16:57
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Quote:
Originally Posted by Steve C
Hi Jezza no worries, thats what looked like after sitting in shed for 19 years.
I'm watching with bated breath on your new project. Your last car was quite ahead of its time

Quote:
Originally Posted by Steve C
The Ackerman problem showed up when I 1st fitted the rack, going hard on highways the inside front wheel would give a little chirp if I crossed the centre line, this was chased back to a slightly bent strut and too much caster.

Steve
Too much caster? I didn't think this was possible? What amount of caster were you running in the end?

I was lead to believe that when a car was dramatically lowered you needed to make the wheel alignment more aggressive than the stock measures.

Other than that Steve, I take it you never noticed any Akerman problems?

Thanks
Jeremy
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  #19  
Old April 18th 2005, 05:52
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Fitting a steering rack

The steering rack bolts to the body and the strengthening plates which it bolts to are already there on 1303's. These double as the strengthing plates which your steering box and idler box bolt to.
The only thing you need to add is the M10 captive nuts for the rack to bolt to.
The chassis frame head needs clearancing for the rack aswell as has already been pointed out. Once this is done, it is a real bugger to get the gearshift rod in and out so if you're going to replace that flaky old gearshift rod bush.. do it beforehand!!
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  #20  
Old April 18th 2005, 18:47
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We are assuming the r&p Bug has the same steering geometry as the steering box '03/'02? This potential difference is near negligable when compared to the difference in Ackerman geometry when using Porsche spindles...

This is my experience with a rack'n'pinion Beetle.

I'm mostly recalling from mental notes here, the distance between the track-rod end and the steering axis is much less on my 951 stub-axles than the '03 stubs they replaced. The angle is different aswell. Also remember the Porsche stub axles have a drop spindle effect. The shorter length sharpens up the steering response/reduces the ratio, less turns lock-to lock, quite noticably. Not going to happen, as the stock wheels won't be going back on. The wide/big offset wheels that now fit under the stock front wing/fender will need steering limiting to prevent tyre fouling at the rear inner sidewall. Old news. I'm not sure if 944 'rod ends have different hieght, angle and length/steering geometry than 951. Mike Ghia, You've seen both Can you check for us? How is that Kab you were building? For you father wasn't it?

Limiting the steering is easy and safe on a steering box Superbug, as the mechanism is external. Unlike the 'rack which needs stop's fitting, to limit the throw of the wheels. This involves major surgery, to do it the way I did. And must be top quality. I will be doing this op again soon as I've aquired another rack as a spare. This time I'll take pics and share them. Some people argue that we do not drive on the steering limits (e.g. common, or garden rat-look Cal lookers). I believe a sorted GL car sould be able to drive at full-lock. Agree?

People in the UK remember, any evidence of welding or even heating on a steering or suspension component is an MOT failure.

The shift rod bush, I struggled and failed to get my shift rod out without bending it when I replaced that on my '79, they must have been flexed when first fitted When the shift rod is slid all the way to the the end of the tunnel, the bush can be changed easily.

Matt
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  #21  
Old April 18th 2005, 19:27
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Matt,

Kab is coming along nicely... looking very shiney in its new paint! Spend lots of time tip-toeing around it not scratching paint!

Not sure about the welding or heating of any steering component being an MOT failure. I worked for an MOT station for a while and its not one I've come across. I'll check it out with my old boss and he can dig out the book

We have lengthened the steering arms by about 50mm per side. With anti bump steer kits fitted so that the track rod enters the spindle from the top, the angle of the track rod is almost identical to that of the bottom arm so pretty good.

If your wheels catch on any part of the car on full lock, its an MOT failure.. I know that much and I'll be looking to sort that out. I've only just dropped the car down on its front suspension and not tried the steering on full lock so we'll see how it goes.

MG
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  #22  
Old April 19th 2005, 13:45
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Quote:
Originally Posted by Michael Ghia
Not sure about the welding or heating of any steering component being an MOT failure. I worked for an MOT station for a while and its not one I've come across. I'll check it out with my old boss and he can dig out the book
Save yourself the bother, I'm also a VOSA/MOT tester

From the MOT bible: "structural repair by welding to a steering linkage component, or signs of excessive heat having been applied"

2.2c reason for rejection d

MOT testers guide
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  #23  
Old April 19th 2005, 15:40
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Hmmmmm... looks like I'll be cleaning them up nicely before they go for powdercoating then

Cheers
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  #24  
Old April 20th 2005, 18:31
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That's the way we do it!
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  #25  
Old April 20th 2005, 23:00
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Welding of steering columns (shafts) is also a failure in NZ and can't be "certified" by an engineer either.

I would be curious to see what you have done regarding steering limiters. I gave this some thought a while ago, but can't remember if I came to a good conclusion

Are either of you able to share with us a measurement of the positon of the rack (eg its center) to a body component?

We didn't get 1303's out this way - other than private imports- and none that I've seen are late model ones.

Thanks
Jeremy
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  #26  
Old April 21st 2005, 17:10
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Jeza, I'm hoping to clean up the front underside of my Bug this summer, when the 'rack is off, I'll trace a template of the innerwing box section, picking up the exact position of the captive nuts and some relative reference points. I'll get it scanned along with a scale maybe, so it can be scaled 1:1 and printed off. Then cut out by anyone who is interested.

Matt
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  #27  
Old February 11th 2010, 08:56
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It's been a while since I was on the forums so apologies for that.

I'm just back on with my dads 1303LS Cab and among other things, I've noticed now that the suspension is all built up and fitted, we are going to have problems with the wheels hitting suspension on full lock. It's only running 6's up front with 205/55/16s but they touch.

I think the only way around it is going to be to dismantle the rack and fit a section of tube over the rack so that it can't move as far. Obviously the tube will have to be as close as possible in diameter to the rack so as not to catch the boot. The other option would be to have some clamps machined up to go around the rack shaft, again to limit movement.

Regarding the steering track arms, we managed to find some which were the correct length so the welded ones were used only as templates.

MG
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  #28  
Old February 11th 2010, 09:15
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Looking again at it, I think I might be able to just remove the boot clamps, move the boot along and slot in a section of tube with a cut in it and see what we need rather than having to take the rack off.

MG
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  #29  
Old February 12th 2010, 13:47
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Hi Mike,

Did you read my post's about what I did?

http://www.germanlook.net/forums/sho...ht=rack+pinion
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