rack and pinion on 02

[Uber Affe]

I own a 74...I thought 1302's were only made 71-72
or is 73 1302 first half and 1303 second half of 73?
Confused...Just the same...Does my '74 1303 have rack and pin or worm and roll?

[oasis]

Originally Posted by Uber Affe

I own a 74...I thought 1302's were only made 71-72 or is 73 1302 first half and 1303 second half of 73? Confused...Just the same...Does my '74 1303 have rack and pin or worm and roll?

Supers in the 1971-72 model years were 1302s. 1303s started with the 1973 model year. Rack and pinion started with the 1975 model year.

There were some other changes which were made mid-1973, so some 1303s share parts more commonly associated with 1302s. How this affects a rack and pinion conversion, though, I'm not sure.

[Jeza]

Thanks Wally, the urethane bushes make an enourmous difference to the handleing of supers!

John, yes that rack I believe is a late 1303 rack fitted to an early 03 (which previously had a steering box).

A friend of mine had looked at fitting an Alfasud rack to his super. His suggestion was to fit it higher than the stock location and use a bracket to mount the central tie rods to so they remain in the same position as they would with the stock steering box, cunning

Actually someone has just pointed out the Ackerman angle thing- I don't know how the factory dealt with it but it could be a lot trickier than it first seems. Ackerman is where the inside wheel turns tigher than the outside wheel- this helps reduce tyre scrb etc http://www.compgoparts.com/technical/001/Ackerman.asp

CU
Jeremy

[Steve C]

Hi

I fitted on to my old 1302.

It’s a hard job but I believe the benefits are worth it. First find a 75 1303 that has a rack fitted. Take some measurements to get an accurate idea where the rack will bolt to the chassis rails. This is important because the inner guard has some stiffening in it that weaves around the stock steering box and idler arm mounting points.

There is a cross brace that needs to be removed that runs across the base of the spare wheel well. The depression in the 1302 chassis that the rack fits into is not deep enough so you need to make this depression much deeper. I heated mine and flattened it down with a mallet. If I ever did again I would cut the section out and weld ½ circle of heavy wall tubing in there. The job on my car was made a little easier because I have no spare wheel well as it has been removed to fit a radiator. To hold the rack in place you will need to fit some captive nuts in the chassis rail, I just cut a slit in the outer side of the inner guard, fitted some captive nuts and then re-welded the slit. I have seen these mountings fitted another way, make some sturdy 90-degree brackets to bolt to the existing the stock steering box and idler arm mounting points and then the rack can bolt to these.

The 1303 steering shaft will also hit about ½ way along so the body will need a small amount of clearancing.

Steve

[Jeza]

Thanks Steve

I hope you don't mind, that is your new project I have linked to above

Do you or anyone else know if the Akerman angle is an issue with the rack mounted in that location with steering arms facing forward on the spindle / steering knuckle? It isn't the ideal setup from what the current thinking is, but the factory must have realised what they were doing when they made the car.

Cheers
Jeremy

[oasis]

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.)

[Steve C]

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

[Jeza]

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

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