ok, so hear me out.
I'm in the process of sourcing al the parts for a rack and pinion conversion. I just prefer the predictability of a rack and pinion over the old steering box.
But in my quest to find al the parts it seems that the rack and pinion of a polo 86c is the way to go because the connecting rods are longer and prevent bump steer. witch I understand, BUT:
why do all the big cars have the rack and pinion setup were the rods connect to both the outer ends of the rack? porsche has it, the newer vw's have it. Porsche 924 en 944 that see a lot of trackdays tend to use a golf MK1 R&P because of the shorter steering ratio. Hell, even the mazda guys upgrade the first gen RX7's to golf MK1 R&P//
I understand dat the rods are at an angle on the spindles of a beetle, but this can be overcome with a bump steer kit?
is there an other reason I don't see why aircooled folks prefer the polo rack?
thank you,
Glauco
rack and pinion question
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Ian Godfrey
- Posts: 213
- Joined: Thu May 27, 2010 2:52 am
Re: rack and pinion question
Glauco, the golf rack has tie rods that are about the same length as the lower suspension arms so that gives them the least bump steer. I've got a golf rack with special tie rods on my Mendeola suspension for the same reason. I have less than 1mm of bump steer over 100mm of suspension travel. Another reason is you can get RHD and LHD quick steer racks for the Golf from Quaife to make them more responsive.
With a beam suspension you need the tie rods as long as possible to reduce the bump steer, so a polo rack with the inner tie rods ends almost touching each other in the middle is the best answer. The short Golf tie rods would be terrible, worse than the stock steering. I've got one of the Polo racks for a beam front end. It has more bump steer than the Golf/Mendeola set up, but pretty good. I hope this helps.
With a beam suspension you need the tie rods as long as possible to reduce the bump steer, so a polo rack with the inner tie rods ends almost touching each other in the middle is the best answer. The short Golf tie rods would be terrible, worse than the stock steering. I've got one of the Polo racks for a beam front end. It has more bump steer than the Golf/Mendeola set up, but pretty good. I hope this helps.
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Bruce.m
- Posts: 903
- Joined: Sun Aug 11, 2013 1:44 pm
Re: rack and pinion question
Yup.
VW torsion beam has zero camber change over the suspension travel, unlike pretty much any other suspension design. So ideally the steering arms should be infinitely long so the steering angle doesn’t change with suspension travel. More “normal” cars have the rack pivot in line with the inner suspension pivot, so the track rod end moves in the same curve as the suspension.
VW torsion beam has zero camber change over the suspension travel, unlike pretty much any other suspension design. So ideally the steering arms should be infinitely long so the steering angle doesn’t change with suspension travel. More “normal” cars have the rack pivot in line with the inner suspension pivot, so the track rod end moves in the same curve as the suspension.