Rack and Pinion Conversion

[Daniel]

What causes power steering to be so hard once your engine dies is it the fluid trying to back flush in the lines and pass
the pump?

[spiderrey]

The people I talked to to left power steering fluid in it.

[v6spider]

The people I talked to to left power steering fluid in it.

You'd have to as that is how it gets lubrication is from the ps fluid...manual tracks typically use gear oil...
At least mine does...

Rob

[djape1977]

if i told you all that there is a hydraulic power steering box produced now and few years back that is pretty much straight bolt on to a 124?

i'm always on a lookout for quicker ratio steering, so in my oppinion steering rack VS box, old type steering box always wins.

[spiderrey]

Thanx Rob, I get that. I posted that because someone said something about putting grease in there.

[FiatMac]

The people I talked to to left power steering fluid in it.

You'd have to as that is hire it gets lubrication is from the ps fluid...manual tracks typically use gear oil...
At least mine does...

Rob

Not necessarily. Check out this article on the Flying Miata Site on de-powering a power steering rack:

http://www.flyinmiata.com/tech/depower.php

[vandor]

>i'm always on a lookout for quicker ratio steering, so in my oppinion steering rack VS box, old type steering box always wins.

Ratio has nothing to do with it being a rack or a box. Racks can be made in any ratio, boxes can be made in any ratio. It just so happens that Pininfarina used a slower ratio rack on their cars, but that does not mean one could not fit a quicker one.

[djape1977]

sure, but there are very few cars with less than 3 turns lock to lock. just so it happens that 124 box has 2.8.

if there was an easy way to fit 124 box to my 131, i'd do it because 3.8 ratio on 131's rack is driving me nuts. feels just like driving a big rig, with endless turning of the steering wheel. naturally, there is a small matter of heavy steering as a result of small ratio, but when you're 6'2" and 200lbs, that's not such a big issue. PAS box would be the right way to go for 124, and PAS rack for 131 converted to a faster ratio.

PAS box for lada niva is in production since 2010, but i haven't laid my hads on one yet so i don't know the ratio. early ladas had 2.8, as my 2103 from 1979 has, and later ones switched to 3.5 to ease the job a bit. price of over 1000$ us for a new unit is preventing me for now, but in a matter of few more years used ones will become available.

[v6spider]

The people I talked to to left power steering fluid in it.

You'd have to as that is hire it gets lubrication is from the ps fluid...manual tracks typically use gear oil...
At least mine does...

Rob

Not necessarily. Check out this article on the Flying Miata Site on de-powering a power steering rack:

http://www.flyinmiata.com/tech/depower.php

Nice article..makes sense too..

Rob

[SoFlaFiat]

In an effort to experiment I picked up an early 90's Honda manual steering rack.
Loaded with this:

"A critical dimension for minimizing bump steer is the dimension from ball end to ball end on the inboard side of the tie rods (where the tie rods mount to the rack). This should be roughly equivalent to the dimension between the passenger and driver side lower control arm pivot points. Or to match up with the stock steering system, this would be the length of the drag link between the steering box and the steering idler arm. (Eyeballing this shows the location to be about 1.5-2 inches per side inboard of the lower A-arm pivot.) I measured the drag link and it is 19.5". I also measured the stock tie rods and found them to be approximately 12" which gives an overall length with tie rod ends of 43.5". If one were to use the distance between the A-arm pivot points then the rack ball ends would be about 22.5" apart and the tie rods would be shortened to about 10.5"."

I went about measuring my car and the rack.
(car is an 81 2000)
Lower A-arm pivot point, center to center, 25.5"

The rack:
3.75 turns, stop to stop
5.75" of travel
Am I correct that this gives it a ratio of 1.533 to 1?
And here is the bad news...
Ball end to ball end (center/center) on the rack is 30"

This puts the ball ends 2.25", on each side, outboard of the lower a-arm pivot.
From what I have read so far, this will cause bump steer. Correct?

If it were not for bump steer, I could make this rack work by cutting 3" off the racks tie rod ends and welding a shortened tie rod sleeve to them. I would then drill thru and pin the sleeve to the tie rod for double measure.
This would give me adjustment and ability to use the stock outer tie rod ends.

[FiatMac]

After further study, I find that the proper dimension to use for the ball end to ball end dimension on the rack should be as close to 19.5" as possible. Use of the dimension between the lower control arm pivots (25.5") will result in significant bump steer in the opposite direction to that of the stock suspension.

The steering arm on the knuckle locates the outer tie rod end approximately 2.125 inches inboard of the lower control arm ball joint. The lower control arm and the tie rod must be close to the same length to minimize bump steer. It looks like the geometry used by Fiat has a tie rod length that is Approximately 1" longer than the lower control arm which will result in slight steer to the right for the left wheel with suspension travel, and slight steer to the left for the right wheel.

If the rack has a 25.5" ball to ball, the tie rod will be 2.125" shorter than the lower control arm with a resulting steer to the left for the left wheel and steer to the right for the right wheel with suspension travel. The steer in involved would be at least double that of the stock suspension and in the opposite direction.

I am working on a full documentation of this and will try to publish in a form that can be used by all.


V6spider, you wrote earlier:

Here are the specs for the Pininfarina rack:

40.5" overall length (outer tie-rod ends removed).
63mm input shaft length.
3.5 turns lock-to-lock.
M12x1.5 threads on inner tie rod end

Do you have the dimension between the centers of the inner rod ends and how much travel the rack has lock to lock for the Pininfarina rack?

Thanks!

[FiatMac]

By the way if we can find a rack with suitable travel and turns lock to lock, but with too long a dimension between the inner tie rod ends, the rack can be shortened by cutting the passenger side end (re-machining to accept the ball end or tie rod end) and removing the same amount from that end of the housing. This might be done more cheaply than having a custom rack made.

[fiat124v8]

Turbo124.com has a good thread on this and as mentioned by another poster, they tend to use an Alfa rack.

I used an X1/9 rack on a '75 Coupe and the inner tie rod end dimension happens to closely match that of the 124's. Outer tie rod ends are no problem and can be sourced even custom from racing rod end specialists, OR, you can source custom tie rod sleeves that connect the X1/9 tie rods to 124 stock outer tie rod ends.

The swap was for a V8 project, so I have not investigated steering input clearance. If I recall correctly, the stock steering linkage fits the X1/9 steering input shaft splines, but the shaft needs to be lengthened. I did this by drilling and press-fitting a spacer shaft in, then welding the perimeter.

A caveat is the X1/9 uses two rack mounting straps that bolt to the front firewall of the X1/9. Generally, this means you need to make / modify the mounts so they work with the 124.

[FiatMac]

I used an X1/9 rack on a '75 Coupe and the inner tie rod end dimension happens to closely match that of the 124's.

So, what is the x1/9 rack travel and turns Lock to Lock?

Thanks!

[v6spider]

I used an X1/9 rack on a '75 Coupe and the inner tie rod end dimension happens to closely match that of the 124's.

If this rack is mounted ahead of axle center then it won't work used behind axle center as in the stock fiat spider. In my v6 conversion the rack is mounted ahead of axle center which has a completely different set of dimensions than the steering geometry for mounting the rack behind axle center as in the stock pinninfarina spider...not to mention a rack used for ahead of axle center turns opposite direction..

Rob