Power steering vs manual steering

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Power steering vs manual steering

Post by Ted FM 13 on Fri Jul 28, 2017 9:42 pm

I have a 2012 Super Stalker kit; one of the last of Dennis' original designs, I believe.  It has a 87 Chevette rack and pinion.  

I wasn't thrilled with the feel of power steering so I tried manual steering (fresh reman rack).   It was 1) OK on the street; 2) kinda stiff and a PITA up in the twisty bits in the hills at speed and 3) totally unworkably stiff on the track at speed.  I'm not a small guy and raced a standard Formula Mazda with a manual rack for 12 years and never gave steering a thought.  So I never expected this SS manual rack to be too stiff and hard to turn to the point of distraction on track.  

Now for comparison, the Formula Mazda carried 270# (wet on track) on each front tire whereas the SS is about 450#on each front tire.  the tires are the same:  GY 475 7x9 racing slicks set to 20# hot.  The steering ratio is about the same; the SS steering wheel is maybe slightly larger diameter.  

What's up with that?  is the extra 180# on each tire the only difference and the reason for the extra effort?   Anyone have a similar experience and went to or back to power steering?   or you're perfectly happy with the steering feel and effort at speed on track at 1.3-1.5 lateral G's ?  And if so, where did your rack come from?  

Just wondering what else might need to be considered. I'll call Sweet (https://sweetmfg.biz/home.php) next, just thought I'd check in here first.
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Ted FM 13

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Re: Power steering vs manual steering

Post by Ted FM 13 on Tue Feb 27, 2018 12:47 am

In case anyone comes across this in the future, here's the rest of the story.

I went back to the PS rack. Had to go thru a lot gyrations to bleed air out of the system and............put in a 12" long aluminum finned transmission type cooler. The PS fluid overheated on the track and the power steering assist just gave up after 3-4 laps. The additional volume and solid aluminum fins of the cooler makes a difference. Don't use the radiator type cooler is what I heard.

The key besides cooling is to bleed the system completely. With Scott's direction, I

1) put the car up on stands,
2) disconnected the toe links to allow the rack to cycle fully back and forth. (The geometry and movement of the uprights/wheels do not let the rack fully cycle thru it's extremes, hence leaving room for air to remain)
3) cycle the race back and forth 20 times without the engine running then
4) cycle the rack back and forth with the engine running.

After doing that, it still felt a little slow/unresponsive on initial turn in. Per suggestions from an old salt, I put a vacuum on the system and now it's precise and smooth as silk.

for "sporty" driving up in the twisty bits of California mountains, it's great. I haven't completely put it thru it's paces for 20 minutes on a hot 90F track yet, so we'll see.
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Ted FM 13

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Location : Sacramento CA

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