Corvette Forum : DigitalCorvettes.com Corvette Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
636 Posts
Discussion Starter #1
Looking for technical advice on a power rack conversion (C4 suspension). As our stock power system is a (cylinder) assist system, rather than a power box, what's the word on pressure/volume output of the stock pump? I understand, and correct me if I'm wrong, that rack systems use a lower pressure than the power box systems. So, is anybody using a rack system, such as Steeroids, finding that the stock pump works just fine, or did you need to adjust the pump output in one way or another?
Thanks for any relevant technical advice.
Mike
 

·
DC Crew
Joined
·
4,751 Posts
Stock pump works fine. I couldn't be 100% sure of this until I beat the snot out of my car on the track a few weeks ago with a rack and hydroboost. It didn't fade even once and maintained constant strong power assist on a 100 degree day with wide front tires slinging the car hard around cones.
 

·
Banned
Joined
·
3,855 Posts
Stock pump works fine. I couldn't be 100% sure of this until I beat the snot out of my car on the track a few weeks ago with a rack and hydroboost. It didn't fade even once and maintained constant strong power assist on a 100 degree day with wide front tires slinging the car hard around cones.

How did it feel?? good and solid?? was it a steeroids kit?? or you roll your own like I did?? if you did rolll you own, I"d LOVE to see some pix of the brackets, and final rack position/tie rods with engine in car....curious how you solved the problems, also the input linkage, oviously....

and how did the brakes work?? stock except for HB?? or with mods to the calipers also?? which M/cyl.....??

come on now, give it up allready.....

:rolling: :WTF :cheers:
 

·
DC Crew
Joined
·
4,751 Posts
How did it feel?? good and solid?? was it a steeroids kit?? or you roll your own like I did?? if you did rolll you own, I"d LOVE to see some pix of the brackets, and final rack position/tie rods with engine in car....curious how you solved the problems, also the input linkage, oviously....

and how did the brakes work?? stock except for HB?? or with mods to the calipers also?? which M/cyl.....??

come on now, give it up allready.....

:rolling: :WTF :cheers:

Here you go...with hydroboost:

http://mcspeed.homestead.com/Rackinstall.html
 

·
Registered
Joined
·
512 Posts
Mike, The original pump for your 69 was rated at 900-1000 psi. Now that's with skinny tires and very little caster. Most modern "metric" pumps are rated at 1300-1500psi. I am using a modern pump that I am having the bypass pressure reduced to 1000psi. This pump also has an EVO (electronic variable orifice) valve. I have operated the EVO valve with a programmable controller on a bench however I really need to "develop" this on the car and I am a long way from that.
 

·
Banned
Joined
·
3,855 Posts
INteresting how you did that Chris.....I still can't see how you got that what appears to be a severe upper angle to work with two U joints on the input shaft.....column extended bet you if you put the car on the ground with the engine off, it will bind up....I tried all sorts of methods doing that...curious to see that in person sometime....

second off, it looks like you did a lot of support on that driver's side mount...mine been there 5 years now and not a problem with maybe 30% if that in weight of support....IMO< just as strong....course like any other part of something like this, I inspect periodically...but it's been 5 years street driven daily....and quickly too....course then again, IM not racing with super wide tyres either....

:cheers:
 

·
DC Crew
Joined
·
4,751 Posts
INteresting how you did that Chris.....I still can't see how you got that what appears to be a severe upper angle to work with two U joints on the input shaft.....column extended bet you if you put the car on the ground with the engine off, it will bind up....I tried all sorts of methods doing that...curious to see that in person sometime....

second off, it looks like you did a lot of support on that driver's side mount...mine been there 5 years now and not a problem with maybe 30% if that in weight of support....IMO< just as strong....course like any other part of something like this, I inspect periodically...but it's been 5 years street driven daily....and quickly too....course then again, IM not racing with super wide tyres either....

:cheers:
With 275 40 18 front tires and all the weight of the big block (less aluminum heads) and a/c - I have no binding, noise, or snags out of the double joints when the engine is off. This is the ultimate joint as it has a slip joint in the middle and has the pinch clamps on each end unlike the triple joint set screw stuff that you usually see.

The passenger bracket is not super strong, but the driver side if heavily reinforced.
 

·
Banned
Joined
·
3,855 Posts
OK, couple things I notice, you got that VBP suspension up there, the clarance issues would be not so snug with the tie rods, I suspect....I also notice you have equal length tie rods, something I did not accomplish, and I see you used what looks like a piece of angle iron for a bracket in the middle there, I wound up modding a chunk of steel I had machined for the bracket, I could not seem to make the stock tie rods fit because of the shape and the positiion I had to have the rack....in order to make the input linkage work, the joints you used must have much better angle capabilities then the junkyard stuff I used, because your rack apparently sits lower than mine, I had to cut a crescent piece outta the back of the engine horn to allow my angles to be relaxed enough, it was kinda rough doing with no engine in the car, turned out I had to ding the oil pan about 1/4 inch to keep the bellows from rubbing, I surely think that BB pan you got there is much deeper....

where did you get those joints from? remember what they cost??

and yes, you bracket there is much stronger than mine, more on the size of the Steeroids setup, ran into a nieghbor guy just yesterday at the Gate station next door, he driving a '68 red camaro vert, he my age...anyway he has a Steeroids rack in it, I gotta knock on his door some time, he very sneaky about having a 3 car garage in his back yard, and I been here ten years, and never met him or seen the car....he has had that car nearly 25 years here.....so anyway, I gotta see that conversion.....

maybe tmrw/today....

:thumbsup:
 

·
DC Crew
Joined
·
4,751 Posts
The U joint assembly fits a late model Chevy Malibu. Picked it up at the dealer FREE as it came from a car the custom complained of noise in the steering. My buddy is a tech up at Gordon Chevy in O.P. The fix is to lubricate the slip joint - but this one was just replaced. Not a stinking thing wrong with it. The late model silverados have the same slip joint design - and my 04 got noise a year ago - lubricated it...all is good.

The rack is not the lowest point under the car. The main oil pan and headers still hang lower.

I also built this things with the engine out - which was scary because I thought I was going to get into the pan. If anything, I did push it to the low side. Was doing it by myself, so test fitting was a PAIN as I had to put a jack down there, then clamp each side and measure. If you remember Gene -you were my main inspiration for jumping in and building this thing a year ago. I wouldn't and couldn't have done it without you.

I have installed four Steeroids racks now, and had to notch the frame pocket with a crecent on all of them to make sure there was ample room. I also slightly notched this one.

The tie rods are a pair of PASSENGER tie rods and and tie rod ends off a Grand Am. I used angle iron to center them just like Steeroids does. I put the angle iron in the press and gently worked the perfect angle so the tie rod would run true from the rack out to the spindle. Because of the VB&P dual mount front spring, I was able to unhook the spring and practice run (no pressure on the a arms then) the controll arms all the way up and down in all directions with the car on jackstands to confirm NO binding.

I have a Steeroid rack in my 69 Camaro. Nothing Exotic there - it is just a late model GRAND PRIX rack on a genius large bracke that uses the lower control arm bolts to secure to the K member.

 

·
Banned
Joined
·
3,855 Posts
[

I have a Steeroid rack in my 69 Camaro. Nothing Exotic there - it is just a late model GRAND PRIX rack on a genius large bracke that uses the lower control arm bolts to secure to the K member.

[/QUOTE]


That's cute, reminds me of my first rack attempt using a Taurus rack I thought my tape told me would work, found out I was RONG, big tyme, but that setup/concept was what I worked with...looks I freeking Dentical...

what car that rack come off of????, being ETO and all, the rack looks short enough to give all radius the car needs, and still has long enough tie rods...


:thumbsup: :crazy:
 

·
Registered
Joined
·
636 Posts
Discussion Starter #12
Mike, The original pump for your 69 was rated at 900-1000 psi. Now that's with skinny tires and very little caster. Most modern "metric" pumps are rated at 1300-1500psi. I am using a modern pump that I am having the bypass pressure reduced to 1000psi. This pump also has an EVO (electronic variable orifice) valve. I have operated the EVO valve with a programmable controller on a bench however I really need to "develop" this on the car and I am a long way from that.
Keep me updated on your setup. In the event I ever get caught up on stuff I wouldn't mind updating my setup to something adjustable. I remember driving a development '85 Corvette with electric power steering years ago. There was a slide switch on the console to adjust the assist. You could easily change the assist from two handed effort to one finger ease. It was pretty neat. It would be amusing to have a speed dependent controller to lower the assist at higher speeds.
 
1 - 12 of 12 Posts
Top