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Power steering needs some help???

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Old 08-09-2011, 01:31 PM   #1
hugie82
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Default Power steering needs some help???

This might be an odd ball question but is there anyway to boost the power steering on these old vettes? Mine is an 82 and because of authritis I'm starting to have a had time with parking. I thought there might be a way to bump up the hydralic pressure but I can't find anything on line.
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Old 08-09-2011, 04:37 PM   #2
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I guess the first question is, are you sure your steering is working properly now? These aren't designed to have so much assist that you can turn the wheel with a finger, but they aren't that tight if things are working properly. If you have a stuck flow control valve, faulty control vavle or some other failure, that's an entirely different issue. Then there's the problem that these systems were designed to work with a specific pressure, if you go over that, I'd think you run the risk of blowing seals or hoses.

That being said, you could always swap to a Borgeson steering box or a rack system if you need more power assist.
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Old 08-09-2011, 04:44 PM   #3
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What tire pressure are your running, higher is easier to turn.
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Old 08-09-2011, 05:31 PM   #4
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You might want to make sure your stock piston is not stuck before you try this modification.
http://westtexasoffroad.homestead.co...rsteering.html
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Old 08-09-2011, 06:13 PM   #5
Jim Shea
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I know that this may not sound correct but trust me! You don't want more absolute pressure from your pump, you want more flow in order to reduce the amount of effort to turn the steering wheel. When you have more flow, pressure builds quicker, your steering will be more responsive, and your effort at the steering wheel will be less. Your Corvette pump puts out a controlled flow of around 2.9 gallons per minute.

You could try this, obtain a power steering pump from a Chevrolet Astro van (or the GMC equivalent - the name escapes me right now.) The connector & fitting assembly #24 is threaded into the back of the pump. This fitting controls the amount of flow out of the pump. Astro van pumps have fittings that allow pump fluid output of something like 3.3 gallons per minute. You want to swap that fitting with the one in your pump. It should increase the flow by a measurable amount.

You do NOT want to swap the control valve assembly #6 behind the discharge fitting. That valve will increase the absolute pressure that the pump can produce. The control valve assembly inside your Corvette pump was designed to limit pump pressure to around 1000 psi. The control valve in the Astro van is set at 1400 psi. There is a good chance that your Corvette hoses will leak from the increased pressure if you swap the control valves.

However, while you have removed the fitting assembly from your pump, reach into the pump with a rod and press on the control valve assembly. It should easily slide inside the pump bore and compress the spring #5 behind it. If it feels sticky or binds, it could cause your steering effort to increase and feel like manual steering.

Good luck,
Jim

Last edited by Jim Shea; 08-09-2011 at 06:19 PM.
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Old 08-09-2011, 07:41 PM   #6
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thank you mr shea. this is something i have also been wondering about, and for the same reason as hugie82. getting older sucks.
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Old 08-09-2011, 10:16 PM   #7
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Default More flow NOT more pressure!

Yes, thank you Mr. Shea for this and all the other tips you've shared.

Turning the wheel on a parked Vette always seemed harder to do than my dd but I figured they were made that way. Your suggestion seems like an easy fix.

Regards,
PG
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Old 08-10-2011, 07:27 PM   #8
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Yes Mr. Shea, that was exactly what I was looking for!!! Question, if I were to replace the #5 spring with a stiffer spring. Will that bump my pressure up?
My PS is working but I installed 255/60-15 year ago and the small diameter steering wheel is starting to be a problem
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Old 08-10-2011, 11:13 PM   #9
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jim shea,
just curious after reading your reply and the reply from pets74ttop is it possible to just enlarge/drill out the stock fitting on the pump? i was thinking it would save me a drive to the junkyard this weekend.
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Old 08-11-2011, 07:32 AM   #10
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You can drill out the throat of the discharge fitting. However, here are the pitfalls to trying to do it yourself.

The discharge fitting has several very precise set of holes, surface finishes, intersections, etc that Saginaw designed to make the pump put out consistant flows. By going in and disturbing the diameters and surface finishes, as well as leaving burrs, etc your really don't know what you might end up with. But if you want to try, here is a guideline.

Opening up the hole by 0.016 inch on the diameter will give approximately 1/2 more gallon per minute. Opening up the hole by 0.031 inch on the diameter will increase flow by about one gallon per minute.

0.1144 inch diameter = 2.0 gpm
0.130 inch diameter = 2.5 gpm
0.145 inch diameter = 3 gpm

There is a very small hole that communicates from the throat to the bottom of a groove in the OD of the fitting. If you inspect the discharge fitting carefully you will find it. It is in the groove just before the threads. That hole sends a low pressure signal to the opposite side of the flow control valve. If you raise a burr in that tiny drilled hole you will have very erratic power assist. So the hole is very critical to the operation of the pump.

Jim
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Old 08-11-2011, 08:53 AM   #11
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Perhaps a larger diameter steering wheel is in order. 68's had 16". That might help.
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Old 08-11-2011, 09:46 AM   #12
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Quote:
Originally Posted by 69 Chevy View Post
Perhaps a larger diameter steering wheel is in order. 68's had 16". That might help.
255's on the front will make turning the steering wheel while at a stop harder also.
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Old 08-11-2011, 09:56 AM   #13
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What tire pressure are you using?
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Old 08-11-2011, 12:10 PM   #14
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I keep my tires pretty hard usually 35-40 on the front. I like the smaller wheel because in my older vettes my knee would get stuck between the wheel and door. Don't laugh, I'm 6'2" and I have slammed the door on my knee a few times in my 74 vette

I was thinking of using the manual steering holes on the steering knuckle. Do you think it would work after an alignment???
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Old 08-11-2011, 09:50 PM   #15
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Go with what Jim says he is the expert
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Old 09-09-2011, 12:47 AM   #16
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i finally got around to doing the modification that jim shea mentioned this past weekend. it takes less than an hour and really makes a difference. only needed two tools to get the fitting off the back of the pump. a one inch open end and a 5/8 inch flare nut wrench. when you get to the last thread on the fitting it will pop right out from the spring pressure on the fitting. lost about a cup of fluid doing the change.
i measured the hole as about 0.108 inch diameter. i don't have gage pins at home so i used drill bits. a number 36 went through but a number 35 didn't. using jim's guidelines i enlarged it by about 0.016 inches by using a 1/8 inch drill. i used a mini-lathe since it is actually a very well made part as shown in the pictures.
i did take care to make sure i did not raise a burr on the small hole through the side. it is a stepped hole. the larger hole is 0.062 and the smaller hole was 0.040.
i am very happy with the results. i have been driving for a few days and the steering effort is lower. if i had been thinking i would have measured the force it took to turn the wheel before and after, but i didn't.
sorry i don't have a picture of the actual part, but none of the pictures i took were any good. the images below are from a solid model i made of the part.
i am going to leave it like it is for now. maybe as i get older i will enlarge it again.
thank you Jim Shea!




[IMG][/IMG]

Last edited by oldboat; 09-09-2011 at 12:52 AM. Reason: add pics
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Old 09-09-2011, 07:20 AM   #17
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Oldboat,
Glad to be of help. Do you mind if I download your graphics? I could use them to be of considerable help to other owners in the future.

Jim
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Old 09-09-2011, 08:39 AM   #18
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Jim,
Help yourself. I can send you models when I get back from vacation if you like.
Nick
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Old 09-09-2011, 11:15 AM   #19
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One thing about opening the throat of the discharge fitting is that more flow also translates to higher system fluid temperatures. More flow out of the pump causes higher back pressures down stream and the pump has to work a bit harder. This will cause somewhat higher system temperatures. I'm not saying that you will need a cooler but just be aware of this drawback.

Jim
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Old 09-09-2011, 05:18 PM   #20
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Quote:
Originally Posted by hugie82 View Post
I was thinking of using the manual steering holes on the steering knuckle. Do you think it would work after an alignment???
This sounds like it would work to me, but at the cost of more turns lock-to-lock. I'd be interested in what Jim Shea has to say about it.
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