Based on everything I have read, your car, and my 41 Chevy, are borderline cars. They at the top of the scale when people recommend manual steering and at the bottom of the scale when people recommend power.

While my 41 is a way from my having experience driving it, I have driven R&P and RB, both styles in both power and non-power. IMHO, either rack gives you better road feel and better steering response. The only reason I would stick with a RB would be to keep a car "correct" or if it were just too difficult to change over.

Not sure about your pump question. I have a question. Is the Cavalier unit front or rear steer? If rears steer, are you going to have room for it or can you flip it for front steer?

The #1 cause for power R&P "twitchyness" is probably from using a MII rack and a GM pump. MII's need about 700-800 psi and GM racks put out about 1200 psi. There are kits to reduce the pressure. Next would be not enough caster. On a light car (remember, ours is at the light end of power recommendations) you need a lot of caster. I am going to shoot for around 5 deg. and see how that works.

 

Redsdad, thanks. You are kind of confirming my dilemma.
I built my front end ( a whole separate story) that works well, but I can only get 2 1/2 degrees of caster, without tearing it out and doing the job over.
Makes me think a manual unit might be the best, but want to be sure it makes the steering a little easier, not harder.
The Cavalier is a rear steer unit. I picked it for the center take off. With the right bracket I can make the tie rods the right length to control bump steer.
Every end take off unit i've seen is too wide. Is the Cavlier manual R&P to light for my car?
If I take a chance on a power unit (have one in hand), how do I power it?
Cavalir has serpentine belts in a cross mounted FWD. I would need to change the pulley and fabricate a mount for my SBC, or use an early model GM pump. Where would I find info on how much pressure the cavalier R&P uses?
Do you know any other center take off R&P's.
What are you going to put in your Chevy?
Sorry for all the questions, but I'd like to get it right the first time.

 

Redsdad is correct the pressure in the manual is 1250 psi, the rwd vehicles listed for the same year are 1000 psi, so the pump may fall a little short. Thats a pretty small r&p, the only other center take off unit I can think of is from a 90's era dodge intrepid which is a bigger car. It's designed to mount flat, I can't get the pressures though and not available manual.
Stock car products has a manual rack thats 18 1/4" pivot to pivot in about 10 differant ratios avalable, and power available but the 41 Pontiac is about 14 1/2" from pivot to pivot , the bumpsteer would have to be adjusted with spacers at the spindle end or on how high the gear was mounted..

 

i believe SR mag had a article some time ago stating u could remove some coils from the pressure reg. spring in the GM pump?

 

the pressure in the manual is 1250 psi, the rwd vehicles listed for the same year are 1000 psi, so the pump may fall a little short.

If the pump pressure is a little low compared to the rack, it may increase the required steering wheel torque by the driver. May be the ticket for relieving twitchyness. Problem would be if it required too much driver torque on the wheel.

Is the Cavlier manual R&P to light for my car?
If I take a chance on a power unit (have one in hand), how do I power it?
Cavalir has serpentine belts in a cross mounted FWD. I would need to change the pulley and fabricate a mount for my SBC, or use an early model GM pump. Where would I find info on how much pressure the cavalier R&P uses?
Do you know any other center take off R&P's.
What are you going to put in your Chevy?

I think, at 3300 lbs. you are about 1000 lb. heavier than a Cav. However, the FWD has a greater front weight bias, so it would be a close call. Based on chieftain's info about the pump pressures, if I were you, I would try the early GM pump first. It is probably going to by trial and error. I am using a TCI Mustang II set up with a power MII R&P. I figure my Chevy will probably weigh in at around 3200, so it is only about 200 lb heavier than a V-8 MII. Right now, I am leaning toward the March pump on their bracket and pulley kit. I have to research their pump pressure.

 

Man. or pwr. r& p

A few years ago I put a MII with a power rack in a '46 ford. I felt the steering was too sensitive on the highway. After switching to a manual rack the feel I was looking for was there. I don't know if it was the box ratio or the fact that the wheelbase was longer or maybe the weight of the car that made the difference, but the steering really improved. Youngster

 

I have a 31 sedan that has a MII power rack that has been sitting collecting dust etc. with the fluid lines disconnected and open . I will be getting this ready to run soon. From what I'm reading here I may just as well cange to a manuil rack , save myself the trouble of setting up the GM pump "AND" be happier with the steering. Tjis is full fendered (glass) 350/350.
Probably 2500LBS.
Am I right?

 

IMHO, an early to mid 30's car that weighs approx. 2500 lb would be better with a manual R&P. 49 and newer cars would probably be more enjoyable drivers with power R&P. The 39-48 cars are the inbetweeners. A manual R&P may require a little more effort than some would like. A power R&P may have a little less road feel than some would like. Additionally, you need to make sure you have the correct pump pressure and the car will like lots of positive caster.

 

This thread has been hashed out a couple of time in the past 5 years and there seems to be same level of confusion. I installed my first MII power rack in my 36 Ford PU (2650 #s) in 1990. I put nearly 90,000 miles on it before a total rebuild and I upgraded the front end, but stayed with the power rack with one change: I did install a new PS pump with remote reservoir and a pressure reducing spring. I could tell no difference in the handling, but it did cut down on the low speed noise when parking. I had installed a MII power rack in my 36 coupe a couple of years before redoing the PU and it does not have the pressure reduction spring. The two vehicles drive and handle almost identical. I personally would not consider manual steering replacement. I do know that maximum toe in is more stable than the minimum toe in (in reference to MII alignment specs). Neither of my vehicles are very sensitive to caster. We have built other vehicles with MII and all have had power racks and satisfied drivers.

Trees

 

Chieftain, missed your point the first time around. Does the 88-92 cavalier rack and pinion operate at 1250 pounds? And the older 83 - 87 RWD GMs operate at 1000 pounds?
I've spent hours trying to find that information.

 

Those readings are the minimum high pressure the pump should put out on a full lock turn. There are 2 readings to look at for a pump, at idle and full lock.

Normal pressure at idle is 80-125 psi for both types. Anything higher at idle would be a restiction in the lines or gear and lower would be a bad pump. The high numbers like the 1000 psi and 1250 are on a full lock turn, when the system is tested with a gauge inline the fluid is blocked momentarily to check the control valve sticking in the pump and to make sure max pressure is equal after several blockages and above the required high pressure reading.
The pressure #s are higher for the steering racks over a steering gearbox because of how the rack needs its pressure and uses it. A regular pump may be fine , it just might be a little sluggish compared to the pump used on a fwd car. There arent any pressure #s I could find for regular driving since it's going to change with rpm and driving changes.

Here's a short list of 1990 gm cars and pump pressure spec( I just picked that year to show the differane between rwd gearbox and r&p) . I can check about any other year and car model if you like. Hope this helps, Bill.

 

I did a rack conversion on a '69 Corvette. I used a rack from a 92+ grand am which I believe is actually the same as the cav. It is a center take off rear steer rack.

From what I understand you change the power steering sensitivity by changing the pump flow. reducing the flow reduces the sensitivity.

Pump pressure only comes into play to determine the max available force, like at full lock.

You can buy flow restrictors from Speedway etc with different orifaces.

Keith

 

I don't know if this will help at all, but I post so you all can compare.
I just got finished with a Jim Meyer rack conversion on a 56 chevy, the rack came out of a 86-92 Buick Electra (FWD). The pump we used was a RWD GM pump. (application is old enough to still have flared fittings)

The steering feels really good, with plenty of road feel and no problem with the amount of assist. We're running 255/45 17 tires (about 9" wide of tread actually touching the ground).

There are no restrictors, the pump is exactly the same as when it was hooked to the 605 box that was in the car when it rolled in my shop.

Also, for another comparison, a while back I did a rear 4 bar suspension on a 40 Buick business coupe. (I am assuming that this car is similar to your Pontiac) That car has a MII with manual steering. I had the opportunity to drive it and it is the most miserable tugboat steering barge I've ever driven. Mr Buick owner guy wants me to put a power rack in it this winter for him.


Hope this helps.
Mikey

 

Thanks Bill, that information leads me to think The newer rack with the older pump would work OK. Picked up a manual rack from an 89 Lemans, identical to the cavalier except for the power part. Think I'll put it in and test it. Piece of cake to swap it for the power rack if I don't like it.
Right now I'm struggling with the mounting brackets. Drivers side can go on the frame, or just inside it, but the passengers side is about 6 inches short of the other frame rail. So far I can only visualize some big ugly monstrosity.

Thanks for the insight Keith and Mikey. anyone got pictures of their fabricated brackets? Especially ones that don't mount to the frame rail?

 

I think i've mentioned this to you before, but Fatman fabrications sells an install kit for the cavalier rack for your 41, $225 though. It has the mounting brackets, tie rod adapters and u joint for rack. Ive never seen the kit installed or used any of the fatman stuff. They have some silimar kits for other cars using the cavalier rack and had a few pictures , check out page 18 on their website.
You could probably make your own like your doing or if someone here has used that kit could give you some more input.

 

pump pressures

Nevermind - just had a DUH moment. The power rack is 5 inches wider than the manual rack, and the passenger side mount slides on the tube. I can do frame mounts on both sides. Looks like we are going for the power system.

 

Wel Mine are Vette Specific, but I have a page dedicated to it.
It uses the power version.

http://temp.corvetteforum.net/c3/427v8/c3randp.html

 

Thanks 427v8. That is pretty much what I had figured out. Nice to know I'm on the right track. I need to reread your posts. did you specify what materials you used on the inner bracket?
I noticed the rack has a 6 inch throw compared to the original 7 inch throw on the RB. Do you notice a significant change in the turning radius? My steering arms are also 1/2 inch longer than the originals.
Chieftain. I have seen, and tried to modify, a fatman kit on a 49 ford a friend owns. Steering is "kinky" from the sever angles involved and turning radius is a good 10 feet more than my Pontiac. It also has bump steer characteristics.
I noticed when the tires are off the ground, they are toed in more than an inch. (The tie rods are about 3 inches longer than on his original 49 ford). I don't think anything short of a complete do over will fix it. In short, I'm not impressed.

 

Inner bracket? Well the center is made from 1" thick wall tubing as is the pass side bracket.

Yes turning radius is less, but it's still better than some cars so it's OK.

Getting toe steer down to a decent level is a real PITA. Lots of trial and error. Tie rod length isn't all that critical, height is much more important nd much more sensitive too.

u-joint angles suck too. Mine are pretty good but I didn't have to deal with the clutch linkage either.

Keith

 

Height could be a big part of my buddies problem. They dropped his rack an inch below the frame to clear the engine. Also its a tail dragger with a high front end, so the control arms run downhill, while the tie rods run uphill, throw in too long tie rods, less turning radius and put the whole mess on a 49 ford, which didn't drive worth a crap in the first place, and it gives me nightmares.
If I can't do better than that, I'd leave it original.
Thing is, he spent the bucks and paid a shop to do the work, and I wouldn't drive it across town.
BTW. How long are your steering arms? The Cavalier (sunbird/lemans/etc) effectively has a 5 1/2 inch long steering arm (pivot to pivot) but chevy has 7 inch. I'm thinking this is the root cause of the bigger turning radius.
Yours is acceptable, so I'm curious about your steering arm lengths.