Simply remove the power steering belt and go for a drive. You'll know right away if you have a pump/pressure problem or an installation problem.
I feel certain that front crossmember/suspension is from a '49 thru '54 Chevy passenger car. Not only did they not have R&P steering gear, they had a center mounted bell crank with long tie rods to each steering arm. The geometry of the existing setup is quite different than original. If one were to keep R&P steering, there are rear steer rack with center pivot tie rods that would more closely duplicate the general geometry, but you would still have to investigate steering arm lengths to ensure reasonable turning radius. Such racks were used on later GM front drive models. Ray
I see at least 2 issues here. Regulate the pump pressure with bypass spring shims, and you will change how the steering feels and reacts. The other major issue is bump steer caused by the tie rods pointing down. When the spindles go up the steering arms must go out, changing where the tires point. They should be roughly horizontal.
That may have some effect on toe, but it appears the tie rods are at about the same angle as the lower A arms and that negates much of the change in effective length....the differing pivot points of the A arm and inner ties rods may be a greater issue. The pivot points of the upper A arms are also a factor in the effective geometry. This is one screwed up system......sadly not unlike a lot of others running around out there. Ray
Yeah the owner of the car doesn't know a single thing about cars,so im supose to fix it but i don't see how im going to pull this one off. I think im going to tell him to take it elsewhere. Thx for the rep Posted using the Full Custom H.A.M.B. App!
That geometry is way off with that R&P and can't be corrected to work as it should. A Cavalier R&P would be better suited with a bar to attach the steering arms. If you draw any imaginary line through the bottom pivot pins, the steering arms pivots off the centre shaft should intersect on those lines.
Thx a lot I'm gonna check with the owner what he wants to do,i also found you could use an ys3d 9-3 saab R&P
It would be unlikely here in the States. Saabs aren't very common. There are companies that make a small gearbox to add into the steering wheel shaft to change the ratio. See link below. How many turns do you have lock to lock? http://www.southwestspeed.com/?sec=view_menu&cat=Steering&sub=Steering Quickners/Reducers&ssub=!Quickners
You Don’t have too much pump pressure, you have “Too Much Volume” "Pressure is Pressure" and "Volume is Volume" Pressure controls how light it feels, Volume controls how quick it turns [or reacts]. The pump should be running on bypass all the time, so if the steering is too quick you need to restrict the flow [ the most flow you'll ever need is "lock to lock" parallel parking at idle]
Yes that looks to be the same as the 54 Chevy front end I put in a 38 Chevy sedan. I used a older rear steer Honda rack and it worked well but non power. The problem with a rack on these front ends is the long length of the lower A arms they have. It is only 15 or so inches between pivot points apart. Ideally the rack pivot point needs to be the same as the lower A arms and the same angle as they are. That is hard to do with the long arms and even longer racks. Center steer rack would be better if they are not too close but may be able to make a bracket that bolts to the rack and pivot the tie rods at the arm pivot points. Also the 54 front spindles get their alignment from a eccentric bolt at the top spindle and upper A arm mount. You may not be getting enough out of these to get a good alignment. If you look at a stock 54 Chevy front cross member, they are mounted to give a little angle rearward to help in a correct alignment. Positive caster. If yours is mounted square to the frame you are not getting enough for positive caster out of the eccentric adjustments. That front end was used in Corvettes thru 1962. I used a friends 59 Vette to copy when I set up my front end angles with the frame set at final ride height.
A little more info; Caster is the tilting of the uppermost point of the steering axis either forward or backward (when viewed from the side of the vehicle). A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect the tire wear. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster. With too little positive caster, steering may be touchy at high speed and wheel return ability may be diminished when coming out of a turn. Most rack and pinion steering units do not self center after a turn. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.
What year SAAB R&P is that? Some later model SAABs were GM architecture and shared platforms with other GM products. That looks similar to some US GM front drive rear steer units. Ray
mj40's ...I beg to disagree with your comments about the spacing of the inner tie rod ends on '49/'54 Chevy (& early Corvette) front ends. The original steering linkage set up had a bell crank in the center of the cross member and the ties rods were only a couple of inches apart, center to center. They were not aligned with the lower "A" arm inner pivot axis. The length and pivot points of the inner ties ends are not automatically determined by the lower control arm inner pivot location. It's a lot more complicated than that. The horizontal angle (if any) of the lower "A" arm pivots and the location and angle of the upper "A" arm pivots are both factors in tie rod pivot placement. Some designs, like MMI type, do require the tie rod pivots to be very closely aligned to the inner lower "A" arm pivots. But that is unique to that specific suspension geometry, not applicable to all others. If one is going to fit one of these front ends with an R&P unit, the center steer type, like the SAAB unit pictured above, will allow more closely duplicating the original tie rod pivot points and, therefore, original geometry. One more important consideration is steering arm length. I have seen R&P conversions that have very large turning radius dimensions that render a car not very pleasant to operate, other than in a straight line. Ray
Lack of positive caster doesn't cause the car to dart off to the side. It actually makes the car feel "washy" and unresponsive. Because of King pin inclination, there will be induced positive camber [which makes the front end unresponsive ] positive caster is used to correct this on the outside wheel. Too much negative camber combined with toe-out will cause the car to dart off aggressively . I've done a few power steering conversions in the past. The biggest issue is too much volume. The pump should be bypassing even when idling. I've used Japanese Aisin power steering boxes [to get a linear 16:1 ratio and quick steer ] and also Aisin power racks. In the hoses there were tiny restrictors [crimped in where the clamps are holding the hoses to the frame ] There are 2 restrictors in the return to prevent air bubbles and shuddering, and 1 restrictor on the pressure side. Most swappers usually get custom hoses and they start chasing their tail from day one. I've done a Mitsubishi p/steer box conversion on a Corvette and a Mustang , the only modification to the system was a larger pulley on the pump [we sit in the 5000-7000RPM range for up to 1/2 an hour] I would check for restrictors first. And the other obvious mistake people do of getting the hoses the wrong way round [ on mismatched box to pumps ] If there is a geometry issue, it would still behave that way with the belt removed.
I didn't count all the words everybody typed, but in this case I'd say the pictures were worth a few thousand words at least. looking at the pics what the heck are the tie rods connected to? you have a rack where the pivots are not the same as where the lower A-arms pivot, the pump looks to me like the one that came with the motor. you may have too much pressure but that won't fix bumpsteer. what that truck needs is a MII to replace the 49-54 suspension that is in there. I would not touch what is in there now other than to remove it.
Your judgment that the words written by several posters have little value is off base. Your own words suggest you lack an understanding of the geometry issues involved. The pictures do indicate 'problems", but the solutions are what is explained in the text. I would agree that a MMII based replacement crossmember/suspension would be a good choice to clean this up with predictable outcome. Since the vehicle now has a '49/'54 Chevy front crossmember, it is worth considering one of the aftermarket bolt in MMII units made for that application. Weld in are also readily available, of course. Chassis Engineering, Fatman Fabrications, Heidts, TCI......and many more offer MMII suspension systems. Ray
True the stock system used a bell crank but he is using a rack and pinion system. To prevent bump steer the pivot end of the rack needs to be as close to the same height as the A arms and the pivot points on the lower A Arm and rack need to run in parallel to each other to prevent binding and bump steer. The lower A Arms are several inches apart from each other over the stock bell crank system that pivoted off the cross member using the double eye pitman arm on the steering box.
Yes, I agree with your description of the original system and tried to describe it in a post above. In my opinion, the center steer rack, an example of which is the SAAB unit posted by the OP, is the best chance of duplicating the geometry of the original Chevy linkage. Ray
Has the OP actually taken it for a run with the belt removed yet? [as suggested to him last Tuesday] I'd be interested in hearing the results of that. We could all be banging our heads against the wall trying to help on this one until we get some feedback.
Not true, Heits has a valve that bleeds off the excess pressure back to the reservoir. It is adjustable for pressure to the Rack & Pinion. My Divco has one for the last 15 years. Gm pumps put out more pressure, then the rack assist needs.
I will disconect the pump tomorow and keep you updated,havent had the time yet. Posted using the Full Custom H.A.M.B. App!
To begin with the GM pumpputs out too much pressure for the Mustang rack. GM power steeringpumps operate between 1000 and 1200 psi. Mustang IIpower racks were only designed to operate between 700 and 800 psi. This difference in pressure requirements can and does cause a couple problems. First is a very "touchy" feel to the steering at highway speeds. This makes any vehicle a pain to drive for long periods since you can't really relax while driving. You have to pretty much be on top of the car at all times. The second problem is blowing out seals in the Mustang rack. You don't want to see power steeringfluid puddling under your car in the driveway but it can and often does happen with this combination. http://www.hotrodders.com/forum/how-properly-mate-gm-pump-mustang-ii-rack-48121.html The solution to all this is of course to lower the pressure of the GM pumpand there are basically two ways to correctly do this. One is to purchase an Adjustable PowerSteering Valvefrom someone like Heidts . They go for about $125 with all the fittings you'll need and basically mount in the high pressure line and allow you to dial the pressure you want. This method works well but for some people it can be a bit pricey.
Your own words suggest you lack an understanding of the geometry issues involved. I fully understand the geometries involved. I fully understand bump steer and what an incorrect rack will do to a car, and have seen in person the results of incorrect rack being installed on a car, the bump steer on the car was so bad you could not drive the car at all, it was crazy. totally undriveable. a friend narrowed the crossmember to put a too wide MII in a 49 or so Studebaker coupe. told him it would not work but he felt I was incorrect and did it anyway. . The pictures do indicate 'problems", but the solutions are what is explained in the text. the solution was not mentioned in the text. the solution is complete replacement. that front end is a turd even when everything is good. Since the vehicle now has a '49/'54 Chevy front crossmember, it is worth considering one of the aftermarket bolt in MMII units made for that application. Weld in are also readily available, of course. I hope I am reading this wrong, and by "aftermarket bolt in MII units for that application" the application is the truck, and not the 49-54 car. the frame has been cut where the crossmember was put in, I don't think he will be able to get by with a bolt in kit, weld in would be the only option. do they make a bolt in for these trucks? not quite sure.
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