I've talked to a few guys at cruises about their power rack set ups being touchy , Mine is easy to steer for parking and manuvering in tight parking lots but on the highway is way too twichy . I put the shim kit in the pump , etc. I'm just wondering if lenthing or stretching the steering arm on the mustange II spindle would make it feel less twitchy ? I guess it probably wouldn't be safe to do this on my own , but if this would theoretically work why doesn't someone offer these aftermarket ?
I'm guessing GM pump ? So that leads me to agree that more than likely it is a pressure issue. When you say shim kit I don't exactly follow you. They make a inline valve that will lessen the pressure reaching the rack if you are running a higher output pump than needed. http://www.speedwaymotors.com/Mustang-II-Power-Steering-Flow-Valve-for-GM-Pump-2-GPM,5852.html
Heidts also sell a pressure reducer - my solution was to have a slow ratio rack built - 16:1 instead of 12:1 which should eliminate the need for the reduction valve.
I also did the shim kit (Borgeson makes it) to reduce the pressure from the pump. It did help, but I wish I'd put in an adjustable valve as suggested above. Fwiw also look at your alignment. A lot of old cars (including mine) were set up with very little caster to make them steer easier at the (low by modern standards) speeds they used to drive. If you can add some caster it may settle things down a little.
Just another thought.....Is your rack new or does it have some wear? I've found that the "twitchiness" is acceptable when everything is new and tight, but it gets really annoying when there's lash in the rack. I also agree with the caster comment.
If the GM pump is the problem, why can't you use the Ford low flow pump? Can't be that hard to mount one on just about any motor style. Even the belly ****on SBC.
GM pump w/ 74-78 MustII power rack has always been a problem. RB's Osolete Auto used to have a fix, by just changing the valve in the pump, with one they supplied. Anyone know what happened to those guys? PM me and I'll give the number of the guys that used to build them for RB'S
first off if you order a rack from a parts dealer you are gonna get a quick steer rack unless you specify the slow ratio. as the slow ones are getting harder to get. they also have a core charge.the slow ratio racks are 3 turns lock to lock and the quicker one is 2 1/4 turn lock to lock.ive got a car i been working on, has a heidts mustang II front , quick ratio rack, i put the borgeson shim kit in (2 shims at a time), that didnt work so i installed heidts reducer valve, that didnt work- put the shim kit in and the original shims and the heidts block - turned the valving down to where it had no power steering at an idle but it came in as soon as the rpm came up and the damn thing still darted like a go cart. brent at fatmans offers an extended tie rod that might help but the one thing all i talked to was that the gm pumps arent compatible pressure wise with the quick ratio racks and sometimes with the slow ratios either.ive learned a lot about them in the last 6 weeks. ive been waiting a month for a slow ratio rack from maval(unisteer) and ended up ordering one yesterday from my buddy at NAPA and as soon as i get done typing im going to pick it up--good luck!!
I worried about the same think when I did the front suspension, on the Divco. Mine was two fold. one would it be twitchy at highway speed, and I knew the GM pump had to much pressure and would blow out the seals in Ford the rack. Did some research about bleeding off access pressure. I installed adjustable pressure bleed off, bye Heidt's. Worked perfectly. Great in the parking lot, and at 80+ mph down the freeway. This is with the rack and pinion I got from Heidt's
I had a slow ratio rack built to order yesterday while I waited at CJ Automotive in South Gate, CA. It was ready in 45 minutes - and I got to eat lunch while I waited at Bob's Big Boy Broiler, just a couple of blocks away. I paid $150 for the rack out the door. You might want to give them a call and speak to George. CJ Automotive, 5909 Firestone Blvd., South Gate, CA 90280. Tel: 562 806-6464
Very few times has dropping the pump line pressure solved an issue as the OP described. It's easy to blame the mix-match of pump and rack so therefore it gets plenty of it. The reality dropping the pressure just takes away ***ist power, it does nothing for feel. Real Mustang II racks come from an era of automotive theory that the numb-er the better with steering feel. Truly effortless, floating on a cloud, one finger control. So expecting modern tactile feedback from vintage parts is only going to lead to disappointment. Reality is, your alignment is what needs altering. Adding caster is definitely the right direction. 3-5 degrees is very acceptable and will help with tracking. Less positive camber will solve the twitchyness as will a lower toe in setting. I shoot for an 1/8 degree positive or straight up on camber and an 1/8" of toe in. Been down this road far too many times and got it right to start second guessing the pump.
When I was looking for a power rack, I had heard all of these horror stories. I called Fatman's, and asked what rack to buy. They said, go for a later T-bird rack. That's what I used and love it. Rich
I asked my supplier about the T-bird rack and they told me the only difference from the Mustang II is that the T-bird rack mounts are 15 1/2"on center and the M II are 16". This is all they do - rebuild steering racks, so I guess they might be right..... Do you have any info on any other differences that would make the T-bird rack preferable?
the cost of a reman M2 rack is typically more than double that of a reman T-bird or Fox Mustang rack, and they are sometimes hard to get or unavailable due to a shortage of cores. and, the steering ratio--get the 16 to 1
I say get rid of the power steering. by thier design racks steer easier than regular steering anyways. as I recall FATMAN recommends manual steering in most cars.
Exactly. Throw out the power rack, bolt in manual rack, problem solved. Also eliminate a bunch of hoses and potential problems and leaks. I've been driving my 37 GMC with a manual MII rack since 1989, over 50,000 miles and it steers as easy as my new Ford pickup and car, unless you are virtually stopped..
i had this problem also . i think you will find the newer racks dont have this problem as i replaced it with a newer rebuilt and no problem . i also have one with the t bird rack no problems at all
Thanks for all the replies and great advice guys ! I had manual rack on this truck and also on a '38 chevy that I drove for about 12 years and both steered ok at speed but Horrible in parking situations . I have the Heits crossmember with stock Ford A-arms and spindles . The steering wheel is still the big stocker that it came from the factory with in '49 . The truck drove fine with the manual rack above 40mph but NOW since the switch to power it seems that it wants to "dive" off the road when I turn too the right , not too the left though . I can kinda get used to the twitchyness but now this is driving me crazy , I gotta slow way down on righthand curves . I have looked over and pryed and pulled on everything on the front suspention and cant find anything worn or even loose . Its GOTTA be the dang power rack , I guess I will have to try to find me one that is the slower ratio , this weekend I'll see if mines a fast or slow ratio. A budy of mine has a wrecked mustang - said I could have the steering . I'll grab it IF its a slow one - might grab the pump also ! The stuff ya gotta do to park one handed !
? More twichyness on right hand turns than left? Rack my need to be centered and the toe in reset. Does it turn sharper one direction more than the other? Check the total number of turns and divide that by half. Turn the wheel to the complete lock on one direction and turn it back the half number, use tape on your steering wheel to be sure you are in the right area. Check to see if your wheels are straight ahead.
ELpolacko I was thinking along the same line as you after I had it aligned . I made an extra notice of where my steering wheel was "clocked" before I took it to alighnment shop - it was turned atlest 1/4 turn from straight before . When I got it back it was now "straight" ! Maybe I need to check and see just how far off of "centered" my rack is . It doesn't turn sharper one way than the other that I can tell - If turned too far the caliper hose fitting stops it by touching the lower tailing(?) stutt rod , but thats turned more extreme than would do at speed , maybe parking it would touch .
The calipers or anti-sway bar or what ever could be limiting the turning radius. Best way to be sure is to disconnect the tie rod from the spindle. Still think you should check the alignment, get a print out if you can and verify the camber and toe settings with a tape measure and an angle finder.
Also, check the toe setting. You won't notice it at low speed, but too much toe-in will definitely feel darty at highway speeds. A little more toe-out will help, just keep an eye on the tire wear to make sure you haven't gone too far... (Oops...haha...didn't see there was a "page 2"...)
You bring up a few rules of thumb when it comes to alignments. Wear issues aside these are typical traits. Excessive toe in = nervousness and rapid turn in Excessive toe out = slow to react (sluggish), tracking issues Excessive positive camber = lack of "on center" feel and steering does not return to centered well. High speed nervousness. Excessive negative camber = heavy on center, rut following. Low or negative caster = poor cornering turn it with radial tires, loss of high speed stability. Excessive positive caster = Heaviness in steering feel, caster shake.
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