solidJ 11 Report post Posted May 25, 2019 1969 coupe 6cyl, 200ci. After I replaced the power steering control valve with a new Lares, the car shudders when turning the wheels left or right from standstill. A few weeks later, the pump started to growl and being 12 years old, I also replaced it with a new Lares. The shudders continued as before. Once I am moving, there is no problem and the steering is fine. Any thoughts? Quote Share this post Link to post Share on other sites
jmlay 80 Report post Posted May 25, 2019 My guess would be air in the lines. Did you bleed them when the pump was replaced? What are you using for power steering fluid, type F trans fluid I hope... 1 JayEstes reacted to this Quote Share this post Link to post Share on other sites
solidJ 11 Report post Posted August 20, 2019 Follow-up--I swapped out the new Lares control valve with an identical replacement from Lares. The shudders continued, though not as bad as before. Lares tech support said the problem is 99% air in the lines and explained proper bleeding technique: coil disconnected, wheels off the ground, turn wheels left and right while cranking. This was done by my mechanic with no change in the shudders. Has anyone else experienced this? Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 21, 2019 8 hours ago, solidJ said: Follow-up--I swapped out the new Lares control valve with an identical replacement from Lares. The shudders continued, though not as bad as before. Lares tech support said the problem is 99% air in the lines and explained proper bleeding technique: coil disconnected, wheels off the ground, turn wheels left and right while cranking. This was done by my mechanic with no change in the shudders. Has anyone else experienced this? yup, this is a very, very, common problem with rebuilt or new aftermarket parts and can be a nightmare to fix and is usually not caused by air in the lines. What is a "lars" unit? Quote Share this post Link to post Share on other sites
solidJ 11 Report post Posted August 21, 2019 larescorp.com Lares sells new and reman steering components, in MN. Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted August 21, 2019 Like Barnett mentioned that is a common problem. I thought it was usually related to insufficient pump pressure. I guess it could be the hydraulic cylinder that is attached between the drivers side frame rail and steering center link. But, truthfully, the only issues I've seen with those hydraulic cylinders are leaks. Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 22, 2019 4 hours ago, 1969_Mach1 said: Like Barnett mentioned that is a common problem. I thought it was usually related to insufficient pump pressure. I guess it could be the hydraulic cylinder that is attached between the drivers side frame rail and steering center link. But, truthfully, the only issues I've seen with those hydraulic cylinders are leaks. We have found it to be either the pump or the control valve on different cars. We tested a rebuilt pump that had a shudder and found the pressure to be LOWER than an original pump with 100k miles on it. After we installed a pump that produced more pressure at low speed, the shudder went away. In the case where the shudder is caused by low pump pressure at low speed, a smaller pulley can help, but it's not something to do on a non stock, high revving engine, and is of course a band aid instead of a proper fix. We had so many faulty "rebuilt" control valves that we had one of the mechanics that knew how to rebuild them, redo them and never had a problem with a control valve after that. I think one of the guys on another mustang forum mentioned what the cause of low pressure in some rebuilt pumps was but I forgot exactly what it is. We also found that slightly thicker power steering fluid would help, but unfortunately I can't remember exactly which one it was at the moment. 1 JayEstes reacted to this Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted August 22, 2019 On Saginaw PS pumps there are pressure regulator shim kits available to adjust the pump output pressure. Is there something like that available for the Ford Thompson PS pumps? Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 22, 2019 10 hours ago, 1969_Mach1 said: On Saginaw PS pumps there are pressure regulator shim kits available to adjust the pump output pressure. Is there something like that available for the Ford Thompson PS pumps? I for one don't know of anyway to adjust low speed pump pressure. There is a pressure relief/bypass valve that controls maximum pressure just like an engine oil pump. The low speed pressure can be increased slightly on an oil pump by machining the housing to reduce the clearance between the end of the gears and the housing and bottom plate if the clearance is excessive but this will only increase pressure at idle by a few lbs at best since the pressure in a ps pump are so much higher, a little wear or excess clearance will change the pressure by a much greater amount. Quote Share this post Link to post Share on other sites
solidJ 11 Report post Posted August 22, 2019 barnett468: "We also found that slightly thicker power steering fluid would help". This seems like something to try before replacing power cylinders, pump, or valve. I'm using Type F now, any suggestions for a thicker fluid? Any harmful/negative effects? Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 22, 2019 45 minutes ago, solidJ said: barnett468: "We also found that slightly thicker power steering fluid would help". This seems like something to try before replacing power cylinders, pump, or valve. I'm using Type F now, any suggestions for a thicker fluid? Any harmful/negative effects? No harmful effects from using power steering fluid. The type f is around 6.5w and I think the power steering fluid we used was around 7.5 - 8w. I will look into it for you when I get a chance. 1 JayEstes reacted to this Quote Share this post Link to post Share on other sites
copb8 97 Report post Posted August 24, 2019 My power steering is effective when car is cold but after it gets hot it's almost non-existent at low RPM's. I have to raise the RPM's and left-foot brake to get any assist. Is it simply an issue of the hoses being too close to the manifold? Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 24, 2019 3 hours ago, copb8 said: My power steering is effective when car is cold but after it gets hot it's almost non-existent at low RPM's. I have to raise the RPM's and left-foot brake to get any assist. Is it simply an issue of the hoses being too close to the manifold? If your hoses and exhaust are stock, then that is not the problem. The fluid will get hot anyway from various factors, but it certainly sounds like a thicker oil would help in your case. Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 24, 2019 Ok, here is some very good info on thick power steering fluids from the oil geeks at bobistheoilguy forum. They post several oils that are thicker than atf. The valvoline max life and lucas ones are most likely available at most auto parts stores. Wally world may have the valvoline one as well. https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3475385/1 Quote Share this post Link to post Share on other sites
