Hello friends
My last post I had a intermittent rotational hard steering. I must have applied too much steering force to the rack when turning and the pinion worm gear popped out of place from the rack making an awful grinding crunch noise when turning. Thinking the root cause was the rack and pinion I purchased from eBay I replaced it. Luckily I had a spare steering rack laying around. The 2nd rack I inspected for wear and damage, freshen it up and installed it. All the u-joints are good and free from binding.
Even with the freshened up rack and good u-joints I am still having the rotational hard steering. I have loosened the u-joint bolts on top and bottom and still no remedy I am convinced the issue is with the angle of the steering shaft and u-joint position.

Note I am running a 911 front suspension with aluminum cross member. the rack does have a bump steer spacers. I can not remove the spacers due to the the steering rack will not clear due to the coolant line that run under the center undercarriage. As temporary measure the bolt to the steering rack were the only ones I had to test, they are too long so a spacer has also been added to the bottom of the mounting bolts.

My question is anybody running a 911 front suspension with aluminum crossmember and using a bump steer spacers had the same issue. Should I be using the 911 shaft that bolt on to the steering puck. I believe the 911 shaft may be shorter. can anyone confirm this? Im tempted to cut the lower shaft 1/2 inch to get me the angle on the u-joint from binding binding up. Any thoughts?

Thanks in advance.
Al


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It would seem to me that the geometry of the unibody has been changed. Are all those component mounting points in the same place as they were before the crunch? Is your body distorted? Not yours, but the car's. I know, it's a dumb question, but sheet metal likes to bend.

Very pretty car Al. Mark

My car and myself are about the same age. Only difference is the car's body is in better shape than I am. All evidence shows that my car has never been a significant impart only superficial scares. All body panels fit without gaps or evidence of structural damage. Could It be that mix and match fitment of 911 suspension and 914 steering with bump steer don't mix well? I was under the assumption that the steering & suspension was interchangeable. Does anyone have a picture of steering shaft / u-joint angle for comparison?

911 front suspension is usually a bolt on switch. Did you install turbo tie rods and off so, did you use the thick washers.

I was just installing steering rack tonight on /4 steel cross member with bump steer spacers.

All I can say is the spacers cause problems by raising the rack up too high in Z and causes the shaft to hit sheetmetal where it comes though the front firewall. That was obvious because shaft wasn't centered in the pass though hole in the firewall.

The other thing spacers do is they push the steering rack input shaft bearing upward. Then when the firewall clamp for the bearing was tightened I got a very pronounced noise and a tight spot. Wasn't to the level of bind but it definitely wasn't right.

Now, I know you have the 911 cross-member . . . but . . . I'd check the basics that I'm talking about before attaching the U-joints. I think you'll find something else is wrong.

With respect to the 1st rack -- there is an adjustment bolt on the rack that controls engagement of the rack to the pinion. You may want to take a look at that.

I think you're on to something. I did notice the shaft not center through the firewall and It makes sense extra tension from tightening the the steering bearing clamp could cause problems not to mention the extra angle from the bump steer spacers. I did install turbo rods with the thick washers but not convinced it would cause a rotational binding in the steering.

unfortunately I have to keep the spacers to clear the coolant lines. Looks like I'll have to come up with a creative solution.

Thanks for the insight.

I also installed turbo tie rods as well when the rack went in . . . . with the thick washers. No issues created for me with the tie rods.

The thick washers are only to prevent the inside ball socket end of the turbo tie rod from going inside the rack housing. in actuality, the inside tie rod end is ever so slightly larger than the housing but I can see over time where forcing full lock turns could allow the housing to be deformed due to the inside ball end from banging on it or gouging into it.

If you have those thick, large OD, washers in place, I don't think you'll find any issue there. Pretty sure it's the bump steer spacers.

I wanted them, but, I ditched them due to the problems they caused for me. Like you, I'd need a creative solution to be happy. Ultimately, we all know the real fix for bump steer is to raise the spindles, not the rack.

Very nice looking car by the way

My coolant lines run similarly to yours. I'm not running spacers and my hoses contact the rack and bend slightly but aren't cutting off any coolant supply at all. When your spacers aren't there, does it put a bad pinch on your hoses?

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The picture on the right seems off to me. What are the long bolts and spacers holding the steering rack? I thought the bump steer kit spacers go in-between the crossbar and mounting tab?

Matt

Al, do you have raised spindles, your car looks pretty low (nice). If you do not your suspension geometry cound be off a bit. Bump steer spacer can not correct for that much lowering. Just my 2 cents. Mark

Not to hijack but @ what point do you need the rack spacers ? my front is lowered just under an inch from memory as after fitting new Boge touring inserts with 911 struts it was way too high.
TIA.

Just throwing this out there, if the issue is coming from the U joint, perhaps you have the wrong one in? There are 2 lengths (shafts from steering puck).

I don't have lowered spindles but I have the torsion bar cranked down some up not maxed out.

As for the extra spacer in the of the crossbeam, the bolts I am using now are temporary. I happened to have some some extra spacers and long bolts laying around but are way to long. unfortunately the old steering rack bolts did not work with the replacement rack. The thread on the current rack are sunken in.

As for the coolant lines at the undercarriage... they are steel pipes that runs the length of the firewall frunk to the rear firewall at the engine bay. The use of the steel pipe and the location they are in has me using spacer to clear the pipes otherwise the rack will not fit.

As for the shaft from the steering puck to the lower u-joint I didn't know the 914 made 2 lengths. I seen the intermediate shat have 2 lengths but not enough to make a difference. I believe the 911 shaft is shorter but not sure if it will work on a 914.

Could anyone post pictures of their u-joint and shaft coming out of the firewall? I am Curious to see how mine differs and at what angle yours is in for comparison purposes.

Thanks.
Al

I'll get you one today. @ahycaramba

Delinquent -- Sorry for the delay.

All these pictures are without bump steer spacers, on a 914/4 steel crossmember.

Input shaft is centered in pass though hole -- it was hitting top with spacers installed

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U joint potion

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Here's one more with a perspective close to what you posted.

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Note: U joint yoke closest to the input shaft is roughly parallel with the sides of the reinforcement welded to bottom of the firewall. Approx 45 degree angle on the joint to the left as the shaft heads to the steering column.

I don't see any big difference in angles between our u-joints.

@ahycaramba

In looking at the OP and the pictures, I'm also wondering if you can elaborate on what hard steering means to you.

From photos it appears you have some pretty large front wheels & tires with a lot of offset. When the front wheels are spaced outboard either with wheel offset and/or wheel spacers, scrub radius is increased. Large scrub radius will lead to heavy steering.

I can't tell from photos, what size steering wheel are you using? Small diameter steering wheel will also increase steering effort.

Large scrub radius, wide front tires, and a small steering wheel, are all going to add up in a way that requires way more steering effort than a stock 914.

Not saying this is what is going on but as I re-read you OP, I was wondering about all this.

@Superhawk996
Thank you my friend for the pictures. It has given me a base line of where and what Needs to be done. for starters if I am to keep the bump steer spacer ( wich I have to keep) I am going to have to fabricate something in-between the steering shaft bearing and retainer to center the shaft in the hole. I am also going to have to cut the lower shaft equivalent to the thickness of the spacer, about a 1/2 inch that should get me the angle that doesn't bind. I should mimic stock steering angles. I have the wheels off the ground and still have binding. I had made a video of u-joint binding but can seem to download the video.
Now come the fun part..taking out the gas tank. Click to view attachment Click to view attachmentClick to view attachment

@ahycaramba

A steering system modification that fatigues, and breaks leaving you holding a steering wheel disconnected from the wheels is no fun. I've know people that have had it happen in race cars - it always ends with a funny story but doesn't end well for the car.

Have you considered local deformation of the coolant tubes?

A gradual change from round to oval will not affect flow over the span of about 10 inches will not affect flow. The trick is you can't just pinch the tube locally over say an inch - that will cause some flow restriction.

I'm betting that isn't easy either but it's an option that is more appealing than cutting / fabricating a steering input shaft - I rather be messing with a cooling system vs. welded shafts on a steering system.

My gut tells me the water pump probably has enough extra capacity to over come a minor flow restriction.

Likewise, have you simply tried loosening the center bearing on the input shaft? You likely to find that is where the majority of the bind is rather than the U-joint. That is what was going on with my spacers which were 8mm. If you're running 1/2" (12.7 mm) spacer, I'm sure you're getting an even worse bind at that bearing.

If that turns out to be the case, I'd modify the body before I modified the steering rack input shaft. I'd cut out the pass though hole in the new location and patch the remnant so the pass though grommet still fits. Likewise, the center bearing retainer could be fabricated to fall in the proper Z height and with the "extra" distance to the firewall so that the input shaft isn't placed in bending when the bearing retainer is tightened.

See where this is going? There's at least two other options that don't involve cutting steering components that are directly related to functional safety.

If you still decide to cut the input shaft (I really wouldn't), you need to mark the shaft so that the "index" where the U-joint bolt goes remains in the same position after welding or you're going to mess up the U-joint phasing. If you're not familiar with U-joint phasing, there are plenty of videos on YouTube. Primarily about drive line U joints and balance / vibration effects. However steering feel and responsiveness is affected by U joint phasing too.

If I understand your steering rack modification proposal - you're wanting to shorten the steering rack input shaft to get the U-Joint back toward it's design position - lower in Z height and centered in the pass though hole. It seems to me you're still thinking the bind is coming out of the U-joint.

The difference in Z height at the pass-though is not what is causing the U joint to bind. Its the bending of the steering rack input shaft.

Shortening the input shaft will not accomplish your goal.

Rather than try to explain with words I hope the picture helps.

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What is happening is the input shaft has been pushed up in the vertical direction (Z height) by the spacers. This puts the input shaft out of alignment to the intended path for the center support bearing.

As a result, the shaft is deflected (red dashed line) when the bearing retainer is tightened. It's putting the input shaft into bending with resulting binding you feel as you try to turn the wheel.

Shortening the input shaft is only going to get you a linear movement (along the shaft axis). Yes, it will affect the end position of the shaft at the U-joint - but only slightly and not in the way you're anticipating.

The Z height of the shaft at the bearing mount will remain unaffected and will still be deformed when the bearing retainer is tightened. I agree with your plan to get the bearing moved up in Z to coincide with the axis of the input shaft - that is a a solid plan. However, cutting the input shaft isn't going to net you anything significant.

I just quickly measured the input shaft angle so that I could calculate how much shortening of the shaft will affect it's Z height at the end of the shaft where the U-joint attaches.

Input shaft angle is about 40 degrees (measured with digital level)

Z height will change as a function of that shaft angle:

Z height change (at end of the shaft) = Distance shortened x Sine(40)

So lets say you shorten the input shaft by 0.5"

Z= 0.5 x Sine(40) = .321"

So if you shorten the input shaft 1/2", you only net 0.321" of Z height change at the END OF THE SHAFT. I can guarantee you that 0.321" one way or the other IS NOT causing U-joint binding.

Since you have effectively 2" of shaft sticking though the hole, you will STILL have a contact between the shaft and the pass-though hole that will need to be addressed by elongating that hole to eliminate the interference.

Thank you @Superhawk996 for all the illustration and calculations and most of all your time to help remedy my situation with the steering. I appreciate your wisdom. I am glad You chimed in this post. I guess I will start with the deflection of the steering shaft. that's something that needs to be addressed regardless. I hope just loosening the center retainer bearing is enough to remedy the problem of binding. Wishful thinking, cross my finger and all other lucky charms I can think of. I'll keep you posted with my findings.

Thanks Buddy.