Installing bump steer rod ends; cut threads on tie rod shorter?

Elombard · 05-25-2015, 10:41 AM

The rod end will not screw in far enough to get the toe adjustment? Am I missing something? Do I need to cut a 1/4 inch of the threads off the tie rod shaft?

Seems odd.

Trackrash · Trackrash's Garage

Are you using new "turbo" tie rods? There sometimes is a spacer installed between the rack and the tie rod that may need to be removed. IIRC.

Elombard · 05-25-2015, 11:58 AM

Ahh these turbo tie rods were on the car, That would be about perfect for the amount of room I need to get the toe where its supposed to be.

Elombard · 05-25-2015, 07:00 PM

This is the spacer shown. But the directions to install Turbo tie rods say the unit will bottom in the rack with out the spacer?

I was going to pull it off and check it but I guess its been loctited and its going to be a bear to get off.

Any other ideas? I guess I can wack the end of the threaded rod off but it seems odd that would be required?

Mahler9th · 05-26-2015, 09:15 AM

Some bump steer kit instructions state that you have to remove the washer/spacer to get an overall length that allows for most common toe settings. As an alternative with these kits, you can shorten the threaded portion on the outer tie rod end.

I chose the latter approach years ago with an ERP kit.

Elombard · 05-26-2015, 09:20 AM

Thanks Mike I thought I was crazy. The threaded portion is very long.

chris_seven · 10:09 AM

This isn't a spacer - it really is a rack stop to limit travel. Tyre 'Rub' Kits sit in this position and increase the thickness of the 'spacer'.

If you look at the original arms the large plate under the Silentbloc which also locates the gaiter provides the same function.

If you remove this washer the wheels can hit the body or if this doesn't happen you can potentially overload the pinion at the end of the rack's travel.

I think it is potentially dangerous to remove the 'spacer'.

Elombard · 05-26-2015, 10:18 AM

Chris do you cut a piece of the threaded portion off?

KTL · 05-26-2015, 02:25 PM

Elephant has some good info on the anti-rub stop spacers

Elephant Racing | Tire Rub Prevention Kit | Porsche 911/912/930

http://www.elephantracing.com/documents/911-914tirerubkitinstructions.pdf

Mahler9th · 07:41 PM

When you install a bump steer kit, or have one installed, it is implied that you and/or the shop know what they are doing.

The bump steer kit I bought years ago is an ERP unit. Eisenlohr Racing Products. Created, owned and run by a person with extensive professional racing experience. I bought mine from Smart Racing Products (SRP). Created, owned and run by folks with extensive professional racing experience.

SRP had detailed instructions for the kit I purchased, and they stated that the washer needed to be removed. I saw and still see no reason to question those instructions.

However, back then I decided to cut my tie rods instead, as I didn't have a thin 32 mm wrench to remove the tie rods and the car's builder used appropriate torque when he installed them, so I couldn't use any of my existing arsenal of tools.

Just this year I installed the excellent ERP front suspension, and my shortened tie rods would no longer work with the settings I wanted. So I had to buy a completely new set. I wish I had not cut those tie rods years ago, and instead had purchased a proper 32 mm wrench to remove the washers.

SRP used to sell a steering rack limiting kit to limit rack travel to prevent wide tires from hitting the chassis. They offered two versions, and one would choose depending on the OD of the rack. In actuality, these parts were just commonly available bolt on clamps with an ID to just fit around the rack. You can buy this type of clamp for about $15 from McMaster Carr and other places (I just did so to solve another issue).

Parts to limit rack travel may be best chosen based on specific needs. I think it may be a good idea to measure how much one needs to limit travel based on their configuration, and then act accordingly. And when in doubt, seek those out with professional racing experience.

I should add that in my case, limiting rack travel has little to do with needs during actual performance driving. My goal for limiting is related to moving the car around in the paddock, where it can be handy to have lots of lock available, but detrimental to have the front tires and/or brake calipers hitting other parts of the car.

Mahler9th · 05-26-2015, 07:48 PM

This is of course just an example. I would follow whatever instructions came with the kit you have chosen.

There is a thread elsewhere in these forums where a person did not follow this type of instruction and had an issue with their bump steer kit.

Tom '74 911 · 05-26-2015, 08:15 PM

Erik,

I just installed a bump steer kit from Tarett and ran into the exact same issue. In the end, I was able to thread the tie rod (turbo version like yours) fully onto the new rod end that came with the kit, and I mean fully, to barely make my toe setting. My issue wasn't that the rod was bottoming out in the rod end, but that there weren't enough threads and I couldn't thread it in enough...

I'm glad you asked the question though as I'd wondered the same thing during my set up.

I'm planning to revisit my alignment and ride height settings again in the near future, and I will experiment with removing the spacers to see what the consequences are...

I was also planning to call Tarett to ask for suggestions too...

Please post back with whatever you end up doing! I don't know that chopping off the end of the tie rod would help me, as it's the lack of enough threads that's my issue...

Tom

Elombard · 05-27-2015, 03:22 AM

Mike thanks for posting the instructions, I bought that exact kit used and they did not come with instructions. I was going to install the bolt the other direction and was not 100% on where the washer was supposed to go.

Tom It will work to cut the threaded rod down if I am understanding you and I have the exact same problem. I need to screw the tie rod end in farther but it bottoms out. So if I shorten the threaded rod a 1/4" it will shorten the tie rod assembly and allow me to get the desired tow setting.

Hmmmmm decisions decisions.

Tom '74 911 · 05-27-2015, 07:38 AM

Quote:

Originally Posted by Elombard

Tom It will work to cut the threaded rod down if I am understanding you and I have the exact same problem. I need to screw the tie rod end in farther but it bottoms out. So if I shorten the threaded rod a 1/4" it will shorten the tie rod assembly and allow me to get the desired tow setting.

Hi Erik,

I think we have different issues actually... (you don't want my issues!) I need more threads on the tie rod as the lock nut for the rod end is only about 1/2 a thread from being screwed on as far as it'll go. Removing the spacer/washers as shown in the Smart Racing instructions will move the tie rod away from the rod end and give me access to more of the threaded portion. I don't think cutting off some of the tie rod end will help me as it's not bottoming in the rod end. I'll still be screwing the the rod as far as it'll go into the rod end, but run into the same limits as before. The rod ends w/my kit seem looooong...

Here's the kit I installed: Adjustable Bump Steer Kit, 911/914

I plan to give Tarett a call this AM to ask about the situation.

Elombard · 05-27-2015, 07:55 AM

Thats wild the rod end looks like the same piece as mine the spacers are different. Do let me know what they say. Have you checked the steering wheel? can you turn the steering wheel the other way and get a bit more room? Have you checked the other side to make sure you dont have extra room? I made this mistake once.

Please let us know what Tarett says.

KTL · 05-27-2015, 08:13 AM

While the SRP kit by ERP is certainly designed by a qualified entity, I would argue its the least effective steering arm drop link solution to the issue at hand- correcting tie rod height for bump steer.

The ERP kit is non adjustable. What you see is what you get. The Tarett (made by Rebel Racing) & Elephant solutions have fine adjustment to dial in your bump steer. Challenge there is, how do you know how much bump steer you're experiencing. Well it can be measured by a bump steer gauge if you know of a shop that has this equipment or want to buy one

DECO Bump Steer Gauge - Speedway Motors, America's Oldest Speed Shop

My point is in this instance the dudes with the most extensive racing experience actually provide the least effective solution. It's still a good solution. But IMO it begs for a bit more to optimize your chances at dialing out the bump steer.

Erik mentions a good point about the assembly of the bump steer linkage. It's important to have the head of the bolt in the steering arm, NOT the threaded end that receives the lock nut. The steering arm is the point where there's the most shearing force. The shearing force has been increased by the offset of the tie rod from the steering arm. That's why the lowering spacer is tapered- to provide increased resistance against shear at the steering arm. If the threaded end of the bolt is placed in the steering arm, there's a greater opportunity for the bolt to break. The threaded area is weaker in bending resistance than is the unthreaded shank.

Elombard · 05-27-2015, 08:35 AM

I mostly agree kevin, but I also think when you can see 1/2" or more elevation difference in the end of the tie rod and the end of the lower suspension arm on a lowered car this solution will improve bump steer although it probably wont eleiminate it with out some fine tuning.

Also that kit linked above appears to have different spaced washers to allow to adjust the angle of the tie rod to match the LCA? I beleive it does have some adjustment?

Great point on the shear strength of the bolt. I am installing this kind of as a step before I raise my spindles, when I raise the spindles I am going to add the reinforcement bracket, the moment that this kit applies to the steering arm is ....sobering. DOuble shear is really a must. But since mine is only 3/4" or so I decided to go ahead (also since many before me have used this...or so I thought until I could not get the toe ...)

I was not even going to install them prior to spindle lowering until I looked and could see that this kit will put my tie rod and LCA pretty close to the same angle.

Mahler9th · 05-27-2015, 08:49 AM

Hopefully Tarett can provide some guidance, or direct you to the kit's manufacturer if it is not made by them. I have found Tarett to be an excellent resource and appreciate what they offer for our cars. Great folks.

There are quite a few threads on bump steer in these forums, some are worthy of a review for those interested in details. I suggest a little searching for some interesting illumination.

I have not done a thorough bump steer yet on my car, but my network of resources tells me that in the range of my desired set up specs, the amount of change to get more optimal characteristics measures in the thousandths of an inch. So kits with big spacers probably offer little or no advantage when tiny shims are the appropriate choice.

I fully suspect that the ERP kit has the most mileage in terms of units in service, and I suspect that it has evolved quite a bit through the years. My investigations thus far lead me to believe that I can use very thin shims at the rack and/or on top of the lowering spacer to get things right. I am pretty sure Cary Eisenlohr at ERP could and would advise me in more detail if I need it.

It would be interesting to hear from folks that have actually performed or have had a detailed bump steer correction, and to understand details of their specs and process.

I think many of the kits out there likely have merits, but I disagree with KTL that the ERP kit is the least effective, as I have seen no evidence to the contrary. And so far in 25+ years, I have not seen a Porsche "street car" tuner come up with a racing product superior to something from folks with extensive professional Porsche racing experience. But that is my own experience.

Since I race my car, my requirements are likely different from most here.

Mahler9th · 05-27-2015, 08:52 AM

And by the way, while I have not yet confirmed with ERP, I have heard from reliable sources that they can replace parts of their bump steer kits. If I bought a used one, I'd inspect it carefully, and change appropirate parts out for new ones.

Mahler9th · 05-27-2015, 09:08 AM

Sorry, a couple of additional points.

1. As many know, the goal of bump steer correction is NOT to get the LCA and the tie rod at the same angle. This is a very common misconception, so I admonish folks to be very careful and meticulous in planning a course of action.

2. I have heard from a couple of pros that adding a reinforcement bracket may or may not be the best idea, depending on other variables. If I were considering such a move, I'd investigate thoroughly.

Its hard for me to imagine that there have been any major technical breakthroughs in bump steer correction for trailing arm 911 family cars in many years. Even the advent of 17 and 18 inch tires happened some time ago, and by now I suspect quite a few accessible pros have plenty of "area under the curve" when it comes to lowered cars with raised pick up points.