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Premium Member
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16,189 Posts
Discussion Starter #1
Hi all,
Spent yesterday and today making up the final rack extensions for my bumpsteer solution. Original post is here . Started out with a kit from Heidts that has 2" extensions, extended boots and clamps. I machined them down to 1.7" and also had to bore them deeper and thread them deeper. The latter took up most of the time since I had to match the existing threads and cut them by turning the lathe chuck by had so as not to bottom out the tool (no tap available since the threads are a very odd 15/16"-20). Turn, test fit, turn, test fit, etc., etc.. Talk about monotonous!!

The goal was to have no toe gain on extension (base will be 1/16" per side) and some toe-in gain on compression. The results are 0.00" toe change on extension and 0.030" toe-in gain at full compression compared to the ride height position. A little extra toe-in should help stability on heavy braking (that's the theory anyway).

Here's some pics.

The 1.7" extension:



Extension and inner tie-rod:





Extended boot:



Outer tie-rod configuration. I had to shorten the outer tie-rod threaded section as well as the adjusting tube.



Overall pic:



Time for a
.

Cheers, Rod
 

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Slacker Extraordinaire
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2,811 Posts
Rod, Get back to work! Beer time is over. Nice work as usual.
 

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Premium Member
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766 Posts
Would you be willing to make more? That's a great solution!

Good job! Enjoy a fine Canadian beer,
Nate
 

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Premium Member
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5,783 Posts
I've been following along Rod!

Put me on the list. Cheque's in the mail etc... :D

You are using Fox spindles right? Do you think either SN95 version would require a different extension? I'm guessing no since the LCA pivot point is the same (unless you are using donor arms and the inner mounting hole).

Thanks for sticking with this one. I think it's a great idea.

Gordon's Konis look great BTW.

Sean
 

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Senior Member
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2,745 Posts
Nice job Rod,

Always a pleasure to see your work. Plus, you have such great tools!

Chris.
 

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FFCobra Fanatic
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2,598 Posts
15/16-20 taps

15/16-20 die
This may help.

Did you make 2, one for each side? Or one and recentered the rack?
Getting the thread to realign in a lathe is no easy task.
 

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just another builder
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8,238 Posts
nice work rod
 

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Senior Member
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6,559 Posts
I had extensions made for mine as well. Huge improvement. Remember folks, the size of the extensions are not universal. It will depend on what rack you're using and what spindles you have. The FR rack takes M14 fine threads.
 

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Junior Charter Member
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319 Posts
Rod
you have the tie rod in the wrong location, it must go on top of the steering knuckle to eliminate bumpsteer. now you are going to have to remove your extention, it is going to be to long
Ricardo
 

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Premium Member
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16,189 Posts
Discussion Starter #10
Thanks guys!!

I'm not really set up for production and it took about four hours each to modify the extensions. I'll check with William at VPM to see if he is interested. But, as Todd mentioned, it is very configuration specific. With all the different possible configs out there it would take a lot of testing to come up with a unique solution for all of them. Stock rack vs. manual rack and stock LCA's vs. FFR LCA's vs. Forte LCA's. Not sure if there are any small differences between the different LCA's and small differences can make a big difference. For example, adding an extra 0.030" spacer on the outer tie-rod to move further away from the steering arm flips the results and gives 0.03" toe-in on extension and 0.0" on compression. The power rack also allows you to run more caster which moves the steering arm up and changes things quite a bit. If I had a manual rack and was running my current set-up (Fox spindles and Forte LCA's) I would have had to drop the rack down to get the proper geometry.

Sean, I think it would take some testing with your actual set-up to determine what the ideal length is and the position of the outer relative to the arm. But I would bet it wouldn’t be the same. Gordon's Konis are great looking but did require some small changes, front and rear, to work with my set-up. All set to go at this point though.

Sanford, DOH!! I looked at a bunch of places trying to find that tap with no luck. Even called one company that makes custom taps and never heard back from them. Thanks for the info! One per end for a total extension of 3.4".

Todd, Heidts also makes the 2" extension for the manual racks with the 14mm threads. How much of an extension did you end up with and what were your bump readings (if you know)?

Ricardo, Not sure why your saying that but you are incorrect and that set-up would be dangerous as it would go to extreme toe out on acceleration. Never good to have two tires pointed at opposite ditches at the same time!

Cheers, Rod
 

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Premium Member
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16,189 Posts
Discussion Starter #13
Hi Bob,
I used the second one here (MP039-4) on my stock '87 rack:



My understanding is the other one would work with the manual racks.

Cheers, Rod
 

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Premium Member
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16,189 Posts
Discussion Starter #15
No problem Bobby. That ad is from a Canadian site so there is the exchange (most companies up here never reduced their prices when the rate got better :rolleyes: ) and some difference for them bringing it into Canada. Actual price was $51.42 so I guess they are one of the good ones that did follow the exchange rate to some extent. Shipping was only $7 so not bad overall.

Cheers, Rod
 

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Senior Member
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6,559 Posts
Originally posted by dv/dt:
Thanks guys!!

Todd, Heidts also makes the 2" extension for the manual racks with the 14mm threads. How much of an extension did you end up with and what were your bump readings (if you know)?


Cheers, Rod
Rod,

I only have a total of 2" extension installed. That only makes up for inner CAs pivot offset. I'm holding off on adding more until I have the SAI kit and SN95 spindles installed. I haven't taken any data yet but will when I get all the other stuff together.
 

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FFR Craftsman
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5,832 Posts
Hey Rod, I could use a couple. I was forced to mount my joint "above" the knucle extension because it wouldn't go that far otherwise. I got mine off a 2000 Mustang so no dog-leg... just stratight.
 

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Junior Charter Member
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319 Posts
Rod
the way you have set the tie rod is no different that from the original set up (with out bump steer kit.
the reason that the bump steering kit in the FFR was developed is to correct tie rod geometry due to the steering rack been mounted higher up in FFR frame in ralation to the steering knucke vs the mustang subframe.
If you notice in the manual states to change the inner tie rods for the ones suplied in the kit. reason they are shorter not longer.
I am just trying to save you some aggrevation.
but if you still not beleave me call FFR tech suport.
Ricardo
 

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FFCobra Master Craftsman
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4,481 Posts
Richardo,
If Rod has achived the numbers listed, below or above the steering arm doesn't matter. The results are what counts. The numbers published above for toe in and out with compression and rebound are about ten times better than what I measured prior to installing my Gordon Levy bumpsteer kit. The stock FFR front end geometry ( on the MKII anyway )is just too excessive. They should have fixed this problem 2 generations ago.
 

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Senior Charter Member
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599 Posts
Rod,

Enviable bumpsteer results. How much suspension travel down from ride height and how much up from ride height did you test?

Bobby B.
 
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