Garth S

The recent thread on 'anatomy of a tie rod inner' was a follow up to my daydreaming of a way to emulate the form and function of a RS/EVO type of solid inner joint to improve steering precision - ie., eliminate the designed in +/- 2.5mm axial play of the OEM 993 joint as provided by its rubber mounting.

For the massive capital outlay today of $2 in parts, the mod is done - and the joint is solid enough to restrain a herd of elephants ... so here is the elected approach and procedure:

Firstly, the integrity of the joint must not be comprimised: secondly, the modification should be reversible - as this is a trial of unknown outcome. Lastly, I wanted a simple method that could be executed on the car, without dissassembly or alteration of suspension settings.

With these criteria, drilling and insertion of a rather robust roll pin was selected. A visit to my friendly machinest for a consult, resulted in the squandering of $2 for 2 of his best quality and strongest 5/16x1.5" roll pins - and the loan of the correct punch to drive them home ( the punch is not necessary for setting the pins, but is the tool necessary to reverse the trial should the results 'suck').

Now comes the matter of precisely drilling through the centerline of the barrel at a point 50mm back from the front edge ( roughly where the screw is shown in the last pic). Not trusting my drill control while at an angle with the car on the hoist, a centering guide was made to pilot drill the barrel ..... so the final drilling could be done by hand. To make such a guide, a piece of pipe of the correct id to fit over the barrel was selected, and drilled through the diameter: then, a block of scrap was welded over one of these holes, and reverse drilled using the two guide holes. Having done this, the sawzall liberated a 'saddle' of the correct dimensions with a pilot drill guide centered on the diameter. A hose clamp firmly attached the guide for the initial small bore hole.

The first hole was drilled 5/32", the guide removed, and a 5/16" hole chased down the pilot ( ~20 thou smaller than the pin, which is ~8mm). Firm tapping with a ball pein hammer set the roll pins ... and the rest will be history ... in a month or so when it is fit to get back on the roads here.

That's it until testing occurs - but for the moment, I'm smugly believing that for 2 bux and a little DIY, my car is sporting RS (equivalent) tie rods ... at least, until reality convinces me otherwise.

1pcarnut

Nice job! That's some creative ingenuity you've got going there. Very curious to hear how you like it. Was watching the first thread and a thought occurred to me. Do you think the rubber coupling is there to prevent vibration or impact damage to the steering rack?

AOW162435

Garth,
Fantastic engineering - as usual.

Andreas

chris walrod

To add a touch of race prep, you can run a loop of safety wire through the roll pin and tie it off around the diameter of the outer housing. Very clean!!

AOW162435

Or, to add a touch of shadetree, you could just slip a hose clamp over the roll pin.






Andreas

chris walrod

But wouldnt that collect too much dust?

AOW162435

Chris,
Everyone knows you would cover the hose clamp with a section of heat shrink tubing.




Andreas

CarreraX

As long as the entire thing was wrapped in duct tape all is good

ppressle

Driving impressions?

Stealth 993

NICE! Let us know how the steering feel is!

Akerlie

Not meaning to spoil the fun, but do you think the roll pin can take the beating ?
Guess you will find out soon enough Waiting for your impressions

Garth S

Alright, already ... I've taken off the duct tape ..... and looped in stainless safety wire

No driving impressions until the snow melt is complete, est. 3 weeks.


After looking at some of the brutal service applications that my local machine shop uses these roll pins in, this application appears mild: should the pin fail in service, the joint itself will not be compromised in the slightest.

Were the pin to fail, I would go the the step as recommended by Essexmetal ..... to a solid tapered pin: part of the selection rational for this particular roll pin was that it shares the same initial bore size for the correct tapered pin: both that pin and the reamer to enlarge the hole are available to me; however, the Machinest was confident that the roll pin was more than adequate..

BTW, this exercise provided an opportunity for inspection of my urethane injected front OEM control arm bushings: they look and feel perfect after ~4000 miles. When flexed with a prybay, the bushing reacts as solid rubber, with the urethane acting with the same modulus/durometer behavior as the OEM rubber.

Akerlie

Garth,

How has the pin held up ?

Garth S

Very satisfied with the result - the steering response is clearly tighter, being more reactive to input ..... and there has been no increase in vibration, etc. at the steering wheel that I can detect . Mechanically, there has not been any indication of movement of the pins, so I suspect that they will outlive the tie rods.
The car was on an alignment rack run by a pal of mine - he commented on the improved precision when setting the toe vs adjusting the rubber edition of the inner tie rods.

Akerlie

GREAT

I will follow in your footsteps and install pins then
Also planned is the installation of Chris's poly bushings, discovered that the originals where shot when i was trying to do a four wheel alignment last week and wasn't able to adjust the camber due to the worn rubber bushings.
Guess i will feel major improvement

Thanks for the quick answer Garth