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  View original topic: Couple of Caster Shim Questions
FL-Frank Tue May 04, 2021 10:59 am

The front suspension of my ‘67 Beetle was totally refurbished 5,000 miles ago including new ball joints, tie rods and ends, steering damper, steering box, anti roll bar, shocks, etc., along with a professional shop alignment. My setup is all stock... parts and ride height. Overall, I’ve been pleased with the way the car steers and turns, however, it still likes to wonder a little at speeds over 65 mph on the highway.

So, after reading several posts on the topic of caster shims, I’ve decided to give them a try to see if they provide more stability at highway speed.

A few questions....using 1 shim per side....

1) will my original lower beam bolts (M12 x 1.5 x 90) work or will I need longer bolts? If longer bolts are required, what length?

2) will I have to reindex the steering box on the beam to achieve proper steering shaft to steering box input shaft alignment? (If yes, what’s the recommended work around for the locate pin on the factory beam?)

3) 36 ft lbs is the torque spec for the beam bolts, correct?

67rustavenger Tue May 04, 2021 11:16 am

I installed caster shims in my 67 a few years ago.

Yes you have to re-index the steering box. But doing so will take the tie rods out of alignment. I didn't re-index mine. The car drives fine. The bummer of not doing that . Is the horn wire will not stay on the lug at the steering coupler. And if you do manage to get the wire to stay in place. THe horn will honk when turning. :oops:

You'll have to grind off the "pin" on the beam, to re-index the box to beam. Then I suppose a small weld bead on the beam is in order to get the box in the proper alignment with the steering shaft.

I used the stock retaining bolts with one set of shims. If you add two shims. You would need longer bolts.

Consult the service manual for the proper torque of the frame head bolts.

FL-Frank Tue May 04, 2021 11:27 am

67rustavenger wrote: I installed caster shims in my 67 a few years ago.

Yes you have to re-index the steering box. But doing so will take the tie rods out of alignment. I didn't re-index mine. The car drives fine. The bummer of not doing that . Is the horn wire will not stay on the lug at the steering coupler. And if you do manage to get the wire to stay in place. THe horn will honk when turning. :oops:

You'll have to grind off the "pin" on the beam, to re-index the box to beam. Then I suppose a small weld bead on the beam is in order to get the box in the proper alignment with the steering shaft.

I used the stock retaining bolts with one set of shims. If you add two shims. You would need longer bolts.

Consult the service manual for the proper torque of the frame head bolts.

Thanks. I plan to install the shims this weekend, and I have an appointment for a 4 wheel alignment booked for Monday morning.

I’d really rather not mess with relocating the original steering box locating pin if I can avoid it...wondering if lengthening the horn wire a tad would help keep it connected to the lug...and also keep the horn from blowing while turning?

67rustavenger Tue May 04, 2021 12:43 pm

FL-Frank wrote: 67rustavenger wrote: I installed caster shims in my 67 a few years ago.

Yes you have to re-index the steering box. But doing so will take the tie rods out of alignment. I didn't re-index mine. The car drives fine. The bummer of not doing that . Is the horn wire will not stay on the lug at the steering coupler. And if you do manage to get the wire to stay in place. THe horn will honk when turning. :oops:

You'll have to grind off the "pin" on the beam, to re-index the box to beam. Then I suppose a small weld bead on the beam is in order to get the box in the proper alignment with the steering shaft.

I used the stock retaining bolts with one set of shims. If you add two shims. You would need longer bolts.

Consult the service manual for the proper torque of the frame head bolts.

Thanks. I plan to install the shims this weekend, and I have an appointment for a 4 wheel alignment booked for Monday morning.

I’d really rather not mess with relocating the original steering box locating pin if I can avoid it...wondering if lengthening the horn wire a tad would help keep it connected to the lug...and also keep the horn from blowing while turning?
All I can say from experience. Is that the steering coupler will not be in direct line with the steering shaft. Meaning the coupler will flex about when tuning the shaft. If you have one of those urethane (not recommended) couplers. It won't last very long.
Do it correctly!

The horn blowing is caused by the steering shaft coming into contact with the column tube when turning.

TDCTDI Tue May 04, 2021 1:02 pm

Remove the steering box clamp, let the steering box find its natural center or move it so that the coupler is as straight as possible, then install the clamp & see how much you need to open up the slots for it to tighten down, remove the clamp & file or grind the least amount necessary for the clamp to tighten down without moving the box.

FL-Frank Tue May 04, 2021 2:05 pm

TDCTDI wrote: Remove the steering box clamp, let the steering box find its natural center or move it so that the coupler is as straight as possible, then install the clamp & see how much you need to open up the slots for it to tighten down, remove the clamp & file or grind the least amount necessary for the clamp to tighten down without moving the box.

Thank you. It’s been a couple of years since I removed and replaced the steering box so please refresh my memory...can I access and perform the procedure you explained regarding the clamp from below, or should I plan to remove the fuel tank for access from above?

TDCTDI Tue May 04, 2021 3:14 pm

You can do it from underneath.

FL-Frank Wed May 05, 2021 11:02 am

So, my plan is to install the caster shims to determine if that causes any obvious misalignment of the steering coupler and/or any horn misbehaviors. . If not, I’ll forego the steering box reindexing procedure in order to avoid modifying the original steering box bracket.

TDCTDI Wed May 05, 2021 11:15 am

It will cause misalignment of the coupler & cause rapid degradation of an older coupler.


It might also twist the steering shaft downwards enough for it to make contact with the column where it exits through the bulkhead.


Extreme cases can cause the collapsible mesh to fracture. (If your car has it)


ALL of which can be avoided by doing it right & making the minute modification to the clamp. :roll:

FL-Frank Wed May 05, 2021 2:30 pm

TDCTDI wrote: It will cause misalignment of the coupler & cause rapid degradation of an older coupler.


It might also twist the steering shaft downwards enough for it to make contact with the column where it exits through the bulkhead.


Extreme cases can cause the collapsible mesh to fracture. (If your car has it)


ALL of which can be avoided by doing it right & making the minute modification to the clamp. :roll:

Good advice, thank you!

I decided to get under the car this afternoon and get started, even though the shims I ordered won’t arrive until Friday.

After lifting and supporting the front of the car at the 4 large chassis to body bolts, I removed both front wheels, then I removed the bottom beam bolts, loosened the top beam bolts, moved the bottom beam tube out and away from the frame head about 1/4” with a prybar, and slid a piece of wooden paint stir stick in on both sides temporarily to simulate the aluminum shims.

Next, I removed the steering box clamp, and let the steering box settle where it wanted to be. I dont’t think it moved much if at all. Then I double checked to make sure the center Mark on the steering box shaft was still indexed correctly with the mark on the box body with the steering wheel in the straight ahead position...which it was. Then, without moving the steering box, I restarted the clamp bolts into the steering box with the clamp in place to see how much I’d have to clearance the notches in the clamp to get a good fit. Surprisingly, with the clamp bolts finger tight, the pins on the beam line up with the unmodified notches in the clamp. And, the steering coupler doesn’t look distorted at all.

I’ll be curious to see what if anything changes at the box/clamp/coupler once I install the shims and tighten the 4 beam bolts to spec.

FL-Frank Thu May 06, 2021 12:55 pm

This afternoon I slipped the shims into place, tightened everything up (including the original beam bolts), eyeballed the steering column/coupler/input shaft to make sure everything was aligned, checked again to make sure the steering is centered, popped the wheels back on, and took it for a quick test drive.

My initial impression is that the steering feels a little heavier than before at 5 mph...which I believe is to be expected. The car tracks straight, and seems a little more stable than it was before at 65 mph. The steering wheel turns smoothly with no binding or interference, and no shenanigans from the horn.

I’m eager to get the 4 wheel alignment done Monday morning to make sure everything is dialed in.

67rustavenger Thu May 06, 2021 5:41 pm

Nice, you'll like the stability when driving in windy conditions.

No more twitchy "shenanigans" when passing trucks and cars that have a heavy wash of air dumping on the front of your little beetle.

wimkever Fri May 07, 2021 3:12 am

FL-Frank wrote: The car tracks straight, and seems a little more stable than it was before at 65 mph.
I wonder why the VW engineers never implemented this improvement.
It's not an expensive upgrade, so that makes it even more odd.
Questions, questions.

FL-Frank Fri May 07, 2021 3:39 am

wimkever wrote: FL-Frank wrote: The car tracks straight, and seems a little more stable than it was before at 65 mph.
I wonder why the VW engineers never implemented this improvement.
It's not an expensive upgrade, so that makes it even more odd.
Questions, questions.

Possibly their primary objective was to keep the steering as light and effortless as possible?

MrGoodtunes Sat May 08, 2021 3:41 pm

wimkever wrote: ... I wonder why the VW engineers never implemented this improvement ...

Actually, I believe they did! Once read (a post here on Samba by an oldtimer who used to work at a Beetle dealership) that caster shims were used on some bugs new enough to still be on warntee whenever a customer complain'd of wandering steering.

Max Welton Sat May 08, 2021 6:20 pm

67rustavenger wrote: The horn blowing is caused by the steering shaft coming into contact with the column tube when turning.
... or the bottom of the gas tank. This happens if the tank is mounted without the padding between the tank and the car body causing the tank to sit low.

Also, check the front tire pressure.

Max

FL-Frank Wed May 12, 2021 5:30 am

I had a 4 wheel alignment done earlier this week, and have driven the car approximately 200 miles since.

$10 in parts and about 30 minutes installation time (plus the alignment cost).

Adding the caster shims is a noticeable improvement. The steering feels a little firmer than before, and the car now feels more sure footed and tracks perfectly straight.

I only wish I would have added the caster shims years ago!

67rustavenger Wed May 12, 2021 5:48 am

=D>
Good to read this.



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