Need some first-hand experience: notching the front beam

[Dirk Heinrich]

I would like to know your experience with notching the front beam for a lower adjustment.

Sure, I understand the idea, I just want to learn about a good way of getting the slot a little longer. I cannot imagine a grinder would be a good tool for it. If you have done it without taking the leaves out and disassembling everything, please let me know your experience and any unexpected difficulties you ran into.
Also, how much should I notch it for about 3/4" of a drop? I am thinking 1/4" should be enough maybe?

Thank you!

[Jack Staggs]

I'm thinking 1/4" should be enough for a 2 1/2" drop.

[Dirk Heinrich]

so then, Jack, it seems I am going the right direction. But how ...

everybody, this is not one of those posts where the poster - in this case me - gets tons of pms and emails with hesitant suggestions.


... nothing so far

...

well, except a(n always well appreciated) bit from Jack.



please, anybody ever done it !

[Bruce Baker]

so then, Jack, it seems I am going the right direction. But how ...

everybody, this is not one of those posts where the poster - in this case me - gets tons of pms and emails with hesitant suggestions. ... nothing so far ..well, except a(n always well appreciated) bit from Jack.

please, anybody ever done it !

(I like your comment about "hesitant suggestions" via PM and email....what's the point?)

Dirk, perhaps few have done this work and less have done it without removal of the bars, grease, etc.?

I know I've been spoiled over the years by doing this with clean bare tubes and usually on a rotisserie so the slivers made by a carbide burr that didn't get stuck in the grease didn't fall in my face.

I sorta remember doing this once with the bars in, a long time ago when I wanted more lowering adjustability and didn't feel like taking the time for the total disassembly. Memory fact or fantasy, I have a smooth-ended coarse cylindrical carbide burr that would chew on the edge of the tube's existing slot and not the blocks on the bars inside if I needed to do that now.

How much you think you want to grind, grind a little more, but the tool may be your limiter.

It's been over 10 years since I've done this, but I'll be doing that task in the near future on an interesting project. The best news for me there is that it'll be 'on the bench' with a clean bare set of tubes from a later car being installed in an early car to correct damage and add end bearings, lower arms with sway bar mounts and height adjustability all at one time. The owner wants to be able to lower this non-alphabetized 356 to his own pleasure.

No matter how it's done, extra protection and care of the eyes must be recommended. Assuming you have hair, cover that as well. I'd wear goggles AND a clear face shield, gloves and a tight-collared long-sleeved shirt...I hate those little slivers!

[Dirk Heinrich]

thx Bruce - this helps. I am actually considering to disassemble now. Well, maybe I'll try it first all assembled and see how smooth it'll go.

As to the effect, I estimate that the shift of the axle (spindle) is about 7-fold of however-much you move the adjuster on the beams (based on 55mm diameter beams and 400mm diameter of the theoretical rotation of the spindle around the torsion bars).

A 1mm notch will allow for a 7mm travel of the axle. As the axle does not move vertically, but rotates around the torsion bars (in an ellipse rather than in a circle), a 7mm travel does not mean 7mm drop/lowering. Depending on the previous position of the axle towards the torsion bars, the actual lowering effect per 1mm notch will vary.
The lower you are already, the stronger the effect.

I planning on 5mm cuts. I figure, that should give me plenty of adjustment leverage.

[Jack Staggs]

Dirk, you don't have to disassemble the beam. The limiting factor will be the adjuster screw perch. You will probably need to trim the bump stops down a bit to allow for suspension travel. They can be trimmed in place with a sawzall.

[Guest]

Dirk,
The first thing you need to do remove all the front suspension and the center
torsion bat anchors. To enlarge the openings use a carbide burr bit on a high
speed grinder. 6000+ rpm.

Alan

Dirk Heinrich wrote:

I would like to know your first hand experience about notching the front beam for a lower adjustment.

Sure, I understand the idea, I just want to learn about a good way of getting the slot a little longer. I cannot imagine a grinder would be a good tool for it. If you have done it without taking the leaves out and disassembling everything, please let me know your experience and any unexpected difficulties you ran into.
Also, how much should I notch it for about 3/4' of a drop? I am thinking 1/4" should be enough maybe?

Thank you!

------------------------
Dirk

Post generated using Mail2Forum via email.

[Vic Skirmants]

And keep the slot tight. Remember, the cornering loads in the suspension are resisted by the anchors bearing on the sides of the slots. If the slot is too wide, and the clamps aren't really tight, your trailing arms start to move side-to-side. Interesting handling.
ALSO, Check that your shocks don't bottom out.
AND, make sure the sway bar upper mounts don't rotate into hard contact with the shocks. I know everything looks great and clear when it's all unloaded. Now check it fully loaded and note how close the sway bar mount comes to the shock; so that's what those dents in the shock body are from!

[Dirk Heinrich]

Okay, here is what I did today:

Tried to get a good start early:


Here is how it (the bottom slot) looked before and after the $15 angle grinder worked on it:


I ran across a problem - the upper torsion bar retaining screw didn't clear the steel bracket. I had to notch the bracket as well for clearance and to be able to tighten the lock nut:


Well, I had some lunch and a coffee, but time went by fast. It is about 1/2 lower now:


I think it's no big deal to do it assembled. All you have to do, is watch out that you don't cut in the wrong areas (just the bream), which isn't hard at all, and clean thoroughly. The advantage is that it is easier/faster to check for the result of your work and make adjustments.

I don't think I am happy with the result yet - need to go 1/2 more I think.

Thx again for all the inspirational suggestions!

[Dirk Heinrich]

Now - one day later - I am finished for good and feel, that I should highlight 2 issues not mentioned so far and how they could be solved ... to serve the purpose of a technical forum where people might look up subjects, hoping to find answers to their questions :

- Clearance of locking nuts on torsion bar retaining screw. Since you notch towards the top for lowering, the locking nuts slide under the bracket, and you lose leverage you need to tighten them. I used a grinder to increase the openings in the brackets as you can see in the picture indicated by the scissors. In addition I flattened/cut the 19mm wrench I used to tighten the bottom one.

- Load-difference on the upper and lower torsion bars (this is only an issue if you don't disassemble - if you disassemble you can use the method described in the owners workshop manual). The trick is to have no load on the torsion bars while when you put in the retaining screws (just jack the car up and let the wheels hang down. I then hand-tightened the adjusting screws till they touch the block of the retaining screws. I then got the ramps out and let the car sit on the front tires - full load on the torsion bars. Now you can crawl under the car and loosen the adjusting screws while keeping count of the turns (should match up for both screws). Every turn out will lower the car a little.




Have fun! I was dirty like a pig, yet a happy pig!

[Jack Staggs]

Like I said earlier, "The limiting factor will be the adjusting screw perch". That is the bracket that you had to notch to tighten the lock nut. I guess I wasn't clear enough in my explanation.

[Mark Pribanic]

Dirk,

Can you post a before & after profile shot of your 356?

[Ralph D]

If you're ever concerned about metal shavings getting in there you could use a little trick used when drilling oil pans. You could pack a bunch of grease in there and use a rare earth magnet to pull the shavings out afterward. Works better than you would expect.

Thanks for the pictures. I'm going to press forward with lowering mine.

[Greg Scallon]

I'll second (or third) the thanks to Dirk for posting this. I'll likely tackle this job sometime in the future.

Do you have any other photos you could post Dirk? They always help out. For instance, I'd love to see the die grinder and bit you used to do the grinding.

Thanks again,
-Greg

[Mark Pribanic]

X2, I'm either going to notch it or put lowered spindles in the future.