Front axle preparation

[brian]

Greg is dead on regarding the sway bar and his procedure is the same as mine. Your bushing are offset and the carriers need to be refaced. Since the pins no longer go through the carrier straight (90 degrees) the faces that the shims ride on should be refaced. LRE has a machining fixture for this and I use a die grinder on mine to make the faces flush. The lips caused by the width differences in the bushing and carriers will cause the front end to tie up.

[jstoezel]

Thanks for the replies.

Looks like I could salvage this sway bar, thanks for the details.

What I get from Dietmar is that the bushings are already modified, and unless they have too much play, I should be able to reuse them.
I was going to send the spindle assemblies to Vallis in Toronto. Do you know if he has the machining fixture to modifier the carriers?

I guess I could call him tomorrow to ask too...

[brian]

I use a small disc grinder on a dremel tool to reface and remove the lips on the mating surfaces. I also relieve the id of the carrier to avoid the shims from rubbing on the outside. Put a link pin in the carrier and slide the shims on, they should completely clear the carrier.

[jstoezel]

Hi Brian:

Thanks for the detailed answer. English is not my first language and I would like to clarify a few things. What I understand is that the lips have to be cut flush on the carriers. After you do this the carriers should not be countersunk anymore. If this is what needs to be done I think I could handle it myself.

Now about this:

I also relieve the id of the carrier to avoid the shims from rubbing on the outside. Put a link pin in the carrier and slide the shims on, they should completely clear the carrier.

Are you referring to what I circled in this picture?

[ external image ]


If anybody has a picture of what the finished product should look like that would be appreciated!

JS

[problemchild]

Brian is referring to grinding/machining the shim surfaces so they are perpendicular to the now offset hole. VMS does not have a fixture to do that BTW.

[jstoezel]

Alright, thanks for clarifying this. I guess it would be a neater result if I had a fixture to do this. I've prepared the assemblies for shipping, this morning I'll contact one of the shops in the US to let them know I'm sending this.

Thanks for everybody's input.

JS

Brian is referring to grinding/machining the shim surfaces so they are perpendicular to the now offset hole. VMS does not have a fixture to do that BTW.

[brian]

After removing material from the mating surfaces, you may have to use more than the specified number of shims but that should not matter as long as you can still insert the pinch bolt. You can grind the groove on the pin a bit further as well. If you place a link pin through the offset bushing in the carrier, you'll notice that the shims will be very close to one side of the carrier and sometimes they will make contact before sliding all the way on the link pin. This area of interference on the carrier will have to be relieved with a die grinder. Sometimes the upper turkey leg will have to be ground a bit to fit all the way on as well.

I prefer to fit the carrier on the legs without the spring involved. This makes it a lot easier to assure full movement and contact.

[Veefan]

Not sure I'd call this an instructional video... I'd call it interesting...

Replace King & Link pins

http://www.youtube.com/watch?v=WtBltm9Z ... re=related

http://www.youtube.com/watch?v=MYpLTLju ... re=related

[jstoezel]

I thought I would provide an update on this.

I sent away the spindle assemblies to get serviced by Dietmar from Quixote Racing. They came back today and everything looks and feel great!

Dietmar was very helpful and knowledgeable, he worked fast and I got the parts back very quickly (the parts spent more time in transit than at his shop). I recommend his services to anybody-I will be ordering a set of spare spindles from him in the next few months, and will have him check my spindles periodically.



Jean

[jstoezel]

Hi,

I cleaned the H beam as it was full of thick grease inside, which was very heavy. The beam is lighter now without the excess grease in it.
The towers seem half full of something though, either pieces of rust or sand. I got the beam sand blasted and I'm wondering if somehow sand may have gotten inside the towers (through the vertical seams or the partially welded connection between the towers and the tubes).

Any idea how much a new H beam weight? Would help to know if there's any significant amount of anything in the towers.

Jean

[jstoezel]

At what torque should the front axle be bolted to the frame? Like most I guess I have 3/4" grade 8 nuts and bolts, but I'm thinking the beam may collapse first if the fasteners are torqued at the proper values.

Same question with the bolts that fasten the brake plates to the spindles.

[Dietmar]

Jean:

I have always used 43 # on the backing plates ( same as the rear) but when I looked it up, it says 36# for the front. So I would guess between 36 and 43 should work fine.

On the beam, yes, depending on what you are using to clamp on the beam and where would matter. On the D-13 with the "U" bolts, overtightening could actually compress the beam and not allow the torsion arms to turn. So, I would say, "TIGHT" but don't make it bleed!
If you are using the STOCK mounting holes, VW used 36# for their torque (beam to frame)
Hope this helps

Dietmar

[jstoezel]

Hi Dietmar:

Thank you for the reply. Did you get the values from the service manual? I use the stock beam mounts (no clamps). Hum indeed 36lbs is very "light" considering a grade 8 3/4" bolt (1/2" diameter) can be torqued at around 100lbs... The beam would probably get damaged at that torque. Makes you wonder of the use of grade 8 bolts to attach the beam... Unless I guess the load would be spread over a wider area. On my Lynx the beam is mounted on 2x2 posts.

Jean

Jean:

I have always used 43 # on the backing plates ( same as the rear) but when I looked it up, it says 36# for the front. So I would guess between 36 and 43 should work fine.

On the beam, yes, depending on what you are using to clamp on the beam and where would matter. On the D-13 with the "U" bolts, overtightening could actually compress the beam and not allow the torsion arms to turn. So, I would say, "TIGHT" but don't make it bleed!
If you are using the STOCK mounting holes, VW used 36# for their torque (beam to frame)
Hope this helps

Dietmar

[Dietmar]

Jean:

The stock bolts are 12mm so that is close enough to 1/2 "

And yes, that number came from the VW manual. Thought that was a bit low also. So, since it is NOT a clamp arrangement, tighten to your heart's content- just don't compress the part on the frame that it is bolted to!

Dietmar
http://www.quixoteracing.com

[jstoezel]

Alright thanks Dietmar...

...And it is awesome you took the time to explain in details how to set the sway bar/carrier shims over the phone, much appreciated! Thanks!

Jean

Jean:

The stock bolts are 12mm so that is close enough to 1/2 "

And yes, that number came from the VW manual. Thought that was a bit low also. So, since it is NOT a clamp arrangement, tighten to your heart's content- just don't compress the part on the frame that it is bolted to!

Dietmar
http://www.quixoteracing.com

[cendiv37]

Jean,

My crib sheet for torques lists my "recommended" torque for the 1/2-20 bolts that retain the beam is 40+ ft-lb. (The Mysterian design is the same as the Lynx.) I seldom actually torque them anymore (that I can remember), but I'd estimate I'm torquing then to 40 - 50 ft. lb. I've never had them or the beam come loose. I use "Nylock" nuts and heavy washers to spread the load. I'd assume that there are reinforcing "spuds" inside the 2x2 frame segments. If so the weak points will be the brackets on the beam and the contact points between the frame and beam tubes.

[jstoezel]

Hi Bruce,

Thank you for the reply.

Following Dietmar's reply I ended up torquing at 40lbs. I realized last year I tend to over tighten fasteners, and I find that using a torque wrench has been giving me references of how tight specific fastener sizes need to be.
You are right, the 2x2 posts have reinforcing tubing inside, somehow the whole structure has collapsed a bit though.

I've been referring to this sheet: http://www.imperialinc.com/pdf/A_Fasten ... Charts.pdf, page 2 for grade 8 stuff. Are the values in your sheet in the same order of magnitude (for equivalent grades)?

The beam fasteners that came with the car were mostly grade 8. So I've been using grade 8 fasteners. Now I come to realize that grade 5 bolts could be used, based on the recommended torquing value for the beam, and possibly other VW parts.

The fasteners used to attach the beam are 3/4" (cap screw) so that makes them a 1/2" diameter, coarse thread (13 thread per inch). From the sheet it looks like they need to be torqued at 110lbs (dry) or 80lbs (lubricated).

I use nylock nuts too, I wonder if that changes the way you need to torque, since it offers some resistance when you tighten.


Jean

Jean,

My crib sheet for torques lists my "recommended" torque for the 1/2-20 bolts that retain the beam is 40+ ft-lb. (The Mysterian design is the same as the Lynx.) I seldom actually torque them anymore (that I can remember), but I'd estimate I'm torquing then to 40 - 50 ft. lb. I've never had them or the beam come loose. I use "Nylock" nuts and heavy washers to spread the load. I'd assume that there are reinforcing "spuds" inside the 2x2 frame segments. If so the weak points will be the brackets on the beam and the contact points between the frame and beam tubes.

[cendiv37]

Jean,

I assemble these and most chassis fasteners dry, especially when using Nylocks. You don't want to lube the interface between the nylon and the bolt. As your chart shows, dry assembly means that you need to go to a higher torque to put the same tension on the bolt (more torque used on overcoming the friction in the threads and sliding nut faces, etc.

I tend to prefer fine thread fasteners since as the chart shows, they a bit stronger. In this case, since we are not going anywhere near the maximum tensile strength of the bolt, it probably doesn't matter. The difference in strength is due to the difference in what the chart calls the "Nominal Diameter". What they must mean by this is the "pitch" or "nominal" diameter of the thread, not the fastener itself. That threw me for a minute because the fastener is usually referred to by it's "nominal diameter", which in this case is 1/2". So there is no difference between the nominal diameter of a 1/2-20 bolt and a 1/2-13 bolt.

Overall, I'd go with something between 40 and 50 ft-lb. Just don't crush anything... As the Nylocks "wear in", if reused, they will get a bit easier to turn so theoretically you could use a bit less torque on used ones. I wouldn't worry too much about that, but if you really wanted to, you could probably try to measure the difference between old and new with a small torque wrench

[jstoezel]

Hi:

I've seen pictures of a front beam with 2 ride height adjusters mounted in series, about 6-8" apart, on the same tube (not top and bottom). I guess this is to increase the spring rate of the front axle... Or does it serve another purpose?

Jean

[jpetillo]

Hi:
I've seen pictures of a front beam with 2 ride height adjusters mounted in series, about 6-8" apart, on the same tube (not top and bottom). I guess this is to increase the spring rate of the front axle... Or does it serve another purpose?
Jean

Jean, I did that on my car because there would have been interference with getting at the adjuster by the steering box if I had put the single adjuster in the middle. However, it does increase the spring rate. On my car I think it was by about 20%. John

[jstoezel]

Hi John:

How do you find the increase in spring rate?

Jean

Hi:
I've seen pictures of a front beam with 2 ride height adjusters mounted in series, about 6-8" apart, on the same tube (not top and bottom). I guess this is to increase the spring rate of the front axle... Or does it serve another purpose?
Jean

Jean, I did that on my car because there would have been interference with getting at the adjuster by the steering box if I had put the single adjuster in the middle. However, it does increase the spring rate. On my car I think it was by about 20%. John

[jpetillo]

Hi John:
How do you find the increase in spring rate?
Jean

Jean, the spring rate for a torsion bar is proportional to (1/Length). With the assumption that the spring pack's stack of bars acts like a torsion spring, if you decrease the length by 20%, the spring rate goes up by 20%.

The spring pack is a bit over 18" from the center to the pin down point at each end. If you space the two adjusters 8" apart, you decrease the length of each half by 4". That's a 22% decrease in the length, so that's your increase in spring rate. John

[jstoezel]

Hi John:

I meant: "how do you like the increase in spring rate, at the track".

I enjoyed the explanation though.

Jean

Hi John:
How do you find the increase in spring rate?
Jean

Jean, the spring rate for a torsion bar is proportional to (1/Length). With the assumption that the spring pack's stack of bars acts like a torsion spring, if you decrease the length by 20%, the spring rate goes up by 20%.

The spring pack is a bit over 18" from the center to the pin down point at each end. If you space the two adjusters 8" apart, you decrease the length of each half by 4". That's a 22% decrease in the length, so that's your increase in spring rate. John

[hardingfv32-1]

Basically you can not "adjust" the front spring rate at the track. You can get a small, non linear change with shock gas pressures.

Brian

[Rickydel]

I'm pretty sure, that all Jean was asking is how the increased spring rate affected the car's handling.