custom made trailing arm

[uninformed]

well If I can get the nod to do my TA/Body rigger mount, Im going to have to make new longer arms. Once again im offering up an idea for some technical cretique.

I am thinking of getting some OEM arms (already have them) and using the axle end. Using 45x25 CHB (carbon hollow bar) as the main body for the arms, I would bore the end so it suits the 27mm OD of the OEM arm, for what ever length was possible and required. Slip the new CHB over it and weld where appropriate. For the pin bush at chassis I was thinking of doing something like the track rod/drag link ends. That is to have a threaded end go inside the CHB so it can be adjusted. Once set it is clamp bolted so it cant move. The pin outside will be exactly the same as LR (20mm dia 20x2.5 thread), then a short body with 2 flats machined on it for adjustment, then the section that goes inside the CHB say 27x2 thread with 75mm of length.

I will try and attach the CHB specs and see pics for my quick drawings and photo of clamp bolt end.

http://www.aulro.com/afvb/attachments/modified-zone/51712d1349053885-custom-made-trailing-arm-trailing-arm-004-rs.jpg

http://www.aulro.com/afvb/attachments/modified-zone/51713d1349053910-custom-made-trailing-arm-trailing-arm-006-rs.jpg

[wagoo]

Serg, I don't know how much difference it would make, but later LandRover steering rods, even though they occasionally (all too often on coil sprung Rovers) strike offroad obstacles, were obviously only designed to withstand tensile or compressive loads, so full length and exposed threads as used on LandRover steering rods from series 3 onwards were deemed acceptible.
Because trailing arms are more likely to make contact with Terra Firma, exposed threads may be deemed a weak point. Earlier series 1 and 2 steering rods and TRE's didn't have full length threads. A plain unthreaded section near the balljoint of the TRE spiggoted into the plain counter bore on the end of the steering rod tube, so shear forces were focused there instead of the root of a relatively sharp thread. I would design the threaded connection of the trailing arm similar to the early TRE method.
Bill.

BTW. I want to compliment you on your artistry with the cardboard chassis components.

[uninformed]

Thanks Bill :)

I figured the cardboard mock ups would be alot easier to discuss than my poor ability to verablize/type my ideas. It will also give me something to take to the sheet cutter/folders and see what way to approach it.

I havent seen a SI or SII in person, but I think I can get what you are saying. The smooth shank section, would this be the same dia as max dia of thread? or a touch larger?

Looking at some real would measurements, the ID of the CHB is 25mm, the OD is 45mm. The LR TA pin is 20mm. The min I can internal thread the CHB is 27mm fine (27x2.0, tap drill size 25mm) or 1 1/8 UNF, tap drill 26.50mm

Not sure if a fine or coarse thread would be better in this application?

How long do you think the spigot be? Remembering that the longer in it is, the further the internal thread has to be.....the deeper the thread the more ridgid the boring bar, the more ridgid the boring bar, the larger it has to be....maybe determining the ID??? (btw this is just a guess as im no machinest)

With this design, do I still clamp the new TA at the spigot, same set up as the track rod pic I added?

[wagoo]

Probably best go with Johns recommendation as to length of plain shank, providing he agrees that having one is worthwhile, but I would guess it should be a little longer than the width of the clamp. I'm imagining around 30mm. I think you would have no choice but to use a pinch clamp as your photo shows, because a jamn nut, which incidently keeps working loose on my FC 101 trackrod, would require a full length thread.
From memory the diameter of the shank was only a few thou up on the major diameter of the thread on the earlier TREs.
Bill.

[uninformed]

Rick may chime in here Bill, I seem to remember him telling me of a paper he read regarding F1 cars and going with a similar principle for rod ends...I think the bung with lock nut was deemed not to be as good.

yes was thinking 30mm plane shank, 25mm clamp (made from 25mm flat bar)

from your experience, how deep could one resonably internally thread in a 25mm bore before the boring bar starts to move??

[rick130]

Yep, a pinch clamp is preferable to a jam nut for fatigue life as it doesn't concentrate so much load at the root of just one thread.

Tony Southwall did that on the XJR9 TWR Jags at Le Mans just so they didn't crack any tie rods, as in motor racing we always used jam nuts on rod ends.
He did the numbers and it was pretty conclusive that a pinch clamp was a much better way of locking the TRE's and track rods, etc to survive the bashing over kerbs and wheels of a 24hr race.

I'm guessing they must have had the odd failure.

Good point re the plain section Bill, I didn't think of that.

[wagoo]

from your experience, how deep could one resonably internally thread in a 25mm bore before the boring bar starts to move??

Looking back, I can't believe how long it's been since I did any lathe work, and even then I used to just muddle through as I never had any formal training.
I'd imagine with a 25mm bore, you could have a fairly rigid boring bar a little under 25mm diameter.Just enough clearance to clear the swarfe away. The cutting tip could be of the adjustable cross sliding type.
Bill.

[modman]

Serg, I'm away in SA atm but would you believe I have those very pieces machined up allready!!
Made from 4140, the threaded sections and bush rings axle end
The arms I'm making are to suit 40x10 mm wall 20mnv6 (sp?)
I'm home in ten days if you can wait
I intended to use a ht nut tigged with ss wire at the pin end, then a lock nut to alter the length up against the TA
I'd run this design past an engineer and have the weld proc. documented, he seemed happy enough to pass in VIC.
Dc

[uninformed]

Hi Modman (Dave I think :confused:)

sounds good, im not going to be rushing. No new TA's unless I can do the new mounts.

Are you using the nut welded to the hollow bar instead of threading inside?

[uninformed]

20mnv6 is pretty much the same standard as the CHB im looking at.

[modman]

Threading hollow bar and using lock nut against to lock/set length
Planning on making cranked arm as well
Are you angling your TA Mount for neutral bush bind at standard vehicle height?
I understand pinch clamps work better but we are not bound by lightweight vs. engineering.
IE we can over engineer in the material weight/size
Dc

[uninformed]

Yes my plan is to fold the mount past 90 degrees so the vertical face is perpendicular to the TA. I'm going to keep my straight. I'm sure yours will be fine. My thoughts are to go into it with the best designs I can to keep the engineer/DOT happy. Plus it allows me to fine tune if i change spring height.

[uninformed]

what are the rules for determining wall thickness at the pinch clamp section?

[uninformed]

anyone???

[modman]

Maybe just leave it full thinness and locknut it
Be a bit easier and plenty strong
The locknut theory is factory used locating the TA , a ball joint, even the
RA's
Dc

[Bush65]

what are the rules for determining wall thickness at the pinch clamp section?
No rules for this that I'm aware of.

Apart from physical preventers such as lockwire, cotter pins and such, what prevents nuts and bolts from loosening is friction.

Generally the friction is achieved by pre-tensioning the bolt/nut, forcing one side of the male thread aginst the mating side of the female thread.

Lock nuts are a poor method for developing this friction, and only provide a benefit if the clamped components cannot provide enough resistance against pre-tensioning. In that case the inner and outer locknuts can provide more resistance so the pre-tension can be developed within the pair of nuts. Many people don't understand locknuts and a lot of missinformation is perpetrated about them.

The pinch clamp develops friction independent of the pre-tension. If the wall thickness under the clamp is too great, little or no clamping force will be available to create friction. It won't matter if the wall is thin as this part should not transmit much axial load as it will be re-distributed to the stiffer part.

[uninformed]

thanks John.

lets say I go along the design of what Bill described. Having a smooth shank a touch bigger OD than the major dia of the thread. The thread being furthest/deepest inside the hollow bar and the shank being in the thinner, clamped section of the hollow bar. The idea of the thread is to fine tune length of TA for pinion and truing axle in relation to chassis and front axle.

So the clamp is to stop the pin rotating and there fore changing the length of TA. The TA is still mounted to chassis as per LR OEM style bush, pin and nut.

Will the clamp used on the hollow bar at smooth shank portion of the TA pin, do the job and stop any length movement and/or rotation of said pin?

At this stage Im thinking the smooth shank should be about 35mm long and the thread 35mm long (27mm metric fine) the smooth shank will be mostly in the reduced dia section of hollow bar, with pinch clamp. The threaded section in the increasing dia/tapered section of the hollow bar.

any takers?

[rick130]

Or just weld the entire thing and use washers/shims to fine tune the pinion angle/length ?

Is it possible to get the welds x-rayed or someone to certify the welds for you ?

[uninformed]

I have no idea on the xray or testing, and no idea of $$$. The reason Im looking at adjustability is to minimise welding (none at pin end) and to be able to adjust no matter of spring height.

still open to suggestions though.

[rick130]

I remember why you are doing it this way, the same reasons why I'm sleeving and bonding the sleeve on mine.

[Bush65]

Or just weld the entire thing and use washers/shims to fine tune the pinion angle/length ?

Is it possible to get the welds x-rayed or someone to certify the welds for you ?
X-ray will be out of the question (not possible) for welds on a trailing arm. Because of the hollow arm, there is no way to get the x-ray plate on the other side (inside hollow bar) of weld.

Ultrasonic would be the best method of NDT (non destructive testing), then mag partical. Failing those use dye penetrant.

[rick130]

X-ray will be out of the question (not possible) for welds on a trailing arm. Because of the hollow arm, there is no way to get the x-ray plate on the other side (inside hollow bar) of weld.

Ultrasonic would be the best method of NDT (non destructive testing), then mag partical. Failing those use dye penetrant.

Thanks John, hadn't thought of that.

The only things I've had x-rayed/scanned in the last few years are my shoulders and multiple horse legs/joints :D

We didn't bother with the head, that'd be a waste of time.....

[modman]

I planned on having my TA dye tested then destructive tested against oem item
Engineer was happy with just a welding process
Mine don't have welding at the chassis end
I have pieces made up threaded both ends (4140)
One end copies oem specs through the TA bush
The other end threads into 40 mm hollow bar
That's a mofo to cut that thread:mad:
Dc

[uninformed]

Dave, what dia did you bore and thread the Hollow bar to? Did you do the thread on the lathe (cut) or use a tap?

[steveG]

A lot of aircraft control rod and actuator end fittings are locked by tab washers that engage a small lengthwise keyway in the thread of the end fitting, and also have a protrusion on the face of the washer that engages into a notch in the end of the rod/tube itself. Held in place by a lock nut, but the locking is done by the tabs not the friction of the thread.
Nuts are generally lockwired to the tab to prevent the nut from coming undone.

All have published specs eg NAS513 and the nuts and washers should be easily available through parts suppliers.

Examples here: Locking Devices, Keys & Keyways by New Hampshire Ball Bearing (http://www.nhbb.com/reference/rod-ends-bearings/locking-devices-keyways.aspx)

Steve

[uninformed]

Thanks steve,

maybe getting a bit over complicated for my needs.....I may be already :angel:

[modman]

The tap and paperwork are out of reach
Tapped using lathe about 16 mm I think
Could do by hand but I have electricians chicken arms
All parts are in a mates workshop
I have to pick them up next week so ill have to learn how to do photos
40mm x 10 mm hollow bar is overkill but I specced it to handle cranking
Dc

[uninformed]

Ive been looking through my Sutton industrial catalogue, most normal taps are only good for 1-1.5xdia for depth of tapping.

Dave, are you using RR pin end?

[modman]

Deefer pin end or the larger courser one
The tap has been 'extended to tap/bore deeper
This part is not my specialty
I can bumble my way around a lathe but I leave screw cutting and
Large tapping to the experts that owe me favors



Or pay to have it done
Dc

[Bush65]

Ive been looking through my Sutton industrial catalogue, most normal taps are only good for 1-1.5xdia for depth of tapping.

Dave, are you using RR pin end?
For a lot of taps, the shank is smaller than the root diameter of the thread, so the thread depth is limited by the length including the shank, not simply the length of the cutting thread.

[uninformed]

Looking at the different types of Taps, I thought it may have more been the design that limited it. Im guessing that Sutton are saying that you can reliably tap "x" depth with "x" tap...any more and its a crap shoot.

Can anyone recall the failing of the smaller Range Rover pin end? Im thinking that the bush may have more rubber and therefore a little more flex/complience...

[modman]

Serg,
my specs are.....
M20 x2.5 thread pin end ( deefer/county I think??)
M22 x 2.5 thread adjustable end of pin
M22 course threads nicely into 40 x 10 hollow bar (~20mm ID)
Dc
Can someone confirm pin sizes please??

[rick130]

[snip]

Can anyone recall the failing of the smaller Range Rover pin end? Im thinking that the bush may have more rubber and therefore a little more flex/complience...

Use a Super Pro bush and it's a non issue.

[roverrescue]

uninformed,
Track down mick moyle engineering in summer hill
Mostly 2nd hand gear but some new
Place is a complete and utter lolly shop, was there on friday whilst in sydney for my mums birthday.flew down with hand luggage, taking 21kg bag back

Anyway, ramble ramble. I saw some M20 and 22 taps as well as plenty of large imperial Unf and nc long reach machine and hand taps. Range from 10 to 25 or so bucks.
For a job that needs two threads this is where i would start.

Steve

[uninformed]

Thanks I will look for them

[uninformed]

Yep, Modman, the trailing arms I got off a D1, same as Def AFAIK are M20x2.5 pin. When you said you were using 40x10, I figured that was 40 OD x 10 ID, as some hollow bar is classified....along with the 16mm tap statement had me confused...I didnt think you would have a smaller dia in the hollow bar than the pin end....so your hollow bar is 40x20 ;)

[modman]

20nmv6 seemed like good hollow bar
I'm no metallurgist by far
It was recommended by hsv Rangie many moons ago
It's not expensive or hard to obtain and easy to weld:)
I'm flat out but hopefully find time to post pics this week
Dc