Question about torsion bars

[L1A1]

Are the torsion bars in an M548 (or M113 for that matter) identical (interchangable) from first to last? Or does each have a specific position that it has to go (back) into?

Matt

 

[jdmcm]

Hi Matt

The M113 torsion bars are interchangeable so I would assume the M548's are as well

John

 

[dgrev]

I deleted a line here, I was too harsh about John's comment, so have removed my response, sorry John.

M113 bars are "handed" ie, there are left and right ones. Then they changed by model due to suspension upgrades.

Putting a right bar on say the left side twists it the wrong way, which is a quick way to a breakage.

The bars are scribed with an arrow on the end of the bar indicating the direction they must be compressed.

An M113A2 and an M548A1 are roughly equivalent time wise, below are the respective parts numbers, as
you can see, not interchangeable.

M113A2
Left bar part number 10890849-2
Right bar part number 10890849-1

M548A1
Left bar part number 12268937-2
Right bar part number 12268937-1

Regards
Doug

 

[jdmcm]

Sorry Doug, was not even thinking right to left swapping, yes absolutely correct on that count! But as for where they go in order on each side, they can go anywhere agreed?

John

 

[jdmcm]

And I did not say that M113 torsion bars are interchangeable WITH M548 bars...just that M113 bars do not have to return to a specific position on the M113, save for right and left as you have pointed out, on ours they went back in in no specific order on each side and they have worked fine ever since...

 

[dgrev]

John

Yes, correct.

There is an argument that the more highly loaded bars should go back in the same location
(the ones at the front especially) as they have "bedded in" to that location,
but then there is the counter argument that those should be swapped to the rear to give them a holiday so to speak.

Realistically, I am with you, as long as they are put back on the same side, I expect all should be fine.

The WW2 Germans were highly protective of torsion bars and were VERY concerned about any
scratches or rust pits. Although I have not see any direction markings on their bars, it was
understood that you put them back on the same side.

I don't know about the US, but all the ones I have seen here in Oz have been wrapped with
insulation tape presumably for rust and scrape protection. An Oz M113 crew man told me that
as crew, the one thing they were really careful about was parking the vehicle such that any one
wheel station was not loaded more than the others (eg, on a mound or on a rock or tree branch).
He said that nothing compares to a torsion bar failing around 6am (coldest part of the night) when you are sleeping alongside
the vehicle, he said it sounds like someone fired a shotgun next to your ear.......

The hazard is in buying used bars, you just don't know what they have been up to. eg, knife edge demos - a sure way to abbreviate the life of torsion bars.

In civilian usage, unless the owner is out to destroy his equipment, the average vehicle will see far less use/weight/abuse eg, no slamming into creek
beds, overloaded with kit, rations, ammo and a squad, no high speed jumps etc.

Having said that, I see in another post that one of the US museums has broken 2 torsion bars on an FV-432, I am hoping they reply to my question as to
how they did that.

Regards
Doug

Sorry Doug, was not even thinking right to left swapping, yes absolutely correct on that count! But as for where they go in order on each side, they can go anywhere agreed?

John

 

[jdmcm]

Hi Doug

In our 113 the torsion bars were also wrapped, I assume to prevent damage like you have said. I believe, and I could definitely be wrong, that torsion bars in some German WW2 AFV like the panther were all the same as the suspension arms on the left hand side faced one way and the ones on the right faced the other...I know there is a company on Milweb that advertises newly manufactured torsion bars, I believe it is Goldcrest Technologies in the UK. I believe they have manufactured new Torsion bars for Kevin Wheatcrofts Panther collection. They would most likely be able to manufacture new bars for the 432 if none were available. And as for the US museum breaking two torsion bars, sounds like very aggressive driving could be a factor. I know with our vehicles we like to enjoy them but with a mind to longevity.

John

 

[dgrev]

John

Thank you for pointing out something that had totally escaped me and that I should have known.

Yes, to the best of my knowledge, the German vehicles did have the drop arms facing forwards on one side and rearwards on the other.
I have never understood why, but I now realise it may have been for exactly the reason you stated in your original post - to give
them interchangeability and thus to obviate the need for direction markings.
Some vehicles, such as the Kettenkrad also had them stacked ie. one above the other rather than staggered as is normally the case.

Thus, it would appear that the bars have to be pre-stressed or something at time of manufacture - just a guess - for the
direction of torsion?

Last I heard torsion bars for FV-432 were still available, as to the price?
FV-432 have gone a bit weird. Despite the fact that most
Poms hate them (for some reason) so they sell relatively cheap, they are now getting rather hard to obtain.
Lots were scrapped due to no demand and quite a few were cut up by re-eneactors to make fake German tanks.

Which museum are you with?

Regards
Doug

John

Yes, correct.

There is an argument that the more highly loaded bars should go back in the same location
(the ones at the front especially) as they have "bedded in" to that location,
but then there is the counter argument that those should be swapped to the rear to give them a holiday so to speak.

Realistically, I am with you, as long as they are put back on the same side, I expect all should be fine.

The WW2 Germans were highly protective of torsion bars and were VERY concerned about any
scratches or rust pits. Although I have not see any direction markings on their bars, it was
understood that you put them back on the same side.

I don't know about the US, but all the ones I have seen here in Oz have been wrapped with
insulation tape presumably for rust and scrape protection. An Oz M113 crew man told me that
as crew, the one thing they were really careful about was parking the vehicle such that any one
wheel station was not loaded more than the others (eg, on a mound or on a rock or tree branch).
He said that nothing compares to a torsion bar failing around 6am (coldest part of the night) when you are sleeping alongside
the vehicle, he said it sounds like someone fired a shotgun next to your ear.......

The hazard is in buying used bars, you just don't know what they have been up to. eg, knife edge demos - a sure way to abbreviate the life of torsion bars.

In civilian usage, unless the owner is out to destroy his equipment, the average vehicle will see far less use/weight/abuse eg, no slamming into creek
beds, overloaded with kit, rations, ammo and a squad, no high speed jumps etc.

Having said that, I see in another post that one of the US museums has broken 2 torsion bars on an FV-432, I am hoping they reply to my question as to
how they did that.

Regards
Doug

 

[jdmcm]

Not with a Museum Doug, just a private collection here in Canada. We do some restorations, build a bit for film projects and spend the rest of the time hunting for parts and vehicles. But with the slide of the Canadian dollar, will probably be keeping acquisitions to a minimum for the next couple of years...but a great time to sell parts and pieces to our neighbors to the south

John

 

[dgrev]

John

Yeah, know what you mean, our $ is down too. Add to that the rip off prices USPost is charging for parcels and it is almost unaffordable to buy any MV parts out of the USA.
They have "Standard rate boxes" which have been very cleverly designed such that almost nothing fits in them. They are exorbitant for what does fit in them.
So if you have something that has a dimension that won't fit and you have to use a non-USPost box, the prices are horrific.
The days of Seamail are gone, it is all Airmail now.
They pretty well killed the overseas 2nd hand book market instantly.

Bit surprised you have stuff to sell to the south, I would have thought you would mostly have to buy from them.

Regards
Doug

Not with a Museum Doug, just a private collection here in Canada. We do some restorations, build a bit for film projects and spend the rest of the time hunting for parts and vehicles. But with the slide of the Canadian dollar, will probably be keeping acquisitions to a minimum for the next couple of years...but a great time to sell parts and pieces to our neighbors to the south

John

 

[L1A1]

Thanks for the replies and information. Thought it was kind of odd that the torsion bars in my M548 were not wrapped with anything where as the ones in my old M59APC were. Looked like electrical tape to me at the time.

Matt

 

[dgrev]

Matt

When the British re-started the Panther and JagdPanther production line, they hired ex-factory workers to do it. As you would imagine, these people would have been desperate for work, given the conditions in Germany
at that time. I have read an account by the Major (IIRC) who was in charge of how one day he walked along the inside of one of the vehicles stepping on the bars as he did so.
He received a right telling off by one of the German workers that left quite an impression. That was how ingrained it was regarding the care of torsion bars - that someone who
you would think would be doing their utmost to stay out of trouble and keep their job, was prepared to risk the sack by confronting the occupying power!

Regards
Doug

Thanks for the replies and information. Thought it was kind of odd that the torsion bars in my M548 were not wrapped with anything where as the ones in my old M59APC were. Looked like electrical tape to me at the time.

Matt

 

[L1A1]

Doug
I was thinking of that exact same story while reading through the posts on this thread . Need to due more research and find out if the bars in the M548 were wrapped with something or left bare as they are in mine now.

Regards, Matt

 

[dgrev]

That I don't know, but given that the M548 is more open than an M113, I would be surprised if they weren't wrapped.

Regards
Doug

 

[Foxtrot Oscar]

John

Yes, correct.

There is an argument that the more highly loaded bars should go back in the same location
(the ones at the front especially) as they have "bedded in" to that location,
but then there is the counter argument that those should be swapped to the rear to give them a holiday so to speak.

Realistically, I am with you, as long as they are put back on the same side, I expect all should be fine.

The WW2 Germans were highly protective of torsion bars and were VERY concerned about any
scratches or rust pits. Although I have not see any direction markings on their bars, it was
understood that you put them back on the same side.

I don't know about the US, but all the ones I have seen here in Oz have been wrapped with
insulation tape presumably for rust and scrape protection. An Oz M113 crew man told me that
as crew, the one thing they were really careful about was parking the vehicle such that any one
wheel station was not loaded more than the others (eg, on a mound or on a rock or tree branch).
He said that nothing compares to a torsion bar failing around 6am (coldest part of the night) when you are sleeping alongside
the vehicle, he said it sounds like someone fired a shotgun next to your ear.......

The hazard is in buying used bars, you just don't know what they have been up to. eg, knife edge demos - a sure way to abbreviate the life of torsion bars.

In civilian usage, unless the owner is out to destroy his equipment, the average vehicle will see far less use/weight/abuse eg, no slamming into creek
beds, overloaded with kit, rations, ammo and a squad, no high speed jumps etc.

Having said that, I see in another post that one of the US museums has broken 2 torsion bars on an FV-432, I am hoping they reply to my question as to
how they did that.

Regards
Doug

G'day Doug,
Reference your query on the other thread ( http://www.steelsoldiers.com/showthread.php?147666-Finaly-cutting-down-and-giving-up )
You'll note that I'm in NZ, not US. The museum I volunteer at is the Museum of Transport and Technology (MOTAT) in Auckland ( www.motat.org.nz ) where I manage the Military Section workshop.

So, our 432 is used to give 'Tracked Vehicle Experience' rides to the civilian public and to save wear & tear on our M113 artifact. We can entertain/educate up to 500+ passengers a day on our once per month open days of 'Live' activity.

The area we run on is an old volcanic lava flow quarried out and re-filled as an urban rubbish dump then capped off with clay/top-soil. Various rates of subsidence have created an interesting terrain with hillocks and dips which demonstrate the benefits of tracked vehicle mobility for military transport compared to wheeled vehicles. Rocks and debris have caused us to dispense with the track-pads in normal use as they tear off easily in sharp turns and we only fit them for ANZAC Day parades and other street use. The circuit we run is an overlapping twin circle route which we run in either a clock-wise or counter c-w direction.

On the day of the double breakage we were running CCW and as such the port side of the vehicle was continually out of view of the loading staff/observers.

A lesser-experienced driver was behind the tillers... It is presumed that he didn't notice the initial failure of the first torsion bar and continued to run. Some severe drops, humps, dips, crests and turns make for an exciting ride in a closed-up APC and the public react approvingly. The second torsion bar probably broke due to carrying excess strain while operation continued after the first breakage. The two broken bars are on adjacent stations (#2 & #3).

The vehicle was noted to be listing to port at post-running wash-down whereas it was fully checked during First Parade at the start of the day.

We are aware we drive it hard (But not fast) but have no knowlege of how it was driven when in service prior to arriving in our care.

Torsion Bars are best bought new so you know their history. We have one Port Side spare and will source another from UK.

If you ever come across the ditch do get in touch and pop-in. You're most welcome.

Happy New Year to all.

 

[dgrev]

Hello

> You'll note that I'm in NZ, not US. The museum I volunteer at is the Museum of Transport and Technology (MOTAT) in Auckland ( www.motat.org.nz ) where I manage the Military Section workshop.

I take it you are still located on that hill a couple of miles from the main MOTAT?
Many times as a kid we drove past the Sunderland and Sandringham sitting forlorn after they got marooned by the power lines.
I hope that Sunderland is under cover now?

> So, our 432 is used to give 'Tracked Vehicle Experience' rides to the civilian public

Using an FV-432 for that sort of thing would be high maintenance. I note that Bovvy run the pants off 2x M548 for their rides. Does make you
wonder why they don't use an FV series vehicle......................

> A lesser-experienced driver was behind the tillers...

In his defence, I would say that over undulating terrain, with civilian passengers on board, and keeping an eye
out for any trespassing children on the course, his vehicle awareness was probably a low priority.

> We are aware we drive it hard (But not fast) but have no knowlege of how it was driven when in service prior to arriving in our care.

Assume = flogged. It would be highly unusual for it to have been driven gently.

> Torsion Bars are best bought new so you know their history. We have one Port Side spare and will source another from UK.

I suggest you source more. Won't make make much difference to the price as freight and
import will not be cheap and won't go up much for a couple of more bars.

> If you ever come across the ditch do get in touch and pop-in. You're most welcome.

Most appreciated.

Dad's side of the family grew up in Birkedale, they then moved to Brown's Bay (Grandad was mayor of East Coast Bays at one time).
My uncle, in his 80s is still there.
Haven't been back over since 1996. We are looking at another trip over in the next year or 2.

Regards
Doug

 

[Foxtrot Oscar]

Hello

> You'll note that I'm in NZ, not US. The museum I volunteer at is the Museum of Transport and Technology (MOTAT) in Auckland ( www.motat.org.nz ) where I manage the Military Section workshop.

I take it you are still located on that hill a couple of miles from the main MOTAT? Yes. Meola Road aka MOTAT2
Many times as a kid we drove past the Sunderland and Sandringham sitting forlorn after they got marooned by the power lines.
I hope that Sunderland is under cover now? Sandringam is actually a Solent. The last remaining one in the world and is now indoors. The Sunderland is outside still but undercover of shrink-wrap having corrosion removed from inside wings. Fuel tanks are removed.

> So, our 432 is used to give 'Tracked Vehicle Experience' rides to the civilian public

Using an FV-432 for that sort of thing would be high maintenance. I note that Bovvy run the pants off 2x M548 for their rides. Does make you
wonder why they don't use an FV series vehicle...................... Yes. We are used to the high level of running maintenance. It's very labour intensive.

> A lesser-experienced driver was behind the tillers...

In his defence, I would say that over undulating terrain, with civilian passengers on board, and keeping an eye
out for any trespassing children on the course, his vehicle awareness was probably a low priority. Children not able to access running track but protected avian wildlife (Dotterils) are to be avoided at all costs.

> We are aware we drive it hard (But not fast) but have no knowlege of how it was driven when in service prior to arriving in our care.

Assume = flogged. It would be highly unusual for it to have been driven gently. Correct. We do assume 'flogged'.

> Torsion Bars are best bought new so you know their history. We have one Port Side spare and will source another from UK.

I suggest you source more. Won't make make much difference to the price as freight and
import will not be cheap and won't go up much for a couple of more bars. Yes. We have that in mind.

> If you ever come across the ditch do get in touch and pop-in. You're most welcome.

Most appreciated.

Dad's side of the family grew up in Birkedale, (Birkenhead?) they then moved to Brown's Bay (Grandad was mayor of East Coast Bays at one time).
My uncle, in his 80s is still there.
Haven't been back over since 1996. We are looking at another trip over in the next year or 2. Look forward to seeing you.

Regards
Doug

Answers in yellow above.

I would add that setting the Torsion Bars for correct ride-height involves use of a gauge. The ends of the bars have differing numbers of off-set splines to enable rotation to set correct pre-load. This is a critical part of replacing T-Bars. You can't just fit them any-old-how.

 

[dgrev]

Answers in yellow above.

I would add that setting the Torsion Bars for correct ride-height involves use of a gauge. The ends of the bars have differing numbers of off-set splines to enable rotation to set correct pre-load. This is a critical part of replacing T-Bars. You can't just fit them any-old-how.

What is your name by the way?

Easy with an M113, and as far as I know it also applies to M548: there is an extra spline missing, they only go "in" one position.

So FV-432 is like a Saracen/Saladin suspension huh? = Nothing is easy.

Someone once told me that an FV-432 has 3 x the number of parts that an M113A1 has. Now admittedly a 432 has the NBC pack
and ducted air, but 3x the number of parts???

Regards
Doug

 

[Jeeagle]

Having said that, I see in another post that one of the US museums has broken 2 torsion bars on an FV-432, I am hoping they reply to my question as to
how they did that.

Regards
Doug

The biggest issue is maintenance I believe. Folks just do not pump enough grease into the torsion bar areas. There is two brass bushings in the hull that support it and two zerk fittings that require alot of grease. The further bushing in requires a lot of pump just to get the grease to it.

So, the fact most FV-432 that come over were used as civilian over seas saw road duty and perhaps not enough maintenance there is considerable amount of wear on them. And when they come over here where we have lots of play room we run them longer, and more often and get issues such as broken bars.

 

[Foxtrot Oscar]

We believe grease is cheap whereas steel is expensive so we grease everything often. Road duty is not hard on the driveline. Rough terrain is. So asking these machines to traverse humps which flex the T.B's to their max is what causes the damage. Something has to give and these T.B's can be upwards of 50 years in service.

I don't know about 3x number of parts but let's say the FV432 is 'delightfully British' and has several 'elegant' engineering solutions on-board. (The designers of the power-pack took inspiration from Sir Alec Issigonis of Mini car fame and crammed a lot into a small space. The Rolls-Royce K60 diesel has 6 cylinders and 12 pistons with 2 crankshafts... )

The T.B's are "settable" so they can allow for weight variations on the whole range of the FV430 family thus using the same bars, for the same side, for the whole range. You need the correct setting gauge for the seperate vehicles and in some cases there are varaitions along the stations to allow for localised weight such as the crane on the 434 or the generators on the radio relay variant.

I'm John.