Another "Convoy" Truck!

[Jürgen M.]

Hello, I'm back and I've made a decision about which (maybe finally Last) Convoy truck I'll be building!

I chose the KW cabover "Bruhn Trucking"!

I haven't yet started building but I have begun to design parts.

I'll post some screenshots of the 3D drawings soon.

Details like chassis and cab interior I'll be taking from my K100 VIT Australia kit and exterior from movie screenshots!

 

Edited March 21 by Jürgen M.

[Jürgen M.]

Here are some screenshots of the first self designed parts:

The cab:

 

and some chassis parts:

The frame had to be cut in half because it would have been too long for the printing bed so I
deigned the front rails with extra centering pieces and a larger glue area.

Considering that the "Big Nasty" Mack already consists of 160 parts of which about 140 are printed and it´s only a two axle tractor
there´s still gonna be a lot to do on this K-Whopper!!

I could of course use already designed chassis and engine parts but I want to make it as authentic as possible. Means I
will try to design as many parts as possible especially for this truck to make it look like a Kenworth from top to bottom and
from front to rear.

Since I´m not planning on building before September or October I´ve got enough time to get all the parts designed. A few I might
actually take over from other printed trucks as long as they´re in a place where it doesn´t really matter.

So I´ll have to ask for patience. There won´t be hardware to see in quite a while! 🙂

 

Edited March 21 by Jürgen M.

[Force]

Nice.
One thing tho'...maybe for the purists.
The movie was from 1978 and shot earlier in 1977, and the Bruhn Kenworth looks to be older than that, so I don't think it could have had the KW Air Glide 100 8 bag air ride suspension as that suspension was introduced in 1978.
As it's a gravel truck it could have had a spring suspension of some sort, Reyco 4 spring or maybe walking beam.
But of course, it's your model and you do as you please.

Edited March 24 by Force

[Jürgen M.]

You're probably right there! I'll have to look for some more scenes and make screenshots on that. Thanks for the tip.

Guess I was too concentrated on making the KW look real that I forgot I was going for an older model.

Guess it'll be a leaf suspension. I can change the drawings any time but I'll keep these for another time! 😉

Edited March 26 by Jürgen M.

[Force]

9 hours ago, Jürgen M. said:

You're probably right there! I'll have to look for some more scenes and make screenshots on that. Thanks for the tip.

Guess I was too concentrated on making the KW look real that I forgot I was going for an older model.

Guess it'll be a leaf suspension. I can change the drawings any time but I'll keep these for another time! 😉

Well it's not easy to keep track of what was current for the trucks all the time, Kenworth had an air ride before the AG100 8 bag suspension wich as I said came 1978, and it was a 4 bag suspension from the late 60's-early 70's, they also had torsion bars, heavy duty 6 rod and a few more suspension options.
You could also get Neway and some other non KW factory suspensions.

[Jürgen M.]

Wow! Amazing how much you know about trucks and such details! Thanks for sharing that. I never gave it any thought. 

I took another look at some movie scenes and I believe I saw leaf springs. You think those were in combination with a 4-bag suspension? 

That wouldn't be hard to change in my drawings especially since I have only drawn the frame.

I think the Peterbilt 359 "Black Magic" hast got that kind of suspension and PB and KW being combined in the Paccar Corporation they might have used the same parts.

I guess most of you know that better than I.

[Force]

The older Kenworth 4 bag suspension looks like this and there was a slightly different version a bit later, this is not available anywhere either in a kit or on the aftermarket as far as I know.
This was replaced with the Air Glide 100 8 bag suspension in 1978.

 

Here is the Kenworth torsion bar suspension, The AMT Kenworth W925/K123 had this when the kits first came out but it was later changed.
This suspension can be found on the aftermarket.

Here is a 4 spring suspension, this is a Reyco but Kenworth had one called Glide Ride and it looks very similar, the AMT White Freightliner Dual Drive kit has this type.

These were medium weight suspensions.

For more heavy weight duty they had these.
Hendrickson Walking Beam and there were a couple of variants of them, the AMT Kenworth W925/K123 has a version and this suspension are in a few more AMT kits.

 

And Kenworth 6 Rod, Rockwell has a similar and I don't know if it's the same, the AMT Autocar Dump Truck kit has the Rockwell style suspension and it's also avilable on the aftermarket.

[Jürgen M.]

Wow!! Thanks for this information! I'm stunned by your knowledge about the different technologies and where they were applied!

Which one do you think would be the right one or at least authentic for the mid 70s KW?

I can design and print any one of them. Just want it to be correct concerning the technology of the time.

I'm really thankful for all this. I don't have that much knowledge about the trucks of that time but maybe I can help out sometime in another way. I hope so! 😊

[Jürgen M.]

I was able to take this screenshot showing the truck from the side. For me it´s hard to tell which kind of suspension this truck has.

Could be the 4 spring suspension, not sure though.

.

[Jürgen M.]

I've got a KW W925 Amt kit with a suspension like the heavy duty Hendrickson you posted above.

Would that be the right one for this project?

I believe this truck might be round about the same model year as the K100 in the movie!

Built this one when I was about 14. 

I'll post it too some time!

[cifenet]

I must admit I am quite impressed that you built this when you were 14!

I see minor spots where you missed in painting, but overall you did a great job putting things together! 

My builds went unpainted at that age, ha!

4 hours ago, Jürgen M. said:

Built this one when I was about 14. 

I'll post it too some time!

 

[Jürgen M.]

I actually put that red on to make it look like rust. Not really realistic but the idea was there! 

The chassis isn't straight either but noone can see that! 😊

[Force]

14 hours ago, Jürgen M. said:

I was able to take this screenshot showing the truck from the side. For me it´s hard to tell which kind of suspension this truck has.

Could be the 4 spring suspension, not sure though.

.

Yes it looks to be a 4 spring and that's what I thought it could have had, that or the Walking Beam...but in this case it looks like a 4 spring Glide Ride.
You can either use the rear suspension from the AMT White Freightliner or if you want to 3D print here is a parts breakdown of the Glide Ride 4 spring suspension.

[Jürgen M.]

Thanks! That's really excellent! I don't know what to say! 

I'll do my best! 😊

[Jürgen M.]

14 hours ago, cifenet said:

I must admit I am quite impressed that you built this when you were 14!

I see minor spots where you missed in painting, but overall you did a great job putting things together! 

My builds went unpainted at that age, ha!

 

Thanks! I began building Models at about 9! First only cars, then planes and ships and at 13 I got my first truck kit. It was the amt Peterbilt 359 1/43 kit with a wrecker and a tractor.

They might not have been the best start into the world of truck kits because the parts we're quite small but I got them together and I was very proud at that time. Unfortunately we moved shortly afterwards and my parents didn't really care about my model kits so a lot of them didn't survive including the two Peterbilts. 

So my first "real" truck kit which survived till today was this Mack R685 that was transformed into "Rubber Duck" as soon as I had seen the movie!

Edited March 30 by Jürgen M.

[Jürgen M.]

I designed the 4-spring suspension. OK, I admit it´s not exactly like the one in the parts breakdown but I

did my best. I designed it in one piece per side to make it a bit easier to build later.

I don´t know what those pins (no. 19 in the drawing) are called in English but I´m gonna make those out of 1mm brass rod. They´re too thin to print.

[Force]

U bolts, yes that's a good idea.
You forgot part number 3 right in the middle of the breakdown picture wich the springs are attached to, it's  called leaf spring equalizer and it's kind of a hinge in the middle hanger and are crucial for this suspension to work properly and smoothly.
Leaf springs can't be solidly mounted, the arch of the spring gets flatter when loaded so they grow in length and has to be able to slide in the mounting points, and this equalizer wich is a pivot point between the front and rear spring are on every 4 spring suspension I have seen.

Here is another picture so you can see how it looks, the equalizer has number 4 in this picture, this is a trailer suspension and it's similar to the truck suspension, but the U bolts holding the axles are the other way around.


Otherwise it looks convincing enough.

[Jürgen M.]

On 4/1/2024 at 12:14 PM, Force said:

U bolts, yes that's a good idea.
You forgot part number 3 right in the middle of the breakdown picture wich the springs are attached to, it's  called leaf spring equalizer and it's kind of a hinge in the middle hanger and are crucial for this suspension to work properly and smoothly.
Leaf springs can't be solidly mounted, the arch of the spring gets flatter when loaded so they grow in length and has to be able to slide in the mounting points, and this equalizer wich is a pivot point between the front and rear spring are on every 4 spring suspension I have seen.

Here is another picture so you can see how it looks, the equalizer has number 4 in this picture, this is a trailer suspension and it's similar to the truck suspension, but the U bolts holding the axles are the other way around.


Otherwise it looks convincing enough.

Thanks! You're right! 

I'll correct that! The drawings of the trailer suspension will help me on the trailer! Thanks for that too. I'm really learning! 👍 

By the way, If I may ask one more thing?

Did the Kenworths of the late 70ies all have twin turbo engines?

I've been following some current builds and took a Look at older ones. I also searched in the www, I only found twin turbos except for my old W900 which I posted shortly.

I'm not sure which engine to choose!

 

On 3/29/2024 at 8:55 PM, cifenet said:

I must admit I am quite impressed that you built this when you were 14!

I see minor spots where you missed in painting, but overall you did a great job putting things together! 

My builds went unpainted at that age, ha!

 

Thanks! I began building Models at about 9! First only cars, then planes and ships and at 13 I got my first truck kit. It was the amt Peterbilt 359 1/43 kit with a wrecker and a tractor.

They might not have been the best start into the world of truck kits because the parts we're quite small but I got them together and I was very proud at that time. Unfortunately we moved shortly afterwards and my parents didn't really care about my model kits so a lot of them didn't survive including the two Peterbilts. 

So my first "real" truck kit which survived till today was the Mack R685 that was transformed into "Rubber Duck" as soon as I had seen the movie!

Edited April 3 by Jürgen M.

[Jürgen M.]

I corrected the 3D drawing. I think that does the job!

[37 caddy]

The twin turbo setup is a newer design,back in the day they would  have only 1 turbo or even a supercharger.Some didnt even have a turbo,the motor in the white freightliner cabover and the autocar dump truck have non turbo cummins motors.The motors in the AMT kenworth kits is a good version of what a lot of rigs had back in the day,a cummins 335 or 350 engine. harvey

[Jürgen M.]

Thanks Harvey,

so I wouldn't be doing anything wrong If I put a single or non turbo engine in that KW cabover?

In the movie you can't see it anyway so why put more in than necessary? 😉

 

[Rockford]

1 hour ago, Jürgen M. said:

Thanks Harvey,

so I wouldn't be doing anything wrong If I put a single or non turbo engine in that KW cabover?

In the movie you can't see it anyway so why put more in than necessary? 😉

 

You're doing another brilliant job Jürgen, great to watch. I'd think your KW would have a single turbo at that age if it had a Cummins or a Caterpillar straight six in it. There were still non-turbo motors around but the turbo engines were becoming much more popular. 

The rear suspension looks like a Reyco 102 setup to me. Your 3D drawing isn't too far of the mark. 

Edited April 3 by Rockford
Text added

[Jürgen M.]

Hi Rockford,

thanks for the info and your feedback! 😊

[Force]

On 4/3/2024 at 7:30 AM, Jürgen M. said:

Thanks! You're right! 

I'll correct that! The drawings of the trailer suspension will help me on the trailer! Thanks for that too. I'm really learning! 👍 

By the way, If I may ask one more thing?

Did the Kenworths of the late 70ies all have twin turbo engines?

I've been following some current builds and took a Look at older ones. I also searched in the www, I only found twin turbos except for my old W900 which I posted shortly.

I'm not sure which engine to choose!

Don't mention it, if I can help I will.
Most of the engines with turbos back in the day only had one, the twin turbo setup on inline six engines is a more recent thing, both Caterpillar and Cummins had twin turbos on some of them and Cat still do on some engines, but Cat stopped doing engines for on highway trucks back in 2010 so after that you couldn get a Cat engine in your truck.
V8 and V12 is another thing, they could have one or two turbos...or none at all.

On 4/3/2024 at 9:12 AM, Jürgen M. said:

I corrected the 3D drawing. I think that does the job!

That looks convincing enough so go for it.

On 4/3/2024 at 12:54 PM, 37 caddy said:

The twin turbo setup is a newer design,back in the day they would  have only 1 turbo or even a supercharger.Some didnt even have a turbo,the motor in the white freightliner cabover and the autocar dump truck have non turbo cummins motors.The motors in the AMT kenworth kits is a good version of what a lot of rigs had back in the day,a cummins 335 or 350 engine. harvey

The engine in the AMT Kenworth W925 and K123 is a NTA wich is not that common, the most common Cummins is the NTC version wich came in different horsepower ratings, but you can of course use the NTA if you want to, both are 855 cui engines and the visual difference is mostly in the oil cooler area.
I don't know what engine was in the Bruhn K100 and you can't see it so use whatever engine you like, engines available back then was Cummins and Cat 4 stroke, and Detroit Diesel 2 stroke, all in various configurations.

Edited April 4 by Force

[Jürgen M.]

OK, thanks again! 😊 

I'll put in a 6 cylinder single turbo. I designed one as a standard engine more or less copied from an old amt Peterbilt kit.