Double Frame Question

[Pauly17]

Hi, I have a W9 and it has a 5/16 frame and I wanted to double frame it. Not the full length just up to he back of the cab. I just looking for some advice if I can use 5/16 for the inside frame rail or does it have to be 1/4 inch?

 

[repowerguy]

If you don't double the frame to the rear spring hanger on the steering axle, you are not only wasting your time, but you create a stress riser in the middle of a span which will cause a break there guaranteed.
You also need to use a steel similar to the existing frame rail. In short, have a frame shop specialist do it.

 

[Junkyard]

X2 on going to the steer axle area. Over long term you will have potential issues where the insert ends. A reputable frame shop can do it waaay faster than you can and it's usually no stupid expensive. At least not around here. I've done it myself a few times and I haven't ever felt like it was worth it. What's your intended use for it?

Junkyard

 

[Pauly17]

I've been using it to heavy haul and thought I would beef it up a little. It's only 5/16 frame. I was also told not to end it by the spring hanger as that is where the most amount of stress is coming from the torque of the motor.

 

[Truck Shop]

I agree with most above. The half way point of the frame between rear spring hanger of steer axle and the front hanger of the front drive is the weak area. That is called the
bending moment area in engineering. With a 5/16 frame I would remove the crossmember at rear of cab and install a rail to the rear spring hanger on front axle. If it had
3/8 rail I wouldn't worry on stopping at back of cab. I use 5/16 on all inside rail inserts, and have 80,000 lb tensile strength steel formed for rail. If you check- a 25 cent piece
will fit the inside radius which means a 1/2 die used in the break. Rails are not hard to install, I pilot drill 1/4" and use Car reamers to finish size. You can buy those in 3/8,
1/2, 5/8 and 3/4 which will cut fast and leave a perfectly round hole using allot of cutting oil. But the big thing is only use Flange Bolts and Flange Nuts for fasteners. Throw
that old crap away. And measure the inside of your existing rail in several places and make precise measurements, the inside rail should fit snug.

Truck Shop

 

[JPV]

I have seen a few long hood W900's and one W900B crack the frame on the driver side by the rear spring hanger on the steer axle. The crack starts from the bolt hole on the bottom flange for the spring hanger. I thought the cardinal rule on frames is no holes in the flanges, only the web. Kenworths come from the factory with holes in the high stress area! We have put short sleaves in a few of them to beef this area up after welding the crack with a full penetration weld. It seems hokey but they have had no issues in several years, time will tell if we created ourselves other problems. So sleeving it to in front of the rear spring hangers is good advice in my opinion.

 

[td25c]

I've been using it to heavy haul and thought I would beef it up a little. It's only 5/16 frame. I was also told not to end it by the spring hanger as that is where the most amount of stress is coming from the torque of the motor.

Yeah Pauly17 . W - 900 have the 8 bag air ride ?
My thinking is that suspension is better at distributing loads to the frame around the axil & fifth wheel area with it spread out over a distance along the frame rail & riding on a cushion of 8 air bags equally holding it all up .
Truck with that suspension for occasional heavy haul would get buy with single frame .

Then on the other hand trucks with the Hendrickson beam where the load was concentrated in a small area generally had a factory double frame insert around the suspension . Not that uncommon to even see a factory triple frame like our GMC has .

We double framed the Kenworth W - 900 years ago just like you are thinking about ( stopped at the cab) . Had a steel fabricator bend the 16 ' channels for us and we took the truck apart drilling & bolting .Quite a bit of work but paid off in the long run .
After 25 years she's still liftin & pullin

http://www.heavytruckforums.com/showthread.php?263-Some-Holmes-750-action&p=1606&viewfull=1#post1606
http://www.heavytruckforums.com/showthread.php?263-Some-Holmes-750-action&p=2519&viewfull=1#post2519

 

[Truck Shop]

I have seen a few long hood W900's and one W900B crack the frame on the driver side by the rear spring hanger on the steer axle. The crack starts from the bolt hole on the bottom flange for the spring hanger. I thought the cardinal rule on frames is no holes in the flanges, only the web. Kenworths come from the factory with holes in the high stress area! We have put short sleaves in a few of them to beef this area up after welding the crack with a full penetration weld. It seems hokey but they have had no issues in several years, time will tell if we created ourselves other problems. So sleeving it to in front of the rear spring hangers is good advice in my opinion.

And I agree with that but on that note Freightliner used counter sunk bolts in the flanges to mount crossmembers for years. Go figure.

Truck Shop

 

[Pauly17]

Yeah Pauly17 . W - 900 have the 8 bag air ride ?
My thinking is that suspension is better at distributing loads to the frame around the axil & fifth wheel area with it spread out over a distance along the frame rail & riding on a cushion of 8 air bags equally holding it all up .
Truck with that suspension for occasional heavy haul would get buy with single frame .

Then on the other hand trucks with the Hendrickson beam where the load was concentrated in a small area generally had a factory double frame insert around the suspension . Not that uncommon to even see a factory triple frame like our GMC has .

We double framed the Kenworth W - 900 years ago just like you are thinking about ( stopped at the cab) . Had a steel fabricator bend the 16 ' channels for us and we took the truck apart drilling & bolting .Quite a bit of work but paid off in the long run .
After 25 years she's still liftin & pullin

http://www.heavytruckforums.com/showthread.php?263-Some-Holmes-750-action&p=1606&viewfull=1#post1606
http://www.heavytruckforums.com/showthread.php?263-Some-Holmes-750-action&p=2519&viewfull=1#post2519

Yes it does have the 8 bag air ride. I have seen this done on other trucks too. I have been doing more and more heavy hauling so I was thinking maybe I should beef this up a little

 

[Pauly17]

Thanks guys I appreciate your help. I bought a set of 46's the (AG 460) 8 airbag to slide under the truck. I currently have 40's the (AG400) 8 airbag and they have the same bolt pattern where the main structure bolts to the frame. The only difference is where the holes are in the frame where the airlines go through the frame to the inside. I would have to punch new holes and they would be close to the old one. Should I weld up the old hole and not worry about double framing the back end? The guy I was listening to before in how to do this I'm finding does have a clue as to what he is doing, so I wanted to hear input from of you guys with more experience.. I'm an owner operator and I am pretty good with a set of wrenches but I am by far not a mechanic.

 

[JPV]

I guess it comes down to how much you like the truck or how long you plan to keep it. If you are swapping rearends and suspension (AG460 is my favorite) throwing a sleeve to the back of the cab isn't to much more work. Going under the cab can be a lot more work! We have a couple dump trucks that the sleeve stops at the cab, nothing wrong with them.

 

[td25c]

Nice looking W-900 pauly17 !

As JPV noted if you plan on keeping the truck and the frame is a concern then by all means go ahead & double frame it while your swapping out the rears .
Myself don't see any problem with running the new liners up to the cab with that wheelbase of tractor .
It's not like your trying to do a tri or quad axil dump truck conversion on it .

When we did our W-900 we framed one side at a time sliding the new frame section in from the rear & used a magnetic drill press to poke out the holes in the liner .
Cross members had slotted holes in them to allow adjustment for thickness of new inner liner .
As member Truck Shop stated throw away old bolts & hardware & go back with new .
Another note.... Make sure the fab shop allows a little tolerance between the flange on the new channel . If anything make it a little short between flanges so the new liner will easily slide in the existing frame .

 

[Pauly17]

Nice looking W-900 pauly17 !View attachment 166290

As JPV noted if you plan on keeping the truck and the frame is a concern then by all means go ahead & double frame it while your swapping out the rears .
Myself don't see any problem with running the new liners up to the cab with that wheelbase of tractor .
It's not like your trying to do a tri or quad axil dump truck conversion on it .

When we did our W-900 we framed one side at a time sliding the new frame section in from the rear & used a magnetic drill press to poke out the holes in the liner .
Cross members had slotted holes in them to allow adjustment for thickness of new inner liner .
As member Truck Shop stated throw away old bolts & hardware & go back with new .
Another note.... Make sure the fab shop allows a little tolerance between the flange on the new channel . If anything make it a little short between flanges so the new liner will easily slide in the existing frame .

Thanks for the compliment.. Yeah I was going to post that the length is not that long I just had to many things to do today. And that was a good idea doing one at a time. A magnetic frame drill is just what I'm going to do. Thanks again for the help!

 

[td25c]

Your KW tractor with short wheelbase looks like the perfect heavy haul rig in rural hill country with narrow county roads leading to the jobsite . I like it

We set our KW up in the early 1990's and back then one school of thought was stretch the truck out & double frame ???
We decided to just double frame & kept the wheelbase at a reasonable limit so we could actually get to the job at hand .
I realize we are moving into the future but the roads are not changing so got to speck the truck out for the environment it's going to work in . Short heavy built tractors rule on and off road.
I like the short exhaust stacks as well , only thing tall pipes are good for is catching tree limbs & low service lines

 

[Pauly17]

Your KW tractor with short wheelbase looks like the perfect heavy haul rig in rural hill country with narrow county roads leading to the jobsite . I like it

We set our KW up in the early 1990's and back then one school of thought was stretch the truck out & double frame ???
We decided to just double frame & kept the wheelbase at a reasonable limit so we could actually get to the job at hand .
I realize we are moving into the future but the roads are not changing so got to speck the truck out for the environment it's going to work in . Short heavy built tractors rule on and off road.
I like the short exhaust stacks as well , only thing tall pipes are good for is catching tree limbs & low service lines

Yeah I haul a lot of blacktop too in the summer and on some real goat paths. The exhaust stacks cant be more than 11' here as one of the blacktop plants has an 11.3 clearance. Being here in NY you never seem to run out of work with all the frost we get in the roads the more they need to be redone!