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R-model Rain Gutter

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Has anyone out there in Mack land ever cut off the rain gutter around the cab roof on a r odel? I was thinking of cutting mine off,so the water doesn't cause rust.My truck is a 1979 with only 70,000 miles on it.We brought a total of 45 macks that year and only have that one and one other that we converted into a box truck. The box truck is for sale.Thanks for any comments.

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Has anyone out there in Mack land ever cut off the rain gutter around the cab roof on a r odel? I was thinking of cutting mine off,so the water doesn't cause rust.My truck is a 1979 with only 70,000 miles on it.We brought a total of 45 macks that year and only have that one and one other that we converted into a box truck. The box truck is for sale.Thanks for any comments.

I don't know how you would do that and retain the roof skin to the cab. The rain gutter has the verticle part that you see on the outside, then transitions to a flat surface, then again turns up a bit and is welded to inner cab structure. In the flat, or horizontal area, the roof skin is welded to.

I have some NOS rain gutter, and roof skins for an R model cab at the shop and will post photos if there is any confusion. I've put a lot of them on through the years and not saying that a person couldn't fabricate somthing to work, but it would be a lot or work to look and function correctly.

Rob

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I HAVE SEEN A R MODEL WITH THE DRIP RAIL CUT OFF IT WAS VERY FUNNY LOOKING I WOULD DIG ALL THE SEAM SEALER OUT OF IT CLEAN IT UP AND USE POR-15 PAINT ON BOTH SIDES OF THE DRIP RAIL

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I HAVE SEEN A R MODEL WITH THE DRIP RAIL CUT OFF IT WAS VERY FUNNY LOOKING I WOULD DIG ALL THE SEAM SEALER OUT OF IT CLEAN IT UP AND USE POR-15 PAINT ON BOTH SIDES OF THE DRIP RAIL

People cut the gutters off cars down here for a more smoother finish, they weld the roof on where the gutter started, it looks wrong/strange/funny and makes roof weeker, and you get dripped on.

Grant

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I've seen the rain gutter removed on very rusty cabs. Then about a 4 inch strip of sheet metal put on to tie it together. It looks a little strange but it keeps the truck working. Personally I think it has about the same appeal of aluminum paint on rusty exhaust systems. Fresh paint over rust is always a favorite at the equipment auctions though.

Chuck

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Has anyone out there in Mack land ever cut off the rain gutter around the cab roof on a r odel? I was thinking of cutting mine off,so the water doesn't cause rust.My truck is a 1979 with only 70,000 miles on it.We brought a total of 45 macks that year and only have that one and one other that we converted into a box truck. The box truck is for sale.Thanks for any comments.

If it's not rusted yet and that sounds like what your saying, I have seen a few guys that filled the gutter in with silicone and it seamed to prevent any rust problems.

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If it's not rusted yet and that sounds like what your saying, I have seen a few guys that filled the gutter in with silicone and it seamed to prevent any rust problems.

The cabs start to rust in this area for a couple of different reasons:

The roof skin "flange" is spot welded to the drip rail all along the perimeter. As one knows you cannot weld through an insulator so this is usually bare carbon steel when the welding takes place. This produces a "sandwich" of sheet metal, (one layer on top of the other) and there are inherent voids between the spot welds. This is usually not adequately sealed on the inside of the cab and the condensation of a cold roof panel, coupled with a warm operators cabin produces condensation that accelerates the sheet metal corrosion. The seam sealer that is poured and worked into the gutter is to seal the outer flange area and bury the weld seam. It does nothing to protect from the inside where the corrosion starts.

The best way to delay the onset of this degradation, (corrosion) is to seal the inside of the cab. Anything, new or old will benefit from this action. I use a product call "Rust Fire" that sprays on almost like a lubricant and litterally runs into cavities, and then solidifys into a wax effectively sealing the area from moisture intrusion. Although this not absolutely perfect, it works much better than nothing at all to counter the elements. It also smells like asphault for about three solid days so there is a delay to return the vehicle to service. The stuff also stay sticky for that same three days!

As was mentioned, one could cut the drip rail off of the cab and fabricate some type of arrangement to retain the roof skin but it would either not look right, or function properly. Although a Mack cab does not gain major strength through the roof skin, there is a lot of vibration present and if not welded solid in some fashion, will crack. I like the four inch wide band type repair myself. I can just imagine how that would look.

Rob

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The cabs start to rust in this area for a couple of different reasons:

The roof skin "flange" is spot welded to the drip rail all along the perimeter. As one knows you cannot weld through an insulator so this is usually bare carbon steel when the welding takes place. This produces a "sandwich" of sheet metal, (one layer on top of the other) and there are inherent voids between the spot welds. This is usually not adequately sealed on the inside of the cab and the condensation of a cold roof panel, coupled with a warm operators cabin produces condensation that accelerates the sheet metal corrosion. The seam sealer that is poured and worked into the gutter is to seal the outer flange area and bury the weld seam. It does nothing to protect from the inside where the corrosion starts.

The best way to delay the onset of this degradation, (corrosion) is to seal the inside of the cab. Anything, new or old will benefit from this action. I use a product call "Rust Fire" that sprays on almost like a lubricant and litterally runs into cavities, and then solidifys into a wax effectively sealing the area from moisture intrusion. Although this not absolutely perfect, it works much better than nothing at all to counter the elements. It also smells like asphault for about three solid days so there is a delay to return the vehicle to service. The stuff also stay sticky for that same three days!

As was mentioned, one could cut the drip rail off of the cab and fabricate some type of arrangement to retain the roof skin but it would either not look right, or function properly. Although a Mack cab does not gain major strength through the roof skin, there is a lot of vibration present and if not welded solid in some fashion, will crack. I like the four inch wide band type repair myself. I can just imagine how that would look.

Rob

Rob,thanks you answered my question about the rain gutter.Mine in not rusted yet so I would like to keep it that way.Thanks again Mike Durkin

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Rob,thanks you answered my question about the rain gutter.Mine in not rusted yet so I would like to keep it that way.Thanks again Mike Durkin

Glad to be of help.

Rob

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Bringing back a old topic. My roof needs to be replace before it gets out of hand. I went pokeing around the few rust bubbles tonight and its clear that its time. The roof rail is still good and intact but the skin around the rear of the cab just above the window is barely hangin on. I found that there is a section about 6" long that is completly detached. I would like to fix this over the summer time before it gets out of hand. Looks like I need to source a roof skin and start driling off the cab. what is to expect under the skin? is there another interior panel under that skin? will that likely have rust as well? this truck had a roof mount AC unit so im sure that dident help the rust issues?

Trent

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Rob I should just gut the interior. Drive down to your shop on a friday. Bring a case of beer and some pizza and have you school me as I do the job at your shop LOL. you make it sound so simple LOL

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Here is you some entertainment value. The red truck is my RL755L, the brown one my RL797L. The red cab will be replaced as it is too far gone up top to work with, but you can see how things fit together.

Rob

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Rob I should just gut the interior. Drive down to your shop on a friday. Bring a case of beer and some pizza and have you school me as I do the job at your shop LOL. you make it sound so simple LOL

Always a good idea to remove the interior. There is a lot of welding, then dressing of those welds for a good job to be had. You can see in a couple of photos the shape of the backlight in the brown cab from someone welding, or grinding in close proximity to the glass as it is destroyed. It is by no shape, nor form a "cake walk" to perform. A novice will find it intimidating, (and they should) although it is not hard. A lot of planning and thinking is in order prior to a satisfactory repair.

I've done this shit for far too many years to not be comfortable, but there are still times when I have to think how to make a repair as I don't know it all, contrary to popular belief.

Rob

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thanks for the pics Rob. I must have missed that post? On the tan truck...did you cut the roof off first before you went around with the rotobroach and remove the skin welds? I dont think my cab is this bad as there was one small spot above the windshield and the rest is all in the back.

Do the skins have all the holes drilled for the horns roof lights etc and have the incerts to retain the bolts to mount them?...?

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thanks for the pics Rob. I must have missed that post? On the tan truck...did you cut the roof off first before you went around with the rotobroach and remove the skin welds? I dont think my cab is this bad as there was one small spot above the windshield and the rest is all in the back.

Do the skins have all the holes drilled for the horns roof lights etc and have the incerts to retain the bolts to mount them?...?

I always cut the center loose from the perimeter of a panel as it is much easier and faster to handle small pieces rather than large. Yes, all the roofs have the holes punched into them. What is kinda funny is they are punched for the old style marker lamps such is on a B model. If I remember correctly you need to drill the rear hole for the newer style lampholder such as were on the Superliners. The dual airhorn holes are there also.

The threaded inserts you refer to are called "Rivetnuts", or "Rivnuts", and they are not in the holes, neither are the braces to hold the interior overhead console. It is just an empty stamping.

There is rust in the front also, you just can't see it yet. If it's rusted in the rear, it's rusted in the front too. I'd bet with 80 grit on a DA sanding the corners you'd see slight discoloration to the metal and would be able to push a screwdriver through it easily. This is just from what I've experienced, your's could be an exception. Sure would hate to not check into it closely and need to redo in six months however.

Rob

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thats what I was afraid of ...rust in the front. hopefully It will be light and some patches will take care of it. Sounds like I need to get the truck inside for a few weeks and pull the roof off, fix all the little rust issues around the rail and hope it lasts for another 30 years? Figures I just start dressing up the interior and now I need to address the roof!!! When I got the truck I had to put in some brakets to support the newer style headliner with over head console. this was not that hard to do. I guess at that point you pull all the stuff off the cab and just repaint the whole cab and be done with it LOL.. talk about a can of worms!!!!

Trent

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thats what I was afraid of ...rust in the front. hopefully It will be light and some patches will take care of it. Sounds like I need to get the truck inside for a few weeks and pull the roof off, fix all the little rust issues around the rail and hope it lasts for another 30 years? Figures I just start dressing up the interior and now I need to address the roof!!! When I got the truck I had to put in some brakets to support the newer style headliner with over head console. this was not that hard to do. I guess at that point you pull all the stuff off the cab and just repaint the whole cab and be done with it LOL.. talk about a can of worms!!!!

Trent

It's always better that once the decision is made to do the job, Do it right. Lot less headaches in the future that way.

Rob

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Rob.....I Got the roof skin on order, will be here tomorrow. got one for $399 from a local dealer.

What size roto broach should I get? I assume I will need 2 or 3 to do all 150 spot welds?

Should I get a new rain gutter as well even if mine looks to be good? how hard is it to replace the gutter with the roof off?

Por 15 or rustfire are they the same? I have only heard about Por 15

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Rob.....I Got the roof skin on order, will be here tomorrow. got one for $399 from a local dealer.

What size roto broach should I get? I assume I will need 2 or 3 to do all 150 spot welds?

Should I get a new rain gutter as well even if mine looks to be good? how hard is it to replace the gutter with the roof off?

Por 15 or rustfire are they the same? I have only heard about Por 15

A "Rotobroach" kit is about $50.00, (www.autobodytoolmart.com) and I use the 3/8ths size. You will probably use two of the three included in the kit.

I'm surprised the sheet metal is that reasonable. I think the last one was about that a few years ago.

The gutter is easy to replace once the skin is off, in fact it has to be off to install the new. I'd wait until the skin is removed and go from there unless the dealer will take back what you don't use. Most do not because they do not stock it.

RustFire, or RustFree are not the same as POR-15. These are both liquid wax, (sort of) to flow into and seal up crevices. POR-15 is more like a paint. Body shop suppliers should have the stuff.

Rob

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thanks rob... I just went out and got a 3/8 rotobroach kit with 3 double sided replacement cutters. the auto body shop had some por 15 so I will likely use that to paint the surface that I can see and then find some rust fire spray yo coat the semas that I cant see.

all I have to say is Wow... a week ago I was just going to put in sound dead meterial. now the roof is coming off!!!

having a guy come out to sand blast the frame, new stainless side box and 1/2 fenders on order as well. Busy few weeks ahead of me here!!!!

thanks for all this help Rob!!!

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thanks rob... I just went out and got a 3/8 rotobroach kit with 3 double sided replacement cutters. the auto body shop had some por 15 so I will likely use that to paint the surface that I can see and then find some rust fire spray yo coat the semas that I cant see.

all I have to say is Wow... a week ago I was just going to put in sound dead meterial. now the roof is coming off!!!

having a guy come out to sand blast the frame, new stainless side box and 1/2 fenders on order as well. Busy few weeks ahead of me here!!!!

thanks for all this help Rob!!!

Take the doublesided cutter kit back. Get the kit that has the mandrel, and a single cutter edge with four cutting flutes. Those double sided ones break and you always get cut.

Here is what you want:

http://www.autobodyt...?keywords=blair

Rob

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Hi Rob

I just got back and have 1/2 the roof off the cab. the roto broaches dont cut as nice as I thought they would. They dig into the glue and then try to take off in a diffrent direction. I may try a diffrent brand as you suggested.. Anyways the whole back half of the roof was held on by paint. rear corners seame ok at the radius. front half of the sides and whole front are solid.... from the out side.

I was able to cut into the drivers side and its is almost done so I am almost half way there getting it off. I figure by Sat after noon I will have the roof off and making repairs to the rails. So far I can see that the rear cab wall gutter has some issues as rust is above and below it. I may need to remove the back section to clean behind it and re seal it. Kinda glad I got into this now and not replace the cab in 5 years when it was two far gone.

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Hi Rob

I just got back and have 1/2 the roof off the cab. the roto broaches dont cut as nice as I thought they would. They dig into the glue and then try to take off in a diffrent direction. I may try a diffrent brand as you suggested.. Anyways the whole back half of the roof was held on by paint. rear corners seame ok at the radius. front half of the sides and whole front are solid.... from the out side.

I was able to cut into the drivers side and its is almost done so I am almost half way there getting it off. I figure by Sat after noon I will have the roof off and making repairs to the rails. So far I can see that the rear cab wall gutter has some issues as rust is above and below it. I may need to remove the back section to clean behind it and re seal it. Kinda glad I got into this now and not replace the cab in 5 years when it was two far gone.

Did you remove the seam sealer before starting to drill? Those hollow cutters always dig, take off different directions, and snap with you usually sporting a bandage and pain afterward.

I used to purchase them by the box until the other type came out from the same company, (Blair). Never have went back and I've used prolly all of the tools over the years available.

Rob

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the seam sealer is still like gum so its hard to get it all off. I used a screw driver to get alot of it off the surface but its still stuck on the sides of the gutter and in between the steel.

I think these were made by blair? will have to check the package. Bought them from a reputable paint store.

Trent

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