Mdmccurr Posted April 10, 2017 Share Posted April 10, 2017 Greetings everyone, I just bought a 1978 U-Model Mack that was formerly operated by Overnite Transportation. The truck is in great shape with only 278,00 miles. Unfortunately there is a small amount of rust in the floorboard between driver's seat and door sill and also at the base of the accelerator pedal. The base of the pedal is completely disconnected because where it normally attaches is a rust hole about 3 inch diameter. The rest of the floor is solid. I have looked underneath and everything looks fine from the bottom, just rusted in those 2 small locations. What is the correct repair for this? Pictures attached. Should I just cut out the damaged area and get some sheet metal and weld over the hole? Apply rustproof from the bottom? Thanks for your advice Quote Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/ Share on other sites More sharing options...
j hancock Posted April 10, 2017 Share Posted April 10, 2017 Welcome! Yup, cut it out and put in new metal. For a hobby truck, I might not do any undercoating. How about a couple more pictures of the truck? Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-366938 Share on other sites More sharing options...
fxfymn Posted April 10, 2017 Share Posted April 10, 2017 You can patch it over, but it will never be quite right. The correct repair is to use a cutting disc on a small grinder to cut the rusted area out and then use the cut piece as a pattern to make a piece which can be welded back into the hole. If it is too rusted out to make a pattern then hold a piece of cardboard up to the hole and trace out what you need, cut it out to fit, and then make up the patch piece. I would wire brush the entire area to remove the loose rust and then paint it with a Chassis Saver or Por-15 type paint. You can also use rust converter and then paint over it. Quote Money, sex, and fire; everybody thinks everyone else is getting more than they are! Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-366939 Share on other sites More sharing options...
Freightrain Posted April 10, 2017 Share Posted April 10, 2017 (edited) Welcome to the forums. Cut out the bad, replace with new. Cardboard makes great templates. I too would not undercoat. Use good paint and be done with it. Edited April 10, 2017 by Freightrain Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-366959 Share on other sites More sharing options...
mowerman Posted April 10, 2017 Share Posted April 10, 2017 welcome about...my friend and have a ball....i didnt know overnight ran any U models Quote Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-366967 Share on other sites More sharing options...
Popular Post Mdmccurr Posted April 12, 2017 Author Popular Post Share Posted April 12, 2017 (edited) Thanks everyone for the excellent advice. This truck has an interesting history. My father was the VP of Maintenance for Overnite Transportation back in the 1980's. When Smith Transfer went bankrupt in 1988, he was instructed to go to the bankruptcy auction and buy as many of these Mack U models as he could for city service in the Overnite fleet. He bought roughly 200 of them and had them all repainted blue/gray and restored to new condition in the Overnite shops. He retired long ago but last month we saw a Craigslist ad for this old truck that had been abandoned in Wilkesboro, NC, and recognized the paint scheme as Overnite. The truck had been sitting parked in a field for over 11 years but we simply put a new battery on it, fresh diesel and it fired right up in less than 5 minutes! It's going to be a project to bring it back to life but it is amazing how durable that truck is. Minor rust on the floorboard, rotten air hoses and a leaking radiator is the only mechanical issue that we have seen. Certainly needs paint and body work but the bones are still solid. I have attached some pictures and will post updates regularly. Thanks for the help! Mike Edited April 12, 2017 by Mdmccurr 10 Quote Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-367104 Share on other sites More sharing options...
Mike Posted April 12, 2017 Share Posted April 12, 2017 Welcome, to BMT . You can fiberglass the hole to but metal done right is best. My 1 penny worth of BS. Quote Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-367110 Share on other sites More sharing options...
57 bcr Posted April 12, 2017 Share Posted April 12, 2017 Welcome! You've stopped at the right place. We have expert U model guy (umodelnut) in house. That is when he's not out chasing the girls in upstate New York! Al " Yo, Vinny" Quote IF YOU BOUGHT IT, A TRUCK BROUGHT IT..AND WHEN YOU'RE DONE WITH IT, A TRUCK WILL HAUL IT AWAY!!! Big John Trimble,WRVA Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-367118 Share on other sites More sharing options...
Timmyb Posted April 12, 2017 Share Posted April 12, 2017 This is an interesting subject. The guy who reapaired my roof overlapped the metal by about 1/4 inch. He is trade qualified, not just a back yarder. I wonder why he did that and not butt weld it? Quote Link to comment https://www.bigmacktrucks.com/topic/49474-floorboard-rust-on-1978-mack-u-model/#findComment-367121 Share on other sites More sharing options...
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