Merc M68 wants highway gears
- Thread starter oldblue
- Start date
Allan, what wheel bolt pattern on your M68? Is the Timken noisy or just too slow? There's a Timken in my '35 2 Ton, probably a 6.6 and I'm just trying to round up a 4.11 set for it now. Probably a 60s and later Ford pickup 9" would fit, depending on what pattern you need to match the front. ..B.
truckdog62563
Well-known member
There are three issues to cover with your M-68, which is the equal of the US F-3 model.
The first issue is what you've described, the 4.86/1 ratio that was standard in your Timken model 51524 axle. There was a 4.11/1 option for that axle, but I've heard of 3 total in the time I've been reading discussions on the subject. A 4.11/1 conversion is available from Chuck Mantiglia of Chuck's Trucks in CT. I have two of Chuck's gear sets in the front and back axles of my F-3 Marmon-Herrington. This would be an expensive solution and might not be what you are looking for, but if you want to keep the truck looking very stock, this is something to consider. The more common solution is to replace the Timken with a Dana 60 axle from a 1967 to 1972 F-250. These rear axles are, for the most part, a bolt in swap. Some minor drive shaft and parking brake mods are probably required, but nothing that can't be worked out.
The other thing this swap does (your second issue) is to eliminate your 14" rear brake drums replacing them with 12" drums. These 14" drums are the plague of the early F-3/M-68s because they required the use of the 17" wheels that were standard on these models (your third issue). The 17" wheels are a multi-part design that have come to be termed "widow makers". The technical term for the outer rim is Firestone RH-5°. You might look at the wheels and think they are a one piece design, but that will be a wrong first impression. Below are pictures of one of these wheels that show the joint along the middle of the wheel. These wheels are very dangerous and should be replaced. Once you've done your rear end swap, any 16" F-250 wheel having your 8 lug x 6.5" bolt pattern will fit the truck. If you want to keep use of the stock hub caps, there were early F-2/F-250 wheels that you could do a search for. Hope that's all understandable. Stu McMillan
The first issue is what you've described, the 4.86/1 ratio that was standard in your Timken model 51524 axle. There was a 4.11/1 option for that axle, but I've heard of 3 total in the time I've been reading discussions on the subject. A 4.11/1 conversion is available from Chuck Mantiglia of Chuck's Trucks in CT. I have two of Chuck's gear sets in the front and back axles of my F-3 Marmon-Herrington. This would be an expensive solution and might not be what you are looking for, but if you want to keep the truck looking very stock, this is something to consider. The more common solution is to replace the Timken with a Dana 60 axle from a 1967 to 1972 F-250. These rear axles are, for the most part, a bolt in swap. Some minor drive shaft and parking brake mods are probably required, but nothing that can't be worked out.
The other thing this swap does (your second issue) is to eliminate your 14" rear brake drums replacing them with 12" drums. These 14" drums are the plague of the early F-3/M-68s because they required the use of the 17" wheels that were standard on these models (your third issue). The 17" wheels are a multi-part design that have come to be termed "widow makers". The technical term for the outer rim is Firestone RH-5°. You might look at the wheels and think they are a one piece design, but that will be a wrong first impression. Below are pictures of one of these wheels that show the joint along the middle of the wheel. These wheels are very dangerous and should be replaced. Once you've done your rear end swap, any 16" F-250 wheel having your 8 lug x 6.5" bolt pattern will fit the truck. If you want to keep use of the stock hub caps, there were early F-2/F-250 wheels that you could do a search for. Hope that's all understandable. Stu McMillan
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