B-61 Cab And Nose On 1974 R-model Chassis

[MackAttack01]

I have a 1957 b-61 that i want to take the cab and hood off of and put on my 1974 r-model frame because the b-model frame is junk and the r-model has a nicer set of rears and is more updatable. will this conversion work? i expect a extensive amount of fabrication but thats no problem i just want to make sure that its not completly impossible.

any info or links to web sites would be good

thanks,

matt

[Freightrain]

I know it's been done. Depending on what motor you have is how much room you have under the hood. I've seen a local guy do a late model type chassis and had to raise the cab up like 4" to get it to clear motor.

The one thing you'll find is the front axle is wider on the R chassis and the tires will be on the outside edge of front wheel well.

[theakerstwo]

I have a 1957 b-61 that i want to take the cab and hood off of and put on my 1974 r-model frame because the b-model frame is junk and the r-model has a nicer set of rears and is more updatable. will this conversion work? i expect a extensive amount of fabrication but thats no problem i just want to make sure that its not completly impossible.

any info or links to web sites would be good

thanks,

matt

I worked for mack when the Bmodel was still in production and for a few years after the R came out you could get a cab kit for a R and use the B frame and radiator so i think you could go the other way using a R frame on a Bcab.The B cab front bracket will have to be used for the cab mount and clutch linkage and the steer box should be used.

I have always wanted to use my B cab and front end on a late modeel straight frame and have checked in to it a little bit.I think the radiator will go down in side of the straight frame rail frame and the cab mounts can be fabed the way you want.

The rear engine mounts will have to be compact to fit in between the trans and frane rail but white and western star did it.

Then you can build a frame as you would like.You could install the steer box on the out side of the frame where it should be using alate steer box or i have a 1976 front alxe with the steer box built on it that would work on the front of a B.

But using a R frame may be better and mount the steer boz behind the axle.

[harryb]

I worked for make when the Bmodel was still in production and for a few years after the R came out you could get a cab kit for a R and use the B frame and radiator so i think you could go the other way using a R frame on a Bcab.The B cab front bracket will have to be used for the cab mount and clutch linkage and the steer box should be used.

I have always wanted to use my B cab and front end on a late modeel straight frame and have checked in to it a little bit.I think the radiator will go down in side of the straight frame rail frame and the cab mounts can be fabed the way you want.

The rear engine mounts will have to be compact to fit in between the trans and frane rail but white and western star did it.

Then you can build a frame as you would like.You could install the steer box on the out side of the frame where it should be using alate steer box or i have a 1976 front alxe with the steer box built on it that would work on the front of a B.

But using a R frame may be better and mount the steer boz behind the axle.

[Freightrain]

R cab onto a B frame: "BCR" was the designation

[harryb]

We are rebuilding a 1982 R model frame with E - 6 / 2 valve motor keeping all the R model frame running gear etc and we are going to fit the B 75 body panels so that once completed it will look like a B 75, but we have a truck that has later model running equipment. We will fit all the usual B 75 equipment such as fuel tanks and the B model cone shaped hubs on the rear spider wheels. We will keep the R model front axle and the spider hubs, they are not that different to the B model spiders. We have fitted the intercooler the sits over the motor because the B 75 front radiator does not have the space to fit the R model intercooler which is in front of the radiator. All said you can do the same with the B 61 however the engine bay is shorter and you cannot fit a clutch fan. Re the steering we suggest you keep the R model steering as it is ex factory, that means you know that it works to regulation. However you will need to fit the R model steering column in the B cab which is ok and if you have full power steer you can fit a smaller steering wheel or you can fit the steering colum from a B 75 series which is like the R model colum but it is a B model steering column. On the wider R model front axle we are keeping the R model axle and to cover extra width we are going to slice the left and right fenders and add a metal strip of say 3 inches thereby making the fender wider to cover the wheel. Or you can also add a wheel arc mould like many modern 4 wheel drives with wide wheels and similar to the current Macks. You will need to modify the internal fenders to allow for the R model equipment but this is relatively small work. And you can run the exhaust pipe directly under the cab not through the fender as the B models.

Also it is practical to raise the body panels say 2 to 3 inches to get more engine space under the hood. Another idea is if you raise the cab 3 inches you can lower the cab floor by 3 inches and combined with the R model steering there will be more cab space for the driver, this way you can fit a modern/current Bostram set of seats so you get a better ride. The cab and radiator mounts can be modified and positioned on the R model frame as required to fit the B model body panels

Overall think about the bus makers they buy a complete frame and fit the body to suit.

Whilst this is a Mack site, you may wish to look at the web page of Courtland Truck Works in California, they specialise doing Peterbilt retrofits, using later model equiped frames and fitting say 1950 body panels, you can get some interesting ideas and pictures of retrofits.

Also have a look at Matt Phaffs pictures on this Big Mack site showing his recent green B 61 model rebuild with an intercooled motor.

Good luck.

[harryb]

We are rebuilding a 1982 R model frame with E - 6 / 2 valve motor keeping all the R model frame running gear etc and we are going to fit the B 75 body panels so that once completed it will look like a B 75, but we have a truck that has later model running equipment. We will fit all the usual B 75 equipment such as fuel tanks and the B model cone shaped hubs on the rear spider wheels. We will keep the R model front axle and the spider hubs, they are not that different to the B model spiders. We have fitted the intercooler the sits over the motor because the B 75 front radiator does not have the space to fit the R model intercooler which is in front of the radiator. All said you can do the same with the B 61 however the engine bay is shorter and you cannot fit a clutch fan. Re the steering we suggest you keep the R model steering as it is ex factory, that means you know that it works to regulation. However you will need to fit the R model steering column in the B cab which is ok and if you have full power steer you can fit a smaller steering wheel or you can fit the steering colum from a B 75 series which is like the R model colum but it is a B model steering column. On the wider R model front axle we are keeping the R model axle and to cover extra width we are going to slice the left and right fenders and add a metal strip of say 3 inches thereby making the fender wider to cover the wheel. Or you can also add a wheel arc mould like many modern 4 wheel drives with wide wheels and similar to the current Macks. You will need to modify the internal fenders to allow for the R model equipment but this is relatively small work. And you can run the exhaust pipe directly under the cab not through the fender as the B models.

Also it is practical to raise the body panels say 2 to 3 inches to get more engine space under the hood. Another idea is if you raise the cab 3 inches you can lower the cab floor by 3 inches and combined with the R model steering there will be more cab space for the driver, this way you can fit a modern/current Bostram set of seats so you get a better ride. The cab and radiator mounts can be modified and positioned on the R model frame as required to fit the B model body panels

Overall think about the bus makers they buy a complete frame and fit the body to suit.

Whilst this is a Mack site, you may wish to look at the web page of Courtland Truck Works in California, they specialise doing Peterbilt retrofits, using later model equiped frames and fitting say 1950 body panels, you can get some interesting ideas and pictures of retrofits.

Also have a look at Matt Phaffs pictures on this Big Mack site showing his recent green B 61 model rebuild with an intercooled motor.

Good luck.

[MackAttack01]

We are rebuilding a 1982 R model frame with E - 6 / 2 valve motor keeping all the R model frame running gear etc and we are going to fit the B 75 body panels so that once completed it will look like a B 75, but we have a truck that has later model running equipment. We will fit all the usual B 75 equipment such as fuel tanks and the B model cone shaped hubs on the rear spider wheels. We will keep the R model front axle and the spider hubs, they are not that different to the B model spiders. We have fitted the intercooler the sits over the motor because the B 75 front radiator does not have the space to fit the R model intercooler which is in front of the radiator. All said you can do the same with the B 61 however the engine bay is shorter and you cannot fit a clutch fan. Re the steering we suggest you keep the R model steering as it is ex factory, that means you know that it works to regulation. However you will need to fit the R model steering column in the B cab which is ok and if you have full power steer you can fit a smaller steering wheel or you can fit the steering colum from a B 75 series which is like the R model colum but it is a B model steering column. On the wider R model front axle we are keeping the R model axle and to cover extra width we are going to slice the left and right fenders and add a metal strip of say 3 inches thereby making the fender wider to cover the wheel. Or you can also add a wheel arc mould like many modern 4 wheel drives with wide wheels and similar to the current Macks. You will need to modify the internal fenders to allow for the R model equipment but this is relatively small work. And you can run the exhaust pipe directly under the cab not through the fender as the B models.

Also it is practical to raise the body panels say 2 to 3 inches to get more engine space under the hood. Another idea is if you raise the cab 3 inches you can lower the cab floor by 3 inches and combined with the R model steering there will be more cab space for the driver, this way you can fit a modern/current Bostram set of seats so you get a better ride. The cab and radiator mounts can be modified and positioned on the R model frame as required to fit the B model body panels

Overall think about the bus makers they buy a complete frame and fit the body to suit.

Whilst this is a Mack site, you may wish to look at the web page of Courtland Truck Works in California, they specialise doing Peterbilt retrofits, using later model equiped frames and fitting say 1950 body panels, you can get some interesting ideas and pictures of retrofits.

Also have a look at Matt Phaffs pictures on this Big Mack site showing his recent green B 61 model rebuild with an intercooled motor.

Good luck.

harryb- my only question is about registration, how do i register it? as a b-model and use the r-model frame numbers? i live in connecticut. also do the later r-models have a straight frame? my r-model has the wider frame in the front will i still be able to make it work with the radiator support and fitting all the tins on it?

thanks,

matt

[Lmackattack]

"East" coast R models all had the wider rails up front. Only the western RS/RL "R"models had straight rails. My advice is to register the truck with the B model title as the emisson laws are less strict and you could put cheep historic tags on if its not for hire. insurance is also cheeper with vintage tags!

[MackAttack01]

does the r-model straight frame models have the same width front end as the r-model wide frame models? the reason im asking is because i need to find a narrower front end for my conversion to make it fit right under the b-model fenders. is there any front ends that are narrower and will fit on my r-model wide frame?

thanks

[MackAttack01]

any one know? im trying to get all my ducks in a row before i start to conversion.

thanks

matt

[CML Service]

any one know? im trying to get all my ducks in a row before i start to conversion.

thanks

matt

Matt, RS type frames use narrow spring mounting same as early R. If you would like to take measurements I have RS, early R and B models sitting here. Give me a call.

Chuck