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R Cubed

GMC 352 Engine Conversion

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I think the majority of post-military users had far more problems with chassis cracking and bending than any of the mechanical components. Even the military had trouble with the chassis on the 353 van trucks, hence the various field mods to add strengthening braces.

 

- MG

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Nope not tenneritis more like fiftyitis :blush:

 

 

As I said previously, ouch, beginning to sound like a 2nd mortgage job:shocked:

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Looks like you have done admirably in that respect!

 

Although I think the extent of the alterations you've had to do is almost tantamount to confirming that it is not possible to put a 6B into a CCKW :D:D:D

 

Ahhh, but I have, and it seems very reliable at the moment, although you would have to be well up on your engineering and fabrication skills, as this beasty has pushed me nearly to the limit, however I do like a challange :wow:

 

Stay tuned for more instalments, if you are a purist on originality dont look any further as there is some serious cutting action to come, but as I have always maintained I would be able to put it back to original spec and I doubt if you did'nt know what had been done I doubt you would ever know, and I am getting about 16 miles to the gallon.

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Ahhh, but I have, and it seems very reliable at the moment, although you would have to be well up on your engineering and fabrication skills, as this beasty has pushed me nearly to the limit, however I do like a challange :wow:

 

Stay tuned for more instalments, if you are a purist on originality dont look any further as there is some serious cutting action to come, but as I have always maintained I would be able to put it back to original spec and I doubt if you did'nt know what had been done I doubt you would ever know, and I am getting about 16 miles to the gallon.

16mpg is pretty good Richard turning all those props, I recall the old Leyland 45 it was in gave me about 18 to 20 to the gallon when freighted to 10 tonne , enjoying your thread :thumbsup:

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This is all very interesting. I am currently working on putting a cummins 6BT in my M5 halftrack but I have taken a very different approach. The cummins engine I have came out of a bus which means it has a flat sump, the only thing I have had to get is a flywheel as buses run with torque converters. I have a Borg & Beck pressure plate and clutch which came out of the previous Ford cargo engine that my halftrack was fitted with when I bought it, and that fits directly on the cummins flywheel. I am now currently in the middle of machining an adaptor plate to fit the cummins engine to the original halftrack gearbox.

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Its a great thread for sure. I suppose it depends on how many miles you drive as wether a conversion of this size is worth it.

I think Richard has had this truck a fair while and I doubt he is any rush to sell it after all this work....well done.

I have found in our 353 careful driving and unloaded (of course we ALL run our historic vehicle unloaded don't we) I get around 9/10 mpg. My hoppo onlys gets about 5/7.....he wears a size 14 leaded boot!

With a margin of about 30p per gal in favour of petrol I would be interested to know what sort of miles are needed to recover the costs, if the conversion was carried out on a cost basis.

That said great thread and very interesting.

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Without doubt there have been more than enough GMCs used abused as lime spreaders in the 20 years following the war to establish with some certainty the weak points. I can only go on what I've been told by other people, some no longer with us, but I'm not aware of any ongoing issues with transfer boxes. However there are still a few former operators around who can testify to the CCKW's strengths and weaknesses.

 

One such example is an operator of several trucks who used to replace the banjo axle diffs with units from Chevrolets. He claimed that despite being a bit faster they were actually stronger than the standard CCKW diffs.

 

What do you reckon, Tom? :cool2:

 

 

My father in law ran two GMCs until 1968 as lime spreaders. They hauled chalk from quarry to farm and then spread on fields so they always carried a lot more weight than they were designed for. One had a Perkins engine which was a Perkins conversion kit. The other was fitted with a Ford engine and to do this the transfer box was moved back. Transfer boxes were hardly ever any trouble. As Tony says they were indeed ran on Chevrolet diffs again not a lot of trouble apart from a few bearing troubles. They always ran on 900 x 20 tyres, rear trunnions were troublesome. Ransomes of Ipswich made some stronger ones which seem to cure the problem. Probably the biggest problem was the short intermediate shaft between the gear box and transfer box mainly due we think to using English UJs. The grease nipple holes were bigger than American ones and this is where they seem to break. We found we normally broke them when spreading on freshly ploughed land where they were sinking in and getting plenty of traction. When considering the work that they were doing they coped very well. I can see no problem with the above conversion as someone who has earnt a living in the past using one, it looks an excellent job.

 

Tom

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[ATTACH=CONFIG]100862[/ATTACH]Hope of interest. Tom.

 

By my calculation at 7.0 mpg Petrol ( what I got to Normandy and back last year ) and 16.00 MPG Diesel which sounds a bit good to me, and current fuel costs, Richard is going to be £375 better of every 1000 miles travelled.

 

Having had my transfer and gearbox out prior to Normandy last year I am only to well aware of the effort required to move these heavy lumps let alone resite them. The engineering job to get the Diesel job to work is first class...and I am well impressed, however its certainly not for me. part of the GMC CCKW thing is the sound and feel of that 6 Cyl Petrol engine, AND that's what went to war in WW2....

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As the engine conversion widow, I'm very proud of whst he achieved. In France last year we were so pleased with how well she went! The mpg now is awesome!!!!

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Hello R Cubed

 

Was wondering why you did not use the original transmission since your truck has a winch.

The transmission you used, Does it have overdrive ?

The Cummins is longer then the 270 GMC, You must cut through the cowl.

Jeff

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I'm waiting to see the cowl too, Jeff! :shocked: Even so, a top job R3!

 

Pretty much all of these modern boxes have an overdrive top, which should replicate the original box (CCKW 4th is top).

 

Some have pto provision but whilst the pto drive mounting might be similar, all that I have seen in UK are on the right hand side of box (is this universal on new boxes?) - the CCKW is on left.

 

Great pic Tom - she must have been like a Rolls Royce to drive compared to the Bedford alongside :-D

 

Tony

Edited by N.O.S.

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As the engine conversion widow, I'm very proud of whst he achieved. In France last year we were so pleased with how well she went! The mpg now is awesome!!!!

 

Hi Rosie,

You have every reason to be VERY proud of what the" cubed one" achieved and in my earlier post there was no knocking on my part as to that.

My point was on a fiscal basis only.Of course its his truck and is entitled as I ALWAYS maintain to as he pleases.

Good luck and hope you get very many cheap miles........;)

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Hi Richard,

 

I fitted one of these engines into a Diamond T Wrecker last year, which so far seems to be a success. I put the original DT gearbox on to it but had to change the clutch housing to the larger SAE 3 fitting which meant finding the larger flywheel, clutch, and starter motor. My question is, having retained the original SAE 2 clutch housing and gearbox, how did you adapt the gear change which I assume was remotely operated?

 

I had hoped to post some pictures of fitting the Cummins in to The DT, but have had problems with my computer and changed from Windows XP which was brilliant, to Windows 8 which to say the least has been a retrograde step and is crap. I have not been able to do half the functions I could do with XP, and posting pictures is one of them.

 

Tony.

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Hi Rosie,

You have every reason to be VERY proud of what the" cubed one" achieved and in my earlier post there was no knocking on my part as to that.

My point was on a fiscal basis only.Of course its his truck and is entitled as I ALWAYS maintain to as he pleases.

Good luck and hope you get very many cheap miles........;)

Awww hun I wasn't suggesting you were knocking it xxx

I was just joining in with the general chit chat!!!!

we were aware of how many differing views people would have on the subject and we are happy with other peoples opinions. He did it so we now have the chance to attend other shows slightly further away.

Cost me a fortune in tea and bacon sarnies that's for sure!!!!!!!!

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Hi Richard,

 

I fitted one of these engines into a Diamond T Wrecker last year, which so far seems to be a success. I put the original DT gearbox on to it but had to change the clutch housing to the larger SAE 3 fitting which meant finding the larger flywheel, clutch, and starter motor. My question is, having retained the original SAE 2 clutch housing and gearbox, how did you adapt the gear change which I assume was remotely operated?

Tony.

Tony,

 

To avoid confusion, SAE 3 is smaller than SAE 2. You converted from SAE 3 to SAE 2 :).

 

- MG

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Hello R Cubed

 

Was wondering why you did not use the original transmission since your truck has a winch.

The transmission you used, Does it have overdrive ?

The Cummins is longer then the 270 GMC, You must cut through the cowl.

Jeff

 

Well Jeff, mainly as the cummins came with the zf gearbox I thought it would be the sensible route to take as it is designed for the cummins engine power output and torque also the clutch is designed to work with both, I have heard some shafts and gears in the GMC Clarke gearboxes are prone to failing, I think 3rd gear as it is only a press fir to another gear and also are very hard to get hold of.

The ZF box is a 5 speed box 1st is between 1st and 2nd on the clarke box, 2nd on the ZF is between 2nd and 3rd on the clarke box, and so on untill you get to 4th on the ZF which is 1:1 and then 5th on the ZF is variable depending on the spec of the box but all are very close to 5th on the clarke box something like 0.97:1

The ZF box has standard PTO take off blank plates on both sides of the box and I am yet to fit the winch PTO to it, a still to do job.

The Cummins and the ZF box are much longer so yes I have cut the firewall but will all have to wait for that.

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Hi Richard,

 

I fitted one of these engines into a Diamond T Wrecker last year, which so far seems to be a success. I put the original DT gearbox on to it but had to change the clutch housing to the larger SAE 3 fitting which meant finding the larger flywheel, clutch, and starter motor. My question is, having retained the original SAE 2 clutch housing and gearbox, how did you adapt the gear change which I assume was remotely operated?

 

I had hoped to post some pictures of fitting the Cummins in to The DT, but have had problems with my computer and changed from Windows XP which was brilliant, to Windows 8 which to say the least has been a retrograde step and is crap. I have not been able to do half the functions I could do with XP, and posting pictures is one of them.

 

Tony.

 

Yep you are spot on the Leyland DAF trucks are all COE and so the gear leaver opperation is via a very strange bar assembly to the side opperated leaver on the gearbox, more on this later too you are all jumping the gun here just sit back and be patient all the goury details will come out sooner or later you are all just going to have to wait. :cool2:

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Tony,

 

To avoid confusion, SAE 3 is smaller than SAE 2. You converted from SAE 3 to SAE 2 :).

 

- MG

 

Yes Mike you are correct, another senior moment on my part!!!

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Trying to put all this in to a logical order, so I think the next step would be to go over the engine and gearbox mounts as it's about this stage that I had decided on the final position of the engine and gearbox.

I was fortunate that the kind person who took the engine and box out ( you know who you are :cool2: ) also took the gearbox mounts off the donor chassis, so I had the brackets which bolt to the gearbox bell housing the rubber mounts and the brackets which would have been rivited to the chassis, a stroke of luck was these chassis brackets fitted with out much adjustment :shocked: but the position on the inside of my chassis rails meant the rivets for the front mounts for the cab were in the way so they had to go and I took the decision to make some new cab mount brackets rarther than cut the originals ( good aren't I )

 

So here are the gearbox chassis mounts there was only a need to split the two parts and move them a tiny bit but too much to not do it but there you are.

 

IMG_5603 (600 x 450).jpg

 

The fourth pic is the bracket which bolts to the gearbox and it's rubber mount, one each side of the bell housing.

IMG_5539 (600 x 450).jpg

 

Cab mount brackets, spot the difference !! yep my one is the bigger and thicker one. The reason for this was that the green bracket is the original one and where they were riveted to the chassis put the rivets in the way of the gearbox chassis mounts. Making the new cab mounting brackets which were longer, meant I could use the same bolts which held the gearbox mounts to the chassis to also hold the cab mounts. Cool.

IMAG0903 (600 x 359).jpg

 

IMAG0905 (600 x 359).jpg

 

 

The next pics are of the original front engine mount and how it comes apart and the parts of it. In the third pic there is from left to right the oil cover for the rubber mount the metal plate is a retaining plate to stop the mount coming apart the third bit is the old rubber mount in it's steel holder and the last bit on the right is the new rubber mount ready to go in place of the old mount.

 

IMG_5536 (600 x 450).jpg

 

IMG_5538 (600 x 450).jpg

 

This is the start of the front engine mounting bracket, nice thick bit of c section channel to fit over the engine mount rubber, and provide a base for the rest of the bracket to fit the engine.

 

IMG_5583 (600 x 450).jpg

 

Here you can see the new 12mm thick side plates for the engine which are at the moment just tacked to the cross piece under the front pulley.

IMG_5587 (600 x 450).jpg

 

Here is the finished front mount with some added cross fillets added.

IMG_5689 (600 x 450).jpg

IMG_5602 (600 x 450).jpg

IMG_5601 (600 x 450).jpg

IMG_5537 (600 x 450).jpg

IMG_5535 (600 x 450).jpg

IMAG0904 (600 x 359).jpg

IMAG0902 (600 x 359).jpg

IMG_5688 (600 x 450).jpg

IMG_5586 (600 x 450).jpg

IMG_5553 (600 x 450).jpg

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Awesome work so far, great ingenuity to overcome little problems all so it can be returned to the original spec, yes it's given you more work but it proves that the people on this forum are a talented bunch.

 

For me swapping to diesel in they way you are is great, you can attend more shows and keep the truck history alive and if needed the original can be put back. Great work sir, I hope to see it in person one day.

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This is all very interesting. I am currently working on putting a cummins 6BT in my M5 halftrack but I have taken a very different approach. The cummins engine I have came out of a bus which means it has a flat sump, the only thing I have had to get is a flywheel as buses run with torque converters. I have a Borg & Beck pressure plate and clutch which came out of the previous Ford cargo engine that my halftrack was fitted with when I bought it, and that fits directly on the cummins flywheel. I am now currently in the middle of machining an adaptor plate to fit the cummins engine to the original halftrack gearbox.

Hi Jamie,

We fitted a 6BT to an International HT something like 10 years ago. We were discussing it yesterday and we are sure the engine just bolted straight on. Has yours got a non-original gearbox?

- MG

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Hello Mike,

 

Yes I have an original gearbox, the bell-housing of the engine and gearbox is about an 1 1/2" difference.

I have made my adaptor plate now and all bolts together perfect.

I will start a thread soon about the plate and conversion.

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Sounds like a different SAE flywheel housing. Early engines had just one size but later engines like the 6B can be fitted with a choice of SAE size housing, so it pays to check what you need first.

 

If you're lucky you might be able to obtain / swap the necessary housing and flywheel but breakers are often not willing to split a complete engine as the foreign buyers sometimes get wary when an engine has been tampered with.

 

Also worth remembering that some engine types are available with optional housings to accommodate starter on either side - another very useful feature for us!

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