View Full Version : D2 Generator to alt conversion

04-04-2009, 11:46 PM
I am working on a generator to a Alterator conversion and i was wondering if ther were others out ther that would be intrested in buying one or having me convert your generator i will be posting some pic when i get it done so you can see how i did it thanks pm if you want

04-05-2009, 03:51 AM
2bluejon - I'd be interested in seeing the design you produce. My best buddy is a machinist, and we are looking at fabricating an all-steel, alternator conversion for the D4400 engine. I have a D4400 generator and a U/S engine to work from.
I guess the secret is to keep it simple, and the machining to a minimum. I had thoughts of using a larger size, vehicle water pump shaft, about 3/4" diameter and around 8" long, for the main shaft.

The water pump shafts come complete with a sealed needle roller bearing .. but I could see that perhaps the drawback might be the cost, over the counter, at a bearing supplier.

I have another buddy who has a huge stock of surplus commercial products such as bulk bearings, couplers, and whatnot .. who may be a better (read cheaper) source of shaft and bearings.

I'd like to see how many people would be interested in a conversion adaptor, and whether they would be happy supplying their own pulley, or would want it complete, ready to run. I'd also like to get a $$ figure that people would be happy to pay. I'm thinking around about US$250. Any advice/thoughts/recommendations welcomed.

Old Magnet
04-05-2009, 11:02 AM
If it's another variation of these types I'd be interested.....if it's another piggy back generator type.....no thanks.

I would think the most useful conversion would be the double belt pulley version that would also replace that "mickey mouse" adjustable pulley arrangement as well as mount the alternator.

04-05-2009, 02:19 PM
Well looking at the pic you posted i think that the one i am makeing will be the same yours looks good

Old Magnet
04-05-2009, 02:50 PM
Hi 2bluejon,
Didn't mean to imply that it was one of mine, or that I was the fabricator. Just another variation that is already out there. The pictures were provided by one of the BB posters....and the unit purchased in Canada....not sure where as I didn't get any more info on follow up questions. I'd be interested in seeing your version.

04-05-2009, 06:16 PM
OM - Does the standard drive arrangement of the earlier generator setups, develop enough RPM to run an alternator directly, as in the setup you pictured? I see in the parts book where there are numerous size gearsets, with later ones appearing to have smaller and smaller gears, to obviously increase generator speed.

The RD-4 engine I have, has a 26 tooth gear on the generator .. but I haven't counted the gearset teeth yet, to determine the generator RPM.
At a quick glance it appears that the generator is only doing about 1500-1800RPM at rated engine RPM, and I was under the impression that alternators need more RPM than this to produce adequate output.
I do understand that alternators produce near maximum output at relatively low speed, but I have never seen the actual RPM figure.

D318 Marine
04-05-2009, 07:27 PM
Oz, at that rpm a one wire delco rated at 65amps should put out about twenty. More than enough to charge a starting battery. The alternator pictured looks just like the one I built for my d318 marine. I have never seen or heard of another one either. Some minds just think alike I guess.
On the one I built I used a lovejoy coupling to join up the shafts.

Old Magnet
04-05-2009, 08:53 PM
Hi Oz,
The low rpm cut in one wire regulators and also the 2/3 wire low cut in units will start producing amperage (reduced) as low as 1200 rpm with 1200 - 1500 as an operating range. You have to watch the gear ratios for the installation. For example the D318 & D315 drives used with 24V systems typically have a drive of 33T crank, 66T cam, 17T idler and 19Tooth generator drive gear. This gives an overall ratio of about 1.73 times engine rpm so at say 1400 engine rpm your at about 2422 rpm on the drive.

With the same crank and cam gears but with the 26T (single) generator drive gear your at a 1.27 times engine rpm or about 1778 rpm generator drive.

The D4 full load engine rpm is less so dropping back to a 1.27 times say 1200 operating gives a 1524 rpm on the generator which is still withing the low cut in range but is not going to be a high amp output but ample to keep batteries charged.

04-05-2009, 10:04 PM
One Wire alternator. 12 Volt 63 amp.
Excitation speed 850-900 rpm rotor speed
14 volts reached at 1200 rpm
45 amps at 2100 rpm 14.5 volts
the way that i am figuring i think that this will do the job when i get the nose peice built i am going to put it in the cat and i have a RPM meater and i am going to see what the low idle and the high rpm is that is coming out of the old gen shaft thanks i will keep you posted

04-06-2009, 06:58 AM
OM - Thanks for the assistance with those figures. I like the idea of the direct coupled alternator, it's whole lot more compact and the adaptor should be simpler to build, too.

Old Magnet
04-06-2009, 09:24 AM
Found yet another picture of a direct drive unit.....good view of coupling and cooling fan feature.

04-06-2009, 02:53 PM
Has anyone ever seen a later (1V series) DW10, with the D318, with a direct electric starter? My bellhousing is already drilled and has a bolt on cover plate on it, but there doesn't appear to be enough room between it and the shaft coming out of the steering box to allow one to fit. It would have to have a very short starter body to make it work.
Just curious...

04-07-2009, 08:18 PM
Well tonight i put part of the alt together and i did a RPM CK and the Low Rpm was 1100 and the High Rpm was about 3100 so i think that that is enuf rpm that was coming off the back of the old gen shaft in the cat thanks

8C 361
04-08-2009, 02:30 AM
On the Farmall board some of the guys speak highly of the Japanese alternators they use on Nissan trucks. Maybe that would be something to consider.


04-08-2009, 01:55 PM
Please post a price of your kit when it is finished. I would be interested in one if price is reasonable.

05-01-2009, 08:47 AM
OM - How many different generators are there on the older Cats? I have one off the RD-4 that we are currently designing an adaptor for .. but I wondered how many different adaptors are needed to cover all the engines from the mid 1930's to the late 1950's.

My buddy and I have been doing some brainstorming, and have come up with a simple, compact adaptor that utilises a 10SI alternator, fitted directly to the generator drive gear.
We believe this setup is simple and effective .. and will be a lot cheaper than the designs you pictured previously, that entailed using a lovejoy coupler.
There is a small amount of extra work involved in coupling/decoupling the alternator, over and above the lovejoy coupler design .. but not enough to make coupling/decoupling a chore.

Our design involves the requirement of some machining on the inner bore of the generator gear .. as well as a specially-machined, sleeve-style, retaining nut .. to enable the coupling of the gear directly to the alternator shaft. The alternator pulley is removed, but the fan is left in position. There is one additional bearing and a spacer in the design, besides the mounting/adaptor plate.
We should have the working model finished and installed on the D4400 by next weekend.
Pics will follow, and if general approval by consensus, of the design, is reached, we will have the adaptor available for general sale.

Old Magnet
05-01-2009, 10:04 AM
Hi Oz,
I haven't really payed that much attention. There certainly are many styles but I don't think there are more than two-possibly three different diameters. I am guessing but will root around in my assortment and measure what I have.

I could live without a flex coupling if you can control alignment but I feel the cooling fan is a must, along with ventilation flow. Be sure to include the adjustment slots in the ASME flange mounting if you are starting new.
Will this be a two bearing or three bearing shaft arrangement when assembled?

05-02-2009, 09:04 AM
The new flange mounting will be a nearly exact copy of the original Cat generator flange .. and there will be one extra bearing, mounted in the centre of the new flange mounting plate.

The fan stays in place .. the pulley is removed .. and spacers and bearing are fitted onto the end of the alternator (rotor) shaft. The flange mounting is slipped over the bearing with a normal bearing installation clearance fit. The spacers and bearing are retained by a sleeve-style, or barrel-style, specially machined nut .. which effectively carries the bearing and gear.
This sleeve-style nut, when tightened on the rotor shaft thread, clamps the gear, spacers, additional bearing, and rotor shaft, tightly together .. exactly as happens when the nut on the pulley is tightened under normal alternator assembly.

There are angle-iron brackets welded to the flange mounting plate, which mate with the original alternator bottom mounting lug, and the adjuster lug .. and two bolts in these lugs retain the alternator in position, and align it. The additional bearing also assists with alignment.

For alternator replacement, the entire assembly is unbolted at the mounting flange, and the sleeve-style nut undone, to disassemble.
A new or replacement alternator then has the pulley removed, and the spacers, bearing, flange mounting plate, gear and sleeve-style nut, are reassembled and tightened. The whole assembly is then bolted back up to the timing cover.

Why are the slots needed in the flange mounting? .. is there a range of different mounting holes between the various Cat engines? Many thanks for your great assistance.

Old Magnet
05-02-2009, 10:31 AM
Hi Oz,
Generally a three bearing support requires the flexibility of a coupling to maintain alignment and equal bearing loading.

In reading your description a seems you have three bearings on the shaft, the two alternator bearings plus the drive end bearing supported on your sleeve. This would appear to give you two bearing support (desired for no coupling) but the clamping of the alternator housing returns it to a three bearing support with the coupling requirement again.

The slots are your gear mesh/backlash adjustment. It is not a full diameter piloted mount so there is room to float (rotate around the bottom bolt axis) the mounting. Not sure you could guarantee mounting if you have a fixed flange drilling. All the factory generators I've seen have the slotted flange.

If I am envisioning this correctly the angle iron brackets are standoffs (horizontal) for the alternator mounting and provides the ventilation access, is that correct? Should work fine and avoid a lot of lathe work.

Will get the dimensions I mentioned today.

Out of six generators I find housing diameters of:
4 3/8
4 1/2
4 7/8
5 1/2 (24V unit)

All are adapted with various bolt pattern end plates to fit the one SAE dimension flange.

05-02-2009, 06:47 PM
OM - O.K., thanks for the info in relation to the reasons for the flange mounting slotting. The gear mesh adjustment reason never occurred to me.

I understand where you're coming from, on the 3 bearing support requiring a coupling to eliminate rotor shaft stress. I don't believe this will be a problem on our adaptor, because of the following reasons ..

1. The assembled components comprise a very stiff assembly, able to withstand any small amount of misalignment.

2. Bolting up the alternator housing will not create any serious misalignment, as the angle-iron brackets will be welded into positions that will essentially keep the alternator in line.

3. Any slight misalignment will be compensated for, by the third bearing being able to twist slightly in the mounting flange, with normal bearing fit clearance of, say, .0005" to .001".

4. The rotational speeds are not substantial enough to create high shaft stress. The alternator rotor shaft is a pretty robust shaft (17mm diameter), and I seem to recall the alternators are regularly capable of, and attain, speeds of up to 12,000-14,000 RPM under high-speed automotive use. We're talking about 1/8 of these speeds in antique Cat tractor applications.

Yes, the angle iron brackets will be a stand-off style. The fan will be running fairly close to the mounting flange plate, as this assists in air flow, anyway.

My other concern would be related to trash and dust getting sucked through the alternator on a constant basis, as is common with nearly all crawler applications. Has this ever posed a problem to tractor owners who currently have Delco 10SI's fitted?

I would imagine a light trash screen, mounted on the rear of the alternator, would be a highly advisable addition.
The standard Cat alternators and generators, have, or have had, generous-size bearings, that coped with heavy concentrations of dust and trash .. as well as inbuilt trash screens.
I'm not sure that the automotive bearings in the 10SI have the same ability to cope with heavy dust and trash concentrations. I'd like to hear opinions.

Old Magnet
05-02-2009, 07:08 PM
You can have a go at the ridged shaft if you like but bare in mind there is a reason for both quality conversions on the market having flex couplings. The test will be bearing and/or shaft life.

As far as dust control for the 10SI there are two options for mounting screens on the back of the alternator. One is the marine application which uses a combined flame arrester/screen consisting of three layers of fine mesh built in to a cover housing. The other is referred to as a "chaff" screen which is similar to the marine unit but one layer of screening and a lighter cover housing.

Bearings in the 10SI are the needle bearing prelubed type on the back end and prelubed enclosed ball bearing on the front.......adequate but not what I would call beefy.

Got the "Supper" call, will add more later:) :)

05-02-2009, 09:16 PM
I would simply remove the bearing next to the fan on the alternator. It's pretty simple to get into one of these and reassemble when you are through. That would eliminate the stress on the shaft and only require a longer spacer between your female threaded shaft extension and the shoulder on the rotor shaft. Any misalignment (inherent in a welded assembly) will result in a cracked housing or cracked hollow shaft extension at the point where the threads end and the solid portion of the shaft begins. I don't believe the bearing will be able to self-align and relieve the stress on the shaft. The most likely misalignment (radial?) will cause a bending of the shaft with every rotation.

Do be aware that some of these alternators have varying lengths of shaft where the pulley mounts which could require modification of the spacers/shaft extension length.

It would be a special order, but the 10SI can be had without many of the normal perforations on the rear of the housing (opposite the drive end). I used to have one that was retrofitted onto a machine by our local gen/starter shop, way back when. I haven't seen any lately like that. The tendency is to demand more and more amps these days with some of these alternators rated @ 90 amps, so for these, cooling is very important. Just keeping the battery charged on a dozer would not likely require very much in the way of cooling.

The delcos don't last forever under agricultural use, but are readily available and easily repairable. In addition, there are several competetive makes that will bolt into the same dimension mounts and use the same connectors.

Old Magnet
05-03-2009, 10:26 AM
ccjersey hits on where I was going with my previous post but I had a heck of a time finding the pictures I wanted showing the option.....had filed it in my "junk" file:rolleyes: :rolleyes:

This approach could satisfy the "gypo" requirements as a cheap solution. This is a current commercial available unit that is a prime example of how not to do it.....free hand torch cut flange, no slotted holes for adjustment and convenient mounting bolt indexing that interferes with lugs on the alternator casting. Does not have a cooling fan.......but does not require a coupling.
Also seems to be a problem of enough space for the mounting bolt wrench access on some of the housings.

But......all is not lost.....if done properly it could be a satisfactory application.
If used at a low amperage (battery charging) mode the amount of heat generated may not be that severe. Also as a one wire set up using the low voltage cut in that eliminates the tri-diode set up you only have to deal with the voltage regulation electronics.

05-03-2009, 07:46 PM
Old magnet. That could be a good idea, just use a ND alt like on a chrysler product where the fan is internal to the alt.

09-01-2009, 08:09 AM
G'Day all! - Well just a little update here .. OzD has been hard at work, figgerin' the ultimate design for an alternator drive adaptor for the old Cats .. and my machinist buddy and I, have finally produced the working prototype ..

Voila! .. the piece-de-resistance!! .. :)

A. http://img134.imageshack.us/img134/2849/alt01.th.jpg (http://img134.imageshack.us/i/alt01.jpg/)

The design of this adaptor has taken us a few weeks of brain racking .. design .. redesign .. rethink .. redo .. and generally running into blind alleys .. until we came up with a design that was as simple and robust as we could get .. without involving vast amounts of components, and work.

After discussions in previous posts, with Old Magnet and ccjersey .. who both inputted excellent advice .. we finally settled on the following ..

1. The adaptor is steel, and comprises machined and welded components ..

2. The design involves a short shaft, carried on two standard 6207 ball bearings .. separated by a spacer, and retained by a circlip .. this shaft is located in a machined, heavy-wall-tube housing .. which is welded into the mounting flange plate ..

3. The original generator drive gear is used, without modification. The original gear is unbolted from the genny, and slipped on the keyed shaft, and retained by the same nut and woodruff key as original ..

4. The mounting flange plate is slotted for drive gear depth adjustment, as recommended by Old Magnet ..

5. The design has a Lovejoy coupler, bolted to the short shaft, as the connection between the adaptor drive shaft and the alternator ..

6. The alternator used, is a standard Delco 10SI, of the voltage, and number of wire connections, of your choice.
There are NO alternator housing modifications, or specially machined faces, or any fancy parts required, to bolt up a bog-standard Delco 10SI.
This allows 5-10 minute changeover of any faulty alternator, and the end user can acquire and utilise a new or used Delco of his choice, and in his price range.
You can run down the street, and pick up a $20 alternator from a wrecked Chevy, and use that, if you wish.

7. The alternator half of the Lovejoy coupler is machined to fit the standard 10SI shaft. The nut is unscrewed, the pulley removed .. and the Lovejoy coupler spider is slipped on and retained by the same nut as original .. the alternator fan stays in position, and is retained on the alternator shaft, precisely the same as original ..

8. The alternator is retained by using a specially-machined stud that fits the lower housing mount hole in the standard 10SI .. with a nut and washer added .. and the top of the alternator is retained by utilising a bolt screwed into the top adjuster lug.
This effectively means that the alternator is retained in precisely the same manner as when fitted to any auto engine ..

To install the alternator, the Lovejoy spider is bolted to the alternator .. the alternator is lifted into alignment with the specially-machined stud .. then slid on .. with just a wriggle to align the Lovejoy coupler spiders .. then the nut and washer screwed on the stud and tightened .. and then the top bolt is screwed into the adjuster lug and tightened ..

Unfortunately, the cost of manufacturing the adaptor, is not as low as I would have liked .. and I don't think we can compete with any commercial adaptor produced in the U.S. This adaptor has ended up weighing around 10 lbs (4.5 kgs) and freight is a killer for any distance nowadays.

We are looking at AU$400 (US$300) for one adaptor, complete with new hardware and installation instructions. Freight anywhere in Australia will be AU$20 .. but freight costs to the US are in the order of AU$100 (US$80).
Hopefully, we will be able to supply enough of these adaptors to Aussie customers, to turn a small profit ..

The adaptor pictured in this set, is our prototype. There will be minor design modifications to the final product. We erred with some length measurements on the prototype, because we never had the RD-4 engine handy to recheck our distances.
The rear mounting plate will end up a lot closer to the alternator fan, in the final design .. with the 80mm tubing that covers the Lovejoy coupler being lengthened by about 3/8" (10mm) .. and spacers between alternator and adaptor being about 3/8" (10mm) shorter, accordingly ..

At present, we are only producing an adaptor for the D4400 engine. If someone wants one for a D3400, we will need accurate diagrams, or a D2 generator, to calculate the modifications required for any other drive gear size (the RD-4 gear is 26 teeth) ..

Here is a heap of pics showing the alternator coupled and de-coupled, and fitted to the RD-4 engine ..

B. http://img522.imageshack.us/img522/6223/alt03.th.jpg (http://img522.imageshack.us/i/alt03.jpg/)

C. http://img522.imageshack.us/img522/134/alt04w.th.jpg (http://img522.imageshack.us/i/alt04w.jpg/)

D. http://img522.imageshack.us/img522/998/alt06.th.jpg (http://img522.imageshack.us/i/alt06.jpg/)

E. http://img522.imageshack.us/img522/9288/alt07.th.jpg (http://img522.imageshack.us/i/alt07.jpg/)

F. http://img522.imageshack.us/img522/9962/alt08.th.jpg (http://img522.imageshack.us/i/alt08.jpg/)

G. http://img522.imageshack.us/img522/1146/alt10.th.jpg (http://img522.imageshack.us/i/alt10.jpg/)

H. http://img522.imageshack.us/img522/1866/alt12.th.jpg (http://img522.imageshack.us/i/alt12.jpg/)

Old Magnet
09-01-2009, 09:37 AM
Hi Oz,
Looks good:) :) ...appears you have included all the design requirements. Basically the same as current US production units except your mounting accommodates the generic alternator without having to use the Delco/Motorolla conversion three bolt hole end housing. Might consider looking into an aluminum casting to help with the weight issue.

Have you done a run trial at speed yet?. Curious to see if the bolt/stud and coupling version will control vibration/alignment as well as the piloted housing mount versions.

09-01-2009, 08:14 PM
OM - Thanks for the kudos. No, we haven't done a run at speed yet, but we don't see any major problems, as the operating RPM is low. We will look for an RD-4/D4 owner shortly, to test her out .. :)

The aluminum casting hasn't been seriously considered .. but now we have the final design, we could look into that. We were under the impression that a low production run of an aluminum casting wouldn't reduce costs by any serious amount .. and the weight saving would only be, maybe 2 or 3 lbs.

The Lovejoy coupler alone, still weighs around 2 lbs, even after machining .. and coupled with the need for the shaft and bearings, the only weight saving is in the housing .. making the total weight, still up around the 7 or 8 lbs mark.

09-01-2009, 09:10 PM
I think it's a good looking design. I doubt it will have any significant vibration problem since it's driven by an axial connection instead of a belt and the spider of the coupling will damp some of the vibrations from being driven by a diesel engine.

You could go with crescent or triangle shaped pieces of steel for the stand-offs at bottom and top to spread the contact across more of the surface of the alternator if you think there might be a problem.

Well that won't work, looking at the picture, there is a raised boss around both the top and bottom bolt holes which would prevent any contact beyond your bushing anyway.

A stand-off made from plate would need to be countersunk to allow the surface of the alternator mounting ears to contact instead of just the boss around the hole if you wanted to get some additional stability.

Old Magnet
09-03-2009, 09:41 AM
On these old engines....everything vibrates....and ya never know what's in tune with what to amplify movement. The two point mounting with limited contact area may not be sufficiently rigid in this application......as compared to the large three bolt mounting flange of the Motorola style adapter.

To cover the range of applications rpm's of up to about 2200 or so should be accommodated.

09-03-2009, 11:47 AM
How about a brace from a convenient spot on the side of the engine over to the tapped hole in the back of the alternator. Perhaps with oblong holes in it to get it aligned correctly before it is tightened down.

09-03-2009, 01:58 PM
Id have to agree with The Old Magnet has posted here.

With a two standoff approach floating in space there are major problems in the kinematics or lack there of beyond taking care of the inherent vibrations that Old Magnet has mentioned. There is nothing to control the yaw axis movement. You are relaying on the accuracy of the spot face on the two mounting standoffs to control that movement. The lower die cast hole in the Alternator being longer might give you some yaw axis control, but that hole is seldom coplanar with the axis of rotation of the rotor.

Anyone who has worked with GM automotive starters knows why they sell eccentric studs and tapered shims to go with those starters. The alternators are not any better in terms of mechanical repeatability as there is a huge variation in the mounting arrangement that must be adjusted for axially. These GM housings are poorly die cast but in the original application that is not as much of an issue as a belt driven arrangement can mitigate a lot of axial and angular misalignment that goes beyond what a Love Joy coupling can accommodate.

John from Fresno
09-05-2009, 01:04 PM
Here is an adapter made from aluminium.


10-07-2010, 12:23 PM
Have you tried to search their web site to get more information?? yuk!

does anyone know what their bracket/kit sells for??


Mike Walsh
10-07-2010, 04:47 PM
Have you tried to search their web site to get more information?? yuk!

does anyone know what their bracket/kit sells for??


$400 plus shipping last winter.

Old Magnet
10-07-2010, 05:28 PM
Hi Mike,
Did they give you any choice of alternator...Last one I knew about came with a Leece Neville unit....what a prize.

Mike Walsh
10-07-2010, 10:44 PM
I bought it but did not install it. I think you are correct. Probably have to replace it with a Motorola one of these days. I saw another post re whether Delco was a good choice. I have been told that Delco will not hold up either due to a lack of cooling.
We bought the same unit over ten years ago with a Motorola and never had any problems. Had to get the tractor out of the shop and put it to work.