Build-up: Jeep YJ w/ Isuzu diesel

[iroc86]

I'll have to check out the spot blaster when I finish up my frame. Right now, it's way too cold to do anything outside... wind chill today is -6 degrees.

SHARPMACHINE, I really haven't looked into anything performance-related for the Isuzu. There is one fellow on the Isuzu board at 4btswaps.com who is designing a twin-turbo setup, though. I think he's shooting for 200 hp and 30 psi of boost pressure.

Sounds like a neat project, Roving Beetle. How much have you done so far?

I've spent the last few days trying to iron out some issues with the transmission and bellhousing. I was going to use one of the adapters from isuzudieselswapper.com, but there may be another way to do it. Dieseltim and I have been talking and he has an excellent idea for adapting an NV4500 to the Isuzu engine. I took some measurements and came up with my own design for the SM465 (or any GM manual with the Saginaw bolt pattern, for that matter).

First things first... I was never keen on using an adapter ring on the 4BD, because it necessitated two flywheels. The original Isuzu flywheel was used for the starter, and a separate Chevy flywheel held the clutch assembly. In some sense, it's a good idea because it essentially turns the back of the diesel into a Chevy V8, but there's a LOT of extra rotating mass on the crankshaft. I estimate about 50 pounds for the Chevy stuff, which is spaced approximately 2.5-3" from the Isuzu flywheel. Not only is there extra mass, but there's a moment affecting the rear main bearing when the clutch is disengaged.

Of course, this might not make a difference at all. The engine is internally balanced, so it's not like the flywheel is anything special. Dave at isuzudieselswapper.com assures me that the engine runs fine, but I'd rather have another alternative to compare it to.

The Isuzu flywheel is set into the engine about 7/8", as shown in the picture below. A Chevy V8's flywheel is something like 0.75-1" beyond the bellhousing mounting surface. So right there, there's a 1.5-2" disparity between the two. Add an adapter ring and you can see why such a thick spacer is needed to fit the Chevy flywheel to the Isuzu motor.




Now, dieseltim is adapting an Isuzu bellhousing to an NV4500. Not only is the bellhousing shorter than a Chevy, the Dodge version of the NV4500 has an input shaft that's about an inch longer than the Chevy. Assuming that you make the adapter thin enough, it's possible to use the Isuzu flywheel as your friction surface -- i.e. no need for a second flywheel. It handles the starter AND the clutch. It's a slick idea, and dieseltim is going to post some pictures when he can.

Unfortunately, this can't be done with the SM465 because the input shaft isn't long enough (it's only 6.5" from the case). Even with a half-inch adapter, the shaft barely engages the Isuzu pilot bearing.

My GMC truck was an automatic, so it has a HEAVY torque converter. I took some basic measurements and generated the following model to show what the stock setup looks like. I left the SM465 and adapter in the following picture, but it's just representative of the Isuzu automatic transmission.




The torque converter is blue, and you can see how it fills the entire bellhousing. It measures about 6.25" from end-to-end, while the case is about 5" thick. It weighs 55 pounds.

Since the SM465 input shaft is too short, a second flywheel is required. With a 1" thick adapter (green), the Chevy flywheel only needs spaced about 0.5" from the Isuzu flywheel to engage the pilot bearing.




Note that the clutch cover (red) doesn't fill the entire bellhousing. This is GOOD because it means there is a smaller moment on the engine rear main bearing. This is only an issue when the clutch is disengaged, but you could probably argue that the pilot bearing provides enough support. Either way, the moment is there.

The distance between flywheels is 0.5", which means a very short adapter. I figure it to be made from aluminum with a 6" diameter.

I conservatively estimated the clutch assembly weight: clutch cover (20 lbs), disc (5 lbs), flywheel (30 lbs), and flywheel adapter (6 lb). This totals 61 lbs.

Here's an overlay of both the Isuzu torque converter and the Chevy clutch assembly. The torque converter extends about an inch past the clutch cover. Assuming that the mass of the converter is uniformly distributed, this creates a moment that's about 25% GREATER than the Chevy stuff. (I'm not giving exact moments here because these are all approximate measurements, but they're close). The torque converter is supported by the automatic transmission better than the clutch cover by the manual, so it's hard to say if this really matters. It's six of one, half-dozen of the other...




So, what does all this mean? Based upon this preliminary analysis, let me sum it up:

• It's possible to adapt a Chevy transmission to an Isuzu engine using a "traditional" adapter ring and flywheel spacer, but we already knew that. Check isuzudieselswapper.com
• It's possible to adapt an Isuzu bellhousing to a Chevy transmission. The bolt holes match up and it's really just a round piece of stock. Nothing special there.
• A Chevy manual transmission has an input shaft that's too short (6.5") to use the Isuzu flywheel. As a result, you need to use two flywheels.
• Even with two flywheels and a Chevy clutch, the whole assembly is only 10% heavier than an Isuzu torque converter. However, the moment produced on the rear main bearing is about 25% LESS than the torque converter (if this really matters).
• Less material (and therefore less $$$) is required to adapt a Saginaw-style transmission to the 4BD. The parts just aren't as big.

Here are some pictures of the Chevy and Isuzu bellhousings, as well as the proposed adapter. Some material needs to be removed from the Isuzu bellhousing to fit the Chevy bolts.










It's hard to say which "two flywheel" method is better. Both add about the same amount of rotating mass to the engine, although the flywheel spacer from isuzudieselswapper.com is probably a bit heavier since it's longer. That method also allows the use of ANY Chevy transmission, not just Saginaw-style manuals. On the other hand, the Isuzu bellhousing adapter places the mass closer to the rear main bearing, reducing the moment over even the stock configuration. It also allows for a shorter driveline, since the Isuzu bellhousing + adapter is about as long as a Chevy bellhousing.

I still need to do some more analysis on this, so it's just rough for now. It'll be easier once I get some parts in my hands.

[dieseltim]

iroc86, don't drop the single flywheel idea just yet, I think I have a way for you to extend the pilot bearing to help the sm465 if your splines will engauge fully. I will get you a pic soon.

Dieseltim

[iroc86]

Anxiously awaiting, dieseltim...

I thought of extending the pilot bushing, but I didn't think the input shaft splines would fully engage the clutch disc. I'm finishing up measuring the parts with a CMM and I'll have some better numbers soon.

[dieseltim]

We have some clutch rebuild places here that can install any hub you want ( within reason), so I was thinking of maybe having a different center hub installed that would set the splines back farther away from the flywheel to make it engage the splines on the input shaft better, if you have to, this might help.

Dieseltim

[DURAtotheMAX]

Originally Posted by iroc86

My GMC truck was an automatic, so it has a HEAVY torque converter. I took some basic measurements and generated the following model to show what the stock setup looks like. I left the SM465 and adapter in the following picture, but it's just representative of the Isuzu automatic transmission.


The torque converter is blue, and you can see how it fills the entire bellhousing. It measures about 6.25" from end-to-end, while the case is about 5" thick. It weighs 55 pounds.

Since the SM465 input shaft is too short, a second flywheel is required. With a 1" thick adapter (green), the Chevy flywheel only needs spaced about 0.5" from the Isuzu flywheel to engage the pilot bearing.

Here's an overlay of both the Isuzu torque converter and the Chevy clutch assembly. The torque converter extends about an inch past the clutch cover. Assuming that the mass of the converter is uniformly distributed, this creates a moment that's about 25% GREATER than the Chevy stuff. (I'm not giving exact moments here because these are all approximate measurements, but they're close). The torque converter is supported by the automatic transmission better than the clutch cover by the manual, so it's hard to say if this really matters. It's six of one, half-dozen of the other...


It's hard to say which "two flywheel" method is better. Both add about the same amount of rotating mass to the engine, although the flywheel spacer from isuzudieselswapper.com is probably a bit heavier since it's longer. That method also allows the use of ANY Chevy transmission, not just Saginaw-style manuals. On the other hand, the Isuzu bellhousing adapter places the mass closer to the rear main bearing, reducing the moment over even the stock configuration. It also allows for a shorter driveline, since the Isuzu bellhousing + adapter is about as long as a Chevy bellhousing.

I still need to do some more analysis on this, so it's just rough for now. It'll be easier once I get some parts in my hands.

that auto should be an allison at545 or 645. 4 speed non OD non lockup. Might be able to sell it for some decent $, or at least the converter.

cool project...keep the pics coming!

ben

[dieseltim]

I have just a few pics of the start of this project. Hope this is enough to get someone else interested in trying this direction.
the oem isuzu 5 speed

comparing the NV4500 input from dodge to the isuzu 5speed shaft

inside of isuzu bellhousing after machining of bearing retainer

backside of isuzu after machining

inserting of the NV4500 bearing retainer

NV4500 bearing retainer inside isuzu bellhousing

More pics to come in the next week. Hopefully some of it being bolted together would be nice

Dieseltim

[tntcherokee]

Originally Posted by guidolyons

Because there is no going back...you have reached the point of no return. You must go forward or you will surely perish.

That spot blaster might work pretty well. It only does about a quarter sized spot at a time, but has a rubber snout and a little bag that catches and recycles the sand/rust junk. I didn't see it on the HF website, but I've seen them in the store. Looks similar like this:

Attachment 346943

EDIT: Found it: ITEM 96972-0VGA $12.99

Attachment 346945

Ive always thought those kind with the bag on the bottom worked pretty poorly especially if humidity is up. Ive used this type with great results. A few more bucks but they work real nice.
http://www.zendextool.com/speedblaster/

[dieseltim]

as you can see here the dodge clutch disk is just a bit too big in dia. I plan to take off about 1/4" and then it will work with the isuzu pressure plate.

Here you can see that I did get the plate drilled and it fits on the NV4500 like it was made from the factory LOL.

In this pic you can see the backside of the plate and that it is bolted up to the isuzu bellhousing

Tomorrow I will try to get it drilled up to the dodge NV4500 transmission and then bolt it up to the engine for a trial fit to see how the clutch and input spline length works out. Then I can finally cut it down to the right shape, and get rid of the excess.

Dieseltim

[war pony]

I would like to keep an eye on your build. I have a 62 scout ,with the thought of going 4bt I do however have that same motor I am trying to hold out for 4bt . Iam runin a dana 60 hp left from a ford and the starter and exhaust is left on the isuzu. Good eng. I here guys geting 30 mpg in chevy pu.

[iroc86]

So much for using Photobucket... according to their traffic reports, my account has already exceeded 20 GB of data transfer in the last month. Must be a popular thread. I edited the other posts and put my images elsewhere.

[navymark08]

Yeah, I hear you on that one. I received a similar email from them about a week ago and all the images on my thread are frozen until the end of the month. I don't want to, and won't pay them for the storage. From talking with friends, flickr and webshots seem to be good alternatives to photobucket.

[dieseltim]

Well, so far I have not been locked out yet. So, here are some pics of the NV4500 bolted to the adapter plate and then bolted to the isuzu bellhousing from the 5speed all behind the 4bd2tc that is going to end up in my CJ7


Here is the pic of the front side, the dodge bearing retainer and throwout bearing installed on the isuzu clutch arm.



Here is the whole assy bolted together.



Dieseltim

[iroc86]

Lookin' good, Tim! Can't wait to see that thing in action.

I spoke to my machinist friend today, and he's going to cut some material for me. If all goes well, I might have my adapter done by the weekend!

[guidolyons]

Originally Posted by tntcherokee

Ive always thought those kind with the bag on the bottom worked pretty poorly especially if humidity is up. Ive used this type with great results. A few more bucks but they work real nice.
http://www.zendextool.com/speedblaster/

Yeah...I have a regular sandblaster, BUT the nice thing about the spot blaster is the rubber tip that contains the blasting media, so there is not a huge mess to clean up if you can't roll the chassis out of the garage.


Diesletim...that is come good tech!

[cherokeefreak92]

That looks really cool, iv never seen that done with trannys like that.

[richharr]

Wow, this is awesome. What does the wiring task consist of? relative a FI v8 swap.

[dieseltim]

richharr,
The 4bd engines are mechanic injected, Other than the starter the only other thing they NEED to run is open the fuel valve, in the oem configuration this is done with an electric controlled pull cable but it can be done with a manual cable ( choke type ). The rest of the engine can be monitored with simple aftermarket gauges.

Dieseltim

[carpekd]

What fuel pressure does the isuzu engine require? Are you going to reuse the YJ's fuel pump?

[Ben Holloway]

mechanical pump... no need to reuse the Yj pump

Ben

[dieseltim]

The bearing retainer and input shaft into the isuzu pressure plate with a dodge clutch disk to check for clearance and fit. Looks great!!

Dieseltim

[iroc86]

Time for an update. The material for the transmission adapter took a few days to arrive, so I kept busy elsewhere.

Tim, your adapter looks great so far. Have you decided if you can step up to half-inch plate?

The aluminum disc for my SM465 adapter came in yesterday. It's 13" in diameter and 1.5" thick. I haven't finalized the flywheel adapter, so I made sure the material was thick enough to handle any design changes. It's probably going to be an inch thick with a quarter-inch lip, so only about 0.25" will need shaved.

Here it is sitting on top of the Isuzu automatic transmission bellhousing.




The adapter will look something like this, with holes drilled for the Isuzu bolt pattern (around the circumference) and the GM Saginaw transmission (in the center, along with the bearing retainer hole). Since this disc is so large, I need to drill four holes to fasten the material to the lathe spindle (equally spaced around the center hole).






I also test-fit the engine in the Jeep frame. Since the transmission isn't bolted up, I obviously can't position it perfectly... but this gives a good idea of its girth. Fits like a glove!






I won't know how low the engine will sit until I connect the transmission. There's an intake tube that crosses over the valve cover from the turbocharger, so it's possible that the hood will need some modifications to clear it.

There's also a good chance that I'll need to cut the transmission tunnel to fit the bellhousing and adapter. The body tub isn't sitting on any mounts right now, so it's about an inch or two lower than normal. I'm going to run a 1" body lift, too. That should alleviate some trimming.






One of the complaints with the Cummins 4BT engines was its height. The Isuzu isn't short by any means, but the oil pan should easily clear the front differential.






That's all for now...

[navymark08]

Originally Posted by iroc86

There's also a good chance that I'll need to cut the transmission tunnel to fit the bellhousing and adapter.

Yes, there is a very good chance - ask me how I know...

[dieseltim]

Wow Iroc86,
That is starting to come together. I am glad to see that you have started to get your adapter made. Keep the pics coming. It is encourging to see someone else making some progress. Makes me want to work harder to get mine inside and get the body off so I can start to get the engine in place and see how it is all going to look. As for the cross over air intake pipe, I was thinking of removing that and rerouting it to the drivers side so that the air filter was under the brake booster this would make it was a shorter run, and it would let me leave the Battery in its stock location.

I am thinking about having the frame powder coated after I get the engine mounts welded in. Then I would like to replace all the rubber mounts for the steering and supension with polyurathane to give it a firmer feel on the road and hopefully make it drive better.

On my to due list for the Jeep before I can even think about getting the engine in, I have to rebuild the dana 300 and the NV4500, then I can bolt them together for good I hope. Or, until the next clutch change anyway.

I did get one thing done today, I found a clutch shop that can make the clutch disk that I needed for the kit, so that it will have the center hub for the Dodge Nv4500 10 spline input shaft and the outside dia. of the isuzu. So, that part is now done, and I can get them locally in just a day or 2.

Dieseltim

[iroc86]

navymark08, I saw your floor... talk about cutting the transmission tunnel! Man, do I wish I had a plasma cutter!

I hear you, Dieseltim. I've spent a bunch of time with this adapter and other "planning" things, so it was nice to spend an afternoon in the garage.

If you move the air filter to the driver's side, do you think it'll clear the exhaust pipe and steering shaft? Routing the exhaust from the turbocharger might be a little tight. What about a snorkel?

I'm going with the polyurethane mounts, too. The rubber stuff is getting harder to find for some reason, and the poly should last a lot longer.

Do you already have a rebuild kit for the NV4500 and D300? If not, I've had excellent results with Zumbrota Bearing & Gear. I've used their parts over the last few years and the service is great.

[iroc86]

My friend and I started making the adapter this evening. The machine is all set up, so it's ready to go for tomorrow.

We're right at the capacity for the lathe. It's so close, the plate needed filed to clear the ways!