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Discussion Starter #1
Hi
I am looking at doing a rear engine setup in my 404 mog. I am actually planning to run much the same setup at the Ubermog vehicle which entreated the top truck trophy in 2004.

I have created a diagram of my setup (below)


I feel quite confident with the actual setup although I do have just two queries.

• As you can see from the Diagram I am planning to connect a prop shaft from the U box directly to the input of the gearbox. Attaching the actual prop to the box will only require a special flange with the same spline setup as the input of the mog box.
The only problem I see me having is that I am not yet sure whether the gearbox shaft was originally braced and held at the correct angle by the engine (via the bell housing).
If it is I can see there being a problem with it accepting the prop without causing damage to the input shaft (as it could move around in its self) :surrender:.
If it is an issue I have come up with an idea of bracing the shaft. I am also seeing if it would be possible to use the U box to hold the Shaft and prop at the correct angle.

If anyone can confirm whether the shaft relies on being braced or whether I cab simply attach a flange and prop to it I would be extremely great full.


• The engine I am hoping to use is a Chevy 350. I am not planning to tune the engine but it will still be creating 370 around ft•lb of Torque and 300 Bhp, at the flywheel. As over engineered as the 404 Unimog is I am still questioning whether the gearbox can actually handle this amount of power and torque in particular.
As I am planning to run 2 gearboxes I have a far greater choice of ratio but with the vehicle in 1st in both the auto box and manual box it is receiving 958 ft•lb and outputting a scary 12382 ft•lb to the transfer box. Even though these seem like huge figures this is only happing at 2mph (with the engine at 4500 rpm with 44” tyres on)
I will be running an auto (which gives slightly softer power) but I just wondered if anyone could see a problem with me sending this much power through the mog drive train.

Hope you guys can help out a little with my plans :confused:
Tom
 

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The input shaft of the transmission is supported/centered by the pilot bearing in the end of the crankshaft (original motor). Without this 'support' you will damage the input shaft/bearings in the transmission. My guess is that just supporting the end of the shaft at the 'U box' won't be enough, plus you would have to have a straight shot from the 'U box' to the transmission. What are you thinking of to support the input shaft of the transmission on the transmission side of things?
 

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x2 on the input shaft support via back end of engine crank.

The good news is you have the bell housing depth and circumferential bolt pattern to support a custom spline coupling supported on a bearing! All that space cleared by evacuating the clutch means you can configure a plate that:

A) supports and mounts the tranny front end
B) Has a bearing cavity
C) creates a guide for the spline coupling needed.

Your drawings look great, please keep us appraised of your engineering/fabrication developments.

Warm Regards,

Rick
 

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Sounds like Rick has an excellent idea for supporting that shaft!

As far as whether or not the 404 components you plan on reusing will support that level of power...I personally don't know. Many reputable Moggers believe that 80km/hr is a safe sustained speed for the transmission. A handful will say they run their Mogs as fast as they can go without problems. Bob R. did some temp testing of the transmission fluid and found that above 80km/hr the fluid starts getting pretty hot. Apparently his tests revealed that speed, not torque, is what caused the heat.

I realize that you are more concerned with the torque you are putting through it. Having an auto trans hooked up to the motor will certainly 'soften' the application of torque, as you mentioned. As you know, higher output engines have been attached to the OEM 404 components. Unfortunately, I haven't run across good long term assessments of how things lasted. Surely, the torque of the 350 exceeds what MB had in mind for these parts. I think it is safe to say that you would be increasing the likelihood of something breaking. Hopefully those with more hands on experience can comment.
 

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I believe that Ubermog retained the stock mog clutch. I would as well, that way you could use the stock 404 box to split the auto gears if needed. You'll need to have some heavy plate and bearings to support the flywheel, a flange on the forward side could accept your forward facing shaft. Keeping the flywheel also keeps the pilot bearing that supports the input shaft.
 

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Zmog on this board was doing the same thing as you plan but with a 454. He's been quiet for a while.
 

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I would get rid of the clutch and just use the auto trans. There are valve body replacements for the turbo350 that give you "manual" shifts for each gear. It wouldn't be terribly hard to lock out line pressure on the clutches to give you a neutral.

If you set it up right, you could even make the shift gates on the mog trans electrically linked to your line pressure gizmo, giving you a clutchless shift from the main gear box. How cool would that be?


I believe that Ubermog retained the stock mog clutch. I would as well, that way you could use the stock 404 box to split the auto gears if needed. You'll need to have some heavy plate and bearings to support the flywheel, a flange on the forward side could accept your forward facing shaft. Keeping the flywheel also keeps the pilot bearing that supports the input shaft.
 

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I would get rid of the clutch and just use the auto trans. There are valve body replacements for the turbo350 that give you "manual" shifts for each gear. It wouldn't be terribly hard to lock out line pressure on the clutches to give you a neutral.

If you set it up right, you could even make the shift gates on the mog trans electrically linked to your line pressure gizmo, giving you a clutchless shift from the main gear box. How cool would that be?
True, would be cool, and way more complex. Where there's a will there's a way...
Paging zmog!?!
 

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I broke a 1" input shaft with a Hercules 4 cyl 3.7L = 268 ft-lb. does anyone know the input shaft diameter on the 404 trans? With the torque converter, your torque multiplication could be up to 5:1 or >1500 ft-lb.
I predict the input shaft of the 6 speed will be what breaks.

Charlie
 

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With the torque converter, your torque multiplication could be up to 5:1 or >1500 ft-lb.
Charlie is pointing at a very important issue. You are probably looking at a 3x increase in twist. I don't believe the German engineers were anticipating your bashing!

Question: How will you use your truck, and in what type of terrain? Do you finesse the throttle or romp on it to clear obstacles?

Also, I'm wondering, hows the SBC motor fit between the 404 frame rails? Is it sitting high or way down in between the rails? Have you done any feasibility studies regarding the fitment at this early period?

Rick
 

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Discussion Starter #11 (Edited)
Thanks for all your help guys and sorry for the slow reply...

I ’ve come up with an idea for bracing the gearbox input shaft.


Can anyone confirm whether they think this will work :confused: Off course it will rely on the U box being mounted exactly right (so that the shaft is completely level)

Tom
 

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It sounds like, with the above design, that you aren't planning on supporting the input shaft to the Unimog transmission with it's own bearing support. I think this is a really bad idea. I realize you are counting on a perfect alignment/positioning of the 'u box' to keep the shaft level, but it will never happen. Even if you mount the 'u box' perfectly relative the the Unimog transmission, any frame flex/twist will will move that 'u box', no matter how you mount it, causing the input shaft of the Unimog transmission to move around, destroying it's bearing and transmission internals. This probably won't be good for the 'u box' either...

If you are dead set on going this route, you are going to have to support the input shaft to the Unimog transmission with it's own support relative to the Unimog transmission. Considering frame flex, you would then need a shaft between the Unimog transmission and the 'u box' that can deal with some amount of angle.

I suppose if you treated the 'u box' like the original motor (pilot bearing) supporting the input shaft via flanges or whatever and bolted the 'u box' directly to the transmission via the bell housing, this might work. Without a good support for that input shaft and a shaft that will allow for different angles between the transmission/'u box' I think that mounting these two items independently will result in disaster.
 

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I'm curious, what application will you 'need' 300hp for? This is obviously a rock crawler, not a highway cruiser, so I guess it isn't speed...

I can't remember how many gears/ratios you might end up with this application, but could those ratios not be achieved with either the 2 or 4 speed Unimog crawler gear setup? If you are concerned about how fragile the crawler gears might be, it seems kind of a mute point because with a SB 350 in there you WILL break things.

Every honest write-up I've seen on 404 components with a huge motor attached to them has mentioned that just about everything has broken. Are you ok with blowing up portals? Diffs? Transmission?

Do you want a functional rock crawler or something that is 'totally different' than all the rest? I'm not sure that throwing a big motor in a 404 is really 'totally different'...it seems that throwing huge motors and horsepower in crawlers is pretty common.

Obviously if this is what you really want, and you have the time, resources and LOTS of money, and don't mind breaking, fixing, breaking, fixing, breaking, re-engineering...go for it. I'm not a very experienced off road guy, but one thing that the 404 has taught me (which I didn't know before) is that you can do amazing things with hardly any horsepower. Apparently it comes down to gear ratios, articulation, and skill. (I'm sure there's more)

If the M180 doesn't do it for you, throw in an M130 and keep it simple and reliable. Get a 2 or 4 speed crawler 'box' designed for the transmission. Spend your money on wheels/bead lockers, suspension, tires, roll cage, power steering, brakes, etc.

Don't get me wrong, I understand the drive behind totally custom projects. I've just seen so many custom projects ending up costing 4x or more what was originally thought resulting in a machine that isn't reliable and arguably isn't as capable as the original platform. If you want a high horsepower machine that will be loud, spin it's wheels and use speed and momentum to get over objects as opposed to skill, there are lots of vehicles out there that will do that in not from far stock trim. The Unimog is a different beast.

If you look at the successful, accomplished and capable 404s that have been built by people (many of them on this forum) it seems you find that they are running propane, are using the M180 or M130, have the crawler gears, and intelligent suspension setups, among a few other odds and ends.
 

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Discussion Starter #14
I am designing the vehicle on doing winch challenge events in England and Europe. Obviously rock crawling requires far less BHP than going through heavy mud and water.
I would agree that in a rock crawling situation the standard M180 with a set of crawler gears would be more than suitable but after driving my standard 404 through some pretty sticky situation in the U.K the lack of power is extremely clear.

I feel that this lack of power will become more of an issue as I begin to prepare the vehicle further and become a bit more adventures (Fit bigger tyres)

I am also looking at using a slightly smaller ford 302 v8 mainly because they are far more available and cheaper in the U.K. They also produce slightly less BHP and Torque meaning blowing portals and gearbox may be slightly less likely.

I do admit that number of different gear ratios is slightly extreme/stupid (especially as some over lap) but the setup allows me to use a auto box which I have found extremely useful in past events (allows me to concentrate on my winching (pressing buttons) and the actual driving and course)

As for bracing the shaft….
The ubermog vehicle (which ran the same setup) used the complete bell housing and attached the u box directly to it. Although he used a custom U box which he got special made… at a pretty extreme cost!
Sadly I wont be getting a custom U box made but as already said it should be possible to use the bell housing (bolted to just the gearbox) to brace the input shaft (by attaching a bearing to the middle of bell housing). Unlike the diagram above no flexing issue would be created by this methord.

Tom
 

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Ok, you can do this. It has been done. I have seen many different engines in the 404 in many configs. Some work some dont.

Now that I stated it can be done, I will go into why you shouldnt do this setup.

Aside from the complexity of the finished product, and the over all cost.
You can acheive similar power of a 302 with many more suitable simpler options.

Quick question what tires did you use in the mud. This makes a huge huge huge difference.

Engine options as follows:

Machine and Tune the M180

Swap in a M130

MAchine and tune the M130

turbo charge either M180 or M130

Now the more elaborate setups.

Swap in an OM617A

Swap in a Ford 300

Another interesting setup is a chevy or ford V6 with auto tranny in front of the 404 tranny. We have or had one of those here in Albuquerque. Not to my likeing but interesting, powerful and versatile.

Another interesting option that I dont think has been done yet is a mazda rotory and is my option of choice due to power and high RPM's. .

All of these options can achieve similar if not more power than an older stock ford 302.
 

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Hi Tom,

I really like reading about those winch challenge events across sloppy muddy hills and creeks. You are certainly right noting that a 404 is woefully inadequate for that.

Some time ago I sat for several hours pondering the remains of a junker 404 tranny which still had the three main output gears in it. If the transmission housing could be shortened significantly, to only 6 or 8 inches, and an input shaft added to drive just those final heavy gears, a high rpm engine and auto-tranny could be divorce mounted ahead of it. A big advantage of this is that the Unimog torque tube suspension could be retained.

Good points on the possible lack of robustness of the 404 tranny input shaft. After all this tranny originated with a 25 then a 34 hp engine! However, a juicer tranny does not shock load a tranny nearly as much as a clutch. My gut feel is the tranny input shaft would hold up fine.

I'd not consider a 404 tranny for a mud machine because of its lubrication and heating issues. Mud means wide open tire spinning rpm.

Tom, this is off topic to this thread, but I ran across a winch that I thought would be ideal as a secondary winch in a winching event. It's military/aircraft and uses an 11 hp 24v motor and runs about a meter per second until loaded, draws only 25 amps while taking up the slack, then the series motor slows and draws higher current for the heavy pull. I'll drop you a PM.

Bob

Tom.H said:
;...chop....
I do admit that number of different gear ratios is slightly extreme/stupid (especially as some over lap) but the setup allows me to use a auto box which I have found extremely useful in past events (allows me to concentrate on my winching (pressing buttons) and the actual driving and course)

..chop...
Tom
 

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Discussion Starter #17
Thanks for the reply’s…
I’ve been doing a little reading and research into the Ford 300. Although I previously said that I would like an auto I believe it wouldn’t be too much of a problem running with the standard manual (After looking at the money and time I would save).

It seems that the Ford 300 is quite a tight fit but can be done. As Doka TD explained and I have researching into further it gives almost the same output as the 302 V8.

I haven’t found any pictures or descriptions of the conversion although it seems that it has been done a few times.
Does anyone know whether the Ford 300 with fuel injectors will fit within the engine bay (without cutting through the passenger foot well)?
Due to the angle the vehicle is likely to be at (when winching) I would really like to run on fuel injections. The injectors also give out a bit more BHP.

Because of the size of the Ford 300 it seems the radiator can not be fitted in its original place. I guess this isn’t any real problem apart from plumbing some tubing to behind the cab (can anyone confirm)?

Also how have people gone round fitting the Ford 300? Is possible to just get an adapter plate made or is it a complete custom bell house job required?

Tom
 

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The ford 300 I have seen has since been sent to salvage so to speak. It consited of a conversion plate and thats it in terms of bolting onto the tranny. They should not require relocation of the radiator. Not sure if the FI version will fit or not. I would recomend propane. It wont increase power, but will run at any angle.
 
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