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Turbobob, and everyone;

I see in an old posting under engine swaps was a mention of 4X4 conversions offered in the future. Has that come to pass?

Has anyone performed the conversion, or have any links to offer?

If I'm going to have a keeper Toyota motorhome, it's my intention to cover both the highway and backroad callings. In five seasons, averaging about 3,000 miles per trip, I've found myself three times staring into the distance when forced to acknowledge I was at the limit of 2WD in beautiful country (I have a highway set-up). Maybe five other times I was able to complete a run off-pavement, including a nice stagecoach passage in central Nevada and a thrilling climb out the back way from Sun Valley.

After coming to these forums, I have to say that I'm honing in on an 18-ft. V-6 Sunrader to convert. It would solve the problem of power (weight, for highway viability) and clearance (length, for effective ground clearance and city parking).

Anyone been down this road? Even if it was only conjecture or a dead-end I'd appreciate your thoughts.

Steve R.

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Nolan is the guy who has done it with the early toys (solid front axle). The vintage you are looking for has a IFS front end. If you go with a solid front axle you will have to do some fabrication.

Lets start over. You will need a doner truck of the same year and engine. You want the trans and transfer case from a V6 setup. If you stay with IFS then you have all that also. The computer might be different so that needs to be swapped also. Wireing should all be in place as long as you stay with the same year. You will probably need to have a rear drive shaft built. Probably need to have some rear springs built also.

I think its 100% possible.

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Thanks for that insight, Greg.

I've caught wind of a 2WD with only 34 thousand on the odometer, and in that case would want to keep that engine, and maybe the auto tranny.

The donor truck for the trans, transfer case, and IFS -- would it need to be a 1-ton?

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I see in an old posting under engine swaps was a mention of 4X4 conversions

Anyone been down this road? Even if it was only conjecture or a dead-end I'd appreciate your thoughts.

Steve R.

Hey Steve, Yes I'll admit I have done a couple 4x4 conversions on some old Chinooks, Just to be different I suppose, no excuse why or no real reason or need other than I wanted to.

Converting your newer model would still be very similar, and depending on your mechanical ability, fabrication skills, would dictate which route would be the most effective and costly.

You could scavenge parts from a donor 4x4 truck and go to work fabricating and building, either IFS or solid axle, the solid axle would be a lot easier, but either way its gonna be a lot of work as the 4x4 and 2wd front frame sections are different and things just don't bolt on.

Second method would cut a lot of work, that would be to graft the front section of a 4x4 frame to your existing truck, be it either an IFS truck or an older solid axle truck, that way you end up with all the correct mounts, steering geometry ect. still other things to consider are the trans/transfer case clearance in the tunnel area, rear suspension change to the 4x4 status, then front and rear gearing.

The third and probably the easiest and most cost effective would be to swap your camper to a 4x4 truck, with the 18' Sunrader I,m not sure on the actual wheelbase so its possible the standard longbed chassis is already the correct length, if not only a frame stretch is in order on the rear section, and some driveline, cable, and brake line stretching is needed to compensate.

I,ve done the front frame graft, and also the complete frame swap and lengthening, both were work, both had their own obstacles to overcome, but both worked fine in the end. Good luck and have fun if you take on the swap. Nolan :bye2:

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Thank you, Nolan;

That's about what I figured the level of effort would be. First I've got to get a keeper coach, if not the whole motorhome. I took a peek online for donor 4X4s of the '90 - '93 vintage and there seem to be plenty of good-quality choices. Are all the 4WD axles the same weight rating?

I also need the space, having lost mine when the Navy called in its leases up here at a local base that's being turned over to the city.

Then I need the time, after going over my stick-frame abode. I've got a fine welder on my side. I installed the hydronic heating in his concrete house. Frame graft sounds more appealing than frame stretch.

Thanks again,

Steve R.

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Thank you, Nolan;

Are all the 4WD axles the same weight rating?

Steve R.

Yes basically all the 4x4 axles are the same weight rating, they didn't offer a 1 ton axle as such, like the 1 ton floater design in the cab/chassis 2wd units.

The 4x4 used a 6 lug wheel pattern, not to be confused with the large 6 lug pattern used on the 1 ton chassis. Seen mention before from some that because they have 6 lug nuts they think they have a 1 ton setup, NOT!! the true 1 ton chassis has a very distinct bolt pattern that is specific to that design.

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Yes basically all the 4x4 axles are the same weight rating, they didn't offer a 1 ton axle as such, like the 1 ton floater design in the cab/chassis 2wd units.

The 4x4 used a 6 lug wheel pattern, not to be confused with the large 6 lug pattern used on the 1 ton chassis. Seen mention before from some that because they have 6 lug nuts they think they have a 1 ton setup, NOT!! the true 1 ton chassis has a very distinct bolt pattern that is specific to that design.

I have a question regarding axles. I have read that for the turbo and V6 trucks that the rear end and axles are more substantial than those that came with a non turbo 22re truck. Would that also apply to the front axles?

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I have a question regarding axles. I have read that for the turbo and V6 trucks that the rear end and axles are more substantial than those that came with a non turbo 22re truck. Would that also apply to the front axles?

Hey Greg, I don't have all the specifics on the axle differences but from what I have read and had experience with,, is the 4wd 4cyl trucks used an 8" gear assembly both the same in the front and rear with the solid axle setup, the IFS front end used a 7.5" third member, supposedly the same as the early 2wd truck rear ends. The 4cyl rear third member was reffered to as a 2 pinion design, the V6 and Turbo trucks used a 4 pinion design, they were basically the same and would interchange back and forth from turbo to v6 to 4cyl, the 4 pinion carrier was built a little haevier on the actual housing and used a slightly larger carrier bearing, other than that they were all pretty much the same, axles would interchange as they remained the same too. In a nutshell the v6 and turbo models had a little beefier housing and slightly larger bearings, other than that they were all the same. as for the front diff, they were all the same for 4cyl, 4cyl turbo, and v6 models. Anyone with more specific info or know how please correct me.

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Thanks Nolan

What I really want to do some day is change the gear ratio. Doing the front IFS though scares me. Not because of getting greasy but because I might not have the proper tools to do it. Guess one day I should sit down with the shop manual and figure that out. The rear should be a piece of cake. Looking at the costs I see the third members selling for $1000 at http://www.marlincrawler.com/htm/diff/pickup_diff.htm#8diff

But I do not see anything for the front. It looks like I would have to build that myself. Looks like alot less dollars, perhaps that would be the way to do the rear also.

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Thanks Nolan

What I really want to do some day is change the gear ratio. Doing the front IFS though scares me. Not because of getting greasy but because I might not have the proper tools to do it. Guess one day I should sit down with the shop manual and figure that out. The rear should be a piece of cake. Looking at the costs I see the third members selling for $1000 at http://www.marlincrawler.com/htm/diff/pickup_diff.htm#8diff

But I do not see anything for the front. It looks like I would have to build that myself. Looks like alot less dollars, perhaps that would be the way to do the rear also.

Greg, What ratio you thinking about doing if and when the time is right? I,m running 4.88's in my 76 with 31" tires and a 5spd and its just right on the highway. I,ve done the drop out third memebers and they are fairly easy to do, never regeared one of the IFS fronts, but they look real similar to doing a Chevrolet style axle where the goods go in through the rear cover.

The gear sets and install kits are not all that bad price wise, you should be able to do both for under a 1000. easily, maybe do the R&R and have a local shop just install and setup the gears for you. Pulling the front diff is not too bad on the IFS, just getting the axle flanges apart and back together is the pain, really tight and will increase your vocabulary in short order, :ranting2:

If and when I have to do it again I'll probably knock the ball joint apart so the axle can swing out a bit to make it easier.

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Nolan - not really sure what ratio I want to go with. Tire size is going to be the same as it is now 215r15.

The gear calc here http://www.toyotamotorhomes.com/files/mphCALC.xls is telling me that 5.29s at 3000 rpm will give me 68.2 mph in over drive. At 2800 rpm in od 63.6 mph. The 4.88s is 69 mph in od at 2800 od is 73.93 mph. 5.71s at 3000 rpm is 63.19 mph od and at 2800 rpm in od is 58.97 mph. At 3100 rpm I would be running 65 mph in over drive. Using that info what rpm should the engine be running considering its moving 6800 pounds down a road that is never flat. The idea would be able to stay in OD with out the engine lugging to much. If the calcs are correct I am liking the 5.29s. I do believe my stock ratio is 4.10 and at 3100 rpm in 3rd gear I run 65 mph. In OD to stay at 65 mph I run around 2200 rpm which matches the gear calculator.

Greg

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Greg, To me the 5.29's seem awful low,.especially with the tire size your running, what about 28.5 to 29" height? but thats personal preference I reckon on how your driving habits are. Mine with the 88's and a 5spd with 31" tall tires I,m running right at 3050 rpm in 5th at about 65, personally thats about where I like the engine to run, higher revs and it gets noisy listening to it humming along, then the fact the low gears are really spinning at highway speed, the 5.29's would really be humming.

My Blew rig has 4.38 with a 4spd, at least until tonight, now the 4spd is laying on the garage floor getting replaced with a 5spd, but with the 4spd, 4.38 gearing, and 32" tires its about 3200 rpm at 65, I know the new 5spd is going to drop me down to around 27/2800 rpm at 65 but the engine seems to have enough power to pull it along with no problems as is without running under boost, but the gain I,m getting is the new 5spd is a turbo truck box with the lower 4.31 1st gear which will make takeoff a lot easier with the weight. We'' see if my therory holds true.

One note for what its worth, I keep my 76 stored about 35 miles from where I live, its freeway driving from there to here and with the 4.88's I could go get it drive it home crawl underneath and you couldn't grab a hold of the rear pinion snout because of the heat, well you could but you didn't hang on long, I switched to synthetic gear oil in the diffs and trans/transfer, now the same trip crawl underneath and you can actually put your hand around the pinion snout and hold on, its still hot but nothing like before the switch, those low gears are really spinning at highway speed and do generate some heat. :o

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Maybe I am using that calculater incorrectly. Its showing me that with a 28.5 inch diameter tire, 4.88 gears, 2.28 transfer case ratio and a A340 auto at 65 mph in OD (4th) I will be turning 2638 rpms. With the 5.29 gears I will be turning 2860 rpms at 65.02 mph. With the 5.71 gears in 4th I will be turning 3087 RPM at 65.02 mph. Like I said maybe I am using the calculater wrong or its wrong. But maybe I am wrong wanting to keep the rpm at around 3k at 65 in OverDrive. With the 5.71 gears 3rd gear at 3087 rpm is 45.84 mph to get up to 55 I would have to take the rpms up to 3705 in 3rd gear. So maybe a higher ratio would be a comprimise. 5.29 in 3rd at 55 mph 3433 rpm. 4.88 gears in 3rd is 3166 rpm at 55.01 mph. My thinking is that I want to be able to use OD (4th) without it searching between 3rd and 4th constantly and to not lug the engine.

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Maybe I am using that calculater incorrectly. Its showing me that with a 28.5 inch diameter tire, 4.88 gears, 2.28 transfer case

Greg, instead of using the transfer case ratio, just forget about it, try running the figures using the transmission ratios and see if it makes any difference for ya, 3rd gear in your auto would be the same as a manual in 4th, 1 to 1 or 1.000 the OD in the a340 I believe is either 0.70 or 0.75 as a final ratio.

,

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I found that changing the transfer case ratio only changes the mph figures under the transfer cases. Here is a screen grab.

I figured you knew what you were doing, :) isn't it fun trying to decide whats the best bang for the buck. :wacko:

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