620 4x4 Reproduction Parts

[Stoffregen Motorsports]

With all the talk here lately of 4x4 swaps for the 620 and 720, my curiosity has been piqued. I am considering reproducing the 4x4 conversion parts and I need help.

 

First off, I need some detailed pics from someone who has one. Transfer case, adapter, mounts, front axle, steering, leaf hangers and shackles. Anything I'm forgetting?

 

Secondly, I could use an existing truck to disect it and take measurements and such.

 

Third and most importantly, is there a market? How many of you guys would be interested in a full blown kit or individual parts to help recreate one? Would originality matter? If not, then the sky's the limit.

 

I'm envisioning a "retro crawler" movement in the near future with lots of resurrected "back in the day" type of trucks on the road, so an original truck that's not necessarily trail ready might not be a foolish idea.

 

Input guys?

 

Thanks.

[HRH]

If I had a good 620, I'd love to do one.  As far as marketability, eh, I don't know.  I'd say most of the Datsun market for 620s are more the do-it-yourselfers.  If my hardbody wasn't in such decent condition, I'd consider dropping a 620 body and bed onto it and SASing, but then that would be a whole different ball of wax for the front being a D21 frame.

[datsunaholic]

One issue is every conversion was different.  Transfer case mounts and spring perches were very non-standard.  What was a little more common was the hub conversion- since almost all commercial conversions used a Dana 30 front axle from a Jeep CJ-5.  Because the CJ used a 5-lug wheel and the Datsun used a 6-lug, a conversion hub was made specifically for the application that not only retained the 6-lug pattern but also used the original Datsun brakes (drum through '77, disc from 78).  The drum brake setup basically just modified the backing plate to fit the jeep axle housing, and bored out the drum to fit over the WARN hubs used to lock them.  The disc brakes used a custom bracket to mount the Nissan caliper, but the disc had to be modified same as the drum to clear the bigger hub.

 

LOW Manufacturing made most of the conversion parts for the better conversions, and most of the hubs and T-case adapters even for the cheaper conversions.  Spencer Low Racing (which was what the business became) went out of business in 2007 or 2008, and I don't know if it would be possible to get ahold of Spencer Low (or Jr) and see if the plans exist and are buyable, since they pretty much got out of that sort of conversion by the mid 80s.

 

I know I'd love to have even one spare hub.  Mine had a bearing explode, had an ill-fitting one jammed in there with the wrong race and tore it to hell.  Fortunately it hadn't cracked, and I found ONE shop willing to bore it out and sleeve it to take the original (correct) bearings. 

[620Turbo4X4]

I'm not sure there would be much of a market. They are not that hard to find if your really searching. I've seen 6 in the past 4 years on CL Seattle. I can send you some photos of mine when I get some time during the day. I work nights, so unfortunately I don't see a lot of daylight.

 

I haven't really looked, but does anyone even make a divorced kit for the dana 20 anymore?

 

I had a exploded bearing on mine when it got it too. My machinist here braised and re-bored it. So far so good.

[]2eDeYe]

I've thought a bit about this myself and I am still not sure if it worth the time and effort. I do think it would be nice to have an option for building a 4x4 Datsun that wasn't 100% custom. 

 

 

I've dissected a couple of the converted 620's now and most of what I've seen could be described as hack. Not sure if it was due to the original build itself or PO fixes, probably a combination of both. 

 

 

When I decided to build mine I put together a CAD model of the front frame, really only the cross member area was needed. I already had modeled the rear frame for my slammed 620, although it wasn't necessary to model the rear. When I swapped in the Yota axle I just used Trail Gear brackets and it was pretty straight forward. Something like that for the front would have been nice, what I came up with worked out well though. 

 

 

Front stuff

 

 

 

 

 

 

 

The transmission cross member brackets made for a nice datum to set the rear spring mounts. 

 

 

 

 

 

Rear stuff

 

Rear frame model for reference. The X's you see in the CAD pictures are the body mount locations at the frame. The only portion of the rails I haven't model is where it tapers in, I will probably get that done sometime before I die :lol:

 

 

 

Trail Gear mounts are handy.

 

Creeper joints 

 

 

 

Front hangers and spring perch
 

 

 

 

 

 

T-case stuff

 

There are two styles of transfer case adapters that I have seen, and I have examples of both. I do plan to model them up when I have the time. 

 

 

This style slips onto the 2wd transmission. It uses a steel sleeve to adapt to different tail housing diameters. Not sure about the patent as there is no number stamped into the casting.

I am in the process of sourcing the bearings, the shaft is made from a Datsun slip yoke and what looks like a T18 mainshaft welded together. 

 

 

 

 

 

 

 

Adapter Shaft. You can see the weld if you look close. 

 

 

 

 

You can see the sleeve in these shots

 

 

 

 

 

 

I have another one that I will be measuring and rebuilding. 

 

 

The other style is divorced. This basically adds a drive flange to the transfer case. Plan to model up this one someday as well. 

 

 

 

The thing is these are for the Dana 20 t-case and they are getting a little hard to find these days. It would be great if there was an easy way to use Toyota t-cases, they have a ton of aftermarket support. 

 

 

 

Steering stuff

 

Steering is the final hurdle. The stock steering column leaves a lot to be desired. I ended up swapping in a 1980 720 column with luckily had the same splines as the Toyota IFS steering box that I used. I used the stock Toyota rag joint. Custom power steering lines are needed as Nissan uses different fittings than Toyota. 

 

 

I modified a Marlin IFS Toyota steering box mount. Next time I build a 620 4x4 the front body mount will get removed to move the box fwd more, clearances are tight on mine. I had to get a shorter pitman arm and just clear the tie rod. 

 

 

 

 

 

An example of the hack with PO fixes..This was done to clear the oil pan and reach forward to the steering arm on the axle.  :sick:

 

 

 

 

 

 

 

 

 

 

 

 

I know I'd love to have even one spare hub.  Mine had a bearing explode, had an ill-fitting one jammed in there with the wrong race and tore it to hell.  Fortunately it hadn't cracked, and I found ONE shop willing to bore it out and sleeve it to take the original (correct) bearings. 

 

 

I have a spare hub for you. Just have to dig it out of my shed.   :)

[Stoffregen Motorsports]

 

T-case stuff

 

There are two styles of transfer case adapters that I have seen, and I have examples of both. I do plan to model them up when I have the time. 

 

 

This style slips onto the 2wd transmission. It uses a steel sleeve to adapt to different tail housing diameters. Not sure about the patent as there is no number stamped into the casting.

I am in the process of sourcing the bearings, the shaft is made from a Datsun slip yoke and what looks like a T18 mainshaft welded together. 

 

 

 

 

 

 

 

Adapter Shaft. You can see the weld if you look close. 

 

 

 

 

You can see the sleeve in these shots

 

 

 

 

 

 

 

I have another one that I will be measuring and rebuilding. 

 

 

The other style is divorced. This basically adds a drive flange to the transfer case. Plan to model up this one someday as well. 

 

 

 

The thing is these are for the Dana 20 t-case and they are getting a little hard to find these days. It would be great if there was an easy way to use Toyota t-cases, they have a ton of aftermarket support. 

This is what I'm mainly concerned with. I've thoght of a few different setups using either the D20 or D300 cases. If I start getting too different from the "original" concept, I feel something would be lost in translation. In other words, I probably wouldn't go Toyota RF1A, but that isn't off the table completely. I really like the slip yoke style adapter adn I'm sure with today's manufacturing capabilities, I could produce these coupler shafts to a much higher quality at a reasonable price.

 

Suspension and axles aren't too high on the "originality" list. I would like to use a front D30 or D44 to keep it somewhat vintage, but brakes and hubs, etc I'm not worried about using something else. Maybe standard Chevy outers/hubs/brakes. Ride height and overall look are most important. If I were building a crawler, I would undoubtedly build it very different from the original trucks. What I'm seeing in the offroad world is a trend towards totally old school 4x4's that may have been cool 20 or more years ago, but would not even be viable on the trail today. Guys who have them use them for camping or just to drive around town when they get home from work or on the weekends.

 

Does anyone have ride height numbers? Frame height at bottom of frame is where I usually measure. How much taller than stock are they? What size tires came on the originals? What size tire fits easily?

 

Thanks guys for all the input.

[]2eDeYe]

This is what I'm mainly concerned with. I've thoght of a few different setups using either the D20 or D300 cases. If I start getting too different from the "original" concept, I feel something would be lost in translation. In other words, I probably wouldn't go Toyota RF1A, but that isn't off the table completely. I really like the slip yoke style adapter adn I'm sure with today's manufacturing capabilities, I could produce these coupler shafts to a much higher quality at a reasonable price.

 

You could always fall back on Toyota t-cases being used in Toyota trucks of the same era :lol: 

I like how modular they are and the gearing options are only beat out by aftermarket t-cases. 

 

I can get the parts modeled up and the bearing part numbers for you. I was thinking that a welded tube and plate configuration would save some manufacturing costs, instead of machining from a block. This would also allow a different plate for different t-cases.  Thoughts? 

 

I could use a new shaft, the one in my truck currently is worn and allows the bull gear to rattle on the splines. The other shaft I have has the threads all buggerd. :(

I can get any measurements you would need, I have the shaft sitting on my fab cart. 

 

 

Suspension and axles aren't too high on the "originality" list. I would like to use a front D30 or D44 to keep it somewhat vintage, but brakes and hubs, etc I'm not worried about using something else. Maybe standard Chevy outers/hubs/brakes. Ride height and overall look are most important. If I were building a crawler, I would undoubtedly build it very different from the original trucks. What I'm seeing in the offroad world is a trend towards totally old school 4x4's that may have been cool 20 or more years ago, but would not even be viable on the trail today. Guys who have them use them for camping or just to drive around town when they get home from work or on the weekends.

 

Toyota or Wagoneer axles are easy 6-lug swaps IMHO. I also think the less custom parts needed for the axle the better.   Of course these days you can order up pretty much any axle configuration you want if you have the $. I wanted to keep the old school look with newer braking and lockers. 

 

 

Does anyone have ride height numbers? Frame height at bottom of frame is where I usually measure. How much taller than stock are they? What size tires came on the originals? What size tire fits easily?

 

I think mine is right around 27" to the bottom of the frame, I can measure it again to be sure. My truck has a 2" body lift though so it's not exactly stock.  It did allow me to clock the t-case flat with minimal floor modification. For comparison my low truck that I am building has the bottom of the frame at 3-4". Not sure on stock or converted 4x4, someone else would have to get that measurement. :lol: 

 

Thanks guys for all the input.

 

I'd love for this to go somewhere. I know if it's designed to be easy enough to install, there would be interest. Just not sure how big the market would be. 

[620Turbo4X4]

On the transfer case, I'd think divorced would be stronger and more reliable in the long run.

 

Here's my thoughts...

 

Now we know you couldn't just hang a 100+ lb transfer case off the tranny mount. It would just break the case. So, that leaves making a cradle for the TC. Since the case is off balance it needs to be fairly rigid to keep it flopping on its side. Now let's say you dump the clutch in 1st gear. Normally the engine would just deflect on its engine mounts, but since the engine is bolted to the trans, trans is bolted to the transfer case and transfer case is mounted ridged to frame that's going to put a hell of a lot of torque and twist on the trans mount, which was only designed to hold the trans up. Anyone else see an issue with this?

 

Steering is defiantly an issue on these conversions and was the first mod I did on mine. I used a late model Jeep Cherokee power steering box and collapsible link, to a tilt fiero column. I love the quick steering ratio. It's like driving a go kart. Mounts inside frame and no clearance issues or cutting of the fender wells. Just had to move bumper mount over a bit for bolt access.

 

 

[Stoffregen Motorsports]

The problem with using a Toyota case is the adapter. As we discussed last month or whenever, the divorced adapter is no longer available, I don't really want to make one and I think a married setup is more along the lines of what I'm looking for so that would require one hell of an adapter. I just had a thought that I am going to look in to, I may have just figured it out...

 

More later...

[Stoffregen Motorsports]

OK, I just looked at a pic of an adapter that I'm familiar with (not saying which one) and I think I figured out how to run the RF1A case behind the Datsun trans.

 

Thanks for the info guys.

 

Are all the conversions spring under? I don't want that.

[620Turbo4X4]

Are all the conversions spring under? I don't want that.

I have two of these. The other one is spring over front and back.

 

This one is getting link suspension and coil-overs.

[620Turbo4X4]

OK, I just looked at a pic of an adapter that I'm familiar with (not saying which one) and I think I figured out how to run the RF1A case behind the Datsun trans.

 

Now that would be something I'd be interested in. Trying to keep the weight down on my truck and the D20 weighs a ton

 

Half the fun in driving a Datsun is they don't weigh anything!

[Stoffregen Motorsports]

Links and coils are cool.

 

I don't think 90% of the trucks out there need a rear link setup, but links in the front offer so much potential.

 

Check out the buggy I'm building right now. http://www.expeditionportal.com/forum/threads/140955-FJ40-Build-thread-Hell-s-Kitchen

 

Back to the Datsun. I would probably just use a Toyota IFS steering box and keep the tie rod on the low side using the stock steering arms, with the intention of keeping the truck low. I see a lot of guys mounting the shackle mount on the bottom of the frame. Is the shape of the frame not conducive to running the shackle mount through the frame? Tacomas have this problem. But then who would use leafs on a Tacoma anyway...?

[Stoffregen Motorsports]

Now that would be something I'd be interested in. Trying to keep the weight down on my truck and the D20 weighs a ton

 

Half the fun in driving a Datsun is they don't weigh anything!

It wouldn't need to hang of the back of the trans. We could easily build a crossmember that goes with it. This is the easiest crossmember to build.

[620Turbo4X4]

It wouldn't need to hang of the back of the trans. We could easily build a crossmember that goes with it. This is the easiest crossmember to build.

Wha?Uhh, no. I was referring doing a married D20 kit vs. a divorced. Seems like it would be stressing on the tranny mount a lot trying to marry them. Looks like Novak still makes the divorced kits for the D20 so I guess that would be the easiest way to go for the 20.

 

Don't know much, and haven't given much thought into transfer cases till now. Not planing on doing any rock crawling or anything with mine so I'll probably just leave mine alone. want my truck setup so I can rip down logging roads, and the 4x4 trails in Belfair. What did you have in mind for the RF1A? Adapting to Nissan trans?

 

Wanted to keep mine as low as possible too, and still have 12" of travel. Cut 3" out of my inner fender/foot wells so I can get the tires up in there more. Axle has about 1" clearance to the engine block on full compression.

 

That's a cool buggy you got and some fine looking work! I'm going equal length parallel 3 link with panhard front and back. Wanted to keep things simple since this will be my first link suspension conversion and, I can keep the gas tank where it's at.

 

I like your mount. Hell, it all looks good!

 

All this 4x4 talk is making me want to get busy on mine. Damn job! Lol.

[Stoffregen Motorsports]

I was showing the blue Tacoma's t-case crossmember as an example of how we could support the married case to alleviate extra load on the tailshaft of the trans. I do think a married t-case is a better idea than a divorced case. Less parts to wear or break and shorter driveline length for better fitment in the truck.

 

The adapter I'm thinking about could be set up as a divorced or maried case.

 

My friend has been making Toyota adapters for 20 years. One of his adapters would make a good starting point for the idea I came up with. Hopefully I can talk him into joining us in this lunacy.

[Stoffregen Motorsports]

I almost forgot. Can one of you guys get me the spline count on the back of the Datsun trans? For the first time in my life I do not have one single Datsun part left in my shop so I don't have one to measure.

 

Thanks.

[]2eDeYe]

I count 24 splines. 

 

[]2eDeYe]

Wha?Uhh, no. I was referring doing a married D20 kit vs. a divorced. Seems like it would be stressing on the tranny mount a lot trying to marry them. Looks like Novak still makes the divorced kits for the D20 so I guess that would be the easiest way to go for the 20.

 

 

 

With the slip style adapter I am using all the transfer case rotational forces are reacted by the crossmember. The adapter slips onto the tailhouse and if the crossmember wasn't there the t-case would spin on the tail housing of the transmission. The transmission and t-case are both supported separately by the crossmember. 

 

You can see in this picture how the transmission is supported separately in this picture. 

 

 

If the transmission and t-case can be bolted together like in Stoffregen Motorsports pic you only need to support the t-case as the trans and t-case become a unit. 

[620Turbo4X4]

With the slip style adapter I am using all the transfer case rotational forces are reacted by the crossmember. The adapter slips onto the tailhouse and if the crossmember wasn't there the t-case would spin on the tail housing of the transmission. The transmission and t-case are both supported separately by the crossmember.

 

You can see in this picture how the transmission is supported separately in this picture.

 

 

If the transmission and t-case can be bolted together like in Stoffregen Motorsports pic you only need to support the t-case as the trans and t-case become a unit.

 

Uh? Duplicate photo to the one above. I was looking at photo at top of page where tranny and transfer case are joined together on the trans mount.

 

I was thinking along the lines of what happens in 2 hi. Rotational forces (torque) would be from the trans. Transfer case would just be a extension of the driveline. Agree married would be better, but I'd want a adapter that bolts around the circumference of the output like stock 4X's. Cool setup you have though. Thats gotta be one of the only datsun specific dana 20 conversion out there!!

 

 

 

I almost forgot. Can one of you guys get me the spline count on the back of the Datsun trans? For the first time in my life I do not have one single Datsun part left in my shop so I don't have one to measure.

 

Thanks.

I had pictured in my mind a L bell housing on a 720 or D21 4x4 trans with adapter for the yota transfer case.

 

Now. ???

 

Curious what you come up with...

[]2eDeYe]

 

Uh? Duplicate photo to the one above. I was looking at photo at top of page where tranny and transfer case are joined together on the trans mount.

 

 

 

Haha oops...

 

You can see where the trans bolts up and the transfer case flange as well as the torque resisting plate to the right by the bushing at the frame. . 

 

 

 

 

Thats gotta be one of the only datsun specific dana 20 conversion out there!!

 

 

 

The adapter was done by Low Mfg. as far as I know. I've found them in a few different conversions, and by different I mean they had different crossmember designs and steering solutions. I know there was at least one place up here doing conversions and several other places along the west coast may have been more across the country. 

 

Looks like the sleeve and on the tail housing could be made transmission specific. I had to hone it out to fit the later 720 transmission that I swapped in. 

[Stoffregen Motorsports]

That's a good looking x-member.

 

So the LOW conversion t-case registers of the ID of the tailshaft? There was someone last week asking about a 5 speed swap in his converted 620, and his looked like it registered on the OD of the tailshaft.

[]2eDeYe]

It interfaces the OD of the tail with the ID of the tube. The cast adapter then interfaces the OD if the tube to the ID of the adapter. 

 

 

Found some more pics that show the parts in the different configurations. 

 

 

The different tail housings, the one on top is the old one. 

 

 

 

Trans I swapped in.

 

 

T-case with the original adapter configuration. It was modified a bit by Jeff when he did the body swap. 

 

 

Original cradle, didn't get a shot before I ground the welds.

 

 

Adapter tube

 

 

I had to hone it to get a nice light press fit onto the tail shaft. 

 

 

Press fit it on while it was still toasty from honing. Will probably take a bit of effort to take off in the future. You can see the adapter and the shaft in this shot. 

 

 

All slipped together.

 

 

Then I built a new cradle and used that for the base of my cross member.

 

[620Turbo4X4]

When you say this is the low conversion transfer case, you mean you've seen more than just yours?

 

This is the first one I've seen that was married. Went and looked at 4 different trucks on CL when I was looking. (Bought two lol.) They all ran a divorced D20. My black truck was the only one that had a somewhat professional looking transfer case support (I saw boxcar has one identical) the rest were all botched together.

[]2eDeYe]

Yep, I have two of these adapters and have seen other ones. I've also seen the other style with the intermediate drive shaft. 

 

 

Botched would be a good way to describe most of them :lol: