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Center Take-Off Rack & Pinion


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#61 thisismatt

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Posted 28 December 2017 - 06:51 PM

Wayno, you can't possibly feel Photobucket owes you something after many years of thankless leaching. That gravy boat has set sail. You have to pay for your own hosting or face the same fate with whatever new 3rd party you're taking advantage of now, before history repeats itself.
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#62 wayno

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Posted 28 December 2017 - 10:06 PM

Wayno, you can't possibly feel Photobucket owes you something after many years of thankless leaching. That gravy boat has set sail. You have to pay for your own hosting or face the same fate with whatever new 3rd party you're taking advantage of now, before history repeats itself.

 

They don't owe me a thing, I only used them for 3/4 years, I then moved on to Picasa, but Picasa is not trying to extort money out of me, they just discontinued hosting anymore photos, this planet would be a better place without the Photolame CEO and others like minded in all facets of life.

 

You do not hear me complaining about Picasa or calling them lame, they gave warning and quit hosting photos as Picasa, all them photos still show to this day.


 

 


#63 distributorguy

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Posted 29 December 2017 - 06:09 AM

Yesterday PhotoBucket was having issues, but today they are up & running again.

All my forum posts have the pictures back up.

 

Apparently they finally had that "oh shit moment"?  Or they extorted enough money out of a few people to stay alive for another fiscal quarter.   :blush:



#64 Stoffregen Motorsports

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Posted 29 December 2017 - 09:37 AM

I think it was the media backlash that helped sway their decision.



#65 Str8jacket

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Posted 30 December 2017 - 04:30 PM

SO here's the skinny:

The MG Midget R&P has a roughly 19" center to center distance measured from the inner tie rod pivot, so its nearly identical to stock Datsun 620 steering.  Its shorter in overall width, so you could make a custom adjuster to mount any outer tie rod to the rack and correct the track width.  The way the rack mounts is via clamp, and its adjustable so mounting it to the truck couldn't be easier, and you will not need an idler arm, which is a ridiculous idea with a R&P IMHO.  Lock-to-lock is 2 1/2 turns, so very quick ratio.  And they're dirt cheap.  There are several on Ebay for under $50.  

 

 

...and the MGB R&P is roughly 45 1/2" wide end to end.  Usable with no modifications if I measured properly.  

 

There is one of these where the steering column appears to join at nearly 90 degrees to the rack and another that it is on an angle, can you tell me which one has the 19in measurement? I have found one here but not sure what the measurements are before I gamble and buy it. 

 

I also have plans down the track to cut a spare chassis in half down the middle and widen it by 4-6in, if I build a jig for the body mounts I can move them back in after wards. I have been staring at it and I reckon it should work. Pair of drop spindles and the steer rack the geometry could be tuned really nice, torque arm rear with watts link, and it would handle like a champ, I have a hilux diff stashed that is 4in wider than the one in the ute. Ahh if only there was more time!



#66 Moist Lightning

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Posted 30 December 2017 - 04:43 PM

Alright let’s get back on track. Ill reviews the three options and what we have learnt.

 

1. End Take Off Rack & Pinion.

  • The distance between LCA’s is 16.”
  • The Stock 620 Center link is about 20”
  • A R&P with 16”-20” Pivot to pivot would work if it we not for the oil pan limiting how high you can mount the rack.
  • You can take a look at this build with a custom 16” pivot to pivot end take off rack: http://community.rat...-with-ac/page-2
  •  Also note that the custom rack had an angled pinion due to how narrow the rack had to be. He still needed 2 u-joints in the column to connect without binding.
  • We do not yet know the largest pivot to pivot distance for and end take off. Someone would have to see how high up they can actually mount the rack and measure the distance between control arm intercepts for us.
  • Lastly the shortest stock rack found is currently 19” pivot to pivot. Let us know if you know of a shorter one.

 

2. Center Take Off With Extensions bar.

  • Originally I said it would need to be 22.75” however I pulled the wrong number from a different thread. The stock 620 center link is actually 20.” Although, after reviewing the build linked above I realized that if mounted lower would only need to be a bit over 16.” You would need a bump steer kit / spacers on the outer tie rods just like in the 16” end take off in the other build.
  • So the main concern with this build was deflection. However, now that we are down to 16 inches I think its less of a concern.

 

3. Center Take Off with 2 Idler Arms.

  • With this setup you would replace the steering box with and idler arm and connect the two idler arms to the center take off.
  • To connect the idler arms to the take off you would build a small extension bar and attach tie rods from the extension bar (on the rack) to the idler arms.
  • The major benefit here is that you keep stock geometry. 


#67 distributorguy

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Posted 31 December 2017 - 09:50 AM

IS stock geometry the best?  Somehow I don't think so, especially when lowered.  You can mount the rack lower than the steering arm centerline if you offset the tie rods so they attach perpendicular to the steering arm instead of "reaching up" to attach to the steering arm.  Essentially correct the offset with a "Z".  A lot of modern cars do this to avoid space constraints.    

 

Am I the only one who thinks that the use of idler arms with a rack and pinion defeats the purpose of switching to R&P???  If you have to use idler arms, you aren't gaining anything.  



#68 G-Duax

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Posted 31 December 2017 - 02:20 PM

Am I the only one who thinks that the use of idler arms with a rack and pinion defeats the purpose of switching to R&P???  If you have to use idler arms, you aren't gaining anything.  



#69 wayno

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Posted 31 December 2017 - 03:56 PM

IS stock geometry the best?  Somehow I don't think so, especially when lowered.  You can mount the rack lower than the steering arm centerline if you offset the tie rods so they attach perpendicular to the steering arm instead of "reaching up" to attach to the steering arm.  Essentially correct the offset with a "Z".  A lot of modern cars do this to avoid space constraints.    

 

Am I the only one who thinks that the use of idler arms with a rack and pinion defeats the purpose of switching to R&P???  If you have to use idler arms, you aren't gaining anything.  

 

Well he is gaining power steering, but I am unsure if he has the room in a 620 to use the idler arms with a center take off type without a major mod to the oil pan, seems like it would be easier to go with the end take off Rack and Pinion straight to the steering arms on the spindles, but that will likely change the front end geometry.

 

I used 2 idler arms because I didn't know shit when I put together my ball joint front end and my power steering(year later), I figured it was reversible if it didn't work and I set it all up on a extra frame in my driveway before I did it to the work truck(the power steering part), I could have done it better but like I said, I didn't know shit back then about this stuff, I was making it up as I went, and I had issues till I figured it all out.

 

In 2007/08 Mike said someone used a Z car power steering unit in the stock steering gear position in a 521 the day he came over and looked at how I did it, but I have no idea how it was done, I didn't even know Z cars had power steering.

 

Before I had the custom center link made I had made my own ladder type center link, it was 2 center links about 3 inches apart with about 4 braces between them, it fell apart the week after I took possession of the custom center link.


 

 


#70 Moist Lightning

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Posted 01 January 2018 - 10:51 AM

IS stock geometry the best?  Somehow I don't think so, especially when lowered.  You can mount the rack lower than the steering arm centerline if you offset the tie rods so they attach perpendicular to the steering arm instead of "reaching up" to attach to the steering arm.  Essentially correct the offset with a "Z".  A lot of modern cars do this to avoid space constraints.    

 

Am I the only one who thinks that the use of idler arms with a rack and pinion defeats the purpose of switching to R&P???  If you have to use idler arms, you aren't gaining anything.  

 

I get what your saying and I think it ultimately comes down to what your goals are. The 2 idler arm method wont gain the improved geometry of a end take off rack. However you are removing the sloppy steering box, getting a tighter steering ratio and potentially gaining power steering. Changing the steering geometry over stock also creates the risk of making things worse if not done correctly. With stock geometry at least you know you didn't make things any worse. It is also a lot simpler.

I'm not saying i've decided to do this yet just stating that based on someone's goals it might be a good solution.

 

I'm also having trouble picturing what you are describing with the "Z" setup. Personally im finding there's just too many obstacles to do a end takeoff without paying for a custom rack. Does this "Z" setup solve the pivot to pivot distance or pinion angle? Could you link me to a picture?

As things stand i think the center take off with 16" extension bar would be simpler and provide the same geometry improvements of an end take off. 

 

However, If we can figure out a end take off that solves the pivot to pivot problem than I would definitely choose it over the others. im doing more research into this now too.



#71 wayno

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Posted 01 January 2018 - 12:02 PM

I want to make something very clear about my 2 idler arm power steering setup I have, it is not tight by any stretch of the imagination, at its best it takes a couple inches to get any significant response at the steering wheel, and it goes down hill from there, every time one adds another tie rod joint it gets looser and looser, but I have gotten used to power steering and even the stock power steering on the 720 is not as tight as a 521 steering gear when it comes to response at the steering wheel.

I stretched the frame 2 feet so in theory I have more weight on the front, but the way I load my truck with debris on a daily basis I take weight off the front end as I start at the back and work my way forward, I rarely ever get all the way to the front of the flatbed before I empty it as I regularly have more than a ton on that flatbed which slows the truck down, all this plays a part in wearing out tie rods/idler arms along with tearing up the frame.

Hauling wood is the hardest on the truck but I only haul wood a hand full of times a year, I load wood from the front of the flatbed back, the front takes a lot of the weight which is why it is likely hardest on the front end of the truck, I never turn the steering wheel of the truck unless I am moving when hauling wood.

I think if your going to go with R&P you should go with end take off, I suspect if you find the right unit that is around the same width as the idler arm/steering gear arm, and you mount the rack so the arms coming out of the rack are at the same angle as the tie rods are coming off the idler arm towards the the wheel spindle connection that you will likely be good and not have to mess with anything else.


 

 


#72 distributorguy

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Posted 01 January 2018 - 01:36 PM

Why not just adapt to a power steering gear box and pump? Then you can leave the steering linkage as-is since you want to leave it stock.  That will also allow you to chose your steering ratio.  Either way you have to adapt the steering column, so that would be the simplest route.  Just chose a box that uses a similar offset and length pitman/steering arm.  Companies like Lares Corp likely have what you need on the shelf.  http://www.larescorp.com/  BTW they retail through Rockauto where you can find detailed specs.  



#73 Stoffregen Motorsports

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Posted 01 January 2018 - 02:42 PM

Changing the steering geometry over stock also creates the risk of making things worse if not done correctly.
 

Don't do it incorrectly!

 

Nothing ventured, nothing gained. Besides, if you don't like it, you can always change it.



#74 Moist Lightning

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Posted 01 January 2018 - 05:41 PM

Why not just adapt to a power steering gear box and pump? Then you can leave the steering linkage as-is since you want to leave it stock.  That will also allow you to chose your steering ratio.  Either way you have to adapt the steering column, so that would be the simplest route.  Just chose a box that uses a similar offset and length pitman/steering arm.  Companies like Lares Corp likely have what you need on the shelf.  http://www.larescorp.com/  BTW they retail through Rockauto where you can find detailed specs.  

 

Ok, that does look like it would be the best solution with a stock geometry, so let’s forget the 2 idler arms. I wasn’t aware it would be that easy, as all I seem to find on the subject is that the 620 was mounted inside the frame while most others are mounted outside making it hard to adapt.

 

 I’m mostly looking at the center take off with 16” extension now. Would that not provide the improved geometry and solve the problems with the end take off (pivot to pivot and pinion angle)? Now that we are down to 16” I think deflection will be less of an issue.

 

If anyone can help figure out the max pivot to pivot we can get with an end take off, finds an end take off short enough and with an angled pinion then I would love to do end take off; I just don’t have $1k to spend on a custom rack.



#75 Str8jacket

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Posted 01 January 2018 - 07:23 PM

Ok, that does look like it would be the best solution with a stock geometry, so let’s forget the 2 idler arms. I wasn’t aware it would be that easy, as all I seem to find on the subject is that the 620 was mounted inside the frame while most others are mounted outside making it hard to adapt.

I’m mostly looking at the center take off with 16” extension now. Would that not provide the improved geometry and solve the problems with the end take off (pivot to pivot and pinion angle)? Now that we are down to 16” I think deflection will be less of an issue.

If anyone can help figure out the max pivot to pivot we can get with an end take off, finds an end take off short enough and with an angled pinion then I would love to do end take off; I just don’t have $1k to spend on a custom rack.


If you measure the suspension up. Ie pivot points for top and bottom arms balljoint locations steer link locations i can run the whole setup through a design program and can tell you the best spot for mounting whatever rack you want to try. I will do it myself one day but i dont have the time spare or someone available to help with the string lines etc.

I did a quick dodgy sim on a file i have already and a rack mounted at the bottom pivot point hieght that is 3in wider can be bumpsteer minimised by moving the rack back a few in inches. It can be done just need to see what fits.

#76 Moist Lightning

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Posted 02 January 2018 - 08:30 AM

If you measure the suspension up. Ie pivot points for top and bottom arms balljoint locations steer link locations i can run the whole setup through a design program and can tell you the best spot for mounting whatever rack you want to try. I will do it myself one day but i dont have the time spare or someone available to help with the string lines etc.

I did a quick dodgy sim on a file i have already and a rack mounted at the bottom pivot point hieght that is 3in wider can be bumpsteer minimised by moving the rack back a few in inches. It can be done just need to see what fits.

 

That would be awesome. Unfortunately, my truck is under a ft of snow so might be a bit before i measure. I will as soon as i can though.



#77 Icehouse

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Posted 02 January 2018 - 04:13 PM

FtMQ5mk.jpg

I had a non power version of this rack - never knew the manufacturer. Who is it?

 

I still have mine if you want to buy it :) 


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#78 thisismatt

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Posted 02 January 2018 - 05:17 PM

I still have mine if you want to buy it :)

Nope, sold mine not too long ago
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#79 Str8jacket

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Posted 02 January 2018 - 08:10 PM

That would be awesome. Unfortunately, my truck is under a ft of snow so might be a bit before i measure. I will as soon as i can though.


Exact opposite here! In my shed its currently 42*C! whats that 108*F?

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