620 lowering issues

[mklotz70]

Thanks for the heads up Wayno!   I've only had a chance to scan the thread, but it looks like Mike and Wayne have given you good info. 

 

Yello620 has some good info in here too....it's pretty close to what you're asking...  http://community.ratsun.net/topic/17769-85-720-spindle-swap/

 

Here's some more info with the dates/years of the 620/720/HB splits to explain the "early/late" models.... http://www.bluehandsinc.com/donor-vehicle-and-part-information.html

Early 720 brakes/spindles are the same as the disc 620.  Mid 720 brakes are vented with a short top hat. Late 720 brakes are the same as the HB

 

You seem to have a couple issues, but it's really hard to tell from your pics.

You definitely have early 720/620 disc on there.  The rotor/calipers will NOT fit the dropped spindle.  The hubs will. 

You have pre-11/82 brakes/spindles....least desirable setup.  Your dropped spindles will mount to the ball joints and the tierod and the hub will mount up....I think you've already found that out, but that's it. 

The mid-720 thru HB calipers are the same and will work with your dropped spindle.  The difference is the top hat height on the rotors.  The mid 720 is short which moves the calipers toward the wheel more and I'm guessing that's what the spacers Wayno showed are for.  The late 720/HB rotors have a tall top hat, pushing the calipers inboard more, eliminating the spacers.

 

I haven't actually seen any dropped spindles available for the mid 720 (11/82-10/85), but if they're including spacers, the HB spindles should work.  The year listing you gave for yours is confusing.  It should have been for '83 and up if you got spacers, or '86 and up if you didn't.

 

Running short on time.....

Your dropped spindles should work with your hubs, '87 HB rotors/calipers.  There's a lot more info in the link to my site's page. 

 

I can't tell for sure in your pics, but it looks like your upper ball joint is in front of your shock.....making the spindle lean forward.  If so, that's just not very safe to drive.  Is the top of the front tire leaning inboard quite a bit? 

 

Gotta run for now.

[datzenmike]

Mike this is supposed to be a '73 so I don't see how this has the later looking 620 or early 720 lower and upper ball joint control arms on it.

[wayno]

Mike this is supposed to be a '73 so I don't see how this has the later looking 620 or early 720 lower and upper ball joint control arms on it.

 

Someone has put the lower and upper control arms on it Dmike, I am starting to wonder if my first question should have been, "have you drove this?"

Mike K is right, that upper balljoint is in front of the shock, and when I did it this way, it was scary to drive, but i figured out the fix for that.

I have done all of this plus added power steering to my 1971 Datsun 521, but it took quite a while before I got everything dialed in, and I also suggest openly that it's not the best way to do it, a lot of mods involved, that is why I use 720 frames for my projects.

[illestmatic]

mklotz70
thanks for all of your input i was very usefull. 
as for the tierod it is indeed infront of the shock leaning the tire slightly inward but i dont if this has anything to do with having the truck sitting for 2 yrs. 
iv drove for about 90 miles until i brought back in the garage to work on. it was swerving and was indeed scary to ride at fast speeds. (havnt done an alignment since iv had it in oct) 
the previous owner hasnt been able to confirm his brake conversion with me since it was 5 years ago. thats a bummer.
i discovered that my lowering spindle are 720 D21 HB. so im thinking to go with HB parts like the rotor and caliper.
 
here are some pics with better angles of the brakes.
http://flic.kr/p/iCrKJ7
http://flic.kr/p/iCrRRe
http://flic.kr/p/iCrJVo
http://flic.kr/p/iCrHXw
http://flic.kr/p/iCrHbm
what i received with the spindles.
http://flic.kr/p/iCr4Q8

http://flic.kr/p/iCrQSv

[wayno]

I hate to tell you this, but this is a failed disc brake conversion, that is likely why it was parked, it drove scary and the guy couldn't fix it, it also has negative camber which also is not fixable without a MAJOR modification, I have done all this, but it has issues that will need to be dealt with.

I have wrote all this down before, but I don't know where to find it at the moment, so let me tell you some of the issues I have had and there consequences, one of the first things that happened to me is that the upper control arm(UCA) mounts on the back of the shock tower, your bolts are smaller than the holes in the spindle on that 720 UCA, so it moves around until it breaks one or both the bolts, let me tell you this, you do not want them bolts to break while you are driving down the freeway and you touch the brakes, cause the frontend falls right out from under you, the fastest I have been moving when it happened is 30mph, and I was not a happy camper, it happened so many times to me, that it ripped the threads out of the hole eventually, so what I did the last time was to get a really hard long bolt that stuck out the back of the tower, and I put a thick washer ans a lock nut on the end and tightened the shit out of it, it has not broken since, wish I had thought of that several years ago.

Here is photo with the long bolt, washer and lock nut.

You can also see in the photo above and below that I lengthened the upper control arms, you can see the welds a inch or two in front of the spindles on both sides.

As I mentioned above, the UCA(upper control arm) has been lengthened 5/8 of an inch in these photos above, I had to do this because of the negative camber(top of the wheel tilted towards the engine), doing this aloud me to be able to align it.

Another thing I did was put the left side UCA on the right side, and the right side on the left, that fixed the caster issue it had(wanting to bite into the turns, and the constant weaving back and forth while driving straight, what this does is get the upper balljoint back far enough, and you are going to have to do this, otherwise you will have a wreck one day, and it will likely be a one car wreck, yours.

Another thing I would suggest is that you drill the UCA mount holes out and tap them to use the UCA bolts from a 720, and if this was done already, it was the only smart thing that they did on this conversion.

As I said, this is not the best way to convert over to disc brakes, and some on here will have negative things to say about what I have said so far, but for them to say that their way is the only safe way is total crap, I have been driving this for almost 10 years now, and I have figured it out finally, my truck drives great, and I would not be able to do this on a scary setup that did not drive properly.

 

You can make this work, it's just not an easy bolt on, you have to fabricate things.

My truck above does not have drop spindles, that will be another twist to the story of your ride, and there nothing better than a thread with lots of drama, and no better way to learn things about your ride either.

[mklotz70]

You're welcome.

 

Wayno's post pretty much laid it out.  If you can fabricate/weld, your easiest/cheapest option is to mod your upper arms like he did.  If you can't, you should probably check with Beebani about a set of custom upper control arms.  They should go on pretty easily and fix both the caster and camber issues.  If you're running wide rims/tires and have the rig lowered, you'll have issues with the fact that your track width will be widen by about 1.25" per side.  There's no perfect option yet.  Check out the last few pages of my Mend thread to see the amount of headache involved with trying to swap to ball joints and maintain stock track width. lol

 

Yes....used hardbody rotors and calipers with those spindles.....that should work.  You can use your hubs.

[JNHEscher]

I solved my non-adjusted 620 tie rod issue by replacing both of them with new center links. They use the same end and all you have to do is cut the right-hand threaded end of the shaft down to the right length, then rethread it. Fully adjustable and not as bulky as the 720 rods.