New 620 owner here!

[280Dan]

Hey everyone! I recently acquired a 79 620 after selling my 77 280z for the second time (sold it in 2015 and had seller remorse, bought it back from the same guy in 2019).

 

 

The plan will be to do a "hakotora" 620 using the front end kit from panchkits.com I know this is a common conversion on the sunny trucks but since they're harder to come by, I went with a 620.

 

I was hoping to get some insight from you guys regarding the suspension and engine setup based on my goals for the build. I have been going back and forth about whether I should go with air suspension or if I should go with this full conversion/setup from beebanicustoms.

 

I also am not sure what route to go for the engine. I feel like, and correct me if I'm wrong, about 250whp would be a reasonable and fun hp goal for this truck. I don't know if that's achievable with the L20 without heavy engine work. My original thought was an SR20NA or DET, but my buddies all cringe when I say SR (they've all blown up their fair share of SR's in their drift cars). Had some people tell me to with a Honda K series, but I'm not a huge fan of Honda.

 

I've never had a pickup or a mini-truck for that matter and I'm used to driving my z fairly hard, we had most of our work into the suspension (fully adjustable front and rear LCA's from techno toy tuning, coil over conversion with camber plates, shortened steering knuckles with built in bump steer spacers), so I really enjoyed driving it hard. I don't expect to get the same feel out of the 620 however I would like the suspension and steering to feel pretty responsive and right now it's far from that. Anyway, thought I would introduce myself and I hope to be on here posting up with progress over the next year. I am currently in the market for a new home, so once I get settled it will be full steam ahead with the truck.

 

[280Dan]

*figured out the pictures issue

[datzenmike]

Not a fan of mixed marriages and even less of their offspring. 620 owners and some Datsun enthusiasts might recognize the truck and see that something was done to it. No one else will. I would rather have a 620... or a GTR, but not half 'n half. But that's just me.

 

250 hp from an L20B isn't worth trying. Get a VQ35 makes that all day without sweating. 

 

 

[280Dan]

I hear you but I build my cars for me and I like the look of that front end on the truck. Don’t get me wrong I like the 620 front end also but not as much. That’s what I figured regarding the L20, didn’t think it made sense. 

[datzenmike]

Hey, it's what makes the world interesting. Our differences. If maybe a different car it wouldn't matter so much to me but I really like the 620 looks. Yes you could get 250 from an L20B but it would be almost undriveable on the street. Use something that makes the power you want.

[280Dan]

I hadn’t considered the VQ as something that would fit so I’ll have to look into that. We’re not concerned with fab work however I’d like to not have to cut into the firewall if it can be avoided and I’ve seen that something like an RB would require that being too long. I know the steering shaft poses an issue for guys running turbo setups as well.

[280Dan]

I don’t want to be overly ambitious right out of the gate though regarding an engine swap. I’d first like to get the suspension how I’d like it and go from there. 

[datzenmike]

A V6 is a fit without cutting. An inline six would need the radiator in the back. There are a lot of powerful V6s out there.

 

Yeah get the suspension sorted and you might enjoy the 620 as it is. I can hope.

[280Dan]

Ha I already know a lot of the guys on here are skeptical about people bringing up swaps out of the gate but I don't get rid of my cars easily. Hence the re-purchasing of my old z. I just like to have some goals in mind otherwise I'd be going at it haphazardly. I'm not looking for anything crazy just a fun ride. The z didn't have much in terms of hp but it was a blast to drive with the power it did have. I've always agreed it's better to drive a slow car fast than a fast car slow.

[banzai510(hainz)]

Just leave it as it is its great looking as is and in a low datsun area anyways.  that front end look like it belongs on a car not a truck. Just my opinion and it dont cost nothing

 

I put different wheels on there also

Edited July 16, 2021 by banzai510(hainz)

[MTBiker_Boy]

I recently messaged beebani and he said that he will accept more orders for coilover conversions around december. 

[280Dan]

4 hours ago, banzai510(hainz) said:

Just leave it as it is its great looking as is and in a low datsun area anyways.  that front end look like it belongs on a car not a truck. Just my opinion and it dont cost nothing

 

I put different wheels on there also

I agree on the wheels for sure, that's how I got it but was thinking of going with a 16" setup.

 

4 hours ago, MTBiker_Boy said:

I recently messaged beebani and he said that he will accept more orders for coilover conversions around december. 

Well that may work for my time table since I'm still shopping for a house at the moment.

 

I also need to fix what seems to multiple trans leaks that I recently found after a long crusie.

[banzai510(hainz)]

1 hour ago, 280Dan said:

hat seems to multiple trans leaks that I recently found after a long crusie.

  Simple Park in gravel.  I did a front seal and the rear seal twice. I give up and pulling the front again to do the front. rear aI THINK ITS OTHER ISSUES AS IT STILL LEAKS.  i JUST FILL IT UP EVERY 2 MONTHS. Or evey 4 if not daily driving it

[280Dan]

Problem seems bad though. So here’s what happened. Ran fine and went for about an hour cruise, most of the drive was constant highway speed around 50. When I got to my destination I couldn’t get it into reverse. Drove home another hour and parked it. Came out about an hour later and saw good sized trans fluid leak and the underside was all wet. I cleaned most of it off, I need to get it on jack stands and run it to see where it’s leaking from. I’m assuming I was locked out of reverse due to low fluid level, I hope.

[280Dan]

Also curious on what your opinions about my current suspension setup. All I know is he did drop spindles in the front and I think 3” drop blocks in the rear and removed some springs it seems. I just replaced the tie rods. I want to go lower, so before any major suspension modifications, can I go lower than this? Would you also recommend removing those rubber bump stops and adding pinto front shocks?

 

 

[datzenmike]

 

Absolutely the worst way to lower a truck is to take leaves out of the rear springs. Actually removing a leaf and then using a torch to heat the spring till it sags to the height you want, that's the worst. This lowers the spring rate allowing the truck to travel farther when compressed on a bump. You want a stiffer spring to limit travel when closer to the ground. This seems sensible yet there are people that don't think this through. The leaf spring pack also resists the axle from moving side to side when cornering.

 

 

Has later 720 or D21 hubs vented rotors and larger calipers. Nice!

 

Pinto shocks are for a too light mini car. On top of that they are only 1/8-1/4" shorter. Stock shocks would be better. Cut the top mount away and move 2" higher. Not much sense going higher because soon enough the lower control arm will bottom out on the bump stop and there won't be any suspension travel for the shock absorber to work with anyway. Your suspension will be reduced to the air in the tires and you'll be bouncing like a beach ball.

 

 

38 minutes ago, 280Dan said:

Problem seems bad though. So here’s what happened. Ran fine and went for about an hour cruise, most of the drive was constant highway speed around 50. When I got to my destination I couldn’t get it into reverse. Drove home another hour and parked it. Came out about an hour later and saw good sized trans fluid leak and the underside was all wet. I cleaned most of it off, I need to get it on jack stands and run it to see where it’s leaking from. I’m assuming I was locked out of reverse due to low fluid level, I hope.

 

This is what happens when you don't check all the fluids on an unknown vehicle. If you didn't replace the oils and don't know when the previous owner did it's very risky to go for a one hour cruise. A check would have shown a leak or low fluid indicative of a leak. Transmission oil is changed every 30K bet there are a lot of 620s with 100k on their fluids. Replacing is a good time to inspect. Leaks are usually at the front and rear seal and the vent pipe. Vents are at the high point and only leak if someone gets the bright idea to over fill. The rear seal can be replaced without taking the transmission out. I have seen a rear counter bearing fail and grind away a hole in the case. Only use GL-4 NOT GL-5 (or anything marked for use with yellow metal or copper alloys) in 80w90. I do not recommend a synthetic unless the seals are first replaced. That shit really will leak. 

 

[280Dan]

Regarding the suspension, what would be your recommendation to go lower than? I didn’t think removing leaf springs was ever a good idea either, but this is what I’m working with right now. I plan to go with coilovers eventually. Could you clarify what you mean about cutting the top mount and moving higher? I want to go lower.

So to my defense I work in the service department for a car dealer. I also have a tech background so when I bought the truck I had it shipped to my job so we can put it on a lift before doing anything. Fluids were good no “leaks”. Had some minor seepage at the oil pan and the tie rod ends were shot. Shifter bushing were also MIA. Drove it a few times around the block over the course of a few days. Drove it about 30 minutes home and rechecked. Had no leaks. Drove it a few more times around locally. It was just after the long trip, I’m sure it could probably use all new seals. Thank you for the fluid info, I will probably try to isolate the leaks this weekend if the weather holds and pull it if needed to replace some seals. 

[datzenmike]

Maybe not at all empty just wet. Low wouldn't cause no reverse. I'm assuming the engine was running while searching for reverse?

 

The top shock mount would extend the compressed shock away from bottoming out. But I'm pretty sure the lower control arm would bottom on the rubber bump stop first. What would be the point of a bump stop if the shock bottoms out first?

 

Have a spring shop add more leaf springs to bring it up back to at least stock spring rate. At the same time have them remove some of the arch in them so it rides lower. The stock progressive spring is 100 to 300 pounds/inch and the free arch is 6.3 inches. Flatten to 3 inches and the truck should settle 3 inches. Fine tune the height with lowering blocks. Many on here put 720 4x4 rear springs on. They are both flatter and stiffer.

 

Coilovers? on the rear?? How will you prevent side to side and front to back movement of the axle?? Panhard bar and links??? Way too much bother for something that already is there and works.

[280Dan]

will either use his setup with coils or bags but this is the kit I’m ultimately wanting to install. It’s a lot to weld but luckily we can weld and fabricate. So I’m not worried about the labor. I understand you’re reasoning, “if it ain’t broke don’t fix it”, however like I mentioned earlier I build my cars for my own vision and I have a certain look I want which will require me to really lower the truck. 

[280Dan]

And yes regarding the reverse issue, got to my destination and went to parallel park, couldn’t shift over to reverse. Was like I was locked out. Tried it with the vehicle off, still can’t move the shifter far enough to the right.

[datzenmike]

A four speed then.

[280Dan]

Yes it’s a four speed. I’m wondering if it would just make more sense to try and find a five speed to replace it with at this point. Most of the area around me is major road ways where average speed is 60mph.

[Doobie]

I know this is totally off topic but your z look awesome I really like the color 

[280Dan]

12 hours ago, datzenmike said:

A four speed then.

 

If I want to swap to a 5 speed, the FS5W71B trans would be what I'm looking for as far as a direct swap goes correct?  

[datzenmike]

Yes. The overdrive just lowers highway RPMs. It might save gas. Won't go faster because 4 cylinder and truck wind resistance. The 5 speed is a six cylinder transmission for strength. It was in...

 

'77-78 280z.

79-'83 280zx non turbo

78-80 810

'81-'84 Maxima

'77-'79 620

'80 720 2wd.

 

If wanting 250 hp and an engine swap makes sense to just keep it 4 speed for now as this will all be coming out.