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PostPosted: Wed Feb 10, 2016 12:46 pm 
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AlanDatsomefun wrote:
Subaru WRX STI GDB model seats are a good choice. They are not as wide as the original Datsun buckets and can be installed without cutting out the Datsun front bulkhead/web where OEM seats mount. Retaining the bulkhead/web and utilising the other OEM seat mounting holes and seat belt mounting points, albeit with some modification, makes it easier when it comes to obtaining engineering certification. I wanted seats that gave greater front-to-rear adjustment than the originals, they had to be firm and comfortable, driver side height had to be adjustable, and had good bolsters for lateral support. Installing these turned out to be something of a chore, but the final result was well worth the effort. If you choose to do something similar, this posting may save you time and headaches.

The seats provide same seating height as originals, though you are unlikely to be able to remember what the original seat height was when your Datto 1600 was new, because the old springs in the Datto seats would have have long since sagged. Seating position of the installed STI seats seems higher, but it is not.

The approach involved trimming down three of the four corner mounting brackets, but not the inboard rear. The inboard rear one was retained because this is particularly strong and Subaru deliberately integrated the seat belt mounting into the seat. In my case, I am using the original Datsun floor attachment point for the inboard rear seat mounting point as well as to attach the Subaru seat. After trimming the Subaru mounting brackets (and enlarging a hole in the inboard rear one), 16mm CrMo tubes were welded across both front and rear to ensure seat rails would be fixed together, and precisely located relative to each other. Note that without these tubes it is hard to get exactly the right spacing between rails, and it makes the whole installation stiffer and stronger.

One bracket for the outboard attachment of the seat to the car had to be fabricated and another for the inboard rear attachment. From an engineering viewpoint it is important to retain the Subaru OEM brackets with as little modification as possible, particularly as they are riveted onto the rails. It is practical to weld to the rivetted-on bracket without weakening the rails. Note that riveting is used here because it is stronger and more reliable than welding and allows for steels that are easy to weld to be attached to others that may not be so easily welded or may need pre- or post-weld heating or some other special treatment. In the case of three of the four Subaru OEM mounting brackets, where these were cut down, a steel tab with a bolt through it was welded on to facilitate the seat being attached to the vehicle. All the welding described involved steel parts that could be readily welded without causing problems. Photos tell most of the story.

Details of passenger side are shown. The driver's side is similar, though the height adjusting mechanism makes things a little more complicated. In the case of the passenger side it is very easy to unbolt the rails from the seat and do the fabrication and welding, and to the test fitting without trying to juggle the whole complete seat. However, this was not so easy for the driver's side, so the passenger's side became the test case and when completed it was a matter of replicating the modification process for the driver's side. All welds were done carefully with a MIG, but because the driver's side the rails remained bolted to the seat, and a wet towel was carefully located to protect the fabric and foam padding. This ensured that my seats didn't end up looking like Chinese New Year fireworks.

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PostPosted: Wed Feb 10, 2016 5:19 pm 
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Location: Melbourne, Vic
Once again, like your R&P conversion articles in the past, you've excelled yourself with another insightful technical write up - lot of really good information here!

Can't wait to see the whole car....it's going to be amazing.....


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PostPosted: Wed Feb 10, 2016 5:37 pm 
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Nice write up im running wrx seats in my 1600 and they work well


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PostPosted: Mon Feb 15, 2016 10:22 pm 
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I like what you've done there. It doesn't look like much work if you can weld bits and pieces. But is there any reason you've done it like that rather than just making a plate or weld up some flat bar to attach to the bottom of the Subie seat, then use that to attach the Original Datsun runners and floor mounts?

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PostPosted: Fri Feb 26, 2016 1:54 pm 
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Yes, unfortunately this not the way to go if you do not have a welder or are not confident in using one.
Short Answer:
I wanted: the whole installation to be stronger; seats to move front-to-rear more than is possible with the original Datto rails; and to retain the driver side height adjustment (... not sure if you have to remove the height adjusting mechanism before bolting the driver's seat directly to the Datto rails and mounts - this wasn't a consideration for me at the time).
Long Answer
My thinking went as follows: ... Having seen what happens when a Datto 1600 with original seats / rails / mounts is involved in a minor rear-end shunt and having rallied one for a couple of years with all original seats, I wanted this seat installation to be strong. The original Datto rails and mounts are quite flimsy. The original mounting points can be beefed up very simply to be surprisingly strong. I had previously owned a WRX and was impressed with the way the seats were installed, and Subaru connected the seat belt to the rails/sliders - so these items together (when bolted into the car) have to be strong. Seats are out of an STi and I wanted to keep the height adjustment and have the sliding and raising mechanisms move freely and reliably. I found out early on that if the rails were not exactly the right distance apart and parallel, with the rails/height adjusting mechanism held in place (as it would be when bolted into the Subaru chassis), the mechanisms didn't work smoothly. Simple fix was to make sure the rails were held parallel to each other and the right distance apart (as they would be when mounted in the Subaru) and weld tubes across between rails, front and rear. I had a length of the perfect size thin walled Chrome Moly tube ~16mm OD. From that point it was a logical progression to what is in the photos. Overall, I have the extra front-to-rear travel, plus the height adjustment of the STi seats. The STi sliders have something like 100mm more travel (I can't measure this for you because I sold the Datto seats). When combined with height adjustable steering column installed when I did the rack and pinion conversion, seating can be adjusted to comfortably suit drivers who are shorter or taller than previously. I guess that I am just getting old and looking for more comfort. I had memories of long trips in my first Datto 1600 where by back and legs ached from being forced to sit in exactly the same position for many hours.

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PostPosted: Fri Feb 26, 2016 3:10 pm 
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Yeah, I like what you did. I would be tempted to reinforce under the car where the rear mount point of the seat bolts to and on the front also if you haven't already? I took that idea from Nick when I built my car.
Are the seats aft adjustment limited by the inertia reel placement for your seatbelts? even with an adapter plate mine still hit on full extension.

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Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
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Previous Car: Restored Green 1972 Datsun 510, Hot L18


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PostPosted: Mon Feb 29, 2016 9:22 am 
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Very good idea to reinforce as you suggest: In event of a rear end shunt, the front mounting bolts can actually pull through. Photo included shows one way of reinforcing this area.
At the rear, a piece of flat steel about 3mm x 15mm x 115mm is installed under and plug welded from the top where original holes were: I drilled new holes 10mm diameter 70mm apart (originals were 60). I didn't take a photo of this when it was finished, but easy to imagine. Being narrower, the STi seats have a little more clearance both inboard and outboard. I did a quick test fit when my Datsport retractible seat belts arrived recently and it looks like they should clear OK when the seats are pushed right back: I should double check this - thanks!. But if seats were installed lower, it is more likely they would hit the retracting mechanism when pushed fully back. As indicated earlier, the basic seating positions look higher than a Datto 1600 would have been when new, but actually are the same.


Attachments:
File comment: Method of reinforcing the front mounting points
3 OEM Bulkhead Reinforcings 1.jpg
3 OEM Bulkhead Reinforcings 1.jpg [ 1.38 MiB | Viewed 2995 times ]

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Last edited by AlanDatsomefun on Fri Mar 11, 2016 2:16 pm, edited 1 time in total.
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PostPosted: Mon Feb 29, 2016 12:07 pm 
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FWIW the early 80's Bluebird is the best fit, same width as the std seat rails the flat sliders bolt to the 1600 seat mounts.

The other advantage is to the police RTA etc they look like a factory seat


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PostPosted: Mon Feb 29, 2016 3:07 pm 
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+1 for the Bluebird seats.

Fit in easily and they are a pretty good seat


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PostPosted: Thu Nov 08, 2018 11:45 am 
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A true story follows:
" ... many years ago my brother was stopped by the Police. He could not understand why they were so concerned that he had removed the front bench seat of his car and was using a plastic milk crate for a seat. After all, he argued that the crate was bolted to a welded steel frame which was securely attached to the floor and the marine grade plywood sheet used as a backrest provided adequate restraint whilst having some flex. He told the Police that he was a very capable handyman and had plans to apply padding and cover his home-made seat, but had not done that yet. He also intended to do the same on the passenger's side. The Police slapped him with a fine and a defect notice."

At the upper end of the "engineered for safety" spectrum, vehicle manufacturers build seats that will withstand specified high levels of acceleration or deceleration without breaking or distorting beyond specified limits, even incorporating supplementary restraint systems elements into their seats, and attaching the seat belt directly to the seat frame.

... fundamental question: ... how much effort do you reasonably put into providing safety and comfort? Personally, I position myself firmly at the highly conservative upper end of the "engineered for safety" spectrum. That doesn't mean that cheap cannot be any good, but consider the day you get shunted from the rear by that idiot behind you who just has to TXT whilst driving, have a roll-over on a track day, or get "T-boned" at an intersection: the integrity of your seat and its mountings could be desperately important for your survival and/or the extent of injuries you are likely to sustain. ... just saying!

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