Seat mounts/rear end

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Bababooey

New member
I'm building a 240Z into an ITS car and have a few questions before I go any further.

Do I use the stock seat mounts or should I order mounts for whatever seat I go with? (Also any recommendations on a seat?) I'm going to be using it for HPDE's for the first few times on the track so I'm going to have to put a passengers seat in also...should I just put in a stock seat with a 5 point?

Do I run a locked or limited slip rear end? I've heard running a locked (welded) rear end can break stub axles, which are impossible to find except on a parts car. I have a lead on a LSD, and while putting it in looks easy, putting it in right looks expensive.


I wish I would have just gone ahead and bought one finished looking back, but damn, I can tear a Z apart with my eyes closed now.
 
"I wish I would have just gone ahead and bought one finished looking back, but damn, I can tear a Z apart with my eyes closed now. "

Boy do we know that feeling. We just finished completely re-building ours about a year ago.

As for your questions, you can use the stock seat mounts if you can adapt whatever seat you are mounting to them. That said we welded in two pieces of 1" square-stock between the sill and the trans tunnel to mount our seat to. It's a bit lower than we would have been with the stock mount, and we feel it's safer. If you fabricate bottom mounts for your seat it's important to note that you cannot both weld the mounts to the car, and also weld them to the cage because of the limits on the number of cage attachment points (8). We just have a Kirkey seat, and we are fine with it. There are a ton of nicer seats out there, but this was a place where we had limit our budget to be able to do our car.
As for the passenger seat check with the club you run with as for what they require. We started with auto-x and HPDE's with our car as well, and we used a stock seat with a 5-pt for the instructor. That said if you have a race seat, technically your instructor is supposed to have a race seat by SCCA HPDE rules (last time I checked) which dictate that while stock seats and belts are ok, if the driver has upgraded to a harness or a race seat the passenger has to have the same level of equipment. Driving with the stock seat would be a slippery experience, but you could try going with two stock seats with race harnesses if you don't want to spring for two race seats to get you through your HPDE's.

As for the diff, the LSD is the way to go, but there really aren't any easy buttons out there on the r-180's. What units are out there for sale aren't cheap. $1200k and up. We ran with an open diff for a couple of years, and it's 100% fine to get started. The most important thing is that you get seat time. With or without an LSD it will probably take you a couple of years to get up to speed, and the guys that always run up front are always on fresh ($) rubber. As for welding a diff, it depends on what tracks you run, and your driving style. The car is going to struggle to turn in tight corners if you weld it up, and to get around this you have to really throw it around, but for years many z drivers ran with them. Most guys have LSD's now, but since we only have one LSD, we plan on welding another diff up with a taller ratio for Daytona.

Congrats on the build, and good luck finishing it. They are an absolutely joy to drive on the track. Very well behaved, and enough power to put a smile on your face. Post some pics up if you get the chance. I'll try to get some pics of our simple seat mount when I get home, and add them to the thread. The forum here is a great resource. A ton of z-pilots here with a lot more knowledge than I.
 
As I recall, the seat mounts in the 240 are pretty whimpy at best. I'd be scared to put my life in the hands of 40 year old japanese sheet metal.

When I helped put the seat in a friend's Z, we took a sheet of 1/8" x 4" plate and welded it all the way across the floor about where the rear mounting tabs were. A suitable piece of square tubing would also work. Then you can weld mounting brackets onto the plate or tube.

I do not recommend bolting anything through the floor since the floor of the Z is pretty flat. My first off-course incident in that car involved a section of curbing, the addition of some air miles on my Southwest account, and then a rough landing in the grass.
The impact with the curb sheared off all of the seat bolts going through the floor. When the car stopped, I realized I was only held in place by the back brace and seat belt. Fortunately I was able to limp it back to the pits and I got out of the car. That was the last time I drove it. That coulda been real ugly. We learned the hard way, but at least I walked away from it.


Anyway, make sure whatever you do will survive simple off-course excursions as well as hold the seat in place while you're driving.
 
I guess I'll buy the seat and take it from there. I still have to replace the other floor pan so I've got some more work to do before I start on the cage and seat. I might even farm the safety work out to a shop that maintains Datsun race cars.

As far as the rear end, is there any ratio that is better than the rest? I've got a 70 and a 78 rear end. (Car is a 70) The car is going to see auto-x and hill climbs before the track, which will just be Watkins Glen for awhile. I'm assuming that I'd need two different set ups since the Glen has sweeping corners compared to a tight auto-x course.

I'll get some pics when it's out of the garage. I just finished up grinding the welds on the interior, now I need to get them under the floor pan and shoot some paint on it.
 
As far as ratios go, you are correct that it's track dependent. A 3.9 is probably most desirable, but not easy to come by. Nissan never sold it in any vehicle in great numbers stateside, and that ratio ring and pinion hasn't been available from Nismo for years. They did come in the front differential on 1981-1983.5 Datsun 4x4's and you can still find those at some salvage yards. Otherwise just keep an eye peeled for one on the various Datsun sites or ebay. They come up from time to time. Depending on model year some of the trucks came with R-180s in a 4:11 ratio. We bought one from a salvage yard a few years ago. The 4:11 great for auto-x and tighter courses. The other popular ratio is the 3.7, and it's again not super common. Most z's came with either 3.3 or 3.5 rearends. You really need one of the other 3 (4:11, 3.9, or 3.7) to be optimal. I don't know of anyone who races the 3.3. Some do use the 3.5.

Hopefully I attached some pics of our seat mount. Pretty simple and straightforward. It probably is a good idea to wait until you have your cage in to install your mounts. It just allows you to move things where you want relative to the cage. I look forward to seeing your build pics as we just went through all the same stuff. I never did get our build pics on here, so I might try to do that this weekend. Again good luck.
 

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the first gen Maxima came with a 3.7 R180.

Don't bolt anything to the floor, there is just not enough there to trust your life to it. Two bars across the seat area, tied to the door bars and then braced from the rear to the lateral bar on the main hoop is plenty strong and gives you belt attachement points that are all on the cage. You have to think of the worst case and decide who you want to go with, chassis or cage. And if your seat is on the floor and you belts are on the cage, or vice versa, you will be on the wrong end of a tug of war! My money is on the cage. If you are anywhere near Charlotte, NC, I can help you out. I have done 5 cars and they are all very safe and stable.

I can also hook you up with some good, cheap camber plates if you don't already have them, and you do need them.
Mike
 
Mike Mackaman said:
Two bars across the seat area, tied to the door bars and then braced from the rear to the lateral bar on the main hoop is plenty strong and gives you belt attachement points that are all on the cage.
I can also hook you up with some good, cheap camber plates if you don't already have them, and you do need them.
Mike
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Mike, When you mount to the door bars like this Mike, where do you mount the crossbars on the trans tunnel side???

BTW Mike does make nice camber plates, and you want to get his caliper vents for ducting through the caliper as well. The biggest thing to help your brakes on a track z is to keep them cool. You will burn through calipers if you dont get enough air to them.
 
Thanks for the pics Chris. My seat mount is very similar and I hope to mount a newer Ultrashield before Barber.

+1 more for Mikes camber plates. Had I not gone a different way I would be using his.

To the OP. Good luck on your build. I have used "locked" (welded) diffs for the past 3 years. I recently bought a car that had a Quaife 4.11 and I will be installing it before the next race. THat gives me a full set. 3.36, 3.54, 3.7, 3.9, and 4.11. I traded a 4.62 for the 3.90 so there are some other ratios out there if you do some searching.

Also, I didn't see but are you in SEDIV?EDIT, never mind I miss the reference to Watkins Glen........I am getting old..........

Paul
 
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pballance said:
Thanks for the pics Chris. My seat mount is very similar and I hope to mount a newer Ultrashield before Barber.

+1 more for Mikes camber plates. Had I not gone a different way I would be using his.

To the OP. Good luck on your build. I have used "locked" (welded) diffs for the past 3 years. I recently bought a car that had a Quaife 4.11 and I will be installing it before the next race. THat gives me a full set. 3.36, 3.54, 3.7, 3.9, and 4.11. I traded a 4.62 for the 3.90 so there are some other ratios out there if you do some searching.

Also, I didn't see but are you in SEDIV?EDIT, never mind I miss the reference to Watkins Glen........I am getting old..........

Paul
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Paul, which ratios do you use most often??? We were considering locking up our 3.3, and using it at Daytona where we might be able to take advantage of the taller gearing on the banking. We haven't run there yet, so we don't know for sure if the 3.3 will be a help or a hindrance. Also have you had any issues with the welded diff?
 
Chris, for me it has been 3.7 and 3.9. Now that I have a 4.11 i presume it will be 3.9 and 4.11. Maybe Ron and/or Jeff will chime in about Daytona. I think they ran a 3.54 there.

No issues so far with the wleded diff's. (crosses fingers) but then I recently had the entire rear driveline out a replaced everything. I considered magnaflux for the stubs but decided to just re-assemble everything. They "looked" good and I have been told that I am pretty easy on the car............. Don't know about that :)
 
Thanks for the positive comments about the camber plates!

I have mounted them to a short vertical on a sliding plate on the floor. This keeps in the letter of the rules, even the most draconian interpretation. I have also put a plate on the trans tunnel and welded them in there. That could be interpreted as additional attachement point, but it makes for a strong seatmount. The only negative is that if your exhaust runs on that side it can lead to things getting toasty on the seat bottom towards the end of the race. For that reason I prefer the floor with a little stub and a plate.

Mike
 
Since camber plates were brought up, run them front and rear or rear only? I was told that I could just slot the rear for adjustments and go with the actual plates up front. Of course, these are recommendations from "track day" stars.

Mike, if you could post up some pics of yours, I might buy a set. I'm in my welding stage now so I'm in the mood to stick more stuff on the car. I've got eccentrics in there now but the more I've read about them, the more I want to take them out.

I'll be getting some pics of mine up tomorrow. I'm waiting for the seam sealer to dry under the floor pan and then I can shoot some primer and paint on it. Not looking forward to having to sweep a winters worth of crap out of my garage when I move the car though.......
 
Since you can weld the plates in yourself, I'd recommend putting the plates in both front and rear. You can most likely get the camber you need in the rear with slotting and/or eccentrics, but the right way is to do the plates with the sphericals up top. Since it wont cost you too much to install em, I personlly wouldn't want to cut a corner here. BTW what shocks are you planning to run?
 
We run them front and rear. Easy adjustments, clean, reliable, and they lower the car without giving up travel! If you have a plasma cutter they are a breeze to install. I installed two sets and modified the front strut tubes on a customer car this spring in about 10 hours total from unloading to driving away. I found the pictures, now I just need to remember how to post them.

Mike
 
I've already got a Tokico/Ground Control set up on the car. The front end has to come apart again anyway which would be a good time for the plates. I put Arizona Z Car knuckles on after I was told they were legal. Also bought subframe connectors on the advice from the same guy who supposedly raced ITS before. Lets just say that's why I started posting here. The last thing I want is to be sent home/DQed for illegal parts.

No pics today...pouring out. Finished up the underside paint and if it's not raining tomorrow, I'll gets some pics when I turn it around in the driveway.

BTW, if anybody has a set of later steering knuckles, PM me. (My car is a 70 so I believe 72+) I bought the bigger ball joints for the AZC knuckles and don't feel like spending another $150 for the smaller ones.
 
Bababooey said:
I've already got a Tokico/Ground Control set up on the car. The front end has to come apart again anyway which would be a good time for the plates. I put Arizona Z Car knuckles on after I was told they were legal. Also bought subframe connectors on the advice from the same guy who supposedly raced ITS before. Lets just say that's why I started posting here. The last thing I want is to be sent home/DQed for illegal parts.

No pics today...pouring out. Finished up the underside paint and if it's not raining tomorrow, I'll gets some pics when I turn it around in the driveway.

BTW, if anybody has a set of later steering knuckles, PM me. (My car is a 70 so I believe 72+) I bought the bigger ball joints for the AZC knuckles and don't feel like spending another $150 for the smaller ones.
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Because shocks are free (including housings) if the knuckles are built into the shock assembly they would be considered legal I believe. Simply bolting them up doesn't count per the rules, but if you can tack the AZC knuckles to the bottom of the shock tower I believe the current accepted interpretation of the rules would leave you in good graces. I'm not 100% sure on this so I would search the rules sub-forum for a thread onn the subject, or ask more knowledgeable rules gurus than I about it. The subframe connectors are a no go though. We made some of the same mistakes when we built ours. We had a solid diff mount on, and the knuckles without the tacks in place. If you have some things that aren't quite right, I doubt anyone will send you home. We had the diff mount on through our schools and my brothers first two races. We just wanted to wait til we swapped diffs to change the part. The tech shed doesn't tear into cars unless there is a protest, and people aren't likely to protest you for anything but major rules issues unless you are running up front. Even then your fellow competitors are much more likely to approach you and discuss your car outside of the protest process. If you're reasonable with them, and aren't blatantly trying to game the system, in all likelyhood they will be reasonable with you. I've found the paddock at our SCCA races to be one of the friendliest places on the planet.
 
Oh, and there is a 99% chance we have the knuckles, if you'd still rather switch back. I'll look in the shop tomorrow or Wed. We just stripped down our parts car, and I think it was a 72'. Even if it wasn't we may still have a set somewhere.
 
Don't jump all over me for anything that's not perfect. It's my first time EVER welding. Where the TC box meets with the subframe is totally rebuilt. I had to cut out about 4in more than the replacements had. The floor pans didn't fit right (heard they aren't a good fit from a bunch) so they had to be persuaded a bit with a BFH. They also didn't go up the firewall where I had a lot of rust which is why it's patched up there. The lower shock towers were also completely rebuilt. Like I said, it's not pretty but pretty doesn't make you go faster.

Yes I seam sealed the crap out of it. It's not going to rust again!
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The front is just bolted together, still need to find boots that fit.
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