kj280z

I'm interested in buying one of these units - I saw the unit on the JDM site and also the Unisteer unit - I like this one best (ZBuff's install) ! How can I get one? Zbuff can you "steer" me in the right direction?

I'd like to see some pics of this if you have them

I've installed the aluminum ones and they work great, no leaks and over 2,500 miles

I will be using power windows so I don't need the window crank holes Just the cut outs for the door latch and I'm good!

Spraying prime, base coat and clear coat with no mask = not a good idea!

Lookin good! I'm ready!

OK - My problem is resolved (although I have not exceeded 70 MPH yet but) it drives like a different car!!! Here's the result... We had 2 280z's side by side that had the JCI kit installed... We'll call my Z with the vibration problem number 1 and the other 280Z number 2. Removed the drive shaft of number 2, checked all angles and it was reasonably good. The installer had modified the transmission mount (Number 2) which allowed the rear of the trans to be slightly lower. Then removed drive shaft from number 1 and did some comparison measurements - VERY different! 80% of the problem was that there was SIGNIFICANT differences between the 2 trans mounts. The mount in number one, had the output shaft 1+" inch higher than number 2! I then compared it to a 3rd JCI trans mount that I had and it was different as well!!! I will discuss this with John at JCI as there appears to be inconsistencies in whatever process they're using to make them. OK - Next I used all the laser pointers that I made as per the previous thread. The first thing I did was to get the transmission and diff lined up on a plane... To do this, the tranny had to come down 1 1/4" and the diff had to go up 3/4" (a previous installer had screwed up the installation of the RT mount) Additionally, the trans needed to move toward the drivers side 3/8" and also the diff needed to move toward the passenger side 1/4" By having the laser on the diff flange and another on the trans output shaft you can easily get things lined up - it becomes intuitively obvious what to do... Next take a piece of paper and check your drive shaft angles - they should be more than 1 degree and no more than 3 degrees and also have to be equal front to rear... In my case I have around 2 degrees - When you put the paper as close to the diff flange as possible - if you've got things lined up perfectly, you'll see that both laser dots (one will shine through the paper) as one on top of the other. In my case they were about 1/4" apart at the diff, next repeat the process and insure that you have the same distance between dots at the tranny... in my case - exactly 1/4" on that side too, you'll notice that the dot that was on top is now on the bottom and vice versa (I had 2 different color lasers so it was very apparent). If your angles are off shim and move things left/right as necessary. You can also blow some cigarette smoke (I'm not a smoker but I found someone for this purpose)... You can then see the intersection of the lines and also the plane when you're leveling - quite handy. Use an angle finder to verify that your angles are equal on both sides. OK - now I had things where I wanted them, but then I needed to get the diff and tranny mounts adjusted so that they stay where I had them... (I made my adjustments with the trans and diff mounts removed) The RT mount was fine - I slotted the holes on each side of the poly bushing which gave me left to right adjust-ability. I also contoured the top of the mount so it laid flush on the round section of the diff - it was perfect height wise and only needed a slight tweak from left to right.... Diff done... The tranny mount needed to be lowered significantly. It took several tries but we were able to use some hydraulics to bend the mount so the center was lowered enough to keep the tranny where I wanted it and accommodate the rubber trans bushing. I also slotted the holes in the trans mount so it gave me some left to right adjust-ability... Since every trans mount that we checked was different, I would highly recommend that you check your angles. This would explain why some don't experience any issues while others seem to have issues. I knew that my trans was too high just by looking at pictures of how high my shifter came up through the tunnel compared to others - Mine is now over an inch lower!!!!

Joe I assume you're talking about the JCI trans mount? If so, I'm not using the 240z version. I am using the 280z version. I have an extra 240z JCI mount that I will check out while I'm trouble shooting , but I intend to use the 280z mount unless I find some advantage to switch it.

Yeah that's the plan... measure everything first etc... OK - is it just me or are all you guys also having trouble picturing the contraption that Joe is talking about??? Joe - call me or post a pic! LOL

I have scheduled time on Friday to get the car on a lift so I can fix this once and for all... After doing a lot of searching I haven't found any specific threads that have discussed the JCI 280z tranny mount (and JCI kit in general) as it related to drive line angles... I have suspected all along that this would be an issue, and now this problem is confirming my suspicions. I will certainly share my findings, but in general I suspect that the engine/tranny mounts are positioned about 1 inch too far to the left (these are just general observations - real measurements to follow). Additionally, the transmission mount for the 280z appears to have the output shaft 1 inch too high. I also happen to have a 240z tranny mount which mounts through the floor... I'm going to compare them as part of this trouble shooting effort. To compound the problem, if I'm right and the tranny is too high, the RT Mount lowered the snout of my about 3/4" (very rough estimate)...(which made the problem worse) The fix will be to try to re-position the motor/tranny if necessary, raise the snout of the diff and lower the rear of the tranny... There are several threads on drive line harmonics and how to get the angles right, so I won't cover that here - but I will share the final measurements. For all of you that have had the bolts that fasten your drive shaft to the diff come loose, you should pay attention to this thread! I'd bet I'm not the only one with this problem!!!!

I just did a measurement for you... From the seat cushion to the headliner it's 36" You're going to have to make significant modifications to your floors and it would also be advisable to do your exhaust after you put the seats in since you'll be losing a lot of room that was intended for the stock resonator

Sounds perfect Joe! I don't need the window crank holes in mine since I have power windows, but no biggie either way I can modify them when they arrive Any idea how long before we have them?

Well - I'm having some difficulty with the driveline angles and could use some help. I had the RT Mount installed today. It lowered the nose of the diff so low that the installer had to notch the crossmember so the 2 bolts woudl clear, and I now have a noise on deceleration which I would characterize as interference - it matches RPM and is continuos until I give it gas. Also, I have been frustrated by a vibration in my driveline - (I have an LS1/T56 JCI conversion) - prior to the install of the RT Mount, the vibration started at 80 mph, now it starts at 55 mph. I hope to be able to get it on a lift tomorrow and check out the angles better... Can anyone share any experiences? I have always felt the the JCI 280z Tranny mount (not the 240z mount) causes the rear of the tranny to be about an inch too high... just eyeballing it

So I could use some expertise... I had the RT Mount installed today - local shop did it for me... This eliminates the stock lower mount and replaces it with a polyurethane upper mount which is mounted at the top. The shop had to notch the lower cross member so the bolts would not interfere. They also had to modify my sway bar mounts to lower it slightly because it was too close... Effectively this lowered the front of my diff around 3/4" The vibration now starts at 55 mph. I guess I now know for sure it's the driveshaft - the question is now what to do about it. In the attached picture you can kinda see how the cross member is notched - or if anything else looks suspect feel free to make suggestions... Sorry for the lousy pic from my phone...

Sorry I don't have an extra set but I'll ask around

I'm in!!

This might be bound for the toolshed - but I couldn't pass up the opportunity to share this ridiculousness with you guys http://cgi.ebay.com/...1#ht_500wt_1182 Enjoy

Yep - I started to jack it up today and the hydraulics in my jack blew up, so I'll get all the stuff together and see what I can do tomorrow

Wheels were recently balanced so I've eliminated that... I've done the z31 CV conversion, so the rear u joints are eliminated (although I will check it out again). The drive shaft came from JCI brand new and balanced.... I have always suspected that the tranny mount caused the driveshaft angles not to be optimal - just eyeballing it, it never looked right... And with others having stuff coming loose in the driveline in other posts I am going to start there... I'll share my findings... Has anyone experienced vibration from the z31 CV conversion??

Hey all Today I'll be spending time on my back under my Z. I had posted my suspicions on other posts where members have raised concerns about driveshaft bolts coming loose(mine are still tight). I have always suspected that this is due to drive shaft angles... I have now driven my Z 1,300 miles - it's ok if I stay under 65 but as you approach 70 it starts to have a sound vibration resonance, then by 80 mph it vibrates pretty bad... I think the solution will be a combination of the RT mount (which I already have) and lowering the rear tranny mount to reduce the upward angle slightly (I have the 280z mount) I would like to know if others have experienced this issue. I have also slotted the holes in my tranny mount so I have adjustment from side to side.... What are the optimal angles and what is the best way to achieve them? I guess I'm going to have to invest in a good laser angle finder. I have researched and found that the angles have to be equal front to rear and they cannot exceed 3 degrees...

I need a motor for my car - Sorry for your loss PM me - I'm in Florida so it might be easy

I just brought mine over to the local AC guy - he made all my lines (nothing is stock on mine) It cost $300 bucks but that included a drier, leak test and charging of the system My AC is ICE cold - even in the Florida heat - although it's usually hotter in NJ in the summer

Great stuff When you're ready let me know - I'd like to replace my 300zxt center sections with something I know is sized properly Any idea what you'll charge for them?

What CV's are shown in that pic? Are they the z31 NA shafts?

Yep! That's exactly what I've been saying! And I'm selling a set of 280zxt CV adapters in the Parts for Sale section for anyone who'd like to give it a shot!