bawfuls Posted February 7, 2019 Share Posted February 7, 2019 As I've mentioned briefly here before, I'm nearing completion of my electric conversion on a 1977 280Z. The conversion has resulted in a significant change to the car's weight balance, and I need advice on suspension adjustments to go along with this. In lieu of the ~500 lbs L28, there is now a 120 lbs electric motor: And where the spare tire well/gas tank once was, there is ~300 lbs of batteries and battery housing: As a result, the ride height is quite high up front: The rear looks fine to me though: This car will be a daily driver around town and on freeways. I have no plans to track/autocross/etc (and would need to do a major overhaul of my battery pack to set it up for that). So I'm looking for a way to lower the front while keeping the ride comfortable for daily driving. It's been suggested that I just cut the springs up front, but others have warned that's a horrible idea. I'd rather not spend big money on a fancy setup with a ton of adjustment meant for racing that I'll never use, so is there something in between that might work better for me? Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 7, 2019 Share Posted February 7, 2019 Howdy, noticed you posted in the FAQ section, that area of the forum doesn't allow for replies. I've moved your thread to the correct area. Take a moment to make sure you are posting in the correct section if you would like input from others :D. I'd be a bit worried that with so much weight off the nose and more in the rear the front will feel quite light under acceleration. I would hesitate to cut the springs as the travel on the stock suspension is not that great and you would be loosing more of it. I'd say a basic set of coilovers from a company that does custom spring rates may be worth the investment (BC comes to mind), to get the height and springs right you could just calculate the static load on each corner and calculate the compression if you aren't concerned with dynamic performance or you could call them up to work out a custom solution which would be advisable with the weight moving around so much. You could go with ground control springs and adjustable perches, sectioning the struts would be a good idea to gain more travel, and a new shock wouldn't go amiss, but in the end you would end up about the same if not more than a set of coilovers as above albeit with arguably a better shock and spring. Lastly you could go with an adjustable spring like cosmo sells. No modification and it sits in the stock area. The springs are pretty harsh and the ride isn't pleasant at least with stock shocks, but it is by far the cheaper of the options. I'm sure others may chime in. I will say I cut 280z tokico linear springs when they were on my 240z. It was a bit of a hassle as every time I jacked up and lowered the car I would have to line the spring up or they would pop out of their perch, same thing on off camber hills. The spring perches have holes that you could use with some CV boot steel zip ties to potentially hold the spring in the perch, but it would have to fight the shock, so I'm not sure how long that would last. Quote Link to comment Share on other sites More sharing options...
jhm Posted February 7, 2019 Share Posted February 7, 2019 The BCs have a nice design that allows one to adjust ride height without affecting suspension bump travel...this makes them an attractive option for a daily driver that will see a lot of varied road conditions. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted February 7, 2019 Author Share Posted February 7, 2019 (edited) 2 hours ago, seattlejester said: Howdy, noticed you posted in the FAQ section, that area of the forum doesn't allow for replies. I've moved your thread to the correct area. Take a moment to make sure you are posting in the correct section if you would like input from others :D. Thanks, sorry I miss-read the subforum heading. The Cosmo kit sounds like the easiest option, could I also replace the stock shocks at the same time to address the ride harshness? It looks like the Cosmo kit is only ~$250 for all four, while the BC kit that comes up for this car is $315 for just one corner. I expect to get access to scales this weekend or next week, so I can get more details on weight distribution at that point. Edited February 7, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
Zetsaz Posted February 8, 2019 Share Posted February 8, 2019 The cosmos look like just a cheap sleeve that gets placed on top of the stock spring perches with some minor height adjustability. For a daily driver, any sort of lowering especially the sort you'll need to do on the front end is going to reduce your shock travel significantly. I had considered T3 and other "bolt in" or cheaper options that involved more work, but the full threaded body on the BC coilovers allowing full suspension travel was too much to pass up. For a daily driver I'd definitely recommend eating the cost. It'll be better in the long run. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted February 8, 2019 Share Posted February 8, 2019 3 hours ago, Zetsaz said: For a daily driver, any sort of lowering especially the sort you'll need to do on the front end is going to reduce your shock travel significantly. How will it lower their shock travel if they're simply lowering it back to factory height? (as long as they don't run into coil bind from running too soft of springs) Quote Link to comment Share on other sites More sharing options...
bawfuls Posted February 8, 2019 Author Share Posted February 8, 2019 (edited) Is this a better version of the Cosmos method? Looks like quite a lot of height adjustability. https://groundcontrolstore.com/collections/s30-coilover-conversion/products/coilover-conversion-kit-74-78-nissan-260-280z-not-zx-weld Edited February 8, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
jhm Posted February 8, 2019 Share Posted February 8, 2019 Apples and oranges. With the GC sleeves, one removes the stock spring perch and welds on a new perch ring for the provided coilover sleeves (kind of the standard coilover installation). The Cosmo sleeves sit on the stock spring perch, and are shorter than most coilover sleeves, which is why the others have pointed out that ride height adjustability is limited as compared to other coilover conversions. If the Cosmos meet your needs, however, go for it....you can't beat the price. Here's a pretty decent step-by-step write-up on the Cosmos: Cool project, BTW. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted February 8, 2019 Author Share Posted February 8, 2019 If the GC sleeves give more adjustability and are of higher quality, I don't mind paying a bit more. With my very unusual weight distribution, it is probably a good idea to lean towards more height adjustment. I am also weary of reports the Cosmos are quite stiff, while the GC kit will let me pick from a range of spring rates that may be more suitable to daily driving on our decaying San Diego streets. Particularly if the GC sleeves give me a bit of "future proofing" in case I add power/bigger tires/etc down the road. $500 for all 4 corners and the piece of mind that they'll work for potential future upgrades is worth it to me. Now I just have to figure out how to pick shocks and springs. I might give GC a call and ask them some Q's. This thread has been quite helpful already, thanks! Quote Link to comment Share on other sites More sharing options...
Zetsaz Posted February 8, 2019 Share Posted February 8, 2019 (edited) Sorry, my explanation was more geared towards the average car. that being said, the really short and stiff spring will still create similar problems, and if you go with softer spring rates if they have that option, you'll likely still bottom out if you hit some bad bumps/pot holes. GC would be a better option in your case if you really want to save the money. That being said, the pricing is almost a wash if you decide to buy adjustable shocks. The stock dampers really wont' do well with increased spring rates and likely won't last long even on strictly street use. Edited February 8, 2019 by Zetsaz Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 8, 2019 Share Posted February 8, 2019 The cosmos run a pretty stiff spring, the suspension felt crashy for lack of a better word. @Boog has/had them on his car so he may chime in. The car I was in was lowered a fair amount though so a lack of travel could be the culprit. You can install the cosmo's "correctly," in that you remove the spring perch and you can weld a perch for them to sit on, they come with some allen set screws as an install option, but I really would not want to trust a few grub screws to hold up the springs. The GC spring perches are additionally a good choice, you can choose the spring to match. You can only adjust spring height though so you will be winding preload into the suspension to raise the rear. Not really a problem, you just will be "using up" some of the spring tension to get the height. It will also unload without the use of a helper spring when you jack the car depending on the install point. Depending on the spring both of these options would require a replacement shock. The GC if you chose to, you could shorten the shock body, run a shorter stock and have a good amount of travel at a variety of ride height. If you decided you will never go lower than stock, then you could run a stock shock and not modify the shock body, although with the modification you could dial in the ride height without worrying about shock travel (I think Z's sit a bit high at stock height). Cosmo would work, is cheap, but not ideal in a few aspects GC would work, and if you shortened the shock body you could lower it with no ramifications BC or other weld on cartridges style coilover will have independent height adjustment so you always maintain a set amount of shock travel, but yes price is expensive. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted February 10, 2019 Author Share Posted February 10, 2019 BTW this car runs as of today. Still need to address the suspension and a couple other issues, but at least it's moving now. motor spin for the first time: https://imgur.com/a/jb5W8An test drive: https://imgur.com/a/51VIz4Y Quote Link to comment Share on other sites More sharing options...
socorob Posted February 11, 2019 Share Posted February 11, 2019 What kind of speed and range do you think you'll get? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 11, 2019 Share Posted February 11, 2019 Coilovers are a better solution, but no problems with cutting. I ran my first Z on cut springs for quite a while. My friend who cut mine also ran 240 springs and perches on 280ZX struts in his street 510s. He cut all of the springs, and again, never had any issues. There are a lot of rednecks that cut them with a torch, or just heat the spring up until it sags to the proper height. This takes the temper out of the spring, and can cause the spring to fail. If you cut them with a cutoff wheel the heat is very localized and doesn't cause a problem IME. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 12, 2019 Share Posted February 12, 2019 Congrats! If you do plan on cutting the springs I'd just make sure to grab a set of metal CV ties to secure the springs so they don't fall off the perch or miss the hat on the top or run some limiters to keep the suspension from drooping all the way when you jack it up. I ran cut linear 280z tokico springs for a while in my 240z, but it consisted of lowering the car, stopping part way and slipping my hands between the wheel and the arch to align the spring then lowering it the rest of the way. Good way to loose a hand if it unsettles suddenly. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted February 12, 2019 Author Share Posted February 12, 2019 On 2/11/2019 at 11:24 AM, socorob said: What kind of speed and range do you think you'll get? Motor is rated for 120 hp 179 ft.lbs peak. I should get somewhat better acceleration around town than the stock L28 (particularly since I get peak torque now from 0-3500 RPM), but with a reduced top speed. Continuous power output is only ~40hp, so based on that and gearing/drag calcs I've found online puts top speed around 90-100 mph (this car has the 5-speed transmission), which IMO is plenty fast for a 40 year old tin-can of a car. I expect around 90-100 miles of range out of this once everything is dialed in (suspension leveled out, front aero cleaned up, etc). 1 Quote Link to comment Share on other sites More sharing options...
G-E Posted March 5, 2019 Share Posted March 5, 2019 Why don't you put more batteries up front? Spread the weight a little? Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 25, 2019 Author Share Posted March 25, 2019 (edited) On 3/5/2019 at 3:18 AM, G-E said: Why don't you put more batteries up front? Spread the weight a little? Perhaps I will eventually, but the 5 battery modules I've got in it now were 40% of my total project budget. And with the voltage range of the motor I've got, I can't just add one or two, I'd have to add another 5 in parallel. So for the time being, this is it. I could have designed it originally to split the pack, with say 3 in the rear and 2 up front, but for simplicity I decided against that. Edited March 25, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
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