True Rear vs. Divorced spring (causes damage?)

370Tyler · 01-23-2020, 10:57 AM

So next week i'm thinking of picking up a set of True rear coilovers. HKS HIPERMAX IV GT to be exact. But yesterday at the dinner table my dad made an interesting point. The Z comes standard with a divorced spring/shock setup in the rear, so changing it to true rear coils may be bad. reason it may be bad is cause the car wasn't designed to have all the weight and load on that part of the car. Again he just said it as a thought and it did get me thinking could he be right? Only down side to not going with a true rear setup would be lack of camber adjust ability so that might suck. lets hear some of your thoughts!

elhombre · 01-23-2020, 11:29 AM

Quote:

Originally Posted by 370Tyler

So next week i'm thinking of picking up a set of True rear coilovers. HKS HIPERMAX IV GT to be exact. But yesterday at the dinner table my dad made an interesting point. The Z comes standard with a divorced spring/shock setup in the rear, so changing it to true rear coils may be bad. reason it may be bad is cause the car wasn't designed to have all the weight and load on that part of the car. Again he just said it as a thought and it did get me thinking could he be right? Only down side to not going with a true rear setup would be lack of camber adjust ability so that might suck. lets hear some of your thoughts!

I think that the HKS Hipermax only comes as a divorced setup only. I have them on my car and they are divorced just like the OEM style.

DaveZ03 · 01-23-2020, 12:09 PM

Quote:

Originally Posted by 370Tyler

So next week i'm thinking of picking up a set of True rear coilovers. HKS HIPERMAX IV GT to be exact. But yesterday at the dinner table my dad made an interesting point. The Z comes standard with a divorced spring/shock setup in the rear, so changing it to true rear coils may be bad. reason it may be bad is cause the car wasn't designed to have all the weight and load on that part of the car. Again he just said it as a thought and it did get me thinking could he be right? Only down side to not going with a true rear setup would be lack of camber adjust ability so that might suck. lets hear some of your thoughts!

I have a divorced set up on my car, and to your dads point, I would rather play it safe than sorry. There hasn't been any definitive proof that a true set could lead to shock tower failure, and although the install was a tad more invasive comparatively, my thought process was to error on the side of caution. My two cents is I think it really comes down to personal preference and what you're comfortable with.

To your point about camber, you will need camber arms out back regardless of true type or divorced type.

NorthStyle · 01-23-2020, 12:19 PM

You can go with an OEM-style and get camber adjustment via aftermarket parts or go with a true-style setup and get camber adjustment via aftermarket parts. The stock mounting points are fine for true-style setups as probably 50% of us have them and I've yet to see a BMW-style failure (I've been on true-style for appx 5 years now). You'll be fine either way.

JARblue · 01-23-2020, 12:38 PM

This matter has been discussed before. There is no issues with switching from the stock divorced rear suspension shock/spring set up to a true type coilover. Guys have been running true type coils hard on the track for years without any issues. This isn't a BMW shock tower...

370Tyler · 01-23-2020, 01:48 PM

Quote:

Originally Posted by DaveZ03

I have a divorced set up on my car, and to your dads point, I would rather play it safe than sorry. There hasn't been any definitive proof that a true set could lead to shock tower failure, and although the install was a tad more invasive comparatively, my thought process was to error on the side of caution. My two cents is I think it really comes down to personal preference and what you're comfortable with.

To your point about camber, you will need camber arms out back regardless of true type or divorced type.

How can you get camber arms if the spring is sitting where the camber arm would go? unless I am missing something... lol

DaveZ03 · 01-23-2020, 01:51 PM

Quote:

Originally Posted by 370Tyler

How can you get camber arms if the spring is sitting where the camber arm would go? unless I am missing something... lol

The design of the 370z rear suspension has the spring cup and camber arm divorced from each other. Where the spring sits in the stock midlink is completely different from where the camber arm is located.

370Tyler · 01-23-2020, 01:52 PM

Quote:

Originally Posted by elhombre

I think that the HKS Hipermax only comes as a divorced setup only. I have them on my car and they are divorced just like the OEM style.

what model HKS do you have? I want the HIPERMAX IV GT and all the photos of those I have seen are true rear...

370Tyler · 01-23-2020, 01:57 PM

Quote:

Originally Posted by DaveZ03

The design of the 370z rear suspension has the spring cup and camber arm divorced from each other. Where the spring sits in the stock midlink is completely different from where the camber arm is located.

oh, no ****. I thought they were one in the same all this time. ok so say I got a divorced rear setup for coils I'm good to order and install any rear camber arms?

DaveZ03 · 01-23-2020, 01:59 PM

Quote:

Originally Posted by 370Tyler

oh, no ****. I thought they were one in the same all this time. ok so say I got a divorced rear setup for coils I'm good to order and install any rear camber arms?

Regardless of divorced or true, you will need rear camber arms. I would recommend SPL.

370Tyler · 01-23-2020, 02:18 PM

Quote:

Originally Posted by DaveZ03

Regardless of divorced or true, you will need rear camber arms. I would recommend SPL.

yes I planned on going SPL everything. toe links, camber arms and FUCAS.

redondoaveb · 01-23-2020, 04:11 PM

Quote:

Originally Posted by 370Tyler

yes I planned on going SPL everything. toe links, camber arms and FUCAS.

If you end up with true coilovers you'll need toe arms to take the place of the stock spring buckets. I have a brand new, never opened set of SPL arms I'm selling for cheap.

OptionZero · 01-23-2020, 04:53 PM

To put all the answers in one place:

1) Durability

In THEORY, yes, a true coilover setup will put "more" stress on the strut towers; however, in reality this has not actually shown to be a significant enough difference to worry about. People track their cars with true coilover setups, which is a far harsher condition than bumming around down, without experiencing failure.

More to the point, if you were to run stiff enough suspension with stressful enough conditions to actually need to worry about it . . . you'd be a racing car with no DD duties and you'd have custom fabbed reinforcements in that area.

Bottom line, unless you're shooting for competitive laptimes, don't its not a problem

2) Spring Rate
Changing from a divorced to true style DOES change the geometry of the rear suspension and you should not run the same rates in a true style as in a divorced style.

Refer to this thread:
Aero and Suspension Tuning With True Type Coilovers

Specifically

Quote:

Originally Posted by Brendan

With a true type rear suspension, it makes the motion ratio very close to 1 to 1. If you ran a 750lb/13k rear with the divorced set-up, that would put you at a natural frequency of about 2.00 hertz. If you were to then run that same spring with a true type rear, that bumps things up to over 3.00 hertz. Based on my calculator, you would need to go back down to 7-5k or 400lb to 300lb spring range if you wanted the rear to feel the same as when you were running the divorced set-up with 13k/750lb springs. I don't know how aero effects this as I have been focused on autocross, but I imagine you need to run on the stiffer end of the range since you have a force pushing down on the car.

I would love to see what he comes up with. Have my math checked so to speak.

Summary: if you chose a "true" type setup, you will need to run a LOWER spring rate than a divorced setup

3) Alignment adjustment
There are THREE arms you need for the rear for full adjustment:
- a camber arm. SPL makes two versions, the "billet" style is just a newer design
https://www.splparts.com/products/re...-370z-g37.html
or
https://www.splparts.com/products/re...t-version.html

- a traction arm
https://www.splparts.com/products/re...-370z-g37.html

- a midlink OR toe arm
If you have a divorced setup, get this:
https://www.splparts.com/products/re...-370z-g37.html
***NOTE: The SPL midlink requires a 65mm diameter spring. Check with your coilover provider to see what diameter their rear springs are. Most good places offer Swift springs as an upgrade; Swift makes a spring with the correct 65 diameter that fits perfectly. The STOCK spring bucket is like 4.5 inches and way, WAY wider - it will not fit on the SPL bucket.***

if you have a true setup, get EITHER:
https://www.splparts.com/products/re...-370z-g37.html
or
https://www.splparts.com/products/re...t-version.html

Again, the billet version is just a newer design

NOTE:
You will also need to get an Eccentric Lockout kit:https://www.splparts.com/products/ec...-370z-g37.html

the STOCK adjustment points in the rear are eccentric bolts that may slip over time. These remove that movement, so adjustment is made purely on the arms themselves, which are more stable

Optional
Tie Rod Ends with bumpster adjustment.
https://www.splparts.com/products/bu...5-z34-q50.html

Also, they make swaybar end links which you don't NEED either

cv129 · 01-23-2020, 07:07 PM

Quote:

Originally Posted by elhombre

I think that the HKS Hipermax only comes as a divorced setup only. I have them on my car and they are divorced just like the OEM style.

Yep, it comes in a divorced setup. OP was probably looking at generic pictures, not model specific.

DaveZ03 · 01-24-2020, 08:19 AM

Quote:

Originally Posted by OptionZero

If you have a divorced setup, get this:
***NOTE: The SPL midlink requires a 65mm diameter spring.

I believe SPL makes a smaller diameter cup these days, you just have to order through them and not a vendor.

01-23-2020, 10:57 AM	#1 (permalink)
370Tyler Base Member Join Date: Apr 2019 Location: Winnipeg MB Age: 23 Posts: 66 Drives: 17 370Z DBP M6 Rep Power: 38948	True Rear vs. Divorced spring (causes damage?) So next week i'm thinking of picking up a set of True rear coilovers. HKS HIPERMAX IV GT to be exact. But yesterday at the dinner table my dad made an interesting point. The Z comes standard with a divorced spring/shock setup in the rear, so changing it to true rear coils may be bad. reason it may be bad is cause the car wasn't designed to have all the weight and load on that part of the car. Again he just said it as a thought and it did get me thinking could he be right? Only down side to not going with a true rear setup would be lack of camber adjust ability so that might suck. lets hear some of your thoughts! __________________ Follow My Instagram @tyler_hennebury

01-23-2020, 12:19 PM	#4 (permalink)
NorthStyle A True Z Fanatic Join Date: Aug 2015 Location: Deutschland + SC/FL USA Posts: 1,259 Drives: 2011 370Z Nismo Rep Power: 24277	You can go with an OEM-style and get camber adjustment via aftermarket parts or go with a true-style setup and get camber adjustment via aftermarket parts. The stock mounting points are fine for true-style setups as probably 50% of us have them and I've yet to see a BMW-style failure (I've been on true-style for appx 5 years now). You'll be fine either way. Rusty and wideglideleon like this. Last edited by NorthStyle; 01-23-2020 at 02:15 PM.

01-23-2020, 12:38 PM	#5 (permalink)
JARblue A True Z Fanatic Join Date: Mar 2011 Location: Austin, TX Age: 43 Posts: 36,450 Drives: 11 Z34, 98 E36 M3 Rep Power: 2684440	This matter has been discussed before. There is no issues with switching from the stock divorced rear suspension shock/spring set up to a true type coilover. Guys have been running true type coils hard on the track for years without any issues. This isn't a BMW shock tower... 2011 Nismo#91, Rusty, wideglideleon and 2 others like this. __________________ 2011 370Z 6MT Sport Gun Metallic \| ARC \| CJM \| Ecutek \| FI \| Fujimura \| R2C \| SPL \| Stillen \| TWM \| Z1 \| ZSpeed \|

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Squeaky Noises from rear divorced springs Coilovers	SPDKING	Brakes & Suspension	7	06-21-2019 02:23 AM
Cant Align Rear Tire, Might Have Frame Damage?	Genzen	Brakes & Suspension	12	02-16-2017 08:22 PM
Rear Quarter Panel Damage	black3seventy	Exterior & Interior	0	09-11-2015 09:05 PM
Rear Quarter Panel Damage	2tiNMan2	Western Region	1	05-08-2015 04:43 PM
used parts to fix up a 370z (rear damage)	carvalho360	Wanted	11	08-09-2010 12:09 PM