custom shock for lowering springs?

VChenz · 08-15-2019, 12:20 PM

Im going to preface this with I am not an engineer and I have read through tons of articles and forum posts in regards to suspension but I don't believe this question has been asked outright.

If I am understanding this correctly, the issue with lowering springs and stock shocks is the reduced travel the shocks will provide as they are now "pre-compressed" by whatever drop the new springs give you.

For example. If a stock setup allows for 5" of travel and you swap the springs with ones that give you a 1" drop, you then lose that one inch of shock travel. So the system now only has 4" of travel. I believe this reduced travel is partially what diminishes the ride quality.

Could we not have a shock rebuilder take the OEM shock, disassemble it, cut an 1" (per my example above) of the piston and reassemble it? Would that fix the ride quality issue associated with the loss of travel?

I know you can get a custom setup that already takes all this into account BUT it seems that only the $3-4K+ setups are comfortable, the rest have mixed reviews in terms of comfort. I dont need all the extra "options" that come with the more expensive shocks.

educate me

Cheers
Vince

allinon72 · 08-15-2019, 03:08 PM

This phenomenon can be mitigated with proper spring rates and software, if the kit is designed properly. It makes modification of the OEM shock unnecessary and not economical without talking about coilovers. That's why I went with the MP HAS.

On the extreme, if you put in springs only and slam the car, sure it will ride horribly. Modern cars with tuned suspensions require more finesse.

Racer20 · 08-15-2019, 09:13 PM

There's no way to get the stock shock apart in such a way that it can be put back together.

The travel limitation is the length of the body, not the internal rod, so you'd have to shorten the body, but then you'd have to lengthen the rod, otherwise you'd lose rebound travel, which isn't any better.

Most of the loss on ride quality is due to stiffer springs. Some is due to more abrupt (or too early) bumpstop contact, and this can be mitigated by a different bumpstop tuned for the ride height.

The shortened lifespan is primarily due to the additional side load imparted on the strut by non-stock springs.

08-15-2019, 12:20 PM	#1
VChenz Second Lieutenant 181 Rep 219 Posts Drives: 2015 M3 Base Join Date: Jun 2019 Location: ON iTrader: (0)	custom shock for lowering springs? Im going to preface this with I am not an engineer and I have read through tons of articles and forum posts in regards to suspension but I don't believe this question has been asked outright. If I am understanding this correctly, the issue with lowering springs and stock shocks is the reduced travel the shocks will provide as they are now "pre-compressed" by whatever drop the new springs give you. For example. If a stock setup allows for 5" of travel and you swap the springs with ones that give you a 1" drop, you then lose that one inch of shock travel. So the system now only has 4" of travel. I believe this reduced travel is partially what diminishes the ride quality. Could we not have a shock rebuilder take the OEM shock, disassemble it, cut an 1" (per my example above) of the piston and reassemble it? Would that fix the ride quality issue associated with the loss of travel? I know you can get a custom setup that already takes all this into account BUT it seems that only the $3-4K+ setups are comfortable, the rest have mixed reviews in terms of comfort. I dont need all the extra "options" that come with the more expensive shocks. educate me Cheers Vince
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08-15-2019, 03:08 PM	#2
allinon72 Brigadier General 4921 Rep 3,804 Posts Drives: 20' M2C, 23' X1 Join Date: May 2017 Location: Indianapolis, IN iTrader: (2)	This phenomenon can be mitigated with proper spring rates and software, if the kit is designed properly. It makes modification of the OEM shock unnecessary and not economical without talking about coilovers. That's why I went with the MP HAS. On the extreme, if you put in springs only and slam the car, sure it will ride horribly. Modern cars with tuned suspensions require more finesse.
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08-15-2019, 09:13 PM	#3
Racer20 Major 1030 Rep 1,190 Posts Drives: F80 M3, 228i THP, E46 ZHP Join Date: May 2009 Location: Ann Arbor, MI iTrader: (0)	There's no way to get the stock shock apart in such a way that it can be put back together. The travel limitation is the length of the body, not the internal rod, so you'd have to shorten the body, but then you'd have to lengthen the rod, otherwise you'd lose rebound travel, which isn't any better. Most of the loss on ride quality is due to stiffer springs. Some is due to more abrupt (or too early) bumpstop contact, and this can be mitigated by a different bumpstop tuned for the ride height. The shortened lifespan is primarily due to the additional side load imparted on the strut by non-stock springs. __________________ 2015 M3, 2005 330i ZHP, 2015 228i 6MT Track Handling Pack, 2007 M Coupe (Sold) Last edited by Racer20; 09-05-2019 at 05:42 PM..
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