What are bumpstops and why do they need to be cut when lowering a car?

 

its hard rubber pieces attatched to he top of the strut, usually five or four layers and you cut two off. this allows the strut to compress in even more giving it a stiffer ride: you want the strut to be as stiff as possible when lowered so that the car wont bottom out and cause damage. i think it all depends on how low you are going too, if your only going 1-2 or similar i would'nt worry to much about. With coilovers I think most manufacters recommend it. I did it and it was easy enough.

 

On 5th Gen Accord Eibach Sportline the front is trimmed 40 mm so about half the size of stock.

 

any time you lower it you should be cuttn some of the bumpstop off. or esle you end up riding on the biumpstops...which is the next worst thing to bottoming out.

 

my pro kits say not to trim the backs at all.....

 

trimming depends on the spring, there is no universal guide.

 

i have neuspeed race springs and they say not to cut bumpstops, i didn't, and no i'm not riding on bumpstops

 

when i was on sportlines and tockicos, the ride was pretty rough... the car sat about .5" lower than with stock shocks, so i had to trim the bumpstops even more than the reccomended amount. it smoothed out the ride a lot.

with some coilovers, you need to remove the stops entirely, while with others, you just trim them

 

ditto

 

i am neuspeed race and koni yellows.
i bought them from a friend. i replaced the bushings at the top with polyurethane bushings. when i too the strut apart the bumpstops had not been cut as the instructions read. the problem was the uncut bumpstops were smashed. and i mean like splitting, and all tore up. i cut off half of them and suddenly the ride became a LOT smoother, a LOT more controlled, and on bumpy roads i never felt like the front of the car was about to bounce into the air.