Question regarding Koni bumpstops for Koni/GC suspension - Honda Prelude Forum

KahnBB6 · 02-20-2009, 03:19 PM

I need a little help. I'm going to install a Koni/GC suspension soon in my SH but I am trying to be extra sure about some of the smaller parts I'll need. I have the Koni Yellows and the GC kit for Konis in 400/325. I read a thread here a week ago (I can't find the thread, sorry) where someone said that they prefer using Koni bumpstops instead of cutting the factory bumpstops.

Today I called Koni-NA to put in my order and was informed that they come in two styles: linear 45mm and progressive 55mm.

I looked at the rod on one of the rear Koni's and it looks like 55mm might be taking up nearly half the length of travel.

I know most Koni/GC guys have just cut the factory bumpstops but it sounded as if the Koni versions were a lot beefier. My question is which length is more appropriate in this case?

Thanks!

Craig

71dsp · 02-20-2009, 06:07 PM

It was probably me. I prefer the Koni bumpstops. I just cut the Koni versions to length. Get the progressive bump stops.

55mm is over half the length of the travel of the rear shocks? Have the shocks been modified any? That doesn't sound quite right.

KahnBB6 · 02-21-2009, 01:10 AM

Hey, thanks!

It doesn't sound right but I think I solved the confusion on my own. My Konis are brand new and I haven't had them modified. I think what happened is that I asked the Koni tech approximately how long the 55mm bumpstops are and he gave me a rough 2" guesstimate. Then I measured 2" downward from the welded nub on the metal shaft and saw that it covered about 1/3 of the shaft by using that measurement.

This was all without remembering that I still have to cut the bumpstops. I had *assumed* that only the factory bumpstops needed to be shortened and that Koni or GC units were already the correct length per application

This is the first time I've put together a custom spring and shock combination so I'm just trying to make sure I'm doing everything correctly.

Somewhere else I also read that you should only trim the dustboots but were to leave the bumpstop lengths alone and therein started my confusion, because I've read multiple times that you still need to trim your bumpstops :P

It sounds as if it's up to personal preference because there was no definitive thread regarding bumpstops.

paulyg · 03-03-2009, 07:55 AM

Crap. I just had my front suspension apart this weekend but didn't see this thread. I have cut factory bumpstops. Going from memory they are 1.75 inch or 45mm long.

The one problem I ran into in the long run with the factory bumpstops is they don't really fit inside the rubber isolator GC gives that goes between the spring and the tophat. That seems to have accelerated the isolators getting bent and ripped up. After two years my springs were severly cocked to the side to the point where one spring was rubbing on the shock body. The Koni bumpstops have a smaller ID and should fit inside the isolator. At least the ones that came on my Miata do. I think they are the linears though.

71dsp · 03-03-2009, 09:00 AM

Pauly, do you need some aluminum isolators for your GC kit, or did you remove it from your Prelude?

paulyg · 03-03-2009, 11:11 AM

Quote:

Originally Posted by 71dsp

Pauly, do you need some aluminum isolators for your GC kit, or did you remove it from your Prelude?

The GC kit is still on the car but I'll but putting her up for sale as soon as I can get some pictures without snow on the car. Thanks for the offer though.

KahnBB6 · 03-04-2009, 04:33 PM

Just an update: I got the Koni 55mm progressive bumpstops in the mail a few days ago. They certainly do feel substantial, although I haven't actually compared them to the factory part.

I'm just waiting on a new set of front control arms and a new set of dustboots. I know I could have used the old dustboots but it wasn't that much more to just get a new set and get them cut down correctly *before* getting the suspension installed at a shop.

Then I'm just holding out for 71dsp's aluminum isolators

Pauly, would I just want to cut my Koni pieces down to 1.75" like your factory versions are?

supersano · 03-04-2009, 11:10 PM

I used energy bumpstops on my 5th gen and it works great compared to my OEM ones which didn't last that long.

paulyg · 03-09-2009, 01:33 PM

Quote:

Originally Posted by KahnBB6

I'm just waiting on a new set of front control arms and a new set of dustboots. I know I could have used the old dustboots but it wasn't that much more to just get a new set and get them cut down correctly *before* getting the suspension installed at a shop.

I couldn't use the OEM dustboots with a GC suspension. You would need to use a rubber bellows type dustboot. A metal sleeve like the OEM one will just run into the coilover sleeve when the suspension is compressed.

Quote:

Originally Posted by KahnBB6

Pauly, would I just want to cut my Koni pieces down to 1.75" like your factory versions are?

If I bought them and paid for them I would try them as-is before I cut them up. If you are not to low it may not be an issue.

KahnBB6 · 03-09-2009, 07:06 PM

Quote:

Originally Posted by paulyg

I couldn't use the OEM dustboots with a GC suspension. You would need to use a rubber bellows type dustboot. A metal sleeve like the OEM one will just run into the coilover sleeve when the suspension is compressed.

If I bought them and paid for them I would try them as-is before I cut them up. If you are not to low it may not be an issue.

My impression was that the factory metal dustboots HAD to be used but that they must be cut to 1/2 the original length or shorter and drilled up top for the 12mm shaft. If I were going to use rubber bellows style dustboots, is there a particular part number or brand you'd recommend?

paulyg · 03-10-2009, 03:25 PM

Quote:

Originally Posted by KahnBB6

My impression was that the factory metal dustboots HAD to be used but that they must be cut to 1/2 the original length or shorter and drilled up top for the 12mm shaft. If I were going to use rubber bellows style dustboots, is there a particular part number or brand you'd recommend?

I didn't use any dustboot.