How To: Coilovers and strut tube modification (with pictures!)

[HarryPotter]

The konis are adjustable so you can control the stiffness. Both the bilstein sports and konis are made for lowered suspensions. The ground control setup doesn't require you to chop the shock tubes. Why would you think you would blow them?

Well, just due to lack of shock travel. I will be running as low as possible. Also check out this site for a good read on konis and bilsteins.

http://farnorthracing.com/autocross_secrets6.html

I just can't weld anything I don't have a welder. Or at least one good enough for the job. Or else I'd at least weld a custom perch.

[Moto-Mucci]

The konis are adjustable so you can control the stiffness. Both the bilstein sports and konis are made for lowered suspensions. The ground control setup doesn't require you to chop the shock tubes. Why would you think you would blow them?

[HarryPotter]

Well usually you chop the entire stock perch off and weld on a bead or ring plate like the one ground control supplies.

But no, you don't have to chop the tube down. That's just for people looking to go lower then the system allows.

If you don't chop the tubes then remember to just use regular sized e30 shocks. Not shortened ones like people are talking about in this thread.

Also I'd recommend koni adjustables. I've got bilsteins and they're too soft. I'll be switching to konis

Eh the konis seem to be way off when it comes to shock to shock variation. And the adjusters are shit. Are they really that much stiffer than bilsteins?

I also am worried that without doing the cutting and doing all the shortened shocks jazz that I might blow the shocks pretty quickly.

[Moto-Mucci]

Need some help here, I've read this thread a hundred times just need some answers.

I have the cosmo coilover sleeves. (just the springs) I already have the rears on that's nothing. (obviously) Now I can just cut my stock spring perch and leave a little on so that the adjuster sleeve will sit on the remaining piece of the perch? I don't HAVE to cut my strut housing. This is correct?

I will be running Bilstein sports also. Thanks.

Spring rates are pretty high in the 400's so I shouldn't be bottoming out to much I do not believe.

Well usually you chop the entire stock perch off and weld on a bead or ring plate like the one ground control supplies.

But no, you don't have to chop the tube down. That's just for people looking to go lower then the system allows.

If you don't chop the tubes then remember to just use regular sized e30 shocks. Not shortened ones like people are talking about in this thread.

Also I'd recommend koni adjustables. I've got bilsteins and they're too soft. I'll be switching to konis

[HarryPotter]

Need some help here, I've read this thread a hundred times just need some answers.

I have the cosmo coilover sleeves. (just the springs) I already have the rears on that's nothing. (obviously) Now I can just cut my stock spring perch and leave a little on so that the adjuster sleeve will sit on the remaining piece of the perch? I don't HAVE to cut my strut housing. This is correct?

I will be running Bilstein sports also. Thanks.

Spring rates are pretty high in the 400's so I shouldn't be bottoming out to much I do not believe.

[Wh33lhop]

Well, if you chop the tubes 1.5" then you're only loosing .5" of travel on the shortened shocks (since you're lowing the perches).

If you run stock tubes/shocks and drop it 2" then you're losing 2" of travel on the shock.

So then you need to measure the piston shaft lengths on both stock and shortened shocks and subtract -.5" from the shorties, and -2" from the stockies = shock travel.

This is also assuming your springs are the same sizes/rates in both applications.

I'm sure valving comes into play as well, but I don't know enough about that to comment on it.

I know how to do the simple math to find the travel :p just don't know how much travel there is stock, don't have stock struts or a car nearby, don't know if stock bump stops can feasibly be cut, etc. If there's still 2.5-3" compression travel when lowered about 2" then stock length struts should generally be fine.

I was only recommending staying with the stock GC setup because it's less work. But if the chopping and welding is already done then F it. That would probably get you the most travel.

Yep. Just gotta be on the lookout for a few pieces and I'll be good. :)

[Moto-Mucci]

How much travel are we talking at a 2" drop, though? (I'd check, but my car's far away)

Well, if you chop the tubes 1.5" then you're only loosing .5" of travel on the shortened shocks (since you're lowing the perches).

If you run stock tubes/shocks and drop it 2" then you're losing 2" of travel on the shock.

So then you need to measure the piston shaft lengths on both stock and shortened shocks and subtract -.5" from the shorties, and -2" from the stockies = shock travel.

This is also assuming your springs are the same sizes/rates in both applications.

I'm sure valving comes into play as well, but I don't know enough about that to comment on it.

I was only recommending staying with the stock GC setup because it's less work. But if the chopping and welding is already done then F it. That would probably get you the most travel.

[Wh33lhop]

If you don't plan on slamming it why don't you just stick with the stock Ground Control kit that uses stock E30 sized shocks up front (not stock shocks, but stock dimensions)? The GC kit, without modification, will still get you 2.25" lower, and you still have a lot of travel.

How much travel are we talking at a 2" drop, though? (I'd check, but my car's far away)

Although, re-reading your post, it sounds like they're already chopped??
If that's the case, why not sell them and get stock tubes?

Pretty sure the casings are already cut and welded. I'm working without tools for now and the inserts are stuck in the casings, so I can't actually tell if there's a weld on the inside.

I got the Konis, casings and 2 front adjustable spring perches for about the price of the whole GC kit, and I'm a bit of a suspension whore, so I'm not going to give away extra compression travel if it's not going to have any adverse effects. I'll probably wind up putting the G60 Konis in the stock un-cut casings already on the car at the ride height I want, then see if I bottom out, top out etc. As long as there's no preload on the springs I'll be okay if they top out once or twice.

[Moto-Mucci]

The M3 style tabs have been welded on already and I believe my strut casings have been cut (not sure on that though and it's hard to check at the moment). I get what you mean about the casing/strut body, I'm not sure exactly what was used but my Konis have "adaptors" on them to increase the insert diameter.

What I'm still worried about, however, is droop travel. If you're using a 4" shorter casing it's pretty safe to say you're losing total travel (not saying it's exactly 4", but typically a shorter insert = less travel). Then you're lowering the strut body by another 1-1.5", so in effect you're losing out on a few inches (maybe even up to 4-5" or so) of extension travel. If you're slammed and have stiff rates then it's not such a huge deal but I'm not planning on slamming it to the ground and I'll probably be running 300-400lb/in springs up front.

I ran drastically shortened Konis on the front of my last car and it was baaad news. They never bottomed out and it was heavenly, but I wasn't slammed to the ground so they topped out a few times and were toast within a month or so.

If you don't plan on slamming it why don't you just stick with the stock Ground Control kit that uses stock E30 sized shocks up front (not stock shocks, but stock dimensions)? The GC kit, without modification, will still get you 2.25" lower, and you still have a lot of travel.

Although, re-reading your post, it sounds like they're already chopped??
If that's the case, why not sell them and get stock tubes?

[Wh33lhop]

What Lee said.

And I didn't mean to buy G60 Koni's. Like I said earlier, the G60 shock casings (no matter what make) are a smaller diameter then E30 shocks. I'm pretty sure Ground Control sells shorter Koni shocks with the correct casing diameter for E30's = no ninja wrapping your casings so they fit snug.

I chopped my tubes down 1.5" and used a spacer. (see above diagram.)

NOTE: Cut the tubes down first, then measure how big you need to make the spacer by inserting the shocks and measuring the headroom. I doubt the shocks are EXACTLY 4" shorter, so don't go guessing and cutting.

May I also recommend welding on M3 sway bar end link tabs while you're at it

The M3 style tabs have been welded on already and I believe my strut casings have been cut (not sure on that though and it's hard to check at the moment). I get what you mean about the casing/strut body, I'm not sure exactly what was used but my Konis have "adaptors" on them to increase the insert diameter.

What I'm still worried about, however, is droop travel. If you're using a 4" shorter casing it's pretty safe to say you're losing total travel (not saying it's exactly 4", but typically a shorter insert = less travel). Then you're lowering the strut body by another 1-1.5", so in effect you're losing out on a few inches (maybe even up to 4-5" or so) of extension travel. If you're slammed and have stiff rates then it's not such a huge deal but I'm not planning on slamming it to the ground and I'll probably be running 300-400lb/in springs up front.

I ran drastically shortened Konis on the front of my last car and it was baaad news. They never bottomed out and it was heavenly, but I wasn't slammed to the ground so they topped out a few times and were toast within a month or so.

[Massive Lee]

May I also recommend welding on M3 sway bar end link tabs while you're at it :)

Yup. A more direct connection that equals to having a bigger front swaybar.

[Moto-Mucci]

What Lee said.

And I didn't mean to buy G60 Koni's. Like I said earlier, the G60 shock casings (no matter what make) are a smaller diameter then E30 shocks. I'm pretty sure Ground Control sells shorter Koni shocks with the correct casing diameter for E30's = no ninja wrapping your casings so they fit snug.

I chopped my tubes down 1.5" and used a spacer. (see above diagram.)

NOTE: Cut the tubes down first, then measure how big you need to make the spacer by inserting the shocks and measuring the headroom. I doubt the shocks are EXACTLY 4" shorter, so don't go guessing and cutting.

May I also recommend welding on M3 sway bar end link tabs while you're at it :)

[Massive Lee]

The VW G60 Corrado inserts are indeed much shorter than regular e30 inserts. The G60 inserts are used when the car is lowered a lot and sufficient shock travel needs to be retained. Because the insert is 4" shorter doesn't mean the suspension will be 4" lower. The struts will be cut by about 1" and a 3" spacer/tube will be inserted at the bottom of the strut to make up for the difference.

Swapping inserts between car make is common. My 1969 2002 racecar uses VW Rabbit inserts in the shortened struts.

As for the upper collar/nut, every brand of shock uses their own model of collar. Bilstein has its own model, so does Koni or Tokico. The upper nuts usually come with the shocks/inserts.

[noE30]

I made this a while ago - don't know if it helps your question:

Thank you so much for posting this! I have been trying to visualize all this for almost 2 days hahaha.

[noE30]

I think i read that the G60 shocks are 4" shortere than e30 shocks. Don't quote me on that as I'm still trying to figure this out as well