Coil overs in back?

I'll try to be as brief as possible with the background here; Some of you may remember that I replaced the trailing arms on my car with a set of after market one to narrow things up back there. Since then I've been having trouble with the shocks. I finally got the new mounting points figured out and I still had trouble with the stock shock bottoming out. I have since bought a pair of short shocks (the kind used on hot rods) and I hope to be putting them on next week. If the streak continues with regard to the modifications on my car I anticipate fitment issues. I think these short shock may actually be too short. That and I may have issues with the lower bushings being a bigger diameter, which I can easily fix by enlarging the bolts holes or drilling new ones.
Anyway, anticipating this may not work out I was wondering what the thoughts are with coil overs? Being that they are adjustable will adjusting them to be stiffer eliminate the bottoming out issue I had with stock shocks? Chirco VW sells a set for $60 made for VW's, but I'm not sure if they are only adjustable in relationship to ride height (spring) or stiffness (shock). Even if they are only height adjustable aren't coil overs generally stiffer? Frankly, I can't see why I'm having issues with the shocks bottoming out. The mounts are essentially in the same place as the original spots so the shock isn't stretched or compressed too much to begin with. I was getting a pretty good "bang" going over bumps and when I unbolted my shocks the banging went away so I have assessed the shocks as the cause of the banging. I don't mind a stiff ride I just hate that loud BANG when I go over a bump. Thoughts?

I installed coil overs years ago and absolutely love it. They have 3 adjustments (I think) and each one is basically turning the shock with a little fork that comes with, and it sets raises/lowers the shock about 1/2" in height that gives you a longer travel (softer). Mine are on the shorter one and my car rides normal height with no issues.

Regarding the "banging", it could well be that your existing shocks were/are simply worn out and not doing their job. Installing a new set of KYB's or Bilstein's might do the trick.

Otherwise, regarding the coil-overs - that was a popular trick for raising the rear end of early Mustangs when the rear springs began to sag (not if, but when). Popping on a set of coil-overs was cheap, could be done in half an hour and were adjustable to bring the rear bumper height up to where you wanted it. Not only did they adjust height, but they were adjustable for stiffness, too.

gn

If you switch to coil-overs, do you continue to use the torsion bars as well, or can they be removed?

With the beetle aftermarket coil overs, you still need the torsion bars in place. Coil overs on the lowest setting does raise the rear 1/2" to 3/4" they are great for an easy fix i.e. if the ass end is a bit low and needs to have the torsion bars moved a notch to raise the body level, the coil overs do the trick. I use them in most of the flared speedster's I've done. ~Alan

Mickey,

If you build a genuine coil-over rear shock set-up you won't be using the torsion bars. If you look at the pieces that come in an average kit:

http://www.customstreetdesigns.com/coil_over2.htm

You'll see that, the shock fits inside of the spring and an aluminum outer threaded sleeve fits between the two. A collar with inner threads is fitted and acts as the lower spring mount. An upper cup with a smallish hole secures the spring and allows the top shaft of the shock to pass through and bolt up.

After determining which spring is right for you, that spring based can be raised or lowered on the collar to alter the ride quality.

You'll need to rework the upper shock mounts to work with a shock design similar to those up front. A bolt through rather than an open eye, but it can be done. The whole assembly is fool-proof and infinitely adjustable. As mentioned, the torsion bars are no longer used. In this case you'll probably want to build a four link to replace the spring plates. Even more cool adjustability.

The shocks that they sell with the light weight springs attached that offer the three settings, are pretty much used as a towing option or to pump up the sagging rear end that is so typical on Ghias, like mine. They'll slightly raise the rear but stiffen it and make the ride a little harsher. I don't see these as a real long time solution. You want the car to sit low and firm, with a progressive spring that gets firmer as the road surface or driving demands get harsher. You certainly don't want a spring that's going to raise the rear and make things more choppy, you'll end up bouncing right off the road in a tight off-ramp type turn. One little bump or hole and you'll super-ball off and away into the woods . . .

[In case anyone is at the ready, the super-ball bit was a mildly amusing allusion. Think of a Road Runner cartoon-like image. No need for anyone to take offense and assume that I'm in any way degrading their replicas if they happen to be running the after-market three setting adjustable rear shocks, or that I'm implying that the ride quality is anywhere close to a super-ball, nor that I expect them to simply pick up and go bouncing away into the sage brush because they're using them.]



Forum Prick

Mickey,

Would the diameter of the coil-overs be a problem?

Mickey-

I've got a set of coil overs I bought years ago, when I had the first car (a CMC)- for use a parade when there was a couple of extra people sitting up on the body, with their feet on the parcel tray behind the front seats. I think I used them in one parade for about an hour.

The spring preload set-up works just like it used to on "universal Japanese motorcycles" from the '70s, with a ramped set-up under the springs. I don't have the little adjustment tool any more, but preload is adjustable with a pipe wrench, or channel lock pliers.

I'm not sure if this is what you want or not- but If you want 'em, I'd make you a deal on 'em. Shoot me an email, and let me know what you think they are worth.

I don't want to be a downer here but these "coil overs" are not real "coil overs". A properly operating suspension supports the weight of the car on the spring, torsion bar or other and the movement is dampened by the shock. In this case above the "shock" doesn't carry any weight and is not designed to. The mounts for these springs are designed to support weight. With the package you want to use your shock mounts are just that "shock mounts" and not designed to carry weight-just attach points for the dampeners. People who use "air shocks" or other "weight bearing" devices eliminate the designed weight bearing function of the suspension.--not good. If there is a problem with your present height or movement fix it--you'll be much happier, safer and have a better handling car.--good luck!

Well now, that's quite a wealth of info there.

I'm not looking to completely redo the rear suspension (again). I just want to get rid of the banging over bumps. I need something that isn't so flimsy. The first time I put stock shocks in they were getting beat up as a result of poor positioning. You can see in the picture below that the new trailing arms have a kind of tube that the shock goes through and that I have now mounted the top of the shock to a bracket welded to the sub frame. With the first attempt the shocks were rubbing against the inside of the tube. Since repositioning the upper mount I put a new set of stock shocks in. They no longer rubbed but I was getting that bang over bumps. I unbolted the lower bolt and no more banging. Being that the shocks were new I guess it's possible they were wasted as new, but doubtful. And when I've driven the car without the rear shocks mounted there is no banging at all going over similar bumps that had given me trouble. I think the new trailing arms are the culprit here. Can anyone tell me the 'at rest' length the stock shock set up is from upper to lower mounts? I think the new trailing arms may have raised the height of the lower mount.
The coil overs offered by Chirco or MAMW may have an issue with diameter and I could possibly wind up where I started, with the rubbing, but I'd have to get a set to be sure.
I know the Chirco shocks are not 'true' coil overs in the sense of fine tuning. It would be awesome to be able to set my front and rear suspension with surgical precision but I'm merely trying to get a smooth ride and not worry about beating the crap out of my car when going over anything other than a bottle cap. CB offers these http://www.cbperformance.com/catalog.asp?ProductID=1751 for a coil over set up and they're reasonable in price so maybe there is a compromise between the Chirco shocks and 'real' coil overs?
I am a little concerned about the potential of these raising the rear ride height though, if anything I'd like to lower it a tad so the top of the rear well sits at the top of the wheel. Right now it's just an inch or so too high for my liking(see #5200).

Stan, what kinda deal a we talkin?

The rear doesn't look too bad at all; just s smidge high, but the car is empty. I'll bet that it's pretty dead on when you're in it/when there's weight on the suspension. You can surely get away with just a shorter shock for now since what you're describing sounds exactly like what most describe when they run adjustable/lowered beams with stock length front shocks. Measure things up and have a good parts house hook you up with a set of BOGE shocks at the proper length. They came on tons of European cars in a whole bunch of different lengths and they have a really nice ride quality. Think BMW here.

Is it the pic, or is your front wheel set a bit back in the wheel well? Maybe just me . . .



Forum Prick

All CMC's have the front wheel set a bit back in the wheel well issue. Depending on which CMC mold was used, some are more noticeable than others.
On a few of the pan shortenings, I allowed for this adding 5/8" to the recommended stated pan chassis length. Any more and you run into fit issues at the forward bulkhead base to pan.
Doesn't the front look to be a bit high ?
If the front is lowered a bit the rear will come down hair too. ~Alan

Mickey, you said

With the first attempt the shocks were rubbing against the inside of the tube. Since repositioning the upper mount I put a new set of stock shocks in. They no longer rubbed but I was getting that bang over bumps. I unbolted the lower bolt and no more banging. Being that the shocks were new I guess it's possible they were wasted as new, but doubtful. And when I've driven the car without the rear shocks mounted there is no banging at all going over similar bumps that had given me trouble. I think the new trailing arms are the culprit here. Can anyone tell me the 'at rest' length the stock shock set up is from upper to lower mounts? I think the new trailing arms may have raised the height of the lower mount.

Does that mean the first pari rubbed but otherwise worked well and the second set=no rub but hammered? If so lay them next to each other and fully extend (measure) and compress (measure) and see if all same. In your picture is that a metal tube that the shock sits in between the swing arm and upper mount or is that a black painted shock?

I took a second look -it's a painted shock.

Yeah, that front wheel does sit back a bit. I've always hated that. When I put the new tires on it stood out even more. I guess with a smaller diameter tire more empty space shows.
The ride height I'm OK with, I'd like it to be a smidge lower though if possible, we'll see.
Can someone recommend a way to measure shock length? I was thinking if I put it on a lift and then jacked up the wheel hub to get rid of the sag, I could measure that way. The problem is I don't know how high to jack the wheel hub because I'll have to remove the wheel to be able to get in there. I'll figure it out.
Where would one go to find a pair of these Boge shocks? Websites?


Forum Prick. Heh, I love it. ;)

Bruce,
It's hard to say how the first set performed. They were bottoming out so to speak. They were actually getting hung up on the outer rim of that tube. I cut the casing off the top part of the shock so just the rod was showing to clear things up but I think by then they were destroyed. That's when I repositioned the upper mount and now the shocks travel freely with no rubbing. I'm pretty sure they were the same size though I can't say for sure. The first set was generously donated by Dale Schumacher and the second set was a set of brazilian VW shocks from Cip1.

Remove the shock and measure the extended and compressed length, that's the best way to go about it. Bring the old shock with you when you buy the new ones and compare. You want a shock that's shorter when compressed than the old shock yet long enough to fit between the lower and upper mount when extended. Easy to figure out.

Silly question and the answer may be above but I'll ask it anyway. How do you know you are bottoming? I bet your not. It's probably an interference with the frame, swing arms or other.
Maybe it's not the verticle movement change thats banging but a side to side contact---just a thought. If you want to check for bottoming why don't you set up some sort of "tattle tale"
mark on your shock housing. So after it's compressed the "tattle tale" mark can be viewed
at a stand still after it's removed and you can determine if you ran out of travel or not.

I took a look at a few different sites--they all talk about shortened front shocks but nothing (that I saw) addressing the rear.--Again, I don't think you're bottoming.

Why not make it easy on yourself--call the mfg of the arms. You're not the first person to use these I'm sure. They must have previous experience and maybe recommend something.
By the way, where was that shock contacting the arm- front side, rear side? The reason I ask is maybe the angle of those shock tubes that pass through the arms are wrong.-(just a thought). Maybe your shock is tipped too far fwd or aft?

Bruce,
When I suspected the shocks of bottoming out I pushed the rear of the car up and down and you could feel it clunking. After I disconnected the shocks I performed the highly technical test again and no more clunking. I also drove the car on my normal route, which I am familiar with the bumps in the road, and again no bangs. So I went with the assumption that the shocks were the culprit. It

Mickey-You've got other problems. I'm 250 lbs and I can't "bottom a suspension" by pushing on the corner of a car.
Just how strong are you?

OK, how 'bout this . . .

It's not the shocks, it's the bushings/bolts/sleeves on the diagonals.

When the shocks are in place, causing resistance, the torsion plates are fine, the shocks are fine, but the third point of the triangle (the mounting point of the diagonal) isn't, so the movement occurs there.

When the shocks are removed, there isn't as much stress on the diagonal mount so it pivots in concert with the torsion plate, still loose, but without any real resistance, and things seem to be quiet and normal.

Even if things look fine underneath, just a tiny bit of slop can get multiplied when there is resistance on it especially if it's got a long lever (the diagonal arm) prying against it. Gordon just had a run around with something like this, maybe he can give you the inside scoop.

Probably not being entirely clear, but essentially I'm suggesting that you REALLY get in there and check the bushings/pivots/sleeves/bolts and such. Probably on both the diagonals AND the spring plates. Maybe even on the torsion bar and cover plates. Check both sides as well, sound travels around in a car, especially if it's in the suspension

Maybe?


Just bein' a "Forum Prick" . . .

I may have used the wrong terminology. The suspension isn't bottoming out, just the shocks. As is the case with most of these technical problems, they're hard to explain in words. The car still has plenty of travel in the back and I don't think I could bottom it out bouncing on it. I think this is a case of upper and lower mounting. When the new arms went in the original upper mounts couldn't be used so they had to be relocated. Either they are too low or the shocks are too long, I think. I'm putting in my call to the maker of the diagonals right now to get some insight.

Mickey, If your are looking at the hot rod style coil overs you need to do some homework.Coil over shocks like the hotrod shocks are design to support weight. The springs on a coil over have a spring rate. Spring rate is base on the set angle of the shock and weight of the vehicle. We would figure out the the weight by using race scales beneath each wheel. Once you have the weight value you can go to one of the coil over shock manufacturer ie Proshock ,AFCO, Carrera and use their shock calculator. The coil over shocks from JC whitney are basically suspension helpers ...soft springs.
Before you decide to go with the coil over I would suggest you check your rear torsion system. Your description of your problem sounds like the shocks are bad. And most likely if you had gas shocks . the shock was supporting the vehicles weight. Your may want to check your torsion bar settings to see if they are correctly set or if they just might need to be replaced
Remember the primary purpose of the shock absorber is to control spring and suspension movement.It is a dampening device. Simple way to put it ... its controls the weight of the vehicle ie Bounce,Roll or sway,Brake dive, Acceleration squat.
I'm in the process of building a front engine 54 vw ratrod with a Porsche 944 turbo aluminum swing arms. The frame I have fabbed up eliminates the torsion bar thus requiring the coil overshocks. Once I get the axles and installed I'll get it up on the scales too figure out the weight for the spring rates for typical street driving. Good luck
Joe

TC you still have a resource for BMW part?. I'm looking for a driveshaft yoke 4 bolt for an M3 rearend

Thanks Joe. I'm not going the coil over route quite yet, that inquiry was a "in case this doesn't work" thing. I have a set of short shocks that I got from a hot rod site. They're just normal gas shocks that are shorter than what I had.

I spoke with John at Air Cooled today about the travel issues with the diagonals. He said the guy who builds them makes a spacer for the problem I'm having. That said, they are for a stock VW set up (i.e. no subframe). Also he said they may take a month or two to get if I ordered them.
I brought my car down to my buddies garage and we'll get it on the lift and take a good long look at things. We'll try the short shocks and if they aren't a go we'll probably have to fab up a new bracket for the upper mount. While it's up we'll take a look at the torsion bars and bushings also to see that everything is where it's supposed to be.
I'll keep you posted.

Joe: It would be so COOL to see your mug again in Carlisle this year!
What Up???

***End Hi-Jack***

man - those trailing arms have been a pretty big headache for you, eh mickey?

Amen brother Paul. I'm hoping to get this all sorted out before the nice weather hits. My biggest issue is not having a lift. I would have been past this by now if I could be under there contemplating solutions. I'm at the mercy of weather and open space at my buddies garage, and I would NEVER take up space if I'm taking money out of one of the guys pockets. It's frustrating to say the least. If I can't get it sorted out this time around I'm considering taking it to someone to do it for me. I hate to spend the money but I've about had it with this and just want it done. I have no doubt there is a relatively simple solution.

Mickey,
If you don't mind running your shocks without the dustcovers and you want to see how far things are traveling under road conditions, do this:
Cut the dust covers off of the shocks. That's the top part of the shock that telescopes over the shock body.(Hacksaw works) Now you can see the shafts. While you have the shocks off, push the shafts into the shock body to see how far they have to go before they bottom out.
Put a tie wrap tightly around the shaft then push the tie wraps down the shaft so they are at the bottom or near the lower shock body. This will work as an indicator of how far the shock has traveled.
Drive the car, then see how high up the tie wraps have been pushed after driving.
Now you can determine how much travel you have/need under normal or driving conditions.
Greg

Sorry for the Hijack
Bill... been very busy lately with work, project Ragon Fly, finishing the basement and family. I try to sneak in and take a peak to see what

Great tip Greg! I actually did cut the dust covers off my first pair of shocks because they were getting hung up in the tube. Unfortunately I think they were too far gone by that time and were useless. That's when we relocated the upper mount for the second pair. The hot rod short shocks that are going on don't have dust covers so I'll do the zip tie test with those when I put them on. If they're too short I'll cut the dust covers off the set I have on there now and do the test with those. Then I'll be able to see if it really is the shocks bottoming out or if it is indeed something else.

Yes Joe, I believe they were built for off road buggies. They are not the same ones in the picture shown on the Air Cooled site (made from round steel stock) and they told me they would be different when I ordeded them so I'm stuck with them. I recall someone warning me that they'd heard of fitment issues with them and I asked about that when I ordered them. They of course told me that those issues had been worked out. What fitment issues they worked out, I dont' know, but the shock travel issue is alive and well. I'm still holding out hope that these short shocks will work and/or the cut off dust cover shocks will work. If neither do, as I mentioned earlier I'm sure there is a solution. It'll just take some fabrication and some trial and error. Not really what I thought I was signing up for but it is what it is and I can't see going back now. That would require finding new stock trailing arms, replacing the the brakes front and back again, and still being faced with the 4 bolt wheel dilema that started all this. And I sure as hell ain't doin that! I either conquer the suspension issue or have Carey build me a Spyder and put my new engine in that. ;)

I am using Carerra/QA-1 coil overs and had to modify the rear of the sub-frame to clear the larger OD spring. Torsion bars are eliminated by using a uni-ball plate from Eagle Racing bolting up to the 944T trailing arms.

The coil over is now the suspension and ride height is easily changed, as is spring rate.

Mickey, I had a similar problem on the front of my Spyder, lowered shocks too short and standard shocks would bottom. I have two sets that I modded. I cut the dust shields off, just ground the welds a little until they broke free. Then I cut off half of the rubber bump stop inside the stock length shock. I welded the covers back on and touched up the paint. I have stock COFAP and KYB GR-2, the GR-2s are on now, and for the last 4000 miles.

Maybe this technique could work for you on the back?

Mickey,

Since you're kinda planning on doing some re-painting on your car, complete re-do or spotting in some areas . . .

I sort of think that you would have been better off just keeping the rear end components stock and "adjusting" the body to fit the wide five off set.

Like this:

http://www.patrickmotorsports.com/project/image/653/

Seems that more and more of the 356 builders are doing this alteration with really nice results.

Too late for you, but a nice option for other, maybe.

FP

Way too late for me on that one TC (FP). But I do agree with you on it being the best solution for people with space issues in the rear wheel wells. This project has cost buckoo bucks and it would have been much more if it weren't for me doing most of the work myself. I'm sure there is someone out there that makes a very subtle flare that could be applied to our cars and in keeping with the more traditional lines. I think the cutting and spacing technique shown in your pic is more easily applied to metal bodies, but I suppose it could be done on fiberglass as well.
Sometimes I kick myself in the ass for doing this stupid $hit. I'm one stubborn MF'r.

Danny P. thanks for the tip!


At least I got something done today; I dropped off the interior at the upholsterers and he said a week or two.

It's looks like the short shocks are gonna do the trick. I got a few minutes to get my car on the lift today and put them on. I had to jack up the wheel about an inch to get the bottom mount holes to line up. I took it for a quick spin up and down the street and it seemed to be smoother. It was hard to tell because I have no interior, the top was up (very loud in there) and I was sitting on a phone book (literally, the seats are at the upholsterer). When I get the seats back I'll be able to give it a proper test drive but I'm optomistic that the problem has been solved. Below is the link to the shocks I installed.
Now all that's left is getting those support bars welded in place and I can start the "pretty stuff".


http://www.thehotrodcompany.com/shopnow/show_item.asp?product_id=2517

Did anyone go the coil over route in the rear? I'm thinking you would want the spring plate conversion setup, part number 14-501360, like from this place..(scroll down)

http://www.dansperformanceparts.com/buggy/susp/buggyreararms.htm

Plus the heim joint and bolt. Looks like this would bolt on and replace existing spring plate and torsion bar and then you'd use a proper coil over shock. I'd like to go this route as I've replace the torsion system in the front of my car with coil overs. Wouldn't mind having the rear similar.

Damn Brian where was this stuff when I was doing my set up!? ;)

In all seriousness I would have done a coil over rear set up if I'd know there was the option. The info on the site doesn't indicate any of these arms are made to narrow the rear track, which was the reason I switched my arms to begin with. Got any more pics of your front set up? Some day, far far in the future, I hope to do a body off resto/build up on my chassis and set the suspension up properly. By the way, CB Performance has similar spring plate conversion parts too. Just an FYI.

There's afew places I found that had the rear set up but until the site above the best price I saw was about $250. Its the coil overs and getting the right spring rate that will take some work.

I bought the front kit from a place in the UK. Pic attached. The shocks are Spax, also from the UK. If you go to Ebay.UK you can usually find quite a few for sale. Spax website also has a chart and I'm pretty sure they have the old air cooled VW's listed. I found that most of the offerings on our side of the pond were for modern cars or not true coil overs.

"Sometimes I kick myself in the ass for doing this stupid $hit. I'm one stubborn MF'r."

Ahhhh, Mickey. Two years ago, I suggested Baby Moons would solve your problem ... Personally, I'm glad you stuck it out. I really like what you've done.

I just went to Red 9 Design's website and they have a lot of new products including a double wishbone bolt in front end and a coil over rear kit. Mickey, check out their website as they have a lot of good stuff for VW suspensions. I'm thinking that rear coil over set up is likely destined for my car...IVe got some overtime coming up.