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Race shock/strut options - Bilstein front, QA1 rear
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924RACR  



Joined: 29 Jul 2001
Posts: 8100
Location: Royal Oak, MI, USA

PostPosted: Tue Apr 15, 2008 1:28 am    Post subject: Race shock/strut options - Bilstein front, QA1 rear Reply with quote

Fronts:
Just a sort of a review, of installation/fitment only, on struts we just put on Chris's (ITB) racecar yesterday - the Bilstein 36mm race front strut, for the VW A1 chassis, part # V36-0103. They're threaded body, steel, look very much like these:
http://www.paragon-products.com/product_p/bilstein_escort_cup_944.htm

(the strut pictured there, of course).

Note that this will apply to any 924/924S/944 with the "early" front suspension - with steel a-arms.

What we found on installing them yesterday was the following. As expected, the struts bolted right up to the knuckles (aka spindles), no issues.

However, what we didn't expect was just how much shorter these struts are compared to the Koni yellows that came off. They're WAY shorter. Barely tall enough for an IT car, which runs at a min ride height of 5". I think they're probably designed for a Production class car, as those typically run at about 3" ride height IIRC.

So while these are quite economical race struts (note that we had them re-valved for Chris's car, to match my experience), they really are not suitable for a street car.

I think for those applications, including most track/DE cars, you'd probably be better off with the Bilstein V36-0059 front strut; it's designed for a conventional front spring (5" size or whatever the stock springs are), and then add a coilover sleeve. They're also much cheaper, maybe $100 each less than the threaded-body ones. I believe, but haven't confirmed yet, that they are longer than these threaded body struts also.

I'll post back if I can get a confirmation on length on the V36-0059.

Rears:

Here's one of the cheap rear coilover options we've found. Not trivial to implement, but inexpensive enough to make it worth it. This will apply to any cars with the steel rear trailing arms - 2.0L 924 including Turbo, and early 944, but not 924S with the alloy arms. With the alloy arms, these could probably be made to fit, but different adapters would likely be needed for the lower shock mount. I haven't tried this, so can't comment.

It's the QA1 shock, a single- or double-adjustable coilover with monotube construction, digressive valving. These guys seem to have the best pricing:
http://autofabcart.net/qa1shocks.aspx

It's the Proma Star shocks, $150 for single-adjustable, $250 for double.

The main PITA is that these are 1/2" rod end mounted, not 12mm (as our stock shocks are). What we've done on our racecars (I'm actually running Bilsteins in the back, but same mounting) is to drill out the mounting spots to 1/2" and use 1/2" Grade 8 bolts. This requires a heavy-duty drill up top, as you're milling through a long bushing; it will eat any puny cordless drill.

You also have to make up spacers to locate the shocks centered in the mounting spot; the 1/2" rod ends are much narrower than the bushings on a stock shock. So what is the easiest is to get 1/2" ID pipe or tubing, and cut lengths as needed to fill the gap.

Alternately, if you have access to a machine shop and the time and inclination, you can have the shop machine spacers that will fill the gap and also allow you to use the original 12mm shock bolts.

I will have to see if we can dig out the particular shock we mounted... Hope that helps...

EDIT - the rear shock we fitted was the "Proma Stars" Model DDR5855B. They have recommended ride height of 13.25"-14.5" recommended free length of 12". If you wish to get the single-adjustable, just look for equivalent lengths in that model.
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Last edited by 924RACR on Wed Apr 16, 2008 5:33 am; edited 2 times in total
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Rasta Monsta  



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PostPosted: Tue Apr 15, 2008 4:16 am    Post subject: Re: front coilover strut option - Bilstein Reply with quote

924RACR wrote:
You'd probably be better off with the Bilstein V36-0059 front strut. . .and then add a coilover sleeve.


Please elucidate, Master.

(rasta clings to the hem of Vaughan's coveralls).
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924RACR  



Joined: 29 Jul 2001
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PostPosted: Tue Apr 15, 2008 5:12 am    Post subject: Re: front coilover strut option - Bilstein Reply with quote

Rasta Monsta wrote:
924RACR wrote:
You'd probably be better off with the Bilstein V36-0059 front strut. . .and then add a coilover sleeve.


Please elucidate, Master.

(rasta clings to the hem of Vaughan's coveralls).


Because I think that will be a longer strut, for those of you not driving your cars around threatening to scrape all the time like our racecars!!!

Our racecars have got to be at least a half a foot lower than stock. I mean, the bumper doesn't hardly come up to my knee. You drop the car down on a jack without having something under a tire, you'll never get that jack back out.

I mean, they're DETROIT LOW.
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flosho  



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PostPosted: Tue Apr 15, 2008 5:57 am    Post subject: Reply with quote

I think he wanted you to elaborate on how to ad a coilover sleeve to the strut you mentioned.

I believe paragon has a write up for this kind of thing..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Tue Apr 15, 2008 6:15 am    Post subject: Reply with quote

Oh, sorry. You just slip the coilover sleeve onto the top of the tube, sits inside the stock spring perch. This is, of course, after removing your strut from the car and removing the spring from the strut.

These would be the sleeves such as Paragon sells, yes, and I think you're right about having a procedure on their website.

On the stock strut, you also have to remove the large nut that holds the strut insert in, since the sleeve won't clear it. On these Bilsteins, I think instead you'd maybe have to remove a seal on the top to clear the sleeves - I had to on mine, when I was running sleeves. There's no nut, since these Bilsteins are not inserts (like the street HD's are), but rather a complete replacement for your entire stock strut body.

Here's a pic for reference; stock strut with a coilover sleeve on the right, and a Bilstein (933) threaded-body race strut on the left (wearing a coilover sleeve, at the time):


Note that these strut bodies have had the stock lower spring perch removed, but the coilover sleeve is sitting at about the same position as it would be in the stock lower spring perch.

Does that help?
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Rasta Monsta  



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PostPosted: Wed Apr 16, 2008 4:47 am    Post subject: Reply with quote

It does, thanks. What are the advantages of the coilover setup? What do you do with the adjustability? Corner balance? Anything else?
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924RACR  



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PostPosted: Wed Apr 16, 2008 5:32 am    Post subject: Reply with quote

The front coilover setup, whether a threaded-body strut or the coilover sleeves, allows adjustment of front ride height to corner-balance perfectly for the track. It will also, of course, allow use of standard 2.5"ID racing springs.

The rear coilover setup allows you to increase your rear spring rate substantially without having to replace the rear torsion bars - which is very expensive ($300 per set of t-bars new vs. about $120-150 per spring pair) and very time-consuming and painful. HOWEVER - when going from stock t-bars and normal-ish ride height, you will still have to go through the pain of reindexing the t-bars, most likely. Depends how you set it up a bit.

BUT - to change the rate after this is very easy.

The adjustability of the rear shocks is to change damping rates, and this is for track tuning. You can already adjust ride height (in the rear) with stock hardware, but also with the coilover spring perches - they're threaded-body shocks.

THESE PARTS ARE NOT FOR STREET CARS!!!

You might use them on a dedicated track car.

If your car only occasionally sees the track, you may not want them, they may not be appropriate. YMMV!!!

If you don't understand any of this stuff, and how to set spring rates and dampers for track use... these parts may not be for you.
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Rasta Monsta  



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PostPosted: Wed Apr 16, 2008 6:23 am    Post subject: Reply with quote

So for a hot street/DE setup, you would recommend fatter t-bars instead of these coilovers?
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tomcooper  



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PostPosted: Wed Apr 16, 2008 7:46 am    Post subject: Reply with quote

Vaughan,

What about the front coil overs for a street/DE car, and I am talking about the longer option not the short ones you used on the race car. Casper is due for some new inserts and springs and I am wondering if the coil over setup would work.

Thanks,

Tom
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924RACR  



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PostPosted: Wed Apr 16, 2008 7:49 am    Post subject: Reply with quote

No, I'd still recommend coilovers over the t-bars, since they're still cheaper and offer more/flexible options for tuning. Just don't think they're quite as trivial as a little shock swap.

For the fronts - we're not yet sure if the V36-0059's are longer - need to get that info from Bilstein Motorsport. But assuming they're longer than the 0103's we used, yes, they could work well.
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Rasta Monsta  



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PostPosted: Wed Apr 16, 2008 7:52 am    Post subject: Reply with quote

And how about the front coilover sleeve kit at Paragon, what do you think of that? It's only $265 for both sides. . .
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924RACR  



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PostPosted: Wed Apr 16, 2008 9:12 am    Post subject: Reply with quote

Yes, those coilover sleeves or something similar (I think Ground Control also sells them, for example) would be the things to use with the V36-0059 struts.

Note that some of the coilover kits may need to be checked for compatibility with stock upper spring perches if using such; I'm using Paragon's camber plates, so no issues.
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tomcooper  



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PostPosted: Wed Apr 16, 2008 10:59 am    Post subject: Reply with quote

Vaughan,

You got the old guy confused. I was under the impression that you didn't think coilovers should be used in the rear for a street/DE car. Are you saying that they would be acceptable, and are less expensive than stiffer T-bars? The less expensive part I understand.

Thanks,

Tom

924RACR wrote:


The adjustability of the rear shocks is to change damping rates, and this is for track tuning. You can already adjust ride height (in the rear) with stock hardware, but also with the coilover spring perches - they're threaded-body shocks.

THESE PARTS ARE NOT FOR STREET CARS!!!

You might use them on a dedicated track car.

If your car only occasionally sees the track, you may not want them, they may not be appropriate. YMMV!!!

If you don't understand any of this stuff, and how to set spring rates and dampers for track use... these parts may not be for you.

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924RACR  



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PostPosted: Thu Apr 17, 2008 12:22 am    Post subject: Reply with quote

They may be acceptable - you might prefer to have them ordered with the poly bushings than the rod ends, since rod ends are not usually recommended for the street.

It's more the front strut application that I'd be careful putting on a street car. The threaded body ones really aren't long enough, the conventional body Rallye struts, I'm not sure on, haven't seen them and still am awaiting a reply from Bilstein on how long they are.
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924RACR  



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PostPosted: Fri Apr 18, 2008 11:18 pm    Post subject: Reply with quote

Sorry, got the data back the other day from Bilstein, but haven't had a moment to get back and post it.

Looks like the rallye strut, part V36-0059, will only be about an inch shorter than stock (actually as compared to a Koni). So this should be just fine for street and most track applications (excluding, possibly, the most extreme track/race cars).

My 933 race struts are about 2-3 inches shorter than the stock strut, and I fine them great for the track.

The V36-0103 threaded-body race strut, as we put on Chris's car, is probably a good 4 inches shorter than stock, if not more, and not really any good except for a full-on racecar.
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