aluminum 944 arms--- what shocks? Brakes?

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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun May 29, 2016 12:52 am

Until I sort out the shocks it will have the bars.
It may still have the bars as I really love the way the car handles with the Four-Way spring setup.
(They are technically coil-overs, but they don't hold the car up, in fact I always preload them, oddly works better)
...Which brings me to the current situation:

The thread started out asking " 944 aluminum arms---what shocks?"
I figured someone would know since its been done a thousand times.
Apparently no one is telling.

Pulled the square into my still soggy back driveway and had at it this evening.

The answer? Pick one:
A)944 Turbo/968 shocks with the odd ~15 degree angled bushing on the bottom.
(didn't buy a set but the measurements are known)
B) Std T1/T3 IRS rears with drilled out/larger lower bushing for the 14mm bolt.
C) None of the above, neither can bloody work remotely correctly.

The answer of course is C), but I find it very hard to believe everyone is running that way without some sort of solution...
It's also possible the T3 upper mount is in a somewhat different location vs T1 as the shock mount setup is much differently made.

The 944T rears would be ~2" too long, and the angled bushing appears simply the result of stupid at the factory.
The std IRS rears are about an inch too long, but may not really be a fatal problem

(EDIT:correction-the late 944/968 shocks are the ~stock length, about the same as T1, but the 924/944 upper mount is a lot farther away, also too large OD and 10mm too wide for a T3 upper mount, which is double shear It would probably be the proper choice on a T1, with some upper/lower hard/bump stop work.)

These arms are interesting geometry wise, they appear to have about a ~35-40mm drop built in, as well as far more negative camber built in.
The axle is offset up from the spring plate and TA centerlines like 911 aluminum trailing arms, just not quite as much.

It ended up about 15mm wider/side than it was, but the tires still clear the slightly pulled fenders, and the spring plate height adjuster bits can stay with a little TPS metal stretching on the shock mount behind it for clearance. (TPS==three pound sledge) I suppose i can drill a big hole for the height eccentrics 36mm socket and access to the lock bolt.

On the 944, the "down" hard stop was a small oval of aluminum around the lower rear bolt of the torsion bar cover... so the droop length may simply be a different hard stop angle vs T1/T3 setup. (pretty sure this is the case, and the fix is ~trivial, in fact it allows pulling the bars ~totally safely, just remove the lower stop bolt and lower the spring plate)

The shock compressed length and angle of the lower bolt//bushings is an issue..
Right now, with the IRS length rear shocks (using the std T3 upper mount) the shocks bind some due to the sideload of the oddly angled lower pivot. (Its oddly angled in a 944 as well :evil: )

It also bottoms out the shock about 1.5" off the bumpstop, no bueno.
(no bars and using an old blown Boge OG 311 shock for testing, who would have though it would come in handy)

I can ~easily move the upper mount a little due to the way T3 shock mounts are made (all stamped steel and double shear, plenty to weld to) and get the length and angle proper with zero binding. (bars are out for testing, you couldn't feel the binding with good shocks installed, esp monotubes)

Need to start working on the inverted Kafer brace anyway, might be a way to incorporate a relocated upper mount into that.

I'd like to be able to fit 17" long std Bilstein short track S6G shocks out back, at least, as they are coil over ready and I can still make the Four-Way spring setup work with them..
Last edited by Piledriver on Sun Jul 10, 2016 9:40 pm, edited 2 times in total.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by 681tonburb » Sun May 29, 2016 2:17 pm

If you know some one with a laith you an make a set of these its what the Porsche guys use to swap out shocks and coliover but there expensive to buy . http://www.racersedge-inc.com/racersedg ... id=11.3.14
I use to have a thread saved and it went over someone's car that had tried it all from coil overs to Porsche torsion springs and a mix of everything in-between .but i can't seam to find it now

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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun May 29, 2016 11:00 pm

I have a lathe and mill at work, but I suspect the loading on those bolts will be a LOT lower than the race-coil-over-guys, as I A) plan to use small body (36mm) units, and B) not planning to use 800 lb/in springs.

The larger shock race setups run are based on 46mm shocks and 2.5" coilovers, so if you look, the "adapter"s primary purpose is to allow clearance for the much larger shock/spring. This extension increases the load on the bolt tremendously, requiring the purest unobtanium steel. It also happens to reduce to 1/2" also to suit those shocks, but drilling out the bore of a spherical bearing 1mm is not rocket science.

It is also absolutely critical to set the upper and lower bump stops so that the shock is NOT the suspension limiter
(The 944 Turbos std rear shock has the bump stop built in, but it can still be an issue, even without coil overs)

The small body coil overs with 1 7/8"ID springs (like I'm using now, sorta) have no need for the extension, aside from a tiny bit of sanding on the arm, maybe a mm or three, just a small radius.
The grade 10.9 14mm shoulder bolt will be fine, esp as I'm probably keeping the torsion bars.
I can always get a higher grade std bolt if needed.
Last edited by Piledriver on Mon May 30, 2016 1:33 am, edited 1 time in total.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun May 29, 2016 11:13 pm

So as I'm not really in the mood to relocate the lovely T3 double shear the upper shock mounts or make custom shocks, we are going to make this work properly the old fashioned way.

The length and stroke of the IRS rear shocks is the same within a couple mm vs. the 944/968 shocks, so its really just a matter of setting the upper/lower limits of the car to suit the new arms.

As I suspected, the lower hard stop on the 944 torsion is ~4mm lower than the std T1/T3 one, likely to compensate for the raised axle centerline of the aluminum arms. Given how close the 944 stop is to the torsion pivot point, that's a LOT at the shock.

I proceeded to cut/grind the stop so it ~matched the 944 stop, and the std T3 shock is now right at max extension, you can slide the bolt in/out at full droop. You can also kinda see the raised axle from the centerline of the springplate in this shot.
springplate-full-droop-hardstop-clearanced-like-944.JPG
Shock-at-full-droop.JPG
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Last edited by Piledriver on Sun May 29, 2016 11:56 pm, edited 3 times in total.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun May 29, 2016 11:26 pm

So, the next step of fitting the arms was setting the compression//bump stop, as you never want to have the shock be the limiter.
I'm going to use the VW fitment shocks, so no internal stop.
(944/968 with alloy arms had the stop in the shock, but it can snap off the lower shock bolts...)

Here's the gap between the T3 stop (already cut down to ~1/2 width for tire sidewall safely) and the stop on the arm
(`86 alloy arms have this---later aluminum arms do not)
I'll install a screw in aftermarket bump stop to fill the gap, the stop cups align perfectly.

Appearances can be deceiving: The axle is raised ~30-40mm on these vs the arm and springplate centerline, so at max compression, the tire is ~same place it was with the steel arms and no bump stops, same is true when fully compressed.

All that's left will be tweaking the angle of the top loop of the shock slightly so things are not side-loaded at all.
I'm thinking large steel bar through the loop (bushings pressed out).

I also found I had to shim the rear calipers ~3mm for centering on the correct `86 or 928 rear rotor, so there are more slight variations than the alleged "bolts on" reputation of the swap would indicate. (The calipers used are post-86 944/968 or off a 928)
bump-stop-gap-at-full-compression.JPG
Springplate-shock-compression-limit1.JPG
shock-fully-compressed.JPG
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sat Jun 11, 2016 11:44 pm

So, finally dried out enough, pulled out the plasma cutter and my welder off-road-buggy/welding table -cum fat tired shopping cart and got after it...
And as soon as I got set up, it started raining, for ~1/2 hour.

Was pretty well dried out before, so after about another 45 minutes I was able to get back after it.
(a tarp was sufficient to cover the welding rig and the plasma, not torrential rain per usual)

After playing with this for hours, I decided that the only sane solution was redesign the upper mounts by putting them in the ~ideal place, and at the proper angle relative to the required shock motion.
(placeholder for pictures)

Fortunately it will easily integrate with the original stamped steel double shear mounts for the most part, and easily tie into the bolt to the body.
I did it possibly the hardest way, had a section of 3/16" x 2" angle, sliced it up with the plasma and welded together at exact width of original mounts for stock shocks... should have TIG'd it, had to use flux cored MIG (added gas, helped) due to wind but required way too much time cleaning them up. Carved them to shape a bit with the plasma for good fit to the partially cut back original mounts, they will still work for the std TA setup (possibly better than stock) if I ever wanted to swap back.

I'm still not quite sure what shocks are going out back, but stock length works with a little extra travel to spare on both ends.

I cannot fathom why anyone would use $150 unobtanium adapter studs//bolts necked down to 1/2" for the lower coil over heims, the Bilstein coil over shock eyes I got at least are trivial to drill out to 14mm or even 5/8". Reducing to 1/2" seems an idiot move. (making a clamp setup to drill the heim ball bits takes only seconds)

I suppose having the shock actually mount straight helps.(unlike an actual 944, esp with 2.25" or 2.5" coil overs)

At least they operate straight and true, was able to get the motion ratio to ~62% +/- 1" of ride height, shock is square to the arm relative to cars length at ride height, and just off vertical to the outside as required by the angle of the lower mount bolt in the arm.
Zero binding/side loads, and provisions for alternate shock upper holes exist.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun Jun 12, 2016 7:09 pm

Have pretty much settled on std T1 class 11 rear IRS Bilstein 7100s if I can find them for a reasonable price.
Heim ends, perfect length, 345/135 valving, digressive, already has the Schrader valve.

Can get ~the same shock/valving in 6100 form (B8-0930-H5) and add a schrader valve myself for ~half price.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Thu Jul 07, 2016 3:48 am

Flared the fenders a bit last Sunday with my modded palm nailer, went with small bubble flares just over the tire, up to where the inner fender is tubbed to.

Finally gave up on using a bolt, radiused and shortened the collar a mm or so and put a slight radii on the hardened pin. Works like a dream, far better than with a bolt that gets chewed up in a few minutes, the only bug(?) i it chips the paint off.
(garbage grade paint anyway)

One side was done in 15 minutes, other side had some bondo and previously bondo--covered dents to work through.

(place holder for pics,)

My iThing is at work and my old backup Android phone has a very pre-iPhone grade camera.
Unfortunately I hit the flares both wit some primer so you cant really see the nice bubble and surprisingly smooth finish, turned the pressure down to about 60 PSI and it was fast and very controllable. Should be able to knock off the high spots with a shrinking disc, its already just about to the point where a thin skim of body filler would work.
I'll need to wire brush them clean fo the pics to really show anything.

At full pressure the modded palm nailer would have probably just put a series of holes in the fender.

Scored a set of 2 ~Fox IFP shocks (Ridetech RQs, but really..) for an "odd"' application, short stroke, hard anodized aluminum, rebuildable/revalveable and 179 for all 4.

The 944 turbo arms require ~2" shorter (really short) shocks if the car isn't jacked up miles and you want reasonable travel, as the Porsche shock pickup is much higher vs. IRS arms. The 944 shocks are ~as long as stock T1 but the upper mount is also a lot farther away.

Back to daily driving this week, drives great with decent shock on it...
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Wed Jul 13, 2016 4:36 am

Well, the custom Bilstein 7100s were 6100s, no schrader valve, and I'm not going to hack something I paid retail cost for, they are going back. No excuse for that. Not my problem.

Decided to finally break down and do the needed kafer brace, and integrate the shock mounts into that.

Will simply work with the 2.170" OD Fox "truck" 2.0s, which can be grooved for a coil over kit unlike the regular thinwall Fox 2.0s. (A1 Racing sells 2.170" ID coil over sleeves, usually used for struts)

Considering the Fox 2.0s were only $40 each I can afford to play, or even buy digressive pistons for them..

The shocks will sit almost vertical and have plenty of room for the 2.5" coil over springs.
Not sure what to do up front, still processing.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Mon Aug 01, 2016 12:06 am

Have the Bilstein S6Ms up front, shortened the ends, may weld on some uniball eyes to get them shorter.
... with #100 hypercoils, the bars are preset so that when both are active at normal ride height.
Spring rate is appx 2X stock, ride height is just a little lower than stock, and it works well.

The rear Fox shocks are still awaiting the arrival coil over kits for the #250 2.5" coils, adding heim ends to the stem-mount shocks and placing the coils at the top allows for a trailing-arm interference-free installation. Will also be trying the existing custom valved Bilsteins with ~same setup. These will be used in addition to the stock 23.5mm bars, which will be reindexed to a small preload at ride height. (not sure positive or neg preload, have used both in past)

The spring rate at both ends will be ~2X stock, the calcs say the suspension frequency will be ~1.6hz front, 1.8hz rear.
The effectively dual rate springs make the damper calcs weird, but the ass dyno is the ultimate arbiter of that.

Due to the way the springs are opposed makes for a very progressive spring rate setup on extension.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun Dec 18, 2016 7:01 pm

I forgot about this thread...
First:
There are two good reasons to run reservoir shocks:
One, for extreme duty off road use. More oil/N2 etc.
Two, to shorten the shock while keeping the stroke, by moving the IFP to the resi.
I did this for the latter reason.

Here's the "new" front shocks, 36mm bore, $20/ea new (surplus) Bilstein S6Ms, body shortened about an inch (using the inner snap ring groove as the outer and trimmed to suit) with some used KYB fronts converted to use as reservoirs. Also welded on upper eye with 1/2" teflon lined uniball from Steinjager, the original lowers are shortened and TIG'd onto the shaft for now.
What was originally 17" eye to eye is now 15.25", with 6" of stroke, and will eventually be made about 1/2" shorter by replacing the lower eye with a proper monoball, all while maintaining the original 6" stroke.

The stock front torsion bars on the T3 are installed unloaded or just slightly preloaded at ride height for a dual spring.
They actually limit the coil overs extension, the pic shows them unloaded, arms sitting at just about where they would sitting on the droop stop. I have to pull down the arms ~1/2" to install the coil overs, eventually they will be perfect length once I get around to replacing the lower eye with a std monoball.

I used the low mass plastic Bilsten IFP in the 36mm KYB "resi", and drilled/tapped/slightly machined the steel KYB IFP as the end cap.
These have been revalved to 2010s, and I am runing Redline "Like Water" shock oil (about 1W)
The interconnect line/fittings are AN-4 from Smileys Racing, Goodridge brake lines cost $11/ea.

Day Motorsports in Tyler, Texas has all the valves/pistons/shims and are close enough thet USPS priority mail is overnight if parts are ordered early in the day. The shim kits were only a few $. They also do Carrera/AFCO/PRO and Fox track shocks, and sell parts.

Smileys in Sherman up the road dynos non adjustable shocks for $8, although I have so far only used my personal ass dyno, as you have to drop them off and pick up the following week as they usually have multiple sets of shocks awaiting work, and the shock guy probably does all the rebuilds/revalves and runs them all in a batch on the dyno. They don't rebuild/stock parts for Bilsteins, yet, but are looking at it, they sell Bilstein sealed track shocks like the S6G and its larger brothers. They currently service QA1-Carrera/AFCO/PRO shocks.

The "extra" schrader fitting on the oil side of the resi is to pressure leak test, and after the IFP is under vacuum, evacuate the "oil" side of the shock and allow them to suck the perfect amount of oil in with zero air. (and vacuum degassed oil)
I put a PVC spacer in the IFP section of the resi while doing this to keep the piston in the right place, then once the shocks are full, pop it out, re install the end cap, then charge (250 PSI for now) An 11mm washer and brake hose clip keeps the IFP/cap/spacer from getting sucked in.

I used 1/4" flare AC fittings for the schraders, very easy to do the evacuate/charge setup using my AC gauges for the vacuum and N2, and rated to >800 psi. For charging I just use my AC no loss schrader valve tool, and screw in the schrader valve (under pressure) once finished.

The mounts are conduit mounts from Lowes, ~50 cents ea, with a short strip of rubber weatherstrip to clap tight on the shocks. The forum software is rotating the picture for some reason, cannot fix, sorry.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun Dec 18, 2016 7:15 pm

The rears are ($40-surplus) hard anodized aluminum Ridetech/Fox 2.0 "truck" shocks originally for a Chevy 2500/3500 van. 5/8" shaft.
These came with a stud end, shortened the stud and offset welded (to better clear the alloy arms) on a Steinjager 1/2" loop/teflon lined monoball.(Actually used a Ridetech 5/8" ID monoball thats the same OD as the 1/2" jobs)

These are now right at 15" extended... could be made shorter, but its about right.

There are take-aparts with one-time use rubber needle valve, I was able to revalve these only using the shims included, it had about 20 shims in the stack for the original 1 ton truck app, all are still "present" but only a few are now effective.
I installed an AC schrader valve to allow easy service and no-loss gas charging.

They are digressive comp/linear rebound ~4020 (bilstein track scale reb/comp) with redline likewater oil, and no bleed. (rotated the bleed shims 45 degrees so they are effectively just valve shims)

I used a 55mm coil over shock kit on these, the "truck" 2.0 series are super thick wall, the threaded coil over tubes are normally used for struts, the threaded tubes are actually a shrink fit, had to heat them to 200C to get them to slide in place. I installed snap rings, as these shock are extra thick ~3/16" " thick hard anodized tubing, but the shrink fit threaded bit has never moved. You cannot groove std Fox 2.0s as they are too thin.

I run these with 250 lb Hypercoils and the rear bars installed unloaded at ride height, for a dual spring setup.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Sun Dec 18, 2016 8:39 pm

I took lots of pictures and documented all the original, a couple tests and final shims if anyone is interested.
I haven't gotten these dyno'd yet but they feel ~infinitely better than Monroes or KYB oil filled or gas-a-justs, which I will absoluely never buy again after seeing how they are built inside.

I actually considered reusing a monroe or AFCO adjustable base valve in the front resis so I could adjust compression and run lower gas pressure, but with only 11mm shafts there really isn't much compression adjustment range to be had.

Edit:
Had to go shopping this evening and manage to "test" the new front shock setup.
At ~45MPH you can hear but not really feel the speed bumps in a Wal-Mart parking lot.
(didn't try faster because in use parking lot)
Previously it would remove fillings.
(were valved 4020 and ~1.5" less bump travel, I suspect the shocks were the bump stops, now the angled/cut down factory stops are the bump stops)

It also rides at least as well as stock, despite the ~2X spring rate and ~huge low profile rubber on forged 16s.

I'd like to get some of the high density foam stops for the shocks.
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Re: aluminum 944 arms--- what shocks? Brakes?

Post by petew » Tue Dec 20, 2016 4:29 pm

Sounds great. Could we see some pics of the car too? :)

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Re: aluminum 944 arms--- what shocks? Brakes?

Post by Piledriver » Wed Dec 21, 2016 4:19 am

petew wrote:Sounds great. Could we see some pics of the car too? :)
I'll take a pic of the car with the current setup tomorrow and post up.
It's a Pile.

Does anyone want the valving spreadsheet?
I don't have dyno charts for the shocks yet, the spreadsheet doesn't mean much without those, will be in the new year.
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