fatboycowen

Does anyone know the part number for the rear shock bolt for the 87 944T? I am installing rear coilovers with T/B Delete, and wanted to use fresh bolts, and get some extras for periodic replacement. However, i cant seem to find them on pelican.

KuHL 951

Top: 900 082 044 02 - M12 x 1.5 x 125mm
Bot: 900 082 054 02 - M14 x 1.5 x 85 mm

fatboycowen

Thanks,
Pelican says "no longer available". What should i do?

931guru

msc or mcmaster carr

MAGK944

The rear shock mounting bolt is 900-082-054-02 (M14x1.5x85) DC Auto has them. You may want to condider these instead if going to a full coilover set-up: Shock Mount Upgrade

fatboycowen

Those only work with spherical bearings on the coilovers. The Bilstein Escort Cup rear coilovers do not have sphericals. Paragon's website is not clear on that issue. I went directly to racers edge to find out.

paluck

I just ordered one from McMaster
I think the part # is
91180A794
www.mcmaster.com
$3.80 each

fatboycowen

That part number shows an 80mm bolt. Isnt the factory one 85 mm?? Also, what grade is the factory bolt? That one is 8.8. Im wondering if a 10.9 would be better...

fatboycowen

Ok, i just yanked the bolt off the car to measure, observe, etc. The stock bolt is grade 8.8. According to my reading, shear resistance is not necessarily increased by increasing bolt grade. So, grade 10.9 might not be stronger in this applacation.

The factory bolt is 85mm long, and has about 46mm threaded portion. Im not yet sure how far those threads extend into the trailing arm.

McMaster only sells 80mm or 90 mm length bolts in this size. So, if i buy the 80s, i lose some thread engagement. If i buy the 90s, im not sure i will have sufficient depth in the trailing arm (might bottom out).

The McMaster bolt thread length is listed as "varied 34 to 44 mm thread length" Which might be ok.

Any thoughts?

MAGK944

^ Should be fine, I would get the 90mm and cut/grind it down to 85.

p_tothe_g

No need to cut and grind a 90mm bolt. I bought some 12.9 grade 90mm long ones when I added my tie down hooks. If you have the aluminum control arms (with a 944T you should), there should be plenty of depth to the threaded holes. Just screw one of the new bolts in without the shock attached and wait for it to bottom out (you may want to chase the threads with a tap first, got mine from mcmaster for about $25), after the bolt bottoms out, take a measurement, you should have plenty of room.

I got 90mm bolts from a local "nut and bolt" store for a few bucks a piece. S.A.C. Fasteners in Williston VT.

fatboycowen

Excelent!

Are there any fastener experts, to tell me what grade bolt would be best? I hesitate to use 12.9 because they are brittle, and will fail without warning...

p_tothe_g

Not too sure about them being brittle. I've had mine in the car for a little more than a year, about 8k miles, a few DE events, and the crap roads here in VT. I am sure that if it were to break, I would have had it happen to me already. That is a good size bolt, I think the largest in the whole car. If it were a metal to metal contact point I might be slightly concerned with the impact (without having the T-bars helping out). I was told the 12.9 has a higher yield strength and a higher tensile strength, and only slightly higher "brittleness" with an almost identical Rockwell hardness of around C39. The rating may be due to the size of the bolt. I just put it out there because those particular bolts are readily available on the cheap (if someone stocks them, special order=more $$), very difficult to find a grade 8 in that size.

fatboycowen

I will read up more on bolt grades, and reply back. McMaster has grade 8.8,10.9 and 12.9. Each grade has a higher tensile and yeild strength. It is my understanding (could be wrong) that the hardness increases with grade too. The factory bolt is grade 8.8.

So, if my understanding is correct, the elongation at ultimate tensile strength (breakage) is decreased with each successive higher grade. Therefore, the highest grade would have the lowest ductility. So, grade 12.9 failure mode would likely be fatigue crack, which propagates with more fatigue, then immediate failure. Where, the lower grade bolt might bend first.

Our car will no longer have torsion bars, so where yours would just ride a little lower after failure, mine would dump.

p_tothe_g

It certainly could be a more "fragile" bolt. All I am saying is that due to it's size, and specs, I wouldn't have any worries about using it, unless of course you plan on jumping it out of multi-story garage park, or plan on using it for rally work (which I hear these cars can do pretty well). If tensile strength and yield strength are in the ten thousand pound area, you are using only a couple of hundred pound spring rates, the bolt is not your weakest link. When I used to work for Audi, the most common suspension failure in the rear of the cars was not a bolt, but broken springs. And I live in the land of cavernous pot-holes.

All I am saying is that I would not hesitate to use the higher grade bolt for this application. In my opinion if you are driving the car that hard to worry about breaking a bolt of that size, other componets will probably fail before the bolt. I've seen broken springs, broken sway bar links, even bent control arms, never have I seen a bolt sheared off in the suspension. I speak from experience, I have all 8 ASE auto certs (currently cert'd) and have made my rounds in the german dealership world, I have seen some pretty crazy stuff, but a sheared-off shock mount bolt is not one of them.