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Wanna build your own direct fit strap kit?

20K views 36 replies 14 participants last post by  acer-one 
#1 · (Edited)
i was inspired by jtm0n3y's windage tray build, http://www.srtforums.com/forums/f169/wanna-build-your-own-windage-tray-607397/

here are some pictures of vendor strap kits http://www.srtforums.com/forums/f169/help-needed-strap-kit-drawing-pictures-606322/

I don't have a lot of tools, but i do have a sawsall, harbor freight small drill press $29 (and $5 vice) along with the hf tap/die kit.

Parts numbers for the studs, washers and nuts
Studs------ATP4.650-1LB M11x1.5 & 7/16-20 ---
Studs------ATP4.400-1LB M11x1.5 & 7/16-20
Washers--APN12-1
Nuts-------APW1316N

fastenal has a 3/4" x 3/4" bar great tolerance and strength - http://www.fastenal.com/web/products/detail.ex?sku=47921

i picked up the ARP 2000 bolts from MAP, ~$120 (takes a few weeks to ship) -- update 2/18/13 the long studs are NOT the same as evo1-8 uses (different pitch)

55ft lbs on perimeter strap bolts. Then install the small ones and torque the upper and Lower to 8ft lbs.
here are some pictures and a drawing.. (i don't have that buling so i used a blue sharpie)









 
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#4 · (Edited)
the strap it tapped, and the fasteners just support the bed plate -- offset +- 1/2" from the center
the nuts just lock the fasteners in place so they don't back out (after verifng that the crank still spins.. added a little loctite red)
 
#9 ·
By using something that "feels good in strength" is an issue already. I see this thread creating bad juju. Im sry, but sometimes you really need to leave things to the pros if you dont exactly realized what your doing. B- for effort.

Call me an ass if you will, IDC.
 
#10 ·
He's going.g for a direct fit option...no machining of the bedplate required. However machining would be a better stronger alternative, its not a requirement.
 
#11 ·
He's going.g for a direct fit option...no machining of the bedplate required. However machining would be a better stronger alternative, its not a requirement.[/QUOTE]

ROFL



Yeaaa id love my bottom end to blow through due to shit straps. lol

have fun with your 'DIRECT FIT' straps.

to be honest, the way you have them is just adding weights to the bottom of your block.
 
#15 ·
This type of support has been used for a long time.
Ford Racing M-4033-G2 Ford Racing 8.8'' Rear End Girdles

BUT!

You need the strength in the center where the stress is.
3/4" would be good but looking from the side you only
have about 3/8 left top to bottom.You have drilled a hole
in it. This only leaves you about a 1/4" on each side.
So you have less than 3/8" extra support.
Next your center preload stud can not be wedged between
the ribs.It has to sit flat against the main.
Then after everything, lap the bar flat.

Other than that your idea has worked.
 
#16 ·
Not the same, That "girdle" is casted into the cover itself. For his to have anywhere near enough strength it needs to encapsulate the bed-plate ribs, so that it still has the strength there, not go around them.

Just for reference my strap kit is 1"x1" 6061. With machined bedplate. One of the strongest aluminum alloys with a high corrosion resistance.

All he is doing is barely band-aiding the issue.
 
#17 · (Edited)
t6061 has a tensile strength of t4=16,000 psi, steel starts at 4x -- so why al instead of steel ?

dcr claims 800hp w/ t6061 direct fit-- (w/ my s3 49lb -- i'll be lucky to hit 450-500)

if i had access to to a bridgport i would have milled the bedplate too, 3x4" x 1" -- i have a $29 (w/coupon) harbor freight drill press

reference specs

6061 aluminium alloy - Wikipedia, the free encyclopedia

Guide to Buying Steel Online | Online Metals Guide to Selecting Metals for Your Project

Darrell Cox Racing - Direct Fit 6061 Strap Kit (Powered by CubeCart)
 
#19 ·
You have two types of 6061. Regular forged, then billet. Billet is superior in all aspects strength wise.

Your designed is flawed in the sense of how you cut it. Please explain how your car chassis will hold up if you put a big "U" in it like that if we was to have a full chassis w/o extra structural support. Also factor in harmonics, how well does steel hum compared to aluminum? A whole helluva lot more. Thats your biggest issue.
 
#20 ·
the highest number per wikipeda is T6, temper 6061 has tensile strength of 42,000 psi much less than steel (MAP uses steel 4340, 186,000 psi)

no argument that notching reduces strength.

if DCR (respected name) uses a direct fit t6061 and claims 800 hp, and i choose to use a similar setup with a stronger material (not sure about DCR dimensions, seems like 3/4"x3/4") -- should work for my goals

fwiw, i upgraded to ARP 2000 bolts for the bed plate -- probably way overkill
 
#21 ·
My straps are 1"x1". Think what you will, do what you will. Im making the argument due to i dont want something doing this and creating issues. I do have the backing to debate this is what im saying. DCR isnt the greatest example to me in my opinion. He does what he chooses, and i disagree with quite a bit as hocus pocus. Do what you will with your engine. It will hold for a bit how long i dont now. The biggest issue with steel is going to be the harmonics, which to much will create even more issues for you IMHO.
 
#22 ·
^^^^he is still wondering lol. No wondering here as ours are proven over and over. Example is the most horsepower and reliable horsepower ever for the SRT4s.

Jen.
 
#23 ·
didn't you guys say in another thread the direct fits aren't an actually tested strap but more of a "you guys seriously want this!? fine, here you go..."

also i agree the strap mentioned by OP should have been ground just enough for material to sit between the lips of the girdles and go over them...

oh well.
 
#24 ·
With over 60 sets of DCR Billet 6061 T6 sold, installed and put to use with zero issues they are tested. We have several in cars over 650whp with zero issues. We never made a comment to that. James assumed it. We still offer both DCR Billet Steel and DCR 6061 Direct Fit Straps. Billet steel ones up to 1500hp and 6061 up to 800whp. We were the first to even need straps and the first to offer them period. Darrell knows what works as he has no issues with his ever and proven beyond everytime.
 
#27 ·
I madez my ownz strapz too!!







BUT I have one of these in my garage:


As you can see in the pics, I decided to leave the balance shaft housing in place after machining some clearance into it for the studs. I like the way the balance shaft housing doubles as a windage tray so I kept it.
 
#33 ·
bump to my old thread.. just hit 187k miles (~64k on the strap kit) and i'm building another set for my new project..

also, added ARP part numbers to the first posting
 
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