Help me build the strongest IRS pumpkin possible
- Thread starter supraman1990
- Start date
The mods I did include a ford girdle, ARP studs, Yukon solid pinion spacer, and a regular pinion yoke.
I see you studded the bearing cap. What bearing cap are you using and did you have to modify them to accept a nut? Any pics?
:rockon:
I did that mod as well, forgot to post that. It is a stud speced out for a 9", they take the same size. I didn't have to do anything to my stock caps to make it work. I can go back in my jegs/summit order history and see if I can find the part number if your interested in it.
Couldn't get in my summit account, I guess maybe I check out as a guest all the time. I did find this picture however to show you it works just fine with the stock caps and my ford racing cover
Couldn't get in my summit account, I guess maybe I check out as a guest all the time. I did find this picture however to show you it works just fine with the stock caps and my ford racing cover
If your using the factory bearing caps I think you will be ahead of the game swapping them out for the Mark Williams steel caps and ditching the studs. Remember what I stated about the FRP cover bearing cap backing screws applying a load to the arch in the cap especially on cast aluminum caps.
Just something to consider.
I was considering leaving the studs in the new setup as well, I've always been taught a stud is better than a bolt. We will see what happens on the new setup. Right now I'm going to have to find a new setup guy as my previous guy and I will no longer be working together.
I have never seen a stud loosen the thread fit like a bolt will especially in aluminum (header bolts are a perfect example :nonono
. You are correct, repeated torqueing a bolt in a soft aluminum thread produces lots of heat, galling and thread stretching.In your case I think giving up on the advantages of a stud are overshadowed by the added benefit of having the rear of the bearing race backed with steel over what looks more like a "strap" from the factory. The extra long SHCS as shown in the photo I posted should minimize the effects of torqueing a fastener into aluminum spreading the load over a wider surface.
I have never seen a stud loosen the thread fit like a bolt will especially in aluminum (header bolts are a perfect example :nonono
In your case I think giving up on the advantages of a stud are overshadowed by the added benefit of having the rear of the bearing race backed with steel over what looks more like a "strap" from the factory. The extra long SHCS as shown in the photo I posted should minimize the effects of torqueing a fastener into aluminum spreading the load over a wider surface.
Any updates on the measurements of the bolt used once the cap holes are bottom tapped?
I pulled the pumpkin out of the IRS sub-frame this weekend after a fit check but haven't removed the cover yet. I'll try to get the measurement in a few days.
I did some reinforcement on the IRS sub-frame adding another pick-up point for mounting to the chassis which required the gussets/fins on the pumpkin to clearance ground, it's a tight fit. The sub-frame goes out for powder coat next :rockon:
pics!!
The SHCS I have installed in the Mark Williams caps are 1/2-13 x 2.875 with a 1.375 lg shank. I purchased these bolts from local industrial supply and are sized perfect for the MW caps. McMaster-Carr closest equivalent is p/n 91251A723 SHCS which is 2 3/4" lg and may just bolt into the case without bottom tapping but I have no idea on what the shank length is which is important. The counterbore on the MW caps measure 1.250 from the seat of the bolt to the face of the cap where the shank length of 1.375 worked fine for me when you consider the counter sink in the tapped hole in the case. Any shank length 1.375 or less is "good", anything more is "unusable".
A 3" bolt can be ground down an 1/8" as well just make sure you thread a nut on the bolt on there before grinding to help chase the thread after you grind a 45 degree angle chamfer so it threads-in correctly.
Sorry didn't see this earlier. I'm running the stock caps and did not have to modify them in anyway. I would have gone with Mark Williams' caps but don't have easy access to a machine shop.
Whats the diameter of the head of the fastener that comes with MW caps? I'm going to contact ARP and have a custom run of 180,000 psi, 1/2-13 x 2.875 with 1.25" shank bolts. Just need to know that dimension as I don't have access to the caps I ordered. Thanks
ARP will make you a custom bolt but they will cost you $400 ea.
Most off-the-shelf industrial SHCS are high strength and use 180K psi steel. You looking at $10.
Alright, I'll stay on the hunt then. I put in a quote through ARP just to humor* (been around too many canadians I guess haha) myself. The head dimension would still be usueful to me however. I've come accross possible winners, but one has a head diameter of .562" and another of .750", not sure on which way to lean with this.
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ANSI standard calls for a .750 OD on the head for a 1/2" SHCS.
A .562 head diameter would result in less then a 1/32" wide seat area. A 3/8-18 or 24 SHCS has a .562 head dia.
Must have been mislabeled on the site. Thanks for clearing it up for me.
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