D44 Cover Bolts
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
D44 Cover Bolts
I can't seem to find the bolts I had for the cover. AFAIK, it is an M8X1.25X30. Does this mean any bolt of that size will do or must I get the $3 special from GM? TIA
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
No OE!
The GM part #'d product is actually a self tapping bolt that was used for fresh assemblies. New housings were not threaded either and there are notes to that effect. When using a new housing I use a "bottoming tap" and a quality fastener. The quality of the threads you're observing is the reuse of the OE fastener a couple times or more.
If I were using a "used housing" I would consider the helicoil approach if after cleaning the threads up with a "bottoming tap" I still wasn't happy with the appearance or the condition of the threads. I would think anything 10.9 should do for hardware. It's what I've used and haven't given it a thought.
Find one of your old bolts and if they're original twist it in your fingers and you can feel the "triangular" pitch of the threads which make it the self tapper. Toss-em! No need for or reason to use OE!
Put up a link to the bolt. I tried the Fastenal site and the drop downs seem clutzy! But I'm tired too!
If I were using a "used housing" I would consider the helicoil approach if after cleaning the threads up with a "bottoming tap" I still wasn't happy with the appearance or the condition of the threads. I would think anything 10.9 should do for hardware. It's what I've used and haven't given it a thought.
Find one of your old bolts and if they're original twist it in your fingers and you can feel the "triangular" pitch of the threads which make it the self tapper. Toss-em! No need for or reason to use OE!
Put up a link to the bolt. I tried the Fastenal site and the drop downs seem clutzy! But I'm tired too!
Last edited by WVZR-1; Oct 17, 2007 at 09:49 PM.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
The link you posted also has references to usage by grade. 10.9 is the recommended automotive usage and the 12.9 hardware certainly exceeds that.
Also note that the chart you linked to is for "black bolts" not SS and they are not recommended for exterior usage. Most any dealership or quality automotive shop should have the hardware you need in 10.9 but probably only in a hex head cap screw. Inexpensive also!
Don't exceed the 30mm length though, the bore isn't much deeper. I believe I've generally used 25mm length to avoid for sure bottoming.
Also note that the chart you linked to is for "black bolts" not SS and they are not recommended for exterior usage. Most any dealership or quality automotive shop should have the hardware you need in 10.9 but probably only in a hex head cap screw. Inexpensive also!
Don't exceed the 30mm length though, the bore isn't much deeper. I believe I've generally used 25mm length to avoid for sure bottoming.
Last edited by WVZR-1; Oct 18, 2007 at 04:42 AM.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,473
Likes: 3,291
From: Hartford WI
My reason for them is that the cover takes a lot of weight. Are they not recommended for exterior usage because they will rust and not look good or is there some other reason? anyway, I'll go check out the other bolts in SS.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
But the load is distributed over such a large area I doubt it of any benefit or advantage. A washer faced 10.9 bolt should do very well and maybe the originals are only 9.8's I don't have any close enough to check and I don't recall seeing the hardness on the head of the originals. If you've an original close check it.
I would also assume it much easier to use a box wrench or socket in the area vs. a hex internal socket head with a ratchet. I think I said that right!
If you're really concerned with the "load" the helicoil or wire insert is maybe the "ticket"! An 8 X 1.25 insert is 12 X 1.75 external generally or they might do it in an SAE 1/2" That's pretty substantial.
I would also assume it much easier to use a box wrench or socket in the area vs. a hex internal socket head with a ratchet. I think I said that right!
If you're really concerned with the "load" the helicoil or wire insert is maybe the "ticket"! An 8 X 1.25 insert is 12 X 1.75 external generally or they might do it in an SAE 1/2" That's pretty substantial.