LT5 Crank to Flywheel bolt pattern ??

[5ABI VT]

Tried looking in the service manuals but no mention of it anywhere. I believe it was different than the LT1 bolt pattern or at least the dowel pin was in a different location etc? Will be pulling the trans and setup out soon but just wanted to ask I have a feeling someone may know !

Thx !

[A26B]

LT5 has 8 bolts + dowel pin. All others have 6 + dowel pin

[WVZR-1]

Originally Posted by 5ABI VT

Tried looking in the service manuals but no mention of it anywhere. I believe it was different than the LT1 bolt pattern or at least the dowel pin was in a different location etc? Will be pulling the trans and setup out soon but just wanted to ask I have a feeling someone may know !

Thx !

The LT5 flywheel is an 8 bolt affair and you'll not mistake anything in the install. If you've bought a flywheel you should have a 9 hole flange. 8 bolts and the dowel. Less than a 9 bolt flange? You've bought or been shipped the wrong flywheel.

***Jerry was "typing" and I was thinking!!!

Jerry - Not all others are 6 bolt!! I did an LSx 454 which is also an 8 bolt. I did it before specialty flywheels were an "off the shelf" and had to have one done by a specialty shop. I believe that now all LS are 8 bolt '09+ maybe. Then there's the LS9 - 9 bolt!

[Roadster]

[A26B]

Originally Posted by WVZR-1

..............................
Jerry - Not all others are 6 bolt!! I did an LSx 454 which is also an 8 bolt. I did it before specialty flywheels were an "off the shelf" and had to have one done by a specialty shop. I believe that now all LS are 8 bolt '09+ maybe. Then there's the LS9 - 9 bolt!

Tells you how far I get from LT5's these days.

[5ABI VT]

Curious if there is a pattern measurement size or something of the sort ? Like for wheels 5x4.75 etc

[WVZR-1]

Originally Posted by 5ABI VT

Curious if there is a pattern measurement size or something of the sort ? Like for wheels 5x4.75 etc

I'm quite comfortable mentioning a 3.0 bolt circle since the LT5 uses an SBC 1-piece rear main so I'd think that remained the same. I have a couple that are boxed but Jerry likely has one on the shelf that's easier to dimension. Tom's is also maybe easier to put his hands on.

I've never seen a bolt circle reference for the 8 bolt LS or the 9 bolt LS9.

Way back in 2010 when I did the LSX-454 it was one of the dimensions I did confirm for the fabrication.

[Roadster]

Originally Posted by WVZR-1

I'm quite comfortable mentioning a 3.0 bolt circle since the LT5 uses an SBC 1-piece rear main so I'd think that remained the same. I have a couple that are boxed but Jerry likely has one on the shelf that's easier to dimension. Tom's is also maybe easier to put his hands on.

I've never seen a bolt circle reference for the 8 bolt LS or the 9 bolt LS9.

Way back in 2010 when I did the LSX-454 it was one of the dimensions I did confirm for the fabrication.

Mine is not available at the moment, as it is in transit to get machined. Will be glad to take a measurement when it returns if you don't already have it figured out by then...

[lkeast]

I'm planning a 4L60 series auto trans on my 405HP LT5, prob a 70 or 75. Building a restomod 62 on a Dawson chassis with all C4 components. No racing. Need a flexplate to adapt. Pete's ZR1 Garage shows one but is he around? I got no response. I have a machine shop and can easily modify an existing flexplate but which one? Is the 8 bolt LS the same BC and I just add the dowel? What are the 2 small holes at 180 for?
Thanks, Larry lkeast@venturetechnet.com

[Perry Mitchell]

Way back in 2010, I needed a flex plate for my LT5 in a 67 Camaro project I was doing. I was installing a 700R4 transmission behind it. At that time, a company called Street and Performance, which I think still exists, provided me with the flex plate and other parts, such as billet/polished pulleys, polished lower half of the bell housing without a provision for a starter, etc. I heard that Mark, the guy that was working with me, has passed away, but maybe they still have information or parts for your project. Good luck.