LS4 / F40 swap - fieroguru (Page 143/216)
fieroguru APR 12, 01:03 PM

quote
Originally posted by Will:

Nominally, the traditional small block crank flange is 11/16" proud of the bellhousing. The LS crank flange is 0.400 closer, so around 0.287. However, as you have previously noted, even on the FWD engines for which the crank flange is nominally flush, it can still stand 0.020 or so proud.

Would you have to incorporate the rear cover/RMS support into the adapter plate or just relieve the block side of the adapter plate to clear it?



Due to the limited thickness of the adapter plate, I am planning to pick up 4 of the rear cover bolts with an appropriate spacer to help stiffen the adapter plate. The adapter plate will likely have some steel inserts for some of the thread holes so I can keep the adapter aluminum to minimize any weight gain.

On this LS3, there isn't any interference with the bolt heads on the rear cover but I have seen pictures on line where there was... trying to figure our which combination or parts resulted in the interference, then narrow it down to the specific part, and what/if anything else changed. I can contour the plate or provide clearance to the bolts, I am mostly concerned around impact on spacer thickness between the cover plate and the adapter plate.
Will APR 12, 04:50 PM
May want to specify spot facing the rear cover to a specified thickness at the affected holes to make sure your spacer stack adds up correctly.

I'm working with goofiness resulting from tightening a bolt against an as-cast surface in trying to mount an AMC Eagle front diff to a traditional Chevy for my dad's Chevy Eagle project.
fieroguru APR 27, 08:05 PM
I am still traveling for work 4-5 days per week and have projects in VA, IL and NV, so I still haven't got the LS4/F40 to the dyno. With the HRPT in 6 weeks I am probably not going to get the engine upgrades done before then, unless I do a couple of long weekends...

I did make a little progress on the AWD conversion. I have done a lot of thinking about the front suspension and wanting something OEM with larger/stronger bearings and ability for the bearings to accept axles.

W-body front knuckles are aluminum, have large wheel bearings and use the large 33 spine CVs. The front weight on the W-body is easily 500+ lbs heavier than the 88 front, so they should be a nice upgrade and plenty strong. The two issues are:
1. Designed for struts, not dual a-arms.
2. Rear steer, so new steering arms will likely been required.

So a little cutting and machining, the knuckles now accept the upper a-arm.




To go along with the aluminum knuckle, lets go ahead and use some aluminum upper and lower a-arms.



I am still working on finalizing the suspension mounting points in autocad to optimize the available suspension geometry. It is very close to being able to be used with a modified 88 front suspension crossmember, but I will likely go tubular to shed weight and provide room and mounting points for the front differential. My goal is to shed weight before converting to AWD and keep the AWD curb weight below 2850 lbs.
Will APR 29, 02:14 PM
FYI, basically *ALL* large pattern GM car hubs over the last 25-30 years have had the same external envelope dimensions. I've verified that C7 Corvette hubs fit W-body (and other apps) 33 spline outer CV joints.

Are you targeting a particular kingpin angle or scrub radius for your front end? Or did you just place the UBJ to minimize bump steer?

Also, an adjustable *upper* control arm would be an asset for your build...

Are those Corvette control arms? Did you have to modify the taper in the knuckle's lower boss to accept the Corvette ball joint?

[This message has been edited by Will (edited 04-30-2019).]

ennored MAY 30, 08:19 PM

quote
Originally posted by fieroguru:

2. Rear steer, so new steering arms will likely been required.




Wouldn't a simple right-left swap take care of this?
fieroguru MAY 31, 02:07 AM

quote
Originally posted by ennored:
Wouldn't a simple right-left swap take care of this?



Yes and No.

Flipping them from side to side does move the steering arms to the front, but the steering geometry (ackerman) will be off. There is also the issue with the elevation of the outer tierods not being correct as well... making new steering arms would allow me to address all these small issues that aren't quite right.

[This message has been edited by fieroguru (edited 05-31-2019).]

fieroguru JUN 07, 09:21 PM
Just finished a 700 mile drive in 2 days to start the 2019 HRPT. It also put the swap past the 50k miles since completed just over 6 years ago.

I will try to post some more pics this week.
fieroguru JUN 08, 11:13 PM
Here is the hood I have been working on the last year or so. It has tha driver STM hood scoop and still needs some refinements. The rear decklid has the modified 90s Mustang spoiler as well.
fieroguru JUN 15, 06:05 PM
Back from the 2019 HRPT! I didn't keep track, but easily over 2500 miles with all the side trips. It did put the swap over the 52K miles since completed.

Car only had 2 issues. Loose plug wire on a coil caused a minor misfire on the drive down - pushed it to reseat it and no more misfire. AC hose sprung a leak after the Bristol stop. Other than those items, the car ran quite well and was issue free.

Did 2 more 1/4 mile runs (I think that makes 15 or 16 total on the swap) at Norwalk. Had a best of 13.0 @113 (overall best is 12.8 @114). Launched in 1st gear and even with the 3.091 final drive it wouldn't hook. Time to get some 16" slicks for my spare set of wheels... One of the benefits of the 3.091 final drive is that there is no need to shift to 4th right at the end. 3rd will now pull to 126 mph @ 7000 rpm.

Jack and Joe were great to travel with and I also met up with several more friends.

Lots of positive feedback on the car, wheels, stance, drivetrain, etc...

Even purchased an 88 Fiero project on the way back home...

What a great way to spend my vacation! Can't wait till next year!
fieroguru JUN 18, 08:41 AM
Fieros getting some attention @ 1:06: