Pete. (l33t FS) said:
I have a feeling that the BOP bolt pattern would be partially inside the transmission. That is a lot of why the Metric pattern is what it is.
Although... the LS4 does have a vestigial Chevy pattern on the back, so maybe? Does the Cad have the oil filter on the left or the right?
(HI everybody! In today's episode, we will see how far we can launch a 4T65 drive chain!)
Oil filter is on the right at the front/bottom of the block. Always a pain, but any time I work with Caddys I assume I need a remote adapter.
None of the bolts are common between BOP, Chevy, and the 60-degree metric pattern.
The 4T80E is another possibility, but A) not known for strength, and B) only came with the Northstar pattern
Buuut.... I wouldn't be opposed to trading a Caddy 500/TH400 for an LS4/4T65 or a Northstar/4T80.
I'm also waiting to get excited until I see the car and can get an actual look at what I'm working with. I know it's a unibody, but that's about all I know. It might be beyond the limits of (my) rational suspension fabrication talents for $2000.
The smart approach is to stab in something in the front that can make 300-400 hp and already has a logical transmission that bolts to it. 8.8" rears are cheap.
In reply to Curtis73 (Forum Supporter) :
BOP and Chevy have common dowel pins and bottom bolts. Therefore, by the transitive (heh) property, if the LS4 engine has the vestigial dowel pin and lower bolt locations, a BOP might clear an LS4's transmission.
Looks like the dowel pins are still where they should be, maybe? Hard to tell. For definitely the bottom right of the block would need to be cut back. But it looks like it just might actually be able to get wedged into place, if you can find or make an adaptor.
Note that I know none of those old dowel locations are actually on the transmission. But if they still exist on the LS4 engine, then another engine that has them will clear the transmission.
LS1 (which still uses the bottom four and dowel pins of a Chevy) for reference
I mean, I still think it is a bad idea, but that isn't my judgement call to make. It would be neat to see if it could work.
I wonder how they got the engine/TH425 (supposedly) turned sideways on the Vector W8?
Bing.com: Vector Motors w8
These are the only photos I could find.
In reply to VolvoHeretic :
Ooh, neat, never saw a W8 like that before!
Looking at it, I bet what they did.... the TH425 has a separate differential. It looks like they probably ran a spur gear setup for the differential instead of a hypoid setup. Gets rid of the 90 degree directional turn, improving efficiency, and sticks the engine ahead of the rear axle instead of over it.
Now I want to see more.
Another option is the C8 trans, which gives you a mid-mounted engine. And I'm sure is available at challenge-friendly pricing.
Y'know, I had an idea that is either stupid or genius or both.
That TH425-minus-diff idea? What if you stuffed an old fulltime transfer case where the diff used to go? One in, two parallel outs, 2.5:1 or so final drive.
Only problem is, I am pretty sure this would give you a car with three reverse gears and one forward, unless you put the engine behind the rear axle.
Unless you grabbed portal axles from a Hummer H1. Then you'd get the gear reduction from the transfer case's low range and the gear reduction of the portal axles and the wheels would go the correct direction.
In reply to VolvoHeretic :
They basically took a TH400 and stuck it beside itself with a chain to connect the halves.
TH125/4T40/4T60/4T80 (and probably a few other codes: there are only like four actual transmission species) are laid out the same way, torque converter and pump bolt to engine, big huge chain, then the planetaries. The difference is the transverse models have a hollow planetaries section, and they use a planetary gearset to make the differential coaxial to the transmission part, and the left side output goes through the whole mess before it sees a CV joint. Which is why the left side has a stub sticking out of the case for a female spline CV joint.
Pete. (l33t FS) said:
Y'know, I had an idea that is either stupid or genius or both.
That TH425-minus-diff idea? What if you stuffed an old fulltime transfer case where the diff used to go? One in, two parallel outs, 2.5:1 or so final drive.
Only problem is, I am pretty sure this would give you a car with three reverse gears and one forward, unless you put the engine behind the rear axle.
Unless you grabbed portal axles from a Hummer H1. Then you'd get the gear reduction from the transfer case's low range and the gear reduction of the portal axles and the wheels would go the correct direction.
I'm a little confused with all of the twists and turns of the output shafts. Two meshing gears reverses the rotation? So, an idler gear would correct the direction? How about using the drive chains to keep the direction correct? I suppose the gears would have to be different diameters to wind up with some ratio of gear reduction? I think that with a little cad work and some industrial bearings and gears and some pieces from send-cut-send, someone could start a nice little business. You could also package a T56 the same way. I need one for my 8 wheeled hypercar.
(dang. You beat me to my question Pete.)
Pete. (l33t FS) said:
Y'know, I had an idea that is either stupid or genius or both.
That TH425-minus-diff idea? What if you stuffed an old fulltime transfer case where the diff used to go? One in, two parallel outs, 2.5:1 or so final drive.
Only problem is, I am pretty sure this would give you a car with three reverse gears and one forward, unless you put the engine behind the rear axle.
Unless you grabbed portal axles from a Hummer H1. Then you'd get the gear reduction from the transfer case's low range and the gear reduction of the portal axles and the wheels would go the correct direction.
Yeah, unless I'm thinking backwards, a t-case on a TH425 would have three reverses and one forward. I would also have to look into some other things. Most t-cases are only rated up to something like 35mph, but I don't know if that's because they can only spin that fast safely, or if that was because of something like vehicle dynamics with a locked t-case diff and high speeds causing death. That is to say, are t-cases limited by their own internal speed, or does it cause vehicle dynamics problems in a 4x4? Did they limit speed in low range because the t-case would explode, or do they limit speed because you'll crash and die? Know what I mean?
I just learned a bit more about the Northstar pattern. It's similar to the Metric pattern in the same way that the SBC is similar to the LS pattern. A couple bolts don't line up, but it's basically the same. More here: LS4 to 4t80E Swap - What It Takes - PT 1 - YouTube
Going back to the Vector...
Some of these are the W8, some the WX-8, but they're a similar setup. Take from them what you will.
In reply to Curtis73 (Forum Supporter) :
I think the speed limit for a locked center diff on paved surfaces is to prevent wind-up. My 323 GTX had no such limitation.
As for the reverse rotation - that's just a special camshaft :)
Forgot all about this belt drive IRS setup that was in the magazines many years ago until I found it while looking for the length of the TH425 transmission case to scale it into a drawing.
LS1 Tech.com: Lets build a mid-engine Trans Am - need advice Post 320
And a chain driven version:
LS1 Tech.com: Oh no... lsx/t56 mid engine questions.. Post 40
Here are the other options for the drivetrain, both using that chain drive contraption.
1) Caddy engine, custom bell housing/adapter, T56 transmission, Camero or Ford 8.8, chain drive. It would probably need a double U-joint for a coupler between the transmission and the rear end or two bolt together flanges.
2) Caddy engine, custom bell housing/adapter, Corvette 6 speed transaxle, chain drive.
The chain drive will crowd out the bell house with either style, and that 94.5" wheelbase doesn't help any.
Keith Tanner said:
In reply to Curtis73 (Forum Supporter) :
I think the speed limit for a locked center diff on paved surfaces is to prevent wind-up. My 323 GTX had no such limitation.
As for the reverse rotation - that's just a special camshaft :)
My Subaru spent most of its life with the center locked, and it would happily run at 87mph.
I have a feeling that the "don't go over 35mph" was because trucks rarely had tachometers, and if you were in low range, the engine might be near redline in top gear at 35?
Re: rotation... engines may be reversed easily but automatic transmissions not so much 
For sure the torque converter and pump would not work, and unless you got some planetary sets from a TH475 (straight cut gears!) then some things may see thrust loads they don't like all that much.
Curtis73 should find a dead Prius and stuff in the second drivetrain shown above. If you need to, find two Priuses, one with front end damage and the the other with rear end damage. Cut the two body's in half down the center door jam and weld everything back up.
I new a guy that used to do just that with VW bugs.
For the challenge, you could use narrower wheels up front and 16x6.5" steel dualies out back.
Front wheels and tires: 11x17" wheels - 315/35-17 tires 11.7" tread width per side.
Back wheels and tires: 20x8" wheels - 225/35-20 tires X2 16" tread width per side.
Pete. (l33t FS) said:
Keith Tanner said:
In reply to Curtis73 (Forum Supporter) :
I think the speed limit for a locked center diff on paved surfaces is to prevent wind-up. My 323 GTX had no such limitation.
As for the reverse rotation - that's just a special camshaft :)
Re: rotation... engines may be reversed easily but automatic transmissions not so much For sure the torque converter and pump would not work, and unless you got some planetary sets from a TH475 (straight cut gears!) then some things may see thrust loads they don't like all that much.
Fiero.NL: TH425 reversed rotation design - how I do it......
Somebody designed a spur gear reverse direction engine/trans chain drive replacement.
Pete. (l33t FS) said:
Keith Tanner said:
In reply to Curtis73 (Forum Supporter) :
I think the speed limit for a locked center diff on paved surfaces is to prevent wind-up. My 323 GTX had no such limitation.
As for the reverse rotation - that's just a special camshaft :)
My Subaru spent most of its life with the center locked, and it would happily run at 87mph.
I have a feeling that the "don't go over 35mph" was because trucks rarely had tachometers, and if you were in low range, the engine might be near redline in top gear at 35?
Re: rotation... engines may be reversed easily but automatic transmissions not so much For sure the torque converter and pump would not work, and unless you got some planetary sets from a TH475 (straight cut gears!) then some things may see thrust loads they don't like all that much.
This was my conundrum. A purpose-built AWD T-case might be fine at 150 mph because it's not the gear-reduction part of the equation, but I would be using a T-case in low range as the physical "rear axle ratio." Is the reason an NP242 (for instance) can't go over 35 mph because of over-revs or vehicle dynamics.... or is it because the T-case isn't designed for the guts spinning that fast?
Years ago, maybe in Hot Rod Magazine, there was a section of new products of a company designing a belt driven "side drive" mid engine/transmission adapter that looked very similar the the belt drive contraption shown above. I can not find anything internet searching except of that photo.
I found this little blip from Hot Rod on Motor Trends websight but all of the links are dead. I will keep looking, I hope I don't have to go to the local library and go through 15 years of Hot Rod.
motortrend.com: Transaxle Solutions at PRI from Race Energy and Hot Rod's Restos. Only $10,000
