: Best transmission for a Northstar to LaSalle Street Rod swap

03-11-13, 07:44 PM
Guy and Gals, first time poster, here. I have a 99 STS that I want to use the engine out of in my 40 LaSalle Coupe. I've been told I can use a 700R4 out of a S-10 with minor modification to the bellhousing. Other than one of the RWD Cadillac trannies is there anything that would work for this project? I was going to use my 425/400 at first, but got the deal on the wrecked 99 with the Northstar and really would rather go that route. Any help, direction to books or articles that have done this, or just plain old seat of the pants Caddy ingenuity help would be greatly appreciated. I'm also using a front clip from a C4 Corvette and it's suspension, with the rear C4 suspension attached to the stock frame. Thanks!

03-12-13, 03:07 AM
I used a 700R4 with the bolt hole modification, but with a aluminum block drilled one hole for trans and one hole for engine and it works great, acts as a sandwich between the two. Had to use a custom built converter, basically a cadillac converter housing to fit the flywheel and a 700R4 snout into the trans pump. I have put 48,000 miles on it and no trouble.

03-12-13, 10:36 AM
Ugh. I would think a Chevy LS motor would be easier. Get a carb intake and ign controller. Is already setup for proper motor mounts. What do u do for cooling a northstar? It's got that ugly alum coolant crossover. Where or how do u modify cooling piping on a northstar streetrod?

Manic Mechanic
03-13-13, 07:53 AM
If any one is contemplating the fabrication of a Cadillac engine hot rod or has questions on how it can be done one should visit the web-site of Cadillac Hot Rod Fabricators. He has transmission options, water log solutions, motor mounts, belt drives, cams, etc.



03-13-13, 10:05 AM
Well, I just looked up some used 05+ Sts northstar motors online and found a few for <$1k. Why screw around with an older, transverse fwd motor when u can get a much newer rwd version for reasonable money? I wonder if the 4bbl intake they sell for older northstars will work on the newer rwd motors?

03-13-13, 04:52 PM
I did away with the water pump and ugly coolant crossover, fabbed water manifolds from CHRF and use a 55 gallon per minute Meziere electric water pump, it made the engine about six inches shorter, along with a in line water thermostat and a little more plumbing for the heater core. Made my own motor mounts, Yes a LS motor would be a lot easier than doing a Northstar but then there are a lot of folks with LS cars. Some folks are just marching to the beat of a different drummer. I have been working on getting my Holley EFI and CHRF intake, head work, hot cams etc. to run correctly for about a year now. It is good to have something to do.

03-14-13, 10:37 AM
Ya, I could say get rid of ur fwd motor and get a rwd northstar motor. But why? I see the rwd motor has a more complicated front, lower timing cover that houses the waterpump stuff. I am not sure if the heads even have coolant ports on the rear anymore?

03-15-13, 06:05 AM
I was at the Detroit Autorama last week end and saw a green 32 Vicky with a chromed out Northstar, but never saw the owner to ask him about the tranny he used. That is the direction I was headed on this build, so it is good to hear that someone has done it and it works. Thanks for the reply. Larry J

03-15-13, 09:26 AM