re:Engine Swaps and tranny Questions (Buick Version-LONG)

["Dave Swingle" <swingle@xxxx>]

Hi Louie and list - LONG POST ALERT

As I've just finished rebuilding the transmission in Rich's Buick
Grand-National powered car, I'll make some comments on what we found in the
process and my thoughts at least on this version. This car was (we believe)
assembled several years ago and street-driven for over 10,000 miles.
---This setup uses a custom-cast aluminum bellhousing that replaces the
stock DMC bellhousing and bolts up to the Buick engine. This is the design
formerly sold by Don Steger, and occasionally comes up for auction on eBay.
It has a few shortcomings, IMHO. The custom bellhousing leaves a lot to be
desired. The casting is relatively thin, the mounting arrangement for the
clutch slave is not good, it is difficult to install, and has a very poor
design for the clutch pivot. There were two significant design defects in
this installation.
---I compared notes with Darryl on his Supercharged Vortec installation.
Rather than the cast bellhousing, he used a custom-milled adapter/spacer
plate with the original DMC bellhousing. This is a much more elegant
solution than the custom bellhousing, and I'd recommend to anyone doing this
conversion to go that route. Darrell also has designed and installed a much
stronger input shaft (due to breakage) and other than that has not had
issues with the trans.
---On Rich's car, the transmission had failed in a somewhat common DMC
manner, i.e. the large nut that holds the main shaft together unscrewed
itself through the back end of the shift housing. I've seen this failure on
several stock cars so I'm not sure it was related to the high horsepower,
although the vibration caused by the second "Design Defect" may have
contributed to it. The input shaft, while damaged from "design defect #1"
was not broken.
---The original clutch setup used a pressure plate and disc of undetermined
origin. The disc was smaller than the stock DMC (8-3/4") but had metallic
facings. It exhibited normal wear but there were signs of high heat on the
flywheel. We re-machined the GM flywheel to mimic the DMC flywheel's step,
and are using a stock DMC clutch. I realize this may not last long, but we
figure clutch discs are cheaper than transmissions. At some point if you
keep beefing up the stuff that breaks you just get to the next thing in line
(input shaft, gears, axles, CV joints). A next step would be to put a
metallic face on a stock DMC disc. We explored some alternatives, for
example there is a Toyota 21-spline design that **looks** like it should
work, but the splines are a slghtly different shape and will not mate up
with the DMC trans. The input shaft spec on the DMC/Renault trans seems to
be unique, at least in US-market vehicles.
---The big surprise to me was upon opening up the transmission. Other than
the aluminum shavings all over the place from the failure mentioned above,
the trans was in fine shape. No damage to bearings or gear teeth.
---Design Defect #1 - The original "engineer" had used a GM-type bronze
input bearing, that was much too far into the crank to support the trans
input shaft. The failure caused by this was the destruction of the input
shaft in the area of the splines, but it never broke. We fixed this by
sleeving a stock DMC pilot bearing and putting it in the outer recess of the
crank.
---Design Defect #2 - The Buick engine mounts are all the way at the back
(formerly front) of the engine. The DMC trans mounts are at the opposite end
of the transmission. This leaves the entire assembly unsupported in the
center, which puts a tremendous strain on the (thin casting, remember?)
bellhousing. It was cracked, probably due to the vibration from the
unsupported input shaft and just the unsupported wieght. We added some
renforcement gussets to the bellhousing to try and stiffen it up. We'll fix
this by adding some BMW E30 transmission mounts at the sides of the
bellhousing to try and stabilize the center of the engine/trans combination.

The setup we have built, with the stock DMC clutch, will probably not live
long if Rich decides to show off with lots of smoky burnouts. But, driven
with gusto <<after>> clutch engagement, it should do just fine. I have no
fears about the transmission itself, just the clutch. Next improvement will
have to be a custom disc with metallic facings.

At some point we'll put up more of a pictoral history on this thing. I
expect to have it driveable this weekend, and we hope to have it available
at the midwest Tech session coming up. It does still need a lot of clean-up,
it was driven a lot and certainly was no garage queen!

Another note - according to the owner of the 350-Chevy powered car at
Memphis, he also used a stock DMC transmission but was on his third (or so)
input shaft.

Dave Swingle <--another one of "Rich's Wrenches"


>Date: Thu, 1 May 2003 00:03:27 -0700 (PDT)
> From: Louie G <louie@xxxx>
>Subject: Engine Swaps and tranny questions

>I've been cruising around DeLorean sites the last few days checking out
>various engine swaps people have done. What I'm looking at specifically is
>what transmissions people use when they do these large swaps. I've seen
>where both Bob Brandys Land Rover v8 D, and Jim Strickland's Mazda 3 rotor
D
>both use porsche transmissions. On the other hand Rich W.'s Turbo Buick
uses
>a stock D tranny with a custom bellhousing. There's a couple of swaps I saw
>on Tamir's site that I'm curious as to what trannies they used- the Chevy
>350 powered D which was at the Memphis show, and the Ford v8 powered D at
>the Cleveland show. If there's anyone else out there on the list, or knows
>of someone who's done an engine swap, I'd really like to hear how you got
>around the limitations of the stock D transmission.