In the process of swapping out the TH400 for an electronic 700R4. Test fitting the new trans today I found its too wide for the tunnel.

Ron when you did your swap did you have ti trim the dust cover flanges or form the tunnel?

 

YES had to hacksaw them off, couple small dents in floor, not noticable with carpet in place. dust cover drilled two extra holes to fit it in place, actually drove around for without it for a year ,no probs.

its tight ,but it fits , No touching, i did not use jag rear mounting nightmare, a simple chevy transmission mount,rubber, $25. usd, at local auto store , he had 5 in stock.

custom short steel cross member for mount to set on!

best of luck on your install!

pic of rear mount, not fancy but been 21years.

 

Thanks Ron,

I figured I would need to remove these as soon as I raised the trans.

I am not going to use the Jag mount, I have plenty of steel in my scrap bin, so I will fabricate my own rear mount that will allow the dual 2" down pipes per side.

I have to modify the dust cover as the Marelli engine has the engine speed sensor in an alumunium cover over the flywheel ring gear.

 

are you going with a single piece drivshaft? makes things easier to assemble.

custom made are available in Carbon Fiber or Aluminum with billet ends,and GM HD U-joints,(thats what i used 21years ago) but today i'd go for C/F.

big saving in rotating weight and over all saving in total weight compared to factory stuff!

 

Haven't decided yet. But definitely not CF, it's not durable enough, longevity I think will be an issue as the ends have to be pinned and this is where I think it will fail.

May look at aluminium depending if I can get it in my area. I am a long way from the city.

 

A couple of comments.

1. The "book" that came with my Johnscars conversion kit has an illustration depicting the removal of one ear from a GM transmission.
My 4L60e went in just fine, ears and all. The stuff that came with my LT1 and 4L60E included two dust covers. One nice clean tin one and an alloy unit. the latter had been 'butchered" a bit at the point that it slipped over the front portion of the starter. I used the tin one. Althjoug finnicky about getting it in place easier than the other.

Yeah, as Ronbros says, many SBC's run around sans dust covers just fine.

The GM style transmission mount and one piece steel drive shaft in my car are just fine.

Carl

 

There is NO way this trans is going in with both dust cover flanges, it just will not fit. The flanges were hard against the heat shields both sides.

I have already removed them now anyway.

Remember I'm in Australia so the GM trans cross members we have here are different than yours in the USA. The Commodore mount will fit but not with 2.5" exhaust as I have.

I have a tin dust cover I will modify it to mate with the alloy bit over the flywheel ring gear.

I'll post up pics once I have everything in working and TCU tuned.

 

Making slow progress on the 4L60e swap. Living 40km out of town sometimes has it's down side.

The TH400 was now slipping quite bad in 2nd gear. It broke the secondary apply piston for 2nd gear band a couple of years ago.

The 4L60e I have is a 1994 model out of a VR V8 Commodore. It was in very sad state, what do you expect for $100. Anyway it was rebuilt with all the best bits, Kolene steels, Red Eagle clutches, Delco 5pinion rear planet,etc etc.... So it should live well behind my 6.7L.

Had to get the car up pretty high to get the trans out



Custom trans mount to allow the 2.5" exhaust to live high.



Trans mount in the car for test fitting



Megashift TCU mounted under the drivers seat.



Hole cut in transmission tunnel for TCU wiring harness



Grommet installed ready for the wiring, I still need to prime and paint the plate.




.

 

Very nice work.


Clearly, you weld far better than I. Were I to make a mount, I'd
seek to use the weld to locate supporting steel and little if any of the load on the seam.


A practice carried from my early days in the very early 50's with a "torch". Pal, Bob, and I shared limited welding skills, but sought fab techniques to "work around" that limitation.


We "built" a frame with a rear kick. Made from two, so we could lap the joint and secure it along the edge with what turned out to be a decent seam. Learned how to build a flame that was neither rich nor lean. Just the right blue....


Carl

 

Being only a part time welder (I have a gasless MIG), it has taken me a few years to get my welds to look OK, not great but they are strong.

 

You would be surprised how much better they would be just by going to gas Warren.

 

Here are a couple of pics of removing the TH400 with the engine still in the car.


Tossed this is the bin.







Had trouble getting the dowel pins out. Taped the hole and used a bolt to draw them out.

 

I wanted to use as many stock mounting holes as possible.

The shift cable bracket.







I had to extend the bracket on the shifter so I had enough adjustment.



Flywheel in the Mill ready to elongate the bolt holes for the slightly smaller 4L60 TC bolt pattern.

 

I'm curious about the cable outer anchored to body bracket rather than gearbox Warren. Are you sure there will not be any movement/selector issues?

 

We'll have to wait and see. I started to anchor the cable to the trans and there is not enough clearance between the trans and tunnel to get a bracket in there.

 

No need to wait and see. I can tell you with certainty that shifter approach is incorrect and dangerous.

Cable must be attached to the transmission not the body. The transmission will move relative to the body and that could create a dangerous situation because the it can pop in and out of gear and or park.

Flip it up and over and you will have plenty of room to mount a bracket to the pan's 13mm bolts as shown below. .

New_DSC03486.jpg Photo by warrenscott1968 | Photobucket

 

Amateur's comment:


I like ISO's version of clamping to the transmission instead of the body.
1. He has done it and it works.
2. Yours might and might not.


Don't take this as a slight, it is definitely not so intended. Very tidy work.


A bit curious as to the need to mill the holes in the "fly wheel".
But, neat that you you have access to a real mill, and not a mere
drill press.


Carl

 

The shift cable will not go under the pan, also if I put the cam upside down the shift pattern will be reversed so when the shifter is in Park the trans will be in 1st.

I did fab up a bracket under the pan but the extension needs to go up to where the shift cable is about 4" above the bottom of the pan. It was not very secure.

I'll re-think and see what I can up with.

I need to re-drill the holes in the fly wheel as the TH400 uses 11.5" bolt pattern and the 4L60 has 10.75". I am going to slot the holes as the ring makes it impossible to re-drill new holes.

 

.


warron,like isca showes pic thats how mine is done, cable outer to bracket bolted to pan!

 

Yeah, but you can still make an angle bracket and hang it using the transmission pan bolts. It's tight but it will tuck up and over the edge of the pan and have it kick back so the cable mount is just before the electrical connection.