When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
This is a first time TH400-to-M20 conversion for me, so I don't know what the hell I'm doing.
Have I got the mounting sequence right?
.
I mean it appears to me to be the only way it can fit together.
A little guidance please. Only way I was able to get any picture info was from a Corvette Central parts catalog.
The exhaust hanger goes above the transmission mount which I believe you are calling a shock mount in picture 1.
I assume item 3 in picture 1 is the crossmember.
In picture 2 the back of the shifter bracket is supposed to attach to the crossmember not sure if yours does?
In picture 2 the back of the shifter bracket is supposed to attach to the crossmember not sure if yours does?
Thanks much!
Yes, shifter bracket has holes for a large lag screw to attach to the rear face of the TH400 Crossmember (into which the lag screw holes must be drilled). At least it appears to me that way.
Do a search, there are a lot of good pictures to be found. I did the same project last year and the search function had everything i needed. Good Luck.
Was able to slid the whole exhaust system out so as to attach the Shifter Bracket/Tranny Mount to the Crossmember. Just couldn't get the car high enough to work under it comfortably.
Lag screw holes marked but yet to be drilled. the holes will take a 3/8" bolt. Would like to know the # lag screw I will need for attachment. Can anyone here tell me, along with the proper sized Drill Bit to use?
Lag screws are for wood. You want to tap a machine screw thread in there. 3/8-16 or 7/16-14. Or maybe consider fine thread as there isn’t a lot of depth for more than 2 or 3 threads. I would be happier welding a nut on those holes. Or can you reach behind and use a nut on the back side?
Thanks for those ideas Derek.
Assembly manual calls 'em screws: GM #3975550. They must be self tapping. OR, if it were a Manual Tranny Crossmember, those holes would probably be tapped or nut welded inside. I used the wrong name.
There's a cutout in the middle of the crossmember where YES, I may be able to get a locknut inside there!
technically they are only bolts if a nut is involved. if they screw into an already existing thread, they are cap screws. it can be confusing...
Yes it can ...... if you're a dumb *** like me!
Went with a 3/8" bolt hole.
Yes indeed, a washer, lock washer, and nut can be placed up there.
That dude is secure here. I hope it won't cause problems should shimming of the front Bracket bolts be necessary for Shift Lever-to-Console Cover Plate clearance be necessary (according to the Assembly Manual).
Raised up and installed the exhaust system this morning, now that the Shift Bracket/M20 Mount is attached and secure.
Will have to tweak the Exhaust hanger some for a decent fit.
The Shift Bracket is in position.
Is it right? We'll find out.
Plan now is to bolt the Shifter on the Bracket, with Rods attached, hoping they wont interfere with the M20 installation. Just 2 bolts.
Although not nearly done here, I'm a bit worried about the Pedal Modification. Will work on that as much as I can before installing the transmission.
M20 Crossmember Mounting Question
