BigBlockMopar
BigBlockMember
Transmission tunnel will always need to be clearanced because otherwise the transmission, and engine (!) with everything connected, will be pointing down at the rear at a larger angle.
A500 42RH Crossmember template?
- Thread starter Danizanon
- Start date
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So then we would have to cut out the top of the torsion bar mount and weld in some flat stock to keep the strength there. Kim
I just modified the factory crossmember when I did mine, just used the two outer bolts and reinforced the floor above it after I cut out the whatever hit the trans. Didn’t need to do anything with the floor pan on my 68
BigBlockMopar
BigBlockMember
Yes.
But also the 'bolt-ears' at the flange between trans and OD-unit will hit the tunnel's sheetmetal.
Clearancing that is greatly advised.
But also the 'bolt-ears' at the flange between trans and OD-unit will hit the tunnel's sheetmetal.
Clearancing that is greatly advised.
BigBlockMopar
BigBlockMember
The original crossmember was stamped sheetmetal.
While the OD-transmission is a but heavier than a 904 or 727, the crossmember above looks like something designed to hold 20.000 lbs of weight...
It also seems to extend and hang real low under the car.
While the OD-transmission is a but heavier than a 904 or 727, the crossmember above looks like something designed to hold 20.000 lbs of weight...
It also seems to extend and hang real low under the car.
moparmat2000
Well-Known Member
Looks really great. A guy who just started working at the company I work for has a plasma cam setup. Said he could cut out the pieces for me. He said the pix for the cutter to use had to be formatted a certain way. He gave me a couple different 3 letter formats that his plasma cam could use. Which one is your drawings in ?? What thickness steel did you make this out of. I have a sheet of 3/16" steel I planned on using.
Dwg or dxf
moparmat2000
Well-Known Member
I wrote down the 3 different ones he said his plasma cam understands, I think he said both of these but will check. Have you tried this under your car yet?
Mine is a dart 68
Different patterns. I will have to make more modifications.
TrailBeast
AKA Mopars4us on Youtube
The spool mount was a lot easier to modify, but it does extend a little lower than the biscuit type.
The only place in the floor I had to mod was the hump brace and a 1inch round by .5 inch deep dent in the floor where the fitting off the governor port is for the pressure switch's line fitting.
Inside the car that dent is a very small hump between the seats. (not noticeable at all under the carpet even if you know where it is)
The only place in the floor I had to mod was the hump brace and a 1inch round by .5 inch deep dent in the floor where the fitting off the governor port is for the pressure switch's line fitting.
Inside the car that dent is a very small hump between the seats. (not noticeable at all under the carpet even if you know where it is)
moparmat2000
Well-Known Member
Any new updates on this?
moparmat2000
Well-Known Member
Anybody else ever template one of these cross members out?
do you have any installed pics?
TrailBeast
AKA Mopars4us on Youtube
No I don't, sorry.
Taking pics wasn't a priority during getting my daily driver back up and running.
I might be able to do that when I swap rear ends though.
Shermdog
Member
I'd also be interested in the CAD files if they ever became available.
The early A will be different than the 67-later since the upper crossmember is not as wide as the later cars which means the lower trans support is also not as wide. Here is the start of a modified upper crossmember I’m working on for my 65
I installed a 42 RH in my 1970 Dart 2 years ago and have driven the car 13,500 miles so far. I have a few suggestions from my experience.
It's not just the shape of the crossmember that is important, it is also how heavy the material used is. The USCT crossmember (which must be modified to use with any A500 trans) is REALLY HEAVY. This seemed odd to me. I had the help of a fabricator/race car builder friend and he knew why right away. To have the trans correctly located it is necessary to cut out the hoop of crossmember that follows the trans hump out. You can leave a bit of it in place and insert a heavy band and weld it all up, but it is never going to be as strong as what you cut out. You have to also remove material near where the cross member bolts are and as shown in post #38 move the drivers side inner bolt outward, along with the bolt tube in the frame, to clear the bulge in the side of the A500. This is a BIG DEAL because the torsion bars put serious strain on the overall frame member that tries to tear things out downward in the middle. If you don't get this right, over time it will distort the whole frame member side to side. My friend has built a few C-body wagon race cars and they don't even have a loop over the trans tunnel. Instead they have a really beefy transmission cross member that is seriously attaches to the frame members that carry the torsion bars - that is why you have to take the tension off the torsion bars in a C-body before you remove the crossmember. If you do not, if you let the car sit for awhile, when you go to put the crossmember back in you will find the the torsion bars have bent the frame down in the middle. Although I have not confirmed this with USCT, I believe that this is why their cross members are such heavy material, and why you should back off the torsion bars when ever you remove the crossmember (remove the trans).
Here are some pictures of the modifications that I made to fit my 42 RH in.
If you want other tips not related to the crossmember send me a PM.
If you are successful, you will LOVE the Overdrive. With 3.23 gears my Dart does 75 mph at about 2000 rpms with the lock-up engaged. I'm thinking of 3.55 gears to take better advantage of the OD, and of course 1st and 2nd are both lower (numerically higher) than your old 904.
It's not just the shape of the crossmember that is important, it is also how heavy the material used is. The USCT crossmember (which must be modified to use with any A500 trans) is REALLY HEAVY. This seemed odd to me. I had the help of a fabricator/race car builder friend and he knew why right away. To have the trans correctly located it is necessary to cut out the hoop of crossmember that follows the trans hump out. You can leave a bit of it in place and insert a heavy band and weld it all up, but it is never going to be as strong as what you cut out. You have to also remove material near where the cross member bolts are and as shown in post #38 move the drivers side inner bolt outward, along with the bolt tube in the frame, to clear the bulge in the side of the A500. This is a BIG DEAL because the torsion bars put serious strain on the overall frame member that tries to tear things out downward in the middle. If you don't get this right, over time it will distort the whole frame member side to side. My friend has built a few C-body wagon race cars and they don't even have a loop over the trans tunnel. Instead they have a really beefy transmission cross member that is seriously attaches to the frame members that carry the torsion bars - that is why you have to take the tension off the torsion bars in a C-body before you remove the crossmember. If you do not, if you let the car sit for awhile, when you go to put the crossmember back in you will find the the torsion bars have bent the frame down in the middle. Although I have not confirmed this with USCT, I believe that this is why their cross members are such heavy material, and why you should back off the torsion bars when ever you remove the crossmember (remove the trans).
Here are some pictures of the modifications that I made to fit my 42 RH in.
If you want other tips not related to the crossmember send me a PM.
If you are successful, you will LOVE the Overdrive. With 3.23 gears my Dart does 75 mph at about 2000 rpms with the lock-up engaged. I'm thinking of 3.55 gears to take better advantage of the OD, and of course 1st and 2nd are both lower (numerically higher) than your old 904.
I have read your post and some other ones. Just wanted to get some parts ready before I start dropping the trans to install the new one. Just wanted to know how deep the mount has to be on this type of mount so I can locate the pad section once it’s in the car. This is my daily and don’t want it to be down for an extended amount of time
Even the USCT cross member comes with the pad for mounting the trans mount separate to be welded to the cross member in place once the trans with the trans mount and pad are in position. I think that answers your question? What are you using to shift the transmission? How do you plan to shift into OD and engage the lock-up torque converter? The 42RH is significantly different from your 904 and you should be prepared to do a good deal of fabrication and fiddling to get it in place. This is NOT a quick job, but as you seem to be doing, there is a lot that can be done before you swap the trans. I just can't imagine doing this on a car that I need to have up and running quickly. You need a custom driveshaft length. What car is this going in and what is the rear end? If it is a 111 inch wheelbase like a Dart (NOT Dart Sport or Demon) with an 8 3/4 there are a few of those out there and you can get driveshaft measurements from completed projects from other FABO members. You would have to post a query if it is a Duster/Demon body, but I bet there are some out there.
It’s going in a 69 valiant. I’ll be modifying the existing shift linkage. The od control my buddy has a vacuum and pressure switch thing he says will work. And I have a drive shaft shop locally that will shorten the shaft in a day or so. I’m making templates for the mount. The 2 piece one and just wanna make sure I have enough clearance for the pad mount to be fully secured.
moparmat2000
Well-Known Member
How I did mine. Used a GM RWD mid 1970s trans mount rubber. Floorpan not installed yet. Everything just mocked up. Stock shifter operates just fine.
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