bobkat2

I am working on my project car, a 1987 Cutlass supreme. Today I lowered in a 403 with a th400 transmission. I need information on what to do about a cross member for the th400. The car was originally equipped with the 200 R4 trans. and the cross member does not line up with the transmission mount. It is short about 2 inches. I read some suggestions that say to drill new holes and move the cross member. However, by doing it that way you are unable to utilize the fame supports. Information on other options would be greatly appreciated.

Mikes65

I used 2 pieces of angle iron and relocated the crossmember back by drilling the angle iron to match the holes in the existing frame mounts and cantilevering back as much as needed-then drill the angle iron to the crossmember. This way I did not have to hack and weld so the original set up can be restored easily. I had my car in the tranny shop for a check up and the mechanic asked where I bought the "kit" to relocate the crossmember. I had por 15 on them so they look powdercoated.

Redog

That's all I did with my Delta.

Actually my mech grinded the hole to make it bigger, but it worked fine.

Had a 350/400 combo in that car

Mikes65

Also I used all grade 8 hardware for the attaching bolts.

Mikes65

65 Cutlass 022.jpg
Pic of the mock-up

Allan R

What thickness of angle iron?

Mikes65

Allen-I used 3/16 x 1 1/4 x 1 1/4 angle--worked perfectly.

bobkat2

I want to thank all for that quick response. Saved me lots of time and aggravation.

joe_padavano

Sorry, but you are doing something wrong. The TH400 and the 200-4R have their mounting pads in exactly the same place. The TH400 bolts into a G-body that originally had a 200-4R, assuming you are using the original crossmember. NOTE that the TH200C has it's mounting pad in the TH350 location and uses a different crossmember than the 200-4R. Are you SURE your car didn't have a TH200C originally? All 1983-88 G-body frames are drilled for crossmember mounts in both locations. You should NOT have to fabricate anything.

bobkat2

Joe, thanks for that information. I assumed that the car was originally equipped with a 200 r4. When I purchased the car it was without motor and transmission. Again I assumed that because the car was originally equipped with an overdrive transmission it was the 200 series. In the cross members original position the plate for the trans mount was sitting under the rear portion of the pan. I have since unbolted it and tried reinstalling it using the second mounting bracket located on the driver side frame rail. Could not get it to work. Am I doing something wrong, any suggestions?

joe_padavano

The only OD trans available was the 200-4R. I assume your car has a shifter with an OD position. If the drivetrain was missing when you got the car, it's possible you do not have the 200-4R crossmember. The 200-4R and TH400 both measure about 26" from bellhousing mounting face to the rear trans mount pad, so if you have the correct 200-4R crossmember, it bolts right up. I suspect that you do not. The other GM automatics have the mounting pad at about 19" from the bellhousing face, which WOULD put the crossmember under the pan on a TH400.

bobkat2

I did some internet research on the crossmember application for the th 400 and the 200r4. You are correct in your response that the mounts on both of these transmissions are at equal distance. I found that the problem with the original crossmember is that the driver side end is cut at an angle. There are two sets of frame mounts on that side and the one that is used during assemble is the one closest to the front of the vehicle. I mounted the crossmember to the transmission mount and then attempted to place the crossmember on the frame mounts that are opposite each other. None of the holes line up and the crossmember end angles are not parallel with the frame rail. I believe the less expensive solution to correct this issue is to tow the car to a welding shop and let them do there thing. Or I could spend about $200 - $300 and by one that is made for my car and transmission from Summit or Jegs.

joe_padavano

Let's recap.

This car left the factory with a 200-4R that was bolted up with a stock crossmember. No welding, brackets, or other claptrap was required. The TH400 has the same mount location as a 200-4R. The conclusion is that either 1) you have the wrong crossmember or 2) you're installing it incorrectly. Unless you have money to throw away (in which case, mail it to me) there is NO reason to spend a dime on anything else. Note that the G-body crossmember mounts at an angle. It does not run directly perpendicular to the frame rails.

bobkat2

Joe, I played with it for hours. At the factory installed angle, the position that the crossmember was in when I got the car, the transmission mounting plate was forward the transmission mount by 2-3 inches. What I did was to cut the angle on the right side of the member so it could be position perpendicular and on the 2 existing rail mounting brackets. Of course the bracket and crossmember holes did not line up so I just drilled 4 new ones. The trans mount and cross plate are now aligned with each other. I see no reason for this alteration not to work. I don't know what the problem was but, the next time I go to the salvage yard I am going to check out the crossmember on the 80s Supremes.
Next issue is the driveshaft length.

Mikes65

bobcat--check out dennysdriveshaft.com
The site shows the correct way to measure for the new shaft.
I purchased one from them- custom made for my cutlass-they make a great product for a good price. nice people to deal with also. Can't beat USA made!

bobkat2

Thanks Mikes65, I will check them out. First I want to take a chance that the original drive shaft will work. I purchased a th 400 Yoke from Summit and going to have it changed out with the 200 R4 yoke. Both yokes are the same length and the measurement between the centers of front and rear u joint caps installed on the shaft is 52 1/2". There is 53" between the front yoke when inserted fully into the tailshaft and the center of the rear end u joint cap. Another words will 1/2" space be enough to install?