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pikalpha 06-19-2002 06:11 PM

57 Chevy auto trans cross member
Hey guys, Thanks for taking time to help. I am changing out my two door hardtop 57 Chevy's original 3 speed on the column to a late model 350 turbo trans which will be on the column also. I already have a late model Chev 350 engine in the car mounted on the car's original front pin motor mounts. I got Danchuk to tell me what I needed to do the change over but the gave me no directions. My question is, will the original pin motor mounts be strong enough to handle the torque of the engine? This is a street car not a hot rod and will see no racing or hard driving. Also, I want to bolt the cross member on instead of welding. Is this a good idea and at what angle or special placement should the cross member have? Any help or suggestions would be greatly appreciated. Thanks.

Papadaddio 06-20-2002 04:56 AM

You will have to support the engine in the middle if you are going to use the original frt mts when using a 350TH and rear crossmember, other wise there will be to much stress at the trans ,engine conection.Danchuk sells a side mount trans kit that fits your stock frame trans mnts and works very well.I'm sure other dealers do as well.It would be best to weld a piece of angle iron on the frame to bolt your crossmember to,but bolts could also work as long as you would have it supported in three places now.You could also go with side engine mnts and eliminate the stock front mnts.This would probably be the best route to take.The stock frnt mts should hold up fine esp. with new trans side mnts.....,.good luck :)

j o 10-18-2005 07:27 AM


Onestophotrodshop 12-01-2005 02:53 AM

As good as I once Was.
If you were going to set up a work bench with a simple 5/8 plywood on saw horses you would probably not want to put them at the far ends........ but rather 1/3 of the way from each end. Stress as on the six bolts that hold the trans to the engine will be greatly reduced if you get the new mounting brackets. One of the things I like to do is get grade 8 shoulder bolts at the local hardware store for any swaps I do, kind of like added insurance. As for drive line angle, I would worry more about ground clearance, but the 56 we built had a slight slope and the drive line was almost straight in line. I like the idea of bolting the crossmember in! Put a jack under the mount once the other mounts are in place and see if you need a spacer or not. If it all fits nicely drill some holes. I will use hard grade 8 on these four bolts as well and usuall run the bolt with a washer from the inside of the frame down...... then put the cross member and nuts on from the bottom. This will allow you to see it at a glance when under there for service and way more user friendly. I like to spot weld bolt so I don't have to ever use a wrench on the top side, but not manditory. Love that year of car! Oh keep your original parts they are totally worth $ and you can put things back to original if ever need be for resale value.

Deuce 12-01-2005 07:02 AM

I have seen aluminum bellhousing broken on 55 - 57 Chevrolets that had Turbo 350 and Turbo 400's installed with the front mount and a crossmember under the transmission. TOO MUCH strain on the middle of this combination.... :smash:

Many years ago when I had 55's , I made side motor mounts and a transmission support like the later models for my 55 . Now there are pre fabbed do the same thing. Chevrolet went to the side mount engine mounts and transmission supports in 1958.........and still use the same type system today.......that's got to tell you something :D

THADD 12-08-2005 04:06 PM

When you go to order side motor mounts, be aware that there are two different frames under tri-5's...a one piece and a seamed frame. You need to determine which you have and order your mounts accordingly.
I used McGaughey bolt in mounts, but I welded them in.
I used an Earl Williams classic chevy rear crossmember with a built in driveshaft piece
You can keep your front mounts if you install bellhousing mounts from someone like Classic Chevy International or Danchuck, but then the frame horns will interfere if you go with a shorty style header....It is easier to convert to side mounts and a rear crossmember and whack the frame stubs out of there....

DUKEOFBLUZ 12-08-2005 05:03 PM

im installing side engine mounts this weekend. I will have a set of front trans mounts for sale. Let me know if your interested.


HUH? 12-09-2005 01:02 PM

Camaro Crossmember
25 years ago when I built my '55 Chevy I used a 1968 Camaro transmission cross member. Just weld angle iron to the inner frame rails and drill four mounting holes. The Camaro cross member was the correct width. Nowadays an original 1968 Camaro cross member would probably cost more than a sweet aftermarket piece. Ah, the "Good Ol' Days"!

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