55.2-59 4speed OD trans and original crossmember

[Gribbs]

My 59 has a 200r4 with about 3/8" between its oil pan and my original crossmember. It could cause the need for removing the whole engine, just to drop the trans.
I have a new tubular crossmember installed to hold the transmission in place further rearward on teh frame of course, so how detrimental would it be cut out the old crossmember? I could have two brackets at either end to allow for bolting it back on afterwards, but if it can be cut out safely, I'd rather keep it out. The spring perches appear to be connected to the crossmember, so I am scared to hack at it.
Thanks for any advice. The truck goes to a tranny shop and I'm sure I'll have to let them chop the crossmember, or I'll have to haul the truck back to my much cheaper mechanic to pull the whole engine, but summer isn't getting any longer up here, so...

[dsraven]

brace the frame side to side if you plan to do that because the frame could spring and that will have an effect on the front cab mounts which can have an effect on the door and fender fitment.
brace the frame around it side to side, cut it out, modify it to your needs, or build a new cross member to keep the frame width uniform in that area, bolt it back in. or box the frame for rigidity and hope it is enough or if you have some sort of independent front suspension cross member in front of the old trans cross member you may be able to remove the old cross member without any worries depending on how beefy and reinforced your new trans cross member is, does it tie the top and bottom frame rail together? it is a concern for the front cab mounts though when it gets removed. the front cab mounts sorta give the cab their position in relation to the rad support (like a teeter totter) so any movement in the area may have an effect on door gaps, door latch fitment and change after a hard bump etc so you may wanna keep it but modify it so it is a specific length between abutment points on each side and can be removed and installed for engine or trans work.
make sense?

[dsraven]

sorry, didn't get the spring perches part as I was reading.
so you have the original leaf spring front end. this could definately give you issues with the cab mounts should you totally remove the cross member. I suggest you modify the old member and leave in place or, brace the frame rails side to side to keep the dimensions correct, cut and remove the old member, modify or build a new beefy member to fit around your needs but also connect the top and bottom frame flange and mount in such a way as it will always be the same dimension between the frame rails after the modified member has been re-installed-so tight fitting bolts in all the holes, install the new part and then remove the bracing.
when I cut mine out the frame sprung. it is common to do that. if you look at the old frame it is quite a distance between the "front of the engine" member and the "behind the cab" member. that leaves room for frame flex if the old trans member is removed, which will cause you trouble with cab mount flex because the cab mounts are like a lever on the frame. when you go over a bump or whatever the lever tends to flex the frame and may cause the rivets in the other cross members to loosen over time. since the spring perches are right there the frame can flex as forces transferred from the springs are applied to the frame, like when you hit a bump or go over a speed bump etc and these forces work together or against each other but both against the frame. your tubular trans member probably isn't connecting the upper and lower frame flanges so the frame can twist easier as well because only the bottom frame flange is being held at a certain dimension and this can cause stress cracking around that pinch point in over time and extreme conditions such as high hp engines etc. if you look at the member behind the cab you will see it connects the top and bottom flanges. that is to control the twist. you could modify your tubular member to do that which would help. you could
-cut off the old cross member in such a way as to leave a short section of the old member on each side along with the original frame mount parts (after bracing the frame side to side so it can't spring in/out)
-weld on a flat vertical surface on each side of the remaining nubs still rivetted to the frame. have the flat surfaces predrilled to accept a new member. a couple of bolts on each side at least
-fab a new member to bolt onto these new flat vertical surfaces. fab in such a way as to allow clearance for trans and engine components.
-when trans or engine work is required the new member could be unbolted for access but it would have a predetermined dimension, side to side between the flat ends, so when re-installed the frame seperation is kept original. since you used the original mounts connecting the upper and lower frame flanges the rigidity is also kept intact. ensure you fab a new part from something as strong or stronger than the original part. the new member could be a bit of a job to remove or install after due to frame springing in or out, but could be overcome esasily enough with the design of the new or modified part

[mikebte]

I'm going to ask what engine you have and how is it mounted? Do you have an additional cross-member for the engine and transmission mounted in place or is it stock engine with the front engine mounts?

I have side mounts and rear transmission crossmember welded in and I cut out the old support and installed some bolts.

Also, you could have something of this nature made up to bolt in. Seems easy enough.

[Gribbs]

Thanks brother that is one hell of a novel ou wrote me! If you weren't 2000 light years away I'd buy you a beer for all that trouble!!! If you ever need a place to crash in Oshawa, ON, I'm here.
So, I wouldn't have time to weld anything for support - If the transmission shop wants to cut the old crossmember and I say yes, thats the end of it. I'm leaning towards going the longer route and getting the truck back to my retired buddy who works for cheap to pull the whoel engine and trans out in one piece to replace the torque convertor. Maybe I didn't mention before, but when I bought the rebuilt converter I knew nothing about the used motor I had, and now it seems the motor has cam and I have only 12 inches of vacuum and a 500rpm drop when put in gear, which is what has caused all of this in the first place. Carb and fuel system is brand new, timing is fine, seems to be no vacuum leaks that we know of...

Originally Posted by dsraven

sorry, didn't get the spring perches part as I was reading.
so you have the original leaf spring front end. this could definately give you issues with the cab mounts should you totally remove the cross member. I suggest you modify the old member and leave in place or, brace the frame rails side to side to keep the dimensions correct, cut and remove the old member, modify or build a new beefy member to fit around your needs but also connect the top and bottom frame flange and mount in such a way as it will always be the same dimension between the frame rails after the modified member has been re-installed-so tight fitting bolts in all the holes, install the new part and then remove the bracing.
when I cut mine out the frame sprung. it is common to do that. if you look at the old frame it is quite a distance between the "front of the engine" member and the "behind the cab" member. that leaves room for frame flex if the old trans member is removed, which will cause you trouble with cab mount flex because the cab mounts are like a lever on the frame. when you go over a bump or whatever the lever tends to flex the frame and may cause the rivets in the other cross members to loosen over time. since the spring perches are right there the frame can flex as forces transferred from the springs are applied to the frame, like when you hit a bump or go over a speed bump etc and these forces work together or against each other but both against the frame. your tubular trans member probably isn't connecting the upper and lower frame flanges so the frame can twist easier as well because only the bottom frame flange is being held at a certain dimension and this can cause stress cracking around that pinch point in over time and extreme conditions such as high hp engines etc. if you look at the member behind the cab you will see it connects the top and bottom flanges. that is to control the twist. you could modify your tubular member to do that which would help. you could
-cut off the old cross member in such a way as to leave a short section of the old member on each side along with the original frame mount parts (after bracing the frame side to side so it can't spring in/out)
-weld on a flat vertical surface on each side of the remaining nubs still rivetted to the frame. have the flat surfaces predrilled to accept a new member. a couple of bolts on each side at least
-fab a new member to bolt onto these new flat vertical surfaces. fab in such a way as to allow clearance for trans and engine components.
-when trans or engine work is required the new member could be unbolted for access but it would have a predetermined dimension, side to side between the flat ends, so when re-installed the frame seperation is kept original. since you used the original mounts connecting the upper and lower frame flanges the rigidity is also kept intact. ensure you fab a new part from something as strong or stronger than the original part. the new member could be a bit of a job to remove or install after due to frame springing in or out, but could be overcome esasily enough with the design of the new or modified part

[Gribbs]

Originally Posted by mikebte

I'm going to ask what engine you have and how is it mounted? Do you have an additional cross-member for the engine and transmission mounted in place or is it stock engine with the front engine mounts?

I have side mounts and rear transmission crossmember welded in and I cut out the old support and installed some bolts.

Also, you could have something of this nature made up to bolt in. Seems easy enough.

I have a 350 side mounted with mounts from Speedway and a tubular corssmember at the end of the trans, from CPP. Wow that is one burly bracket set-up you have, I haven't seen that in 4 years of studying these 55-59 trucks. Looks awesome!

[Gribbs]

Here's more or less recent pics...still a ways to go to make it cool. Purple and silver really pop in the sun. Thanks guys for your input - much appreciated!!!

Untitled by Brad Gribben, on Flickr

Untitled by Brad Gribben, on Flickr

[57tailgater]

The original hydromatics had a factory 3 piece crossmember similar as to what dsraven describes about modifying the original manual transmission one. The center section bolted to the side pieces that were riveted to the frame. You will need some cross bracing there as the rear front spring hangers and front cab mounts all meet up around that same area so it's a critical area for support. I had one for an AD but it was too narrow for a TF frame but had the same concept.

[dsraven]

ok, just so we are on the same page here
-59 chevy fleetside
-stock underpinnings
-454 big block with 200r auto trans
-the original trans cross member is still in there but the trans pan is almost sitting on the pan
-you have a tubular cross member installed at the rear of the trans but it doesn't provide enough support for the frame at the cab mounts/spring perch areas
-you have side mounts on the engine (guessing)
-your engine is so lumpy it hardly idles
-you want to swap out your torque converter for one with a different stall (guessing)
-trans isn't gonna come out without getting rid of the old cross member
-there is no room above trans or between engine and firewall etc to jack the engine up enough to get the trans out over top of the old cross member (guessing), or the trans shop is not happy about having to mess around with it so they would over charge you (guessing)
-trans shop says hack the member out of there no biggie (guessing)

-what would be the plan once the trans is fixed? daily driver, weekends, burnouts fairly often, lots of high torque stuff?
-have you thought about a different cam to make drivability better rather than swapping the converter?
-do you like the lumpy engine so you would rather keep it that way and change the trans instead?
-when you say get the truck back to your mechanic buddy for repair, how far away is that? you don't wanna do that because of the long distance to drive or because of the engine drivability issue or you just can't get the time scheduled to get that done?
-are you sure the engine is awesome and no other problems with it or you are sorta hoping for the best in that dept? do you know any of the other internal components? wouldn't want to see you change the trans for drivability then find out the engine is a full race thing and not really great for what your driving style is, or maybe your driving style is full race, dunno.

my 2 cents would be
just get the truck to your buddy and fix it the way you want it and it will be strong. if you have a big torque engine you gotta make sure your frame etc will handle it or it will become one of those "if only i woulda" things that can suck time and money. you may also wanna ensure your brakes etc will handle the duties assigned by the big block engine. if you gotta cut the member at the trans shop tell them to use a zip disc for a clean straight cut and leave the removed piece for you so you can possibly graft it into something you can modify and re-use when the truck gets home. a short drive with the member removed won't kill the truck most likely. not a long term thing to do though.
post up some pics of the actual problem and maybe we can find some answers

[idbeast]

Originally Posted by dsraven

ok, just so we are on the same page here
-454 big block with 200r auto trans
my 2 cents would be
just get the truck to your buddy and fix it the way you want it and it will be strong. if you have a big torque engine you gotta make sure your frame etc will handle it or it will become one of those "if only i woulda" things that can suck time and money. you may also wanna ensure your brakes etc will handle the duties assigned by the big block engine. if you gotta cut the member at the trans shop tell them to use a zip disc for a clean straight cut and leave the removed piece for you so you can possibly graft it into something you can modify and re-use when the truck gets home. a short drive with the member removed won't kill the truck most likely. not a long term thing to do though.
post up some pics of the actual problem and maybe we can find some answers

I'm running 517hp 499 ft. lbs. of torque I went this route...

[Gribbs]

Wow so ya it is planned to be a daily driven, nothing hard, 350/200r4 combo and I'm not sure of the cam and yes, I believe I need a higher stall converter. The frame is all painted after a ground up build, so I can't really add all that bracing without being off teh road for yet another summer (4 year project). I like the idea of a clean cut and I'm thinking some thicker aluminum pieces with 2 hefty bolts on each side to essentially bolt the crossmember back together. Then any trans work will be easy in the future, and that plus the new tubular crossmember two rear of it should give stability.

Dsraven - you guessed pretty well very factor I am dealing. Yes, getting it back to my 'guy' is far away and a time suck for sure. I shouldn't be in a rush now after building this for so long, but I'm growing impatient.

[mikebte]

I’m going on the same idea of all the 4x4 chassis I have seen with leaf spring front ends, no support and they work fine. I have had my 59 without that brace for 5 years and have had no issues at all. I find that support to be a little overrated and would personally not worry to much about it, but that’s just me.

If it’s an issue for you, just add a brace, easy. Get an extra transmission crossmember and bolt it up in that area.

[dsraven]

sorry gribbs, got mixed up with different posts. 350 with 200r. side mounts on engine. have the shop zip disc the old member out, clean straight cuts where you can easily fab a new center section after the fact. drive it for the summer and make a new member at your convenience this winter. a bolt in job. if using aluminum against steel use some plastic between to stop the corrosion electrolysis between the metals.

[Gribbs]

Originally Posted by dsraven

sorry gribbs, got mixed up with different posts. 350 with 200r. side mounts on engine. have the shop zip disc the old member out, clean straight cuts where you can easily fab a new center section after the fact. drive it for the summer and make a new member at your convenience this winter. a bolt in job. if using aluminum against steel use some plastic between to stop the corrosion electrolysis between the metals.

Ya right good point, I forgot about the 'accelerated galvanic corrosion' ... I read much better than I wrench