The topic that wouldn't die... Engine swapping

[dubie]

Ok, I am about ready to drop the 350 and 3 spd back into the 72 with this 1 exception...the tranny crossmember. I have a good memory but it's short sometimes. I am placing my 350 in the factory V8 location therefore the tranny moves forward with it. Am I correct in saying that I need to install an auto crossmember in the forward position the accomidate my 3 speed manual tranny?
The parts truck I acquired was a 350/ auto combo truck, so I have all the right parts including the proper front driveshaft section.
Thanks guys and sorry about having to ask this same question AGAIN!!

[CPNEJR]

I'm pretty thats right. I have the same setup in my 72 I'll check it out and confront my dad and get back to you

[StingRay]

Gee Tim when I still had the 3sp with the 307 in my truck it had a forward manual cross member and the v8 was in the correct v8 location. Is there a mount pad on the back of the tranny you can use with the auto crossmember? If so maybe it will work. On mine the back of the engine was supported at the bell housing and the tranny cantalevered off of the back of the bellhousing.

[tom hand]

I think the 3 speed uses a different crossmember for the v8...I don't think you can just move the I6 crossmember forward

[Palf70Step]

I thought all the three speeds used belhousing mounts and no tranny mounts. Wether it was a 6 or *8. I don't personnally know if the bell housing is different or not, I would assume it is the same except where it bolts or gets riveted to the frame. One of the parts trucks I have access to has same bellmount setup my six has (no rear mount) and it was an original model V8 (69 short fleet)

Msay be a dumb statement, but I belive you'll need different Z bar and clutch pieces to switch it from a 6 to a V8 position 3 speed.

[crazy longhorn]

You can use the auto crossmember for your stick conversion, & it will mount in the same spot as a v8 with 350 turbo combo(dont ask me which holes.....its been too long ago!) I am pretty sure you are right about the foward holes tho.... You might just hang the auto crossmember , & leave the bolts out till you set the eng & trans. I am sure you will find a set of holes to fit the combo Good luck,crazyL On the orig stick crossmember Tom Hand is right on......you cant move them foward, there are different crossmembers for I 6 or sb

[dubie]

I thought all the three speeds used belhousing mounts and no tranny mounts.

Yeah, my crossmember sits right below my bellhousing and has a mount on either side.

But I also talked to a buddy of mine last night that has built 8 of these trucks and he's telling me that I can just move my existing X member forward. Maybe I will just test fit it with moving the existing member up and if that doesn't work, I'll swap it out for the auto one

Thanks guys

[CPNE]

I wouldn't take CrazyL's advice, he's nuts!

My advice, locate the correct small block bellhousing mount and be done with it. The I6 one is different but will probably slide into position for you. The problem with it though is that it'll the angle of your driveline. If you want a reliable driver, take my advice, you'll thank me.

You've got an auto x-member. Use it as trading fodder for someone who is deep-sixing the manual for an auto. Surely in CA there must be someone with a complete small block manual transmission x-member and clutch linkages they'll trade for it.

I did this same swap this summer and used all the "correct" pieces. I was amazed at how easily the parts went together and fit. It practically fell into place. I guess thats why the "hillbillys" are in TN and the engineers are in Detroit.

No offense to our TN members. I was just borrowing from this thread

[crazy longhorn]

Originally posted by CPNE
I wouldn't take CrazyL's advice, he's nuts!

My advice, locate the correct small block bellhousing mount and be done with it. The I6 one is different but will probably slide into position for you. The problem with it though is that it'll the angle of your driveline. If you want a reliable driver, take my advice, you'll thank me.

You've got an auto x-member. Use it as trading fodder for someone who is deep-sixing the manual for an auto. Surely in CA there must be someone with a complete small block manual transmission x-member and clutch linkages they'll trade for it.

I did this same swap this summer and used all the "correct" pieces. I was amazed at how easily the parts went together and fit. It practically fell into place. I guess thats why the "hillbillys" are in TN and the engineers are in Detroit.

No offense to our TN members. I was just borrowing from this thread

For those who have not tryed anything outside of the factory "guidelines" , they dont know what other options they can use! My last 2 auto to stick swaps have used an auto crossmember......trust me,it is a bolt in It would be sacrilage to set the truck up any other way than the factory engineers did tho....right?:p crazyL

[dubie]

Soooooo. I can use this auto X member i have then???? will it work??

You 2 play nice now

[crazy longhorn]

Yes, you can use the auto crossmember.....the 3spd stick trans+ bell, is the same lenght & spline as a short tail 350 turbo. The trans mount also falls in the same spot, so if you are setting in factory sb position, you can use all the factory clutch linkage pcs, d shaft, ect. if you plan to run a 4spd (465), you will need that "proper" bell crossmmber, as they dont have a spot for a trans mount on the rear of the trans. The bell crossmembers are different however(1 for I6,for sb,1 BB).....crazyL

[CPNE]

Originally posted by dubie
Soooooo. I can use this auto X member i have then???? will it work??

You 2 play nice now

Never been so unprepared as to have had to do it it, so I can't say. I always make sure I have a stash of correct parts for any situation. You know what thay say "Those who aren't prepared, hillbilly rig".

If I were you I'd invest in a banjo and learn to "squeel like a pig" . It'll bite you in the a$$ at some point.

Consider this. GM is a business geared to profit. Profit comes from reducing production costs among other factors. Why would they utilize so many different x-members for the various drivetrains if one size truely fit all? It doesn't make sense, it's crazy man!

FYI, we are playing nice. CrazyL and I have agreed to disagree on this topic, but in a friendly manner.:p

In reality anything will work, but you run the risk of having to "invent" another solution to work around your solution. My swap went into place literally in minutes. To me time is $ and piece of mind is priceless that is unless you're out of your mind).

[crazy longhorn]

Take a look at how ,or more to the point where thecrossmembers mount. We all know that there are 3 different positions for the engines(BB,sb,&I6). on the auto crossmember, it rests on a flat part of the frame, & is moved foward or back depending on which eng /trans combo is used......this tells me that there is no change in the height/angles reguardless of position (different eng stands are used accordingly). Th stick X member ,however is mounted on a sloped spot on the frame, & by moving foward or rearward causes a height/ angle difference.....hence the need for 3 different crossmembers. To go a little deeper, the 3 speed stick trannies do have the spot for the mount, while the 4spds do not, but all stick trucks came from the factory with a bell crossmember(thats GM engineers for you!) as far as not being "prepaired for a swap", in some parts of the country, parts are not readilly available.....thats why us "hillbillys" have to outsmart the engineers crazyL, workin on hillbilly technology

[dubie]

Hey I'm all for fabing things up, I don't mind doing that at all, just adds a custom touch to your project eh. I just wanna make sure I'm doing this right the first time. I don't wanna waste my time removing the auto X member and taking the I6 X member out just so I can find out it won't work. I thank the 2 of you as always for both sides to this story. You are both true Chevy enthusiasts that stick to your guns and I respect that. I really do appreciate all the help you guys have given me on this subject, and I will be sure to add you to the THANK YOU list, when my project is finished.

[CPNE]

Originally posted by crazy longhorn
Take a look at how ,or more to the point where thecrossmembers mount. We all know that there are 3 different positions for the engines(BB,sb,&I6). on the auto crossmember, it rests on a flat part of the frame, & is moved foward or back depending on which eng /trans combo is used......this tells me that there is no change in the height/angles reguardless of position (different eng stands are used accordingly). Th stick X member ,however is mounted on a sloped spot on the frame, & by moving foward or rearward causes a height/ angle difference.....hence the need for 3 different crossmembers. To go a little deeper, the 3 speed stick trannies do have the spot for the mount, while the 4spds do not, but all stick trucks came from the factory with a bell crossmember(thats GM engineers for you!) as far as not being "prepaired for a swap", in some parts of the country, parts are not readilly available.....thats why us "hillbillys" have to outsmart the engineers crazyL, workin on hillbilly technology

Agreed, with the caveat of the the rubber tranny mount pad used for auto's. This will change the angle of the transmission. The question still remains, if you use the mount designed for the th350, how will it affect the angle? Insignificant? Maybe. Is there another mount that will work? Maybe. How much effort are you willing to expend to find out?

My point is still this. GM, particulary Chevy is famous for it's parts interchangeability. Why be so quirky with a simple x-member? If I were a betting man, I'd say it's because it's not a simple as it appears. But since it's been done successfully (though we have no long-term studies to prove how well ), give it a shot. Since you'll proably not use the vehicle for the purposed it was engineered for, you'll probably have no long-term issues to contend with.

[jcab]

If I were you I'd invest in a banjo and learn to "squeel like a pig"

ROTFLMAO

[crazy longhorn]

Originally posted by CPNE


Agreed, with the caveat of the the rubber tranny mount pad used for auto's. This will change the angle of the transmission. The question still remains, if you use the mount designed for the th350, how will it affect the angle? Insignificant? Maybe. Is there another mount that will work? Maybe. How much effort are you willing to expend to find out?

My point is still this. GM, particulary Chevy is famous for it's parts interchangeability. Why be so quirky with a simple x-member? If I were a betting man, I'd say it's because it's not a simple as it appears. But since it's been done successfully (though we have no long-term studies to prove how well ), give it a shot. Since you'll proably not use the vehicle for the purposed it was engineered for, you'll probably have no long-term issues to contend with.

There are NO angle issues in that swap......if you measure from the trans mount pad to centerline of the outputshaft on both trannies, you will find them to be the same. Both trannies also take the same mount, so as i said before its a direct bolt in fit. I swapped a 72 350/350 truck to a stick trans, & used the auto crossmember. One might argue that the distance tween eng & trans mounts is much farther that the way the factory set it up........however, i have been running the same "stock replacement " mounts on my 383 for 4 seasons.(and beleive my they have been torked up HARD!) I dont see any issues.....other that it wont look stock crazyL

[CPNE]

No argument here. If the parts aren't available do what you gotta do.

My $$ is still on GM however. Logically there has to be a valid reason for the use of different cross members. I don't think that much can be disputed.

Along the same line of thought, why did they use a 2 piece driveshaft in automatic SWB trucks and a one piece in 3 speed manual swb trucks? The overall length is the same. This one has never made sense to me from a production cost standpoint either. I still say there is more than meets the eye but I can't prove it either.

Happy motoring...

[dubie]

Ok I just went outside to look at both X members and I don't see how the automatic one will work. The I-6 bellhousing has angle threaded holes for the mounts to bolt through the X member and the auto only has 2 center mount holes. My bellhousing doesn't have any threaded holes for it to mount to the auto one.

[CPNE]

I think the idea being proposed is to use the auto xmember in it's stock location and set the yolk end of your 3 speed down on it, rather than try and use the auto xmember as a support for the bell housing. Your 3 speed tranny should have a boss on it that is tapped for mounting points that mate up to the auto xmember's bolt hole locations.

[crazy longhorn]

Just for thought.....as an old mechanic, I have seen some very nice factory designs(for the most part, I will say the 67-72's are pretty well laid out.) I have seen some things on vehicles over the yrs that "would make a preacher cuss"!(or an old mechanic). I think that "engineer " is just a big title ,with big pay....not the answer to everthing.(if every engineer had to work on these cars/trucks....i beleive we would see some very slick designs!) Many things that I have "redesigned" on my truck, have had a lot of thought as to fit, & also ease of maintainance. My dad always said that poverty was the "mother of invention"......for me , custom is a little more of a challenge, & it makes things more interesting crazyL

[crazy longhorn]

Originally posted by CPNE
I think the idea being proposed is to use the auto xmember in it's stock location and set the yolk end of your 3 speed down on it, rather than try and use the auto xmember as a support for the bell housing. Your 3 speed tranny should have a boss on it that is tapped for mounting points that mate up to the auto xmember's bolt hole locations.

Yup, what he said

[CPNE]

Originally posted by crazy longhorn
Just for thought.....as an old mechanic, I have seen some very nice factory designs(for the most part, I will say the 67-72's are pretty well laid out.) I have seen some things on vehicles over the yrs that "would make a preacher cuss"!(or an old mechanic). I think that "engineer " is just a big title ,with big pay....not the answer to everthing.(if every engineer had to work on these cars/trucks....i beleive we would see some very slick designs!) Many things that I have "redesigned" on my truck, have had a lot of thought as to fit, & also ease of maintainance. My dad always said that poverty was the "mother of invention"......for me , custom is a little more of a challenge, & it makes things more interesting crazyL

100% in agreement. But...(you knew there was going to be a but didn't you?)..., I think the reason designs confound mechanics in some instances has nothing to do with poor engineers and everything to do with "bean counters". Again, ecomonies of scale and production costs often overrule a truely ingenious design. Which harkens back to my original argument that there must be something not obvious to you or me as to why the engineers used so many tranny cross members. If the auto xmember was good enough, the been counters would have had the last word.

[StingRay]

Uh I am an engineering technologist and I can personally say that there are lots of things I'd do better or different given the chance. I am working on one such project that is going that way right now. Often with any engineering profession it is lack of experience in the engineering profession, lack of understanding or consideration for the fabrication or assembly process and in turn the disassembly process hence the mechanic cussing. Sometimes it is the bean counter issue and somtimes it is just plain lack of time. NO good engineer likes a complicted messy design.

[tom hand]

Hell if you had just put the v-8 in the i6 position you would have been driving it by now...lol