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Do I need a new trans crossmember? Experts, advice please?

RockBottomRacing

RockBottomRacing

1/2 ton status
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Location
Simi Valley, CA
1974 Suburban K20. Original 4 speed truck. Came with an SM465 and NP203 originally. Just picked up a late model SM465/NP205 combo out of an 86 K30. I have the flat crossmember that was in the Suburban from the factory. I’m trying to figure out if I need a new crossmember or not? I’ve been reading differences between the flat style and the “W” style, and that the only thing that should change is which style trans mount you use, but I’ve seen conflicting info. Can anyone shed some light? My goal is to get the trans/case in and mounted up ready to rock during my Christmas vacation. Any experts hvd some advice for me? :)

Thanks!
 
The easiest way is to get an 85 and newer crossmember. Then use the 85 and newer mount. All stock parts.

Second way is use your current crossmember and 84 and older mounts and build a riser to go between the two. I used 2x3 or 2x4 rectangle tubing to make mine.

All you're doing is making up the difference in tall and short adapters.
Measure your adapter foot to trans output shaft distance on both and that's your difference you need to build onto your original crossmember.
 
Excellent information!! Love this site! Thank you!

I only have the pre-85 crossmember, I suppose I could look around my area for an 85+ W crossmember but I’ll probably just use some rectangle to make a spacer bracket like you did. Thanks a bunch!

Any recommendations for a clutch? 350 is original for 74, .030” over flat tops RV cam, plan to mainly rip her the trail but I’ll probably tow my boat with her every now and then too. Otherwise I hear the regular O’Reilly or Napa kit is good to 400+ hp in these guys. I’m trying to get her on the road on a budget. The only thing I don’t have lined up is the driveshaft but I’m just gonna bring drop her at a driveline shop local to me and have them build me a shaft. A buddy of mine just had them build one for his 77 C30 and it came out bitchin’. So other than that, ready to rock pretty much!

obijuank5 said:
The easiest way is to get an 85 and newer crossmember. Then use the 85 and newer mount. All stock parts.

Second way is use your current crossmember and 84 and older mounts and build a riser to go between the two. I used 2x3 or 2x4 rectangle tubing to make mine.

All you're doing is making up the difference in tall and short adapters.
Measure your adapter foot to trans output shaft distance on both and that's your difference you need to build onto your original crossmember.
Click to expand...
 
As you figured, any quality clutch is going to be fine with that setup. I did a LUK from Rock Auto and am happy with it. Rock Auto is going to be the cheapest if you are on a budget.
 
Thanks guys! I’ll provably compare the price on rock auto and for the Napa gold since my buddy runs my local Napa and can knock a few bucks off. Great info again!
 
Did you do the Luk heavy duty clutch or the daily driver clutch from rock auto? $20 difference at the moment, curious of the extra $20 is worth it

HankScorpio said:
As you figured, any quality clutch is going to be fine with that setup. I did a LUK from Rock Auto and am happy with it. Rock Auto is going to be the cheapest if you are on a budget.
Click to expand...
 
Can't find the order in my email. I believe it was the regular. I wanted a clutch without too heavy of a pedal feel. I do have the hydraulic setup with all LUK parts. Nice stuff.
 
Which parts did you get from Luk? I have the hydraulic pedals I’m gonna swap in and I have a reservoir and slave cylinder but I want to get new stuff so I don’t have to worry about performance or function when I’m away from home lol. I’m thinking l go with the regular daily driver clutch and see how she does on the trail. :D

HankScorpio said:
Can't find the order in my email. I believe it was the regular. I wanted a clutch without too heavy of a pedal feel. I do have the hydraulic setup with all LUK parts. Nice stuff.
Click to expand...
 
I was also doing a swap. Sm465/np205 into a 1990 K5 that started as an auto. I used the factory hydro pedal set and hydro bellhousing. I figured I would have the best chance of it all working if I bought all my parts from a single manufacturer. I wanted easy to source stock type parts. The clutch kit, clutch master cylinder, slave cylinder, fork and pivot ball were all LUK parts from RockAuto. My gmail has deleted the order since it was from over a year ago now so I don't have the part numbers. I didn't buy anything special, just stock replacement stuff. It works great on the first try.
 
Right on, I’m pricing out parts right now. I need to get a flywheel too. The Luk flywheel is for an 11” clutch but the Luk clutch is a 12”, that’s on rock auto for an 86 K30 with a 350, the hell gives?! Lol

HankScorpio said:
I was also doing a swap. Sm465/np205 into a 1990 K5 that started as an auto. I used the factory hydro pedal set and hydro bellhousing. I figured I would have the best chance of it all working if I bought all my parts from a single manufacturer. I wanted easy to source stock type parts. The clutch kit, clutch master cylinder, slave cylinder, fork and pivot ball were all LUK parts from RockAuto. My gmail has deleted the order since it was from over a year ago now so I don't have the part numbers. I didn't buy anything special, just stock replacement stuff. It works great on the first try.
Click to expand...
 
I can't remember but I did buy a flywheel also, and a pilot bearing I'm sure.
 
The spacer welded to the crossmember idea has worked well for me too. Just be careful to get a 1/2 or 3/4T crossmember if you look for the newer version. The K30 crossmember is built around the K30 frame being 2" deeper.
 
Thanks for the replies guys! I made a spaced out of some scrap I had laying around but I haven’t had time or money to start wrenching on her. The plan is to get her in the driveway this weekend to start stripping the crap out of her and start cleaning up to get ready for install.
 
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