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This has been discussed some here and there, but there aren't any reasonably priced solutions to the stupidly designed LCA shafts used on many 3rd gen GM vans.

If you don't already know, Here's a quick overview. For some reason the LCA shafts on the vans have an inner shaft inside of the outer tube and the space between the shaft and outer tube is filled with rubber. (unlike the C-Pickups, which have solid shafts, but are a smaller overall diameter). See cut-away picture:

[Linked Image]


Rare Parts is the only place that I've been able to find new replacement shafts but they sell for over $300/ea. The Rare Parts shafts are nice because they are solid metal, but I can't bring myself to spend $600 on them. Every now and then NOS parts pop up on ebay for slightly less, but still hundreds of dollars, and still filled with rubber.

As seen in my build thread, I redid my whole front suspension recently and tried to replace every 30 year old wear part with new AC/Moog or some upgraded parts. The only parts that I re-used were the lower control arm shafts due to the stupid high costs to replace, and the impression that they didn't really go bad. Mine seemed to be in above-average shape so i chanced it.. This turned out to be a mistake. While the overall driving feel of my van was much improved, it has always had a tendency to wander a little. This is especially pronounced when under braking, crowned road surfaces, or pulling a trailer. And not the typical "old GM truck" type wander. It definitely felt like something was loose. I Inspected everything and even adjusted the new steering box which has no play. Still couldn't figure it out. Recently when I was messing with the carb, I ended up driving around with the doghouse cover removed. From the driver's seat, I was able to see the left LCA shaft. And what caught my eye is that when I hit the brakes, it moved... Significantly. The inner shaft was moving inside of the tube. I don't know if the rubber in mine is just shot or this is how they are supposed to be, but I was able to relate most of what I was feeling while driving to the movement of the LCA shaft. mad

Then yesterday, on Facebook I saw a post from a guy who managed to score (if you can even call it that) a pair of NOS Van LCA shafts for $100 each off of ebay. In the discussion it was mentioned that it was possible to source the solid, but smaller diameter, C10 LCA shafts, along with the C10 brackets and U-Bolts and then you can run the C10 shafts on the G-van.. He made it sound pretty simple, but didn't give much info besides that "LMC has everything needed". (It's the weekend now, but I plan to call LMC to verify this claim on Monday). If this is true, it may be a fairly simple and inexpensive solution to an issue that many here have run into. That being said, after spending more time searching/googling than I care to admit, I can not find anything else on the internet backing up this claim or verifying that it has been done successfully. The only picture I have is from the above-mentioned Facebook post showing the Van shafts next to the pickup shafts:

[Linked Image]


Has anyone heard of this before??


If I can't find any other info before the van goes into hibernation for the winter, then over the winter, I'll pull the LCAs and do some measuring.

If the C10 shaft thing doesn't work out, I am still going to find a solution that doesn't cost several hundred dollars.
-Maybe I'll fill the voids in the shafts with JB weld..
-Maybe I'll see if someone can machine sleeves that can be pressed into the ends of the shafts to hold it solid where the rubber won't..

All I know is that OCD is a bitch and I'm going to come up with a reasonable solution. Hopefully it'll help others too.

I'll keep this thread updated.





I recently replaced them on my 1979 G30 and they were solid, have you looked at them they may be something you could have machined to fit?

[Linked Image]20180224_161457 by shagedemus, on Flickr
I have seen this style of shaft in my research, but I can't find any good info about how they fit into the control arms. And can't find any measurements either.

I did find more info on the C10 style shafts though. Evidently the "U" shaped brackets are still available from LMC and are attached to the crossmember via solid rivets. If that is the case, I should be able to drill/grind them out and attach the C10 brackets with nuts/bolts. Still need to do some more research, but looks promising.
In my photo above if you look at the end cap on the left with the grease nipple on it. That has internal and external threads. The external threads are an interference fit on the inside of the LCA while the internal threads are normal and screw onto the end of the shaft. The shaft is bolted to the frame with U bolts.

[Linked Image]
G30 pins & LCA's are different than the G20.
Looking at your pictures and never having seen one up close...here's a way I think you could do it.
I presume the inner shaft is solid.
.....If so lay a LOAD of weld on there. Have it turned down on a lathe to the inner diameter of the outer tube. Then put it back on the lathe and finish it with a knurling tool. This will give an interference fit with the outer tube which can be pushed on to the inner shaft with a hydraulic press. Worth trying with a scrap one maybe?
Sorry I'm still trying to post a pic from flickr.
https://www.flickr.com/photos/151407392@N07/shares/9j1727
This is a project long on hold. I have 0.040" slop, I suspect the inner sleeves are 26 MM, the OE shaft measured 1". I spent 100 for a 10 foot bar and 3 and change for machining. The new bushings came from Energy suspension, I suspect they are just buying 26 mm Asian made sleeves and calling it close enough. The only reason I can come up with for the 2" shaft is that they did it for the conversions and pass vans to dampen road feel, they also used that shaft on the 3/4 Suburban. The 3/4 is the natural choice for those applications. Your best bet is to use the 1/2 ton shaft and saddle, drill new holes. I have seen online people doing this to their lifted c trucks.


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Hey tuner4life,
any update ? I'm hitting the same issue .

Regards,

F.
Sorry, nothing more at this time. I have just been working on other parts of the van and haven't gotten back to the suspension yet. I do plan on finding a way to address this issue once I get back around to it. Unfortunately just not yet.
Ok; btw does anyone already bought the rare parts shafts and/or have the exact sizes ?
I'm in the same boat here. When I took off my control arms I didn't have that cutaway handy, and I was trying to press out the inner shaft to get the assembly apart. That caused me to damage my inner shaft in the hydraulic press (and twist the bushing mount on the control arm.. Whoops!)..

My current plan which may take some time (as I'm still working on the floor/rockers) is to reuse the outer shaft.. and hopefully 'melt' the centers out of them.. then machine new centre axles out of 1" chromoly so they can slide through (unlike the stepped factory version).

Then make some aluminum tophat 'bushing' style adapters to take up the space between the shafts, and have it all fit snugly between the new energy suspension bushings in the LCA. I think the shafts should also be setscrewed together so that they don't rotate in that spot, and force the suspension movement to rotate the LCA bushings.

Yep. They were shot when I took them off the van.. but I ~feel~ like I made more work for myself by damaging the inner shaft.

I'm going through now and refreshing all the parts grinding off rust and painting.. Once I do the arms, i can press in the bushings, then start to measure out what to machine.
I know I don't post on this forum much, or even have a build thread for my van.. but I feel its important for me to update this thread with info to help the next person who comes across this Chevy lower control arm axle problem.

I FINALLY managed to get through this major hurdle in my front suspension rebuild, and I'm super relieved, as this was a big unknown for me.

Here's how I solved it:

1)Bought Energy Suspension Poly bushings for a C10

2)Bought 1-1/8"steel shaft and 2" OD, 1.5" ID Steel tube

3)Pressed in the bushing sleeves to the LCA, to get an accurate base to base measurement.

4)Measured the heights of the bushings/sleeves etc.

5)Designed assembly in CAD (3D .STEP export attached). I wasn't sure how to tolerance the bushing preload, so I gave it 0.5mm compression per bushing, thinking I might have to adjust the shaft later and give it more.

6)Spent a bunch of time on the lathe making the axles, and the carrier tube. Originally made the carrier tube tophat adapters out of UHMW or white delrin. I guess I was being lazy, but it sketched me out. I knew I would be remaking them before installation.

7)A number of weekends later, I returned with 2" OD Aluminum to remake the tophats.

8)pressed the tophats into the tube, and then threw the tube back in the lathe to do a precision bore to make the 1-1/8" tube slip fit through the carrier without slop.

9)I turned my original Delrin tophats into inner spacers to sit behind the Poly bushings. They're not in compression in use, just sort of 'dust caps' on the inside of the bushings, and keept the grease in. The 2x M8 lock bolts are really what are locating the axle shaft to not spin inside the carrier tube.

10)Added zerk ports to the Poly bushing housings, drilled a hole in the bushing, then used a dremel to cut a circumferential groove into the inner surface of the bushing. This creates a greaseway to distribute the grease around the inner sleeve, where it needs to be. I biased them towards the thrust face a bit, but really, the grease will flow wherever its easiest (hence the inner caps to stop it all from going to the centre.) Sidenote, These poly bushings are happiest with Silicone based grease. Lots of lore on the internet to scare you away from petrolium based grease on Poly bushings.

11)Months later, FINALLY had it all ready for installation. I sprayed 'Fluid Film' into the carrier tube to lubricate the inner surface and prevent rust. I wiped the whole axle shaft in petrolium grease to help slow it from rusting (as rust would stop it from sliding through the alloy slip fit tophat), I greased the inner and thrust faces of the bushing with silicone lube, and tested out the Zerk ports. Then it all went together pretty smooth. I was worried about my preload on the bushings, as it was super hard to turn by hand. Once I mounted them on the van though, they felt perfect. The arm rotation is smooth with very little stiction, and the arms will droop down under their own weight.

Phew. Anyways, if you're reading this far, then the PDF drawings and .STEP file (****STEP FILE RENAMED TO .BMP FILE TO UPLOAD AS ATTACHMENT****)are probably of interest to you. Good luck.

Attached File
control_arm_axle.pdf  (27 downloads)
Attached File
cntrl_arm_axle_carrier.pdf  (30 downloads)
Attached File
CARRIER_TUBE_TOPHAT_ALU.pdf  (30 downloads)
Attached picture 3-carriertube_original_resize.JPG
Attached picture 4_axles-done-resize.JPG
Attached picture 5-axles_install-resize.JPG
Attached picture 6-zerk_test_resize.JPG
Attached picture 7-installed_resize.JPG
Attached picture cross-section_cad.JPG
Attached File
Spotted this ad for a lower control arm bush thought maybe it could help someone following this thread.

ebay ad LCA bush

Chevy G1500-2500 Vans 2WD 1/2 Ton Lower Control Arm Bush GM NOS.

New in the GM Box

Part Number: 15988037
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