SWB 6-lug axle vs LWB 5-lug axle

[mdelosrey]

Hello,

Currently building a 71 C10 LWB 5-lug with leafs and have a chance to purchase a SWB 6-lug coil spring frame with running gear.

My question is will I be able to swap my current 5-lug axle/spindles into the SWB and retain the coil spring/trailing arm setup?

I will be picking this up early next week.

Thanks in advance!

[Grumpy old man]

no, the 71 axles are wider. it's easier to swap front complete cross members if the 5 lug is in better shape .Disc ?

[mdelosrey]

Originally Posted by Grumpy old man

no, the 71 axles are wider. it's easier to swap front complete cross members if the 5 lug is in better shape .Disc ?

Yes sir, I currently have discs in the front.

Real reason I'd like to keep the 5-lug is because of the 5-lug Rally's on it.

[GASoline71]

What GOM said. I have a 1969 housing in my 1972 GMC, but I had to get 5 lug conversion axles made by Moser to slide into the narrower 1969 housing.

Gary

[mdelosrey]

Originally Posted by GASoline71

What GOM said. I have a 1969 housing in my 1972 GMC, but I had to get 5 lug conversion axles made by Moser to slide into the narrower 1969 housing.

Gary

Would you happen to remember what the set of axles cost and are the conversion axles on their website?

Another option I was thinking about was to weld on trailing arm pads on the 5-lug leaf axle assembly from the 71. Found these on a quick google search.

[GASoline71]

I ordered them from Summit Racing and got free shipping. $260 bucks shipped to my door. Here is the link:

https://www.summitracing.com/parts/m...gmt5/overview/

Gary

[mdelosrey]

Originally Posted by GASoline71

I ordered them from Summit Racing and got free shipping. $260 bucks shipped to my door. Here is the link:

https://www.summitracing.com/parts/m...gmt5/overview/

Gary

Thank you for that link!

[lowrollin70gmc]

The axles may be the same width if the axle is a late 1970. In 70, there were 2 widths of axles:

Early: 62 3/8” WMS, same as 67-69
Late: 63 3/4” WMS, same as 71-up

It would help to put a tape measure on the axle in the SWB before ordering parts, as there is a small chance that your 5 lug axles will fit if it’s the late 1970 axle.

[special-K]

First thing we need to know is what year is the SWB chassis. If it's a '70 with a '70 rear then you can swap the 5-lug axles in straight up. '70 was the first year for the wider housing and last year for 6-lug

[mdelosrey]

Originally Posted by lowrollin70gmc

The axles may be the same width if the axle is a late 1970. In 70, there were 2 widths of axles:

Early: 62 3/8” WMS, same as 67-69
Late: 63 3/4” WMS, same as 71-up

It would help to put a tape measure on the axle in the SWB before ordering parts, as there is a small chance that your 5 lug axles will fit if it’s the late 1970 axle.

Originally Posted by special-K

First thing we need to know is what year is the SWB chassis. If it's a '70 with a '70 rear then you can swap the 5-lug axles in straight up. '70 was the first year for the wider housing and last year for 6-lug

Thanks for the invaluable information. I will definitely take measurements and get the production date info as I will be picking it up on the 26th of this month. Again, thank you for all the info as I like to brainstorm my options.

[special-K]

Good luck and now that I'm thinking about it, Welcome to the site!

Not sure if it's been mentioned or if you'd consider going this route, but if it's the narrower housing you can buy 5-lug axles for that length

[mdelosrey]

Originally Posted by special-K

Good luck and now that I'm thinking about it, Welcome to the site!

Not sure if it's been mentioned or if you'd consider going this route, but if it's the narrower housing you can buy 5-lug axles for that length

Thanks! This site was referred to me by another friend who has a 71 SWB himself.

Gasoline71 sent a link for the Moser 5-lug conversion axles, good to know there are off the shelf conversion axles.

[68 TT]

You also need to add a panhard bar mount bracket.

An Eaton HO52 / HO72 housing from a 3/4-ton has a nice design bracket that is welded to the axle tube that is easy to copy and install onto another rear end for a trailing arm conversion.

This is by far the least expensive way to go if your existing brakes and axles are in good shape. If you have worn bearing surfaces on your 50-year old axles (likely) and / or your brake drums are shot then the replacement axle method may be a more cost effective option. Inspect your parts closely before you commit to one way or the other.

One upside to the conversion mounting pad option is that you can set your pinion angle and U-joint angles properly to accommodate for a lowered vehicle. I didn't think this was going to be such a problem as my truck isn't lowered that much but it ended up needing over six degrees of pinion angle correction to bring the U-joints into the correct drive angle. This was after moving the front trailing arm mount point to drop the anti-squat down to 100% so it didn't hit the tires so hard but it is still something that needs to be looked at with a lowered truck.

Originally Posted by mdelosrey

Would you happen to remember what the set of axles cost and are the conversion axles on their website?

Another option I was thinking about was to weld on trailing arm pads on the 5-lug leaf axle assembly from the 71. Found these on a quick google search.

[mdelosrey]

Originally Posted by 68 TT

You also need to add a panhard bar mount bracket.

An Eaton HO52 / HO72 housing from a 3/4-ton has a nice design bracket that is welded to the axle tube that is easy to copy and install onto another rear end for a trailing arm conversion.

This is by far the least expensive way to go if your existing brakes and axles are in good shape. If you have worn bearing surfaces on your 50-year old axles (likely) and / or your brake drums are shot then the replacement axle method may be a more cost effective option. Inspect your parts closely before you commit to one way or the other.

One upside to the conversion mounting pad option is that you can set your pinion angle and U-joint angles properly to accommodate for a lowered vehicle. I didn't think this was going to be such a problem as my truck isn't lowered that much but it ended up needing over six degrees of pinion angle correction to bring the U-joints into the correct drive angle. This was after moving the front trailing arm mount point to drop the anti-squat down to 100% so it didn't hit the tires so hard but it is still something that needs to be looked at with a lowered truck.

Thank you for the alternate housing information.

Good point on setting pinion angles if going the arm pad way.

[special-K]

No need to take on all that's involved with swapping complete axle assemblies to get 5-lugs on a 6-lug axle.