Coachgeo
Explorer
any more information on this...... never seen a freightliner front spring bushings..... didn't know that even existed.... or is that retrofitted spring bushings from another part of a freightliner not ambo related?
GMC Topkick 4x4 Expedition Camper Build
- Thread starter Britboaters
- Start date
Britboaters
Observer
Coach,
I used the rubber / steel bushing from the eye of a leaf spring from a class 8 Freightliner truck front axle.
From memory 4" wide, 2.25" OD, 20 mm bore.
The front axle is designed for about 12,000 lbs, so I figured this would give me more than enough capacity with 3 of these bushings.
Bob
I used the rubber / steel bushing from the eye of a leaf spring from a class 8 Freightliner truck front axle.
From memory 4" wide, 2.25" OD, 20 mm bore.
The front axle is designed for about 12,000 lbs, so I figured this would give me more than enough capacity with 3 of these bushings.
Bob
Britboaters
Observer
Just got the interior spray foamed. Tremendous improvement in rigidity - everything really solid now.
What a mess though !! Lots of clean up still required, and detailed finishing. One thing I should have done is taped the wires sticking out, so they wouldn't get covered in foam. Also lost one set of wires - but I think I know where they are so will have to dig them out !!
What a mess though !! Lots of clean up still required, and detailed finishing. One thing I should have done is taped the wires sticking out, so they wouldn't get covered in foam. Also lost one set of wires - but I think I know where they are so will have to dig them out !!
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Expedition.Report
Explorer
Awesome! Keep posting updates!!!
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Britboaters
Observer
Thanks for the encouragement.
Been working on the wheels last few weeks, and other things.....
Will post some updates soon.
Thanks for bumping me back onto the front page !! LOL
Been working on the wheels last few weeks, and other things.....
Will post some updates soon.
Thanks for bumping me back onto the front page !! LOL
Britboaters
Observer
Wheels......
The GM Topkick / Kodiak use wheels with 8 lugs on a 275 mm circle. Very hard to find wheels other than 19.5".
I want 335/80R20 tires - 41" diameter, about 13" wide.
So, for my projected axle weights, I'll have the following pressures for highway speeds:
Front - 6,700 lbs => 37 psi
Rear - 9,600 lbs => 55 psi.
The best wheels I found were some Hutchinson MRAP wheels. (best for me !).
https://www.ebay.com/itm/20-X-10-MR...MILITARY-4X4-6X6-CTIS-WHEEL-RIM-/182740568762
These are aluminum 75 lb wheels with a massive 10,000 lbs load rating.
The 10 lugs are on a 335 mm circle.
After a lot of analysis we realized that we couldn't just make an adapter as the 8 lug holes on the hub and the 10 lugs on the wheel interfere.
So, we decided to machine out the wheel center - see the photos below.
To get the correct offset to allow the wheels to be used on both front and rear axles we decided to fit an adapter plate inside the wheel, using the 20 bolts that hold the two parts of the wheel together.
This required the inside of the wheel to be machined concentric with the rim, to very tight tolerances, +/- 0.004".
The amount of material removed was kept to a minimum to protect the integrity of the wheel.
The adapter plate was laser cut from 1/2" A36 plate. This included the 8 lug bolt holes, the 20 outside holes and the inside hole.
Laser tolerances were not good enough, so the overall diameter and interior diameter were machined at the same time to ensure concentricity.
The 20 holes around the outside were also drilled out to fit the knurling on the wheel studs.
The original wheels had 16 studs "regular length" plus 4 "long" studs. We were able to order additional "long" studs from Hutchinson to take account of the extra thickness of the adapter plate. ($4.10 ea)
Machining out the centers meant that the CTIS mounting area was lost. So we drilled and tapped for some 1/8" NPT fittings, on both sides of the wheel, picking up on the CTIS drillings. This allows the tire to be inflated from both sides.
When the weather picks up a bit, we can paint the adapters, build the wheels and mount the tires. Hopefully everything will go well !
For interest, this was not a "cheap" project. Some idea of the cost.... not including lots of thinking, analysis and planning time !!
I did a lot of the machining in my own shop, however:
5 wheels including shipping $540
5 laser cut blanks $350 - a deal !
80 studs from Hutchinson $330
Machining wheels $530 - too big for my lathe. done on a 100 year old worn out lathe - but we did it to tolerance !!
About $350 each.
The GM Topkick / Kodiak use wheels with 8 lugs on a 275 mm circle. Very hard to find wheels other than 19.5".
I want 335/80R20 tires - 41" diameter, about 13" wide.
So, for my projected axle weights, I'll have the following pressures for highway speeds:
Front - 6,700 lbs => 37 psi
Rear - 9,600 lbs => 55 psi.
The best wheels I found were some Hutchinson MRAP wheels. (best for me !).
https://www.ebay.com/itm/20-X-10-MR...MILITARY-4X4-6X6-CTIS-WHEEL-RIM-/182740568762
These are aluminum 75 lb wheels with a massive 10,000 lbs load rating.
The 10 lugs are on a 335 mm circle.
After a lot of analysis we realized that we couldn't just make an adapter as the 8 lug holes on the hub and the 10 lugs on the wheel interfere.
So, we decided to machine out the wheel center - see the photos below.
To get the correct offset to allow the wheels to be used on both front and rear axles we decided to fit an adapter plate inside the wheel, using the 20 bolts that hold the two parts of the wheel together.
This required the inside of the wheel to be machined concentric with the rim, to very tight tolerances, +/- 0.004".
The amount of material removed was kept to a minimum to protect the integrity of the wheel.
The adapter plate was laser cut from 1/2" A36 plate. This included the 8 lug bolt holes, the 20 outside holes and the inside hole.
Laser tolerances were not good enough, so the overall diameter and interior diameter were machined at the same time to ensure concentricity.
The 20 holes around the outside were also drilled out to fit the knurling on the wheel studs.
The original wheels had 16 studs "regular length" plus 4 "long" studs. We were able to order additional "long" studs from Hutchinson to take account of the extra thickness of the adapter plate. ($4.10 ea)
Machining out the centers meant that the CTIS mounting area was lost. So we drilled and tapped for some 1/8" NPT fittings, on both sides of the wheel, picking up on the CTIS drillings. This allows the tire to be inflated from both sides.
When the weather picks up a bit, we can paint the adapters, build the wheels and mount the tires. Hopefully everything will go well !
For interest, this was not a "cheap" project. Some idea of the cost.... not including lots of thinking, analysis and planning time !!
I did a lot of the machining in my own shop, however:
5 wheels including shipping $540
5 laser cut blanks $350 - a deal !
80 studs from Hutchinson $330
Machining wheels $530 - too big for my lathe. done on a 100 year old worn out lathe - but we did it to tolerance !!
About $350 each.
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Last edited:
Britboaters
Observer
Jim,
The original wheels were 75 lbs, but I machined maybe 5 lbs out of them.
The plates are close to 30 lbs each - heavy but strong ! I thought about drilling out some more material, but it wouldn't make much difference.
So close to 100 lbs each. More than I hoped, but hopefully plenty strong and reliable.
Bob
The original wheels were 75 lbs, but I machined maybe 5 lbs out of them.
The plates are close to 30 lbs each - heavy but strong ! I thought about drilling out some more material, but it wouldn't make much difference.
So close to 100 lbs each. More than I hoped, but hopefully plenty strong and reliable.
Bob
Expedition.Report
Explorer
Wow! Those rims are going to look great!
I am going to be needing to go down this route in about 6-8months... any chance to fancy making more!?
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I am going to be needing to go down this route in about 6-8months... any chance to fancy making more!?
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Britboaters
Observer
Maybe.....
There's a lot of work in this conversion. I could certainly make you plates, and maybe you could get the wheels machined locally, to specs I could give you.
For those of you with Ford pattern wheels I could make plates with that bolt pattern.
Bob
Expedition.Report
Explorer
I would be open to that, I live in a city with a heavy Oil and Gas industry presence so there is no lack of shops available to do the work.
Cheers!
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I'm still unsure what route I'll go for wheels and tires. I sure like Java's new set up,too bad those were 10 hole ford pattern or I would have gotten some too. I'm going to go to the Canadian Rockwell guy when my truck is out of the shop and try some MRAP wheels and whatever else he has and help decide.
Coachgeo
Explorer
good choice... Neil seems to be a good guy.