Passenger HMMWV springer seat: M818

[MyothersanM1]

After seeing too much of my son getting the dog snot beat out of him while riding down our washboard freeways, I swapped out the HMMWV seat base on the passenger side I installed several years back with an M939 springer base.


I picked up a good used base locally that only needed a little cleaning and a coat of paint. I reused the existing seat. I made seat adapters from some scrap 1/4" X 4" steel plates. The bottom of the seat nor the sliding adjusters required modification. I created a spacer for the right side of seat belt anchor point so the seat belt retractor mechanism would clear the seat on the that side. I had a weld-on anchor tube from a seat belt kit I got a while back. I cut a piece from it approximately 2 1/4" long and reamed out the threading. I had to replace the shorter anchor bolt with 4 1/2" grade 8 bolt.


I replaced the shock absorber with a much better Monroe upgrade (Monroe P/N 66104). The shock does require a little grinding at the bushing inserts so it will fit the stock seat brackets
.

The M809-series cabs already have the captive nuts in the floor for a passenger springer. However, they do not line up with standard M939-series base. The captive nuts are at 14 1/2" front to back and the seat base was 14". I just marked and drilled new holes a 1/2" forward of the existing ones. Everything lined up perfectly. Reinstalled the seat and seat belts. My passenger is now a much happier camper.

 

[MyothersanM1]

I also replaced the return springs on the both sliding adjusters locks. I found a close match, but you have to cut the closed end loops making them into hooks to attach them.

http://www.mcmaster.com/#9044k343/=1423imb

 

[Another Ahab]

I also replaced the return springs on the both sliding adjusters locks. I found a close match, but you have to cut the closed end loops making them into hooks to attach them.

Is it difficult to cut that spring steel?

How did you do that with a cut-off wheel on a grinder?

 

[MyothersanM1]

No, just a good pair of wire cutters/diagonal pliers and a firm grip. You have to get the cutting surface in far enough to get the leverage. It was fairly simple.

 

[Postman515]

I have a box of nos hemmt seat shocks. Wonder if they would work.

 

[MyothersanM1]

I have a box of nos hemmt seat shocks. Wonder if they would work.

They might. The original shock measures 9 3/4" extended, 7" compressed (on bushing insert centers) and the bushing inserts are 1 1/4" wide.