Installing Year One seat relocation brackets in a 70 Challenger

[Dakota]

There are other posts in the forum that refer to ways to modify seats to better fit those of that are of "above average" height.   I'm 6'5", so I think I qualify.   About a year ago, I bought a set of the Year One seat relocation brackets but I didn't install them until this week.   A common complaint about the brackets is that they don't come with any instructions, but fortunately there's a good starting point available on FABO from the link below.  Hopefully this info may be useful is someone else is considering this change. 

https://www.forabodiesonly.com/mopar/ams/seat-relocation-brackets-installation-instructions.211/

I only did my driver seat.   Much of it is straight forward, but as always with any modification to an old car there are a few problem spots that are a pain to address.   This thread is going to involve multiple posts so please bear with me.   

[Dakota]

The first work involves removing the seat mounting bolts from the seat tracks.   The first picture shows one of the bolts (this is the rear right bolt).   On my seat tracks, the metal plate that for the large position spring was already loose around the rear bolt, so I was able to get a close up of the 4 nibs (?) that hold the head of the bolt in place in the square hole in the track.   I chose to cut the bolt close to the track, then used flap disc on a grinder to remove the rest of the bolt.  I alternated light passes with the flap disc and a couple of whacks with the nail set and hammer until the bolt head fell out.

[Dakota]

Adding the relocation brackets to the front positions on the left and right tracks are very straightforward as it's just a matter of putting the bolts provided by Year One through the holes freed up by removing the old mounting bolts.  The relocation brackets are pointed towards what would be the front of the car.   Since there's an extension already built into the right side track, all that's needed for right side rear position is drilling a hole through the bottom side of the extension for the new mounting bolt.

The big PIA is the left side rear bolt.   There's no extension on this side, and the new mounting bolt can't be put all the way through the track because it would interfere with the barrel-shaped bearing that the seat moves on.  I bolted the relocation bracket on and ran a drill for a few seconds to mark the location for the head of the new mounting bolt (I'm using the 2nd of the two hole to maximize the relocation).  After removing the relocation bracket, I used the drill and a die grinder with a carbide bit to open up a hole the shape of the new bolt head.   The trick is to do this without cutting into the metal band under the barrel bearing.  There was just enough room for the bolt head without impacting the bearing once the metal plate for the spring is put back in place (there's a need for hole to be drilled in the spring plate too).

[Dakota]

I didn't take a picture of it, but the final step for the left rear mounting bolt is to sandwich the head of the new mounting bolt into the newly created hole by bolting on the relocation bracket.

Other stuff:

I left the bolts for the relocation brackets provided by Year One just a little loose so I had some adjustment room to get the seat to drop in place.   The right side bolts can be easily reached for additional tightening after the seat's in.  To reach to left side bolts, I'm going to have to shorten a socket and grab it with some vice grips to get them tight as there's not enough room for a wrench or a small ratchet.

I re-used the stock mounting nuts to attach the seats.   The bolt diameter and thread size for these nuts are 5/16"-18.   I had 1-1/2" Grade 8 bolts on hand so that's what I used.   If I did it over again, I'd switch to a 2" length so I wouldn't have to squeeze the seat down on the carpet to get the mounting nuts to catch.

Other than the left rear mounting bolt, the mounting bolts can be dropped into place once the seat and relocation brackets are positioned above the holes in the floor pan.   I elected to use some "push on" nuts (see pic below) to hold the 3 bolts loosely in place when dropping the seat it.   The 5/16" diameter is not a common size for these things so I had to order them online.   I now have a lifetime supply of them.

I have a long enough reach (usually described as "freakish") that I could get a battery powered ratchet onto the nuts under the floor pan and hold a wrench on the head of the new mounting bolts to do the final tightening.  If you're not a freak, it's probably a two person job.

If you're considering doing this, you'll need to decide which of the 2 holes on the extension brackets you're going to use.   Because of the mods needed around the head of the left rear mounting bolt, you'd only get to chose one.

Yeah this was a pain, but now my knees aren't jammed into the back of the steering wheel, so it's all good.


If you have other pictures, questions, or "what the hell were you thinking?" comments for using these brackets, please add them here.   Hopefully by tomorrow, I'll add links to some of the other threads I came across on this forum related to this topic.

Cheers.

[Dakota]

Other threads on this topic, which includes links to other threads with alternate approaches to get some additional leg room:

https://forum.e-bodies.org/interior/6/bucket-seat-extensions/10539/msg145306#msg145306

https://forum.e-bodies.org/interior/6/need-seat-tracks-modified/15517/

[rikkitik]

 I used these same brackets, but modified the brackets, rather than the seat support bracket. I didn't feel like hogging a hole in the support bracket, so I countersunk the Year One brackets instead. I left the countersink about .015 shallow, so the flathead allen would protrude slightly. That way, tightening the bracket to the base frame, would "pinch" the bolt head, and keep it from turning. It worked great. I used stainless flat head bolts, they "bit in" as I tightened, and bolted down solidly.[video][/video]

[cuda hunter]

Great thread @Dakota    Thanks for posting up all the pics and links, they will help a lot!

Great idea @rikkitik