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PostPosted: February 16, 2022, 5:31 pm 
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Location: Buda, Tx
Howdy all, apparently the previous owner of the Rotus was a size 34 pants kinda guy, I'm a size 38, before the holidays. The car has Kirkey 55150 seats, 15" hip width and 16.5" overall width.

I need at least another inch or so to fit my hip bones. Rather than buying or making new seats, do you see any problem with trimming away the red area, and applying some sort of edge trim over the fresh cuts? This might give me enough room, and still fit the seat covers.
Attachment:
Seat Modification Idea -1 .jpg


As for the seat mounting, I'll just say I'm not too impressed with how the PO did it. Maybe it's OK, seems like a lot of room for improvement though.

The rear seat bottom has 2x 1/4" bolts running down thru the frame and extending ~5/8" below the bottom of the car with standard size washers.

The front end of the seat attaches to the original mounts, but they used a ~1" long, 1/2" OD roll pin for the spacer, and 2x M6 screws.

The seat back mounting is still a mystery, there's one point in the upper middle somehow attached to the bulkhead, I haven't found where or how it attaches yet.

I'm thinking I should address both the bolts thru the bottom of the car and the roll-pin front spacers. Originally I thought about using a piece of wood spanning the width of the seat to replace the roll-pins, but maybe I should do 2x wedge shaped spacers running from front to back holes, especially after cutting the sides of the seat. As for the rear mount bolts, not sure what to do there except for using button head screws with just enough length to get the nut on underneath, with jumbo washers.

Maybe I'm overthinking it, seems to be a hobby of mine


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PostPosted: February 16, 2022, 6:13 pm 
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Interesting stuff. For the width, instead of cutting out the sides (that important to maintaining the seat structure), you could spread the sides though it will try to pull the back forward. They could be heated with a torch to anneal before stretching with a scissor jack and wood blocks.

What I would do is completely remove the seats. The car was not intended to have separate seats, just a squab bottom and an upholstered back. Checkout RTZ's build to see how it's done:
viewtopic.php?f=35&t=17715&start=135

You could remove it and without full commitment (cutting out the front seat support tubes), lay three layers of 1/2 inch carpet underlayment in the floor and try it on for size. Should be plenty of room then. I think you'll like it. Adjust cushions for the support you need and when satisfied, take them to a shop for covering and a velcro back to grip the back and floor. Tow squabs and a back. Thin side panels if you need some cushion there also.

Or you can go crazy like this which is still better than a separate seat, especially when it won't be adjustable.


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Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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PostPosted: February 16, 2022, 8:39 pm 
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Location: Buda, Tx
Solid advise, I'll try heating and bending (jacking), hopefully I can get enough room for the short term. I like the simple 3-piece seat, it's more in keeping with what the car is supposed to be. Down the road I intend to civilize the interior just a bit.

Thanks for the link to RTZ's build, that's impressive!


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PostPosted: February 16, 2022, 9:04 pm 
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If you can clamp a 2x4 to the area you want to bend, you don't even need to remove or heat it. I've tweaked several Kirkey seats this way.

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PostPosted: February 17, 2022, 8:45 am 
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I agree with Miatav8, at least for the sides, it looks like you have over an inch on each side you could gain by spreading the seat sides.

Graham


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PostPosted: February 17, 2022, 9:43 am 
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Also, about the mounting, if keeping the seat, I suggest that you don’t change anything but it is worth discussion.

I don’t think the back is attached to anything which is an area that could be improved. Kirkey sells optional panels to secure the back to the car. Consider a rear impact; drivers weight pushes the seat back aft. How much it moves is important since the initial impact loosens the upper belts a split second before they are needed when the driver moves forward.

I expect the rear of the seat pan is bolted through a steel tube or at least a ¼ inch thick x 2 inch wide steel strip above the floor pan. Should be 5/16 grade 8 with at least three threads protruding from the nuts. I don’t any benefit to ensuring the front seat pan does not bend upward if struck hard enough in the rear (from the load applied through the seat back that was allowed to move back, loading the side flanges which removes the spread for comfort). Had you cut the sides, the seat back would be much less rigid. Kirkey’s seat mounts are much better but would be impractical in a locost unless you don’t mind seeing the seat bolts outside the car.

Link to Kirkey’s installation guide for the 55 series:
https://www.kirkeyracing.com/product/10 ... TREET-DRAG

Here is a pic of one way to make locost seats with support and some examples. Foam and vinyl from or through the local sewing supply shop, everything else from lowes or HD. High density foam with less carpet underlay is an option but expensive.


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_________________
Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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PostPosted: February 17, 2022, 10:14 am 
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So many opportunities for making seats. Here is how I did mine, back then: viewtopic.php?f=35&t=4145&p=93160&hilit=seats#p93160 It allowed for headrests and removable seat squabs and backs. Although not mentioned in the post, the backs were attached to the frame crosspiece at shoulder level via a single hinge with removable pin. Both seats were removable in less than a minute. These were very comfortable for long (>12hr) drives. Some have said that they used gen3 or gen4 camaro rear seats as a starting point. A search here will show some pics.

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“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766


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PostPosted: February 18, 2022, 3:06 pm 
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Location: Buda, Tx
Thanks Chuck for the info and link to your (impressive) build. I'll keep an eye out for a cheap seat to cannibalize, I checked CL for seats and it's surprising how much $$ people think they can get, maybe they do.

I'm making some progress with the scissor jack bending the Kirkey, enough to fit w/o pain.

I can see simple foam/vinyl/cloth covered plywood working out nicely in the future, a quick google lead me to this place https://www.thefoamfactory.com/Merchant2/merchant.mvc? they have many types of foam, cut to size, for what looks to be a very reasonable cost.


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PostPosted: February 18, 2022, 4:28 pm 
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I don't see any foams on that site that have sufficient density for a car seat. Those foams are like what they stock at the sewing store; around 2lb density. Underlay is around 7# density. The hard part is trying to shape it.

_________________
Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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PostPosted: February 18, 2022, 7:50 pm 
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Location: West Chicago,IL
Miatav8,MstrASE,A&P,F wrote:
I don't see any foams on that site that have sufficient density for a car seat. Those foams are like what they stock at the sewing store; around 2lb density. Underlay is around 7# density. The hard part is trying to shape it.


If you go with shaping foam, get an electric meat carving knife from Goodwill, Savers or the like. They do a better job than anything else (short of a hot wire) for the DIYer.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766


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PostPosted: February 19, 2022, 6:36 am 
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I use a hack saw blade for rough cut then a radial wire wheel in a drill for final shaping. The trick is to barely touch the surface to remove material otherwise it will grab and rip out chunks.

The nuts in the plywood are called tee nuts and come in many different sizes. I used a thin layer of fleece over the foam in my GO4 Interceptor bench seat, trying to make it a two-seater.

The problem with using the rear seats in many cars is that the floor is molded also, but you could cut the foam flat across the bottom then add another layer of high density foam underneath.

_________________
Miata UBJ: ES-2074R ('70s mazda pickup)
http://www.vsusp.com
ford IFS cheap viewtopic.php?f=5&t=13225&p=134742
Frame L x cockpit W x eng bay HT (w/o hood/bonnet/cowl)
Lotus Super Seven: 115 (no spare) x39x7.25
Tiger Avon: 114x40x13.3-12.6
Champion (Book): 114x42x11
Gibbs Haynes: 122x42x14
Voo Doo: 113x44x14
McSorley “442”122x46x14
Collins “241” 127x46x12


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