Aluminum fixed back UltraShield seat install

[Fair!]

Bought a pair of Ultra-Shield Rally Pro seats because we couldn't get Sparcos after 3 months of trying. Best part: They were considerably lighter than we had hoped.

We were initially content with using a pair of 19# steel framed fixed back seats (Sparco) for $300/each but after we completely struck out with SparcoUSA (and after waiting 3 months and still not receiving them yet, nor our long overdue refund) we did some research and found these UltraShield Rally Sport seats to be a really good option, and only $249 each. There were so many style, width and layback options as to be confusing, but we got good advice from some autocrossers and Solo Performance and I think we ended up with a really great pair of fixed back race seats for under $500.

First thing we did after opening the box was to weigh them. Wow!


Passenger's seat: UltraShield Rally Sport, 20° layback, 17" width, "the Big Boy" that can fit damn near anyone. 15.8 pounds!

Driver's seat: UltraShield Rally Sport, 20° layback, 15" width, "the Skinny seat" that is roughly similar to a Sparco EVO width. 14.9 pounds!

UltraShield Rally Sport, 20° layback, 15" width, without upholstered/foam cover is only 12.7 pounds!

There are seats costing upwards of $1500/each that aren't as light as these seats (most composite FRC or Kevlar fixed back big name seats are 18-21 pounds). The best part about aluminum seats are the additional mounting options: being metal you can drill thru the sides or bottom for side mount or bottom mounting. For a typical fixed back racing seat this just isn't an option. Fabrication quality is top notch.

Bottom mounting options allows us to more easily use Sparcos affordable low-profile double-locking sliders and bolt them to the bottom for a compact, lightweight slider set-up. Others just bolt these seats directly to the floorpan or onto small brackets that align to the factory seat mounting points (like we did to the passenger side). Of course they suggest bolt and washer size for proper mounting.

[Fair!]

Of course mounting the U.S. seat in the E30 took longer than it should have. I've blown too many hours before doing custom brackets, and this was no exception. I started at about 1:30 am the night before a National Tour event... brilliant! I got done with the first seat (passenger's side, non-adjustable) at 5:30 am and bagged the driver's side. And up again at 7:30 am. Measuring, marking and mock-up took as long as cutting and welding, of course.

Finished Passenger side mounting bracket:


Construction:





More pics here. Notes: I used 1.25" ERW square tubing, heavier wall thickness than needed with over 5 pounds of steel. The class this car runs in (SCCA STS) requires a 25 pound seat+bracket, and with a 15.8 pound seat and only a 5 pound bracket I've had to add 4 pounds of ballast to this bracket to meet the minimum. But that's fine - its down low and centrally mounted weight. Excuse the filthy carpet under the seat (it was a $350 car, by the way - looks like someone died in there!) and since its raw steel I'll just zinc plate the whole assembly once I finish the driver's side mount. The joints for the tubes to each other were fully perimeter welded, but it was extremely late so they are far from picture perfect welds.

The mount ended up being 2.5" tall total, which was all just enough to clear a huge hump in the floor in between the side rails and leave barely enough room to fish the nuts/washers onto the thru-bolts for the seat-to-bracket mounting, from above. I kept the passenger seat as low and as far back as possible. Tons of headroom for 6'+ tall passengers, and shorter passengers can just see over the dash mounted like this. Width was fine - tons of room to the door and tunnel for this 17" wide UltraShield Rally Pro (they make 14-18" widths, and we used a 15" for driver's side). I'll tackle the driver's side mount with the Sparco next, which should still make it under the minimum 25# weight with ease.

Used M10 Grade 10.9 Zinc Plated bolts and nylock nuts throughout, as well as over-sized hardened washers to spread the load into the aluminum seat bottom. I kept the washers on the flat area of the bottom of the seat, to avoid the bends. Hex bolt heads are covered by much padding so no worries about comfort - I couldn't feel them unless I stuck my hand under the padding/cover. Front floor mounting holes used the factory M10 floor studs, and I hole sawed an access hole in the tubing there just big enough for a thin walled socket to tighten the M10 nylocks in the front mounting area.

I will go back and add floor reinforcement/mounts for the lap and and sub belts for the harnesses. The sub belts can mount right to the front of bracket I built, and in fact I might add diagonal tubing to spread that load into the main assembly. For now (and to meet class rules which state we must maintain the factory seat belt functionality; a harness is of course optional and encouraged with race seats) I added the factory lower seat belt receptacle to the bracket and fished the factory 3-point belt though the side opening for the seat and upholstered cover. Works great and is easy to use for street use (this car is still driven to many races).


Left: Note low sitting height of a 6' tall passenger. Perfect. Right: Amy running the car in STS-L

With this one lightweight seat in place the car weighed 2423 pounds soaking wet on the SCCA's scales (same model scales as ours'). Factory manual cloth seat + bracket was 48 pounds/each (light for BMWs; E36 seats we've weighed were 62-78 pounds/each). We calculated that we have another 100-130 pounds we can lose from the car, legally and easily.

[Fair!]

Finished the driver's seat install, after putting it off for weeks. I used a Sparco dual locking slider on the driver's side due to 4 different drivers racing this car at various times, each with vastly different heights.

I used 3/8" dia mounting bolts for most everything; the 3/8" bolts' hex heads just slide between the Sparco rails but I had to enlarge the semi-slotted holes in the sliders just a hair for these. Anything larger would have meant the Sparco rail sides would have been notched/weakened. I don't know what bolt size these are made to use (8mm by the look of it - that was the biggest metric bolt diameter that would fit the Sparco holes) but that looked too puny, so 3/8" bolts (.375") were chosen for strength. The OEM floor studs and bolts for the main bracket are OEM 10mm diameter (.393") and the seat belt is mounted also with an OEM 12mm diameter bolt (.472"). On the front of the floor-to-Sparco bracket holes I used two 3/8" Socket Head Cap Screws (SHCS - the kind with an Allen hex drive, and a round instead of hex shaped head) since I couldn't access the nut underneath enough to turn it (too close to the floor). This way I could hold the nut on bottom and turn the bolt on top with an Allen wrench. The other 6 holes for the rails and seat mounting used the normal 3/8" dia Grade 8 hex headed bolt, as it fits between the recessed Sparco rails and those hold the hex head of the bolt still while you tighten a nut from underneath.

Ended up with the bolt spacing into the seat on the driver's side to match the Sparco slider holes (which cannot be relocated safely). This puts the seat-to-slider bolts right near the edges of the seat and "over the bend" at the front, which meant some funky shaped or bent washers.


Left: Washers custom fitted to cover as much area as possible. Right: Finish welded part (prior to bead blasting and powder coat)


Left: Lower bracket bolted into chassis. OEM seat belt buckle added for street use. Right: Bracket with Sparco Slider attached


Left: Seat bolted to bracket. To access bolts the slider is slid fore and aft during installation. Easy.
Right: Finished seat in place, with seat belt buckled. It doesn't look like it but it does fit snugly against your hip bone, like it should.

Four different drivers, all with different builds and heights, sat in the finished seats with sliders and all of us fit comfortably in the seats and to the controls. Height was an issue... any higher and I'd not have enough room with a helmet, but lower and Amy couldn't see over the steering wheel. We used the aluminum fixed back UltraShield 15" wide Rally Pro 20° layback model. On retrospect the 10° layback would have been a better choice as my wife had trouble reaching the pedals in my first iteration of the slider with no forward tilt in the brackets. I did a little trigonometry, some measuring, some cursing, cut the hell out of the lower bracket and changed the design to knock about 5° of layback out of the finished seat set-up.

Its nearly perfect for Amy (this car was built to be "her race car" after all) and feels great to the rest of us, too. Of course we centered the seat with the steering wheel, which would have been offset about 2" to the left (and the seat would touch the door panel; as it is there's over 1.5" of clearance to the door) if I had used the OEM floor seat holes without an offset in the brackets. Leaves plenty of room for a future cage's door bars. The matching passenger seat is fixed in place, lower and further back for better CG with a passenger, just like we wanted.



Here's me (6'3") in the driver's seat at full forward position ("Mr. Magoo") and slid back to where I "fit", which isn't even the full rearward adjustment. The forward position shown is how Tommy R and I have both raced it previously, as the OEM slider was broken/stuck in this position. The seat install was long overdue! There's so much fore-aft adjustment range now that I can actually get into and out of the back seat area relatively easily. To sit back there, as a passenger. I know, that's not supposed to be possible with fixed back seats, but I fit in back with my wife driving in front.

Total time for driver's side bracket fabrication = way too many hours, once again. I chipped away at it over 3 different days or nights, with help from 3 different people (Chris L, Matt P, and Jason M). Making custom seat brackets with sliders is a pain in the rear. Lots of time spent measuring, mocking up, and test fitting before you can do the actual fab work. So when you see custom brackets made for your car that cost $200-400 each... trust me, its worth it if they fit you/the car/the seat. Having to compensate for ordering the wrong layback was my own fault.

[golde30]

how come you didnt use side mounting brackets such as MassiveLee's and just drill some holes in the sides of the seat, utilizing the stock sliders? also, how thick is the padding that comes with those seats, they look pretty good and are freakin lite!

[Fair!]

how come you didnt use side mounting brackets such as MassiveLee's and just drill some holes in the sides of the seat, utilizing the stock sliders?

The stock slider on the driver's side was broken, and besides it was really heavy and would have been super tall. The Sparco dual latching low profile sliders are made to work with a bottom mount seat, and an aluminum seat allows for either bottom or side mounting. So yes, I could have bought side mount brackets and then the Sparco sliders and then made more brackets to align the sliders to the floor... instead I just made the floor mount brackets, bolted the Sparco sliders to those, then bolted the seat directly to the sliders.

also, how thick is the padding that comes with those seats, they look pretty good and are freakin lite!

Pretty substantial padding. We'll be doing some regular street driving in the car soon and we'll see how comfortable they are.

[GotCone?]

Nice work!

I want a set of those seats...

[PiercedE30]

Oh wow. Not the "Kirkey's" you expect when someone says aluminum fixed back seats. Makes me want a set.

[Fair!]

Oh wow. Not the "Kirkey's" you expect when someone says aluminum fixed back seats. Makes me want a set.

Exactly. I have seen Kirkeys aplenty and never gave aluminum seats a second glance but there are some nice options for road race/rally cars from UltraShield. :) Light, strong, and inexpensive...

[AlarmedBread]

Very nice, I'd always seen cautions of needing to use seat back braces and tie in extra mounting points for aluminum seats which is why I steered away from any. I suppose like many things in rule books the information is a little out dated and the internet is a dangerous place. :)

[DSP74]

so care to build more of these and sell them?

Have you swapped out the battery yet....Any pictures of you clam system? A heads up. Quick easy find if a Harley shop is local. They have relatively high CCA batteries for around $80. Had one in the ESP Camaro....Worked pretty good in the stock location....Weighed 13lbs.

[Fair!]

so care to build more of these and sell them?

Nope... its a huge PITA. ;)

Have you swapped out the battery yet....Any pictures of you clam system? A heads up. Quick easy find if a Harley shop is local. They have relatively high CCA batteries for around $80. Had one in the ESP Camaro....Worked pretty good in the stock location....Weighed 13lbs.

Yep, see part of an old post on our forum, below...

11/14/07 Update:
We ordered several lightweight Deka batteries last week and put one of them (Deka ETX18L AGM battery) into the E30 late last night, as part of the STS prep. I also pulled the dead Odyssey PC680 out of my M3 and weighed it, then the Deka, and lastly an OEM replacement E30 battery (which itself was substantially smaller than original; most OEM BMW batteries are larger and 48-50+ pounds). The scale is 0-150 pound, .1 pound accurate.


Left: The non-factory Diehard battery from the E30 weighed 37.7 pounds (now in my E36M3)
Right: The 17.5 pound Deka AGM replacement (an easy 20 pound drop)


Left: PC680 vs. ETX18L
Right: PC680 @ 14.4 pounds


Left: quickie aluminum brace (very secure)
Right: battery box bolted in the OEM location (then the cover was installed)

Crudely fabbed the mount in the wee hours of the night, but its a "race car" and its still very secure. I don't think it will move .001" under racing use.

edit: 8 months later and the battery and mount are holding up perfectly. The battery cranked the car in 20°F weather pretty well back in January, too. AGM batteries are "the bomb".

[2002maniac]

Looks great terry. your stuff is always great!

[DSP74]

Bringing this up.

Those are pretty light race seats!

[Fair!]

New pic of the UltraShield seats with Sparco lower cushion inserts. These velcro in/out easily and make the seats MUCH more comfortable. If you get aluminum seats and don't have enough "natural" cushion", these inserts are worth their weight in gold.



Our new E30/36/46 Trans mounts installed. Drives better than ever. New motor mounts (went form 95A to 70A poly - the stiffer 95A poly mounts were too brutal for the M42 4-banger) and trans mounts (80A) make for a smoother drivetrain than before, but you can still tell they're poly. Shifts much smoother now. Might be too stiff for some with the 4 cylinder but with a 6 they are smooth.



Here is our new E30 steel rear shock tower reinforcement brace. Pretty slick and super stout bolt-on stiffening device.



That's me getting in the trunk installing the new rear shock mount brace. Makes a great mount for...



The AST4300 rear shocks' remote reservoirs

Cheers,