Something funny...[Nitro Funny Car build thread]

Chevyonfuel

Onto the big thing, which was kept under wraps (sort of) until today.

I’d looked at buying a used chassis back at the start of the year, which was a lovely bit of kit, but sadly was snapped up before I was able to get the funds together. So, next up was enquiring about a new build, with a chassis being fabricated from the ground up. To my surprise the cost came back lower than I expected, all things considered. The issue would be timeframe (given how little time is left) and the amount of US sourced hardware that is required.

Fast forward to a couple of months ago; I was contacted regarding a chassis that was soon to become available, due to it being retired from service at the end of the 2015 season. I was asked if I was interested in purchasing it as a rolling chassis - the decision making process took all of a second.

The chassis was built in 2011 by FGR Motorsport and was powered by a 417ci nitro burning Donovan (the race bred variant of the 392ci early Hemi), and has run 6.0/232mph in Fuel Altered guise; the quickest & fastest in Europe (also the fastest Donovan powered Fuel Altered in the world). The fabrication work required to convert it for use as a Funny Car is substantial enough that it’ll take a couple of months (63 days by our build programme), but it’s a quicker and cheaper process than having a new chassis built from scratch. FGR are handling the chassis updates and body fitment – it’s looking more promising than it was, but Easter is very quickly approaching.

Some snapshots of the chassis back during its original construction:

                                                                                                                                                 
In its previous guise as a Fuel Altered (Fiat Topolino body with some aero tweaks).

                                                                                                                                                 
The previous power plant, a 417ci Donovan with an 8/71 blower and shotgun injector. The fuel tank and oil tank sit ahead of the front wheels to aid weight distribution (keeping as much weight over the front end as possible).

                                                                                                                                                 
The titanium roll cage shield, mandatory for Fuel Funny Car but also a good safety feature in this application in the event of rear tyre explosions and barrier grazing. The chassis has a 10.1E tag, but would tag to 10.5, the current Fuel Funny Car spec. It makes future plans easier for when I take the next leap to big show Funny Car, but that’s many years away.

                                                                                                                                                 
A Strange Engineering top loader rear end. These are the modern race bred solution for rear axle design. Up to a point, a strengthened Ford 9” design will suffice (courtesy of a fabricated housing and weapons grade 3rd member & half shafts) but the big tyre, big horsepower cars need something stronger. This is a 9.5” variant, which was used in big show Top Fuel and Funny Car many moons ago. These days it’s a logical choice for nostalgia nitro and top methanol funny cars & dragsters both in Europe and the US.

In terms of work required, the front overhang will need reducing to squeeze under the body, and there’s potential that the roll cage needs lowering in order to get the correct ride height for the rear of the body. New motor plates will be required for the change of engine and the fact that running on smaller tyres (34.5” rather than 36” diameter) drop the rear axle line too much in its current configuration. The rest of the fabrication work focuses more on the body itself and the internal tree and tinwork structure.

                                                                                                                                                 
As a tribute to the chassis’ previous employment, I had some novelty license plates made, one for the car, and a couple that were passed on to the previous owner and driver from when Chaos ran in the Nostalgia Fuel Altered Association.

In summary, it’s getting there. Now onto the shopping list of bits that are either off the shelf (fuel fittings and hoses) or custom bits like the clutch and transmission which should follow at the end of the month.

RBZ5416

So this is just a stepping stone to AA/FC? That's some planning!

Is Easter the first round of the nostalgia series?

Chevyonfuel

The long term plan is to move up to the big show stuff, but that's several years away. I'd wager that it's less fun than the nostalgia stuff, and the money involved is above my budget at the moment. However, it'd be the pinnacle and hopefully one day it'll happen (having to curtail my AV spending habits will be tough, I've managed to not upgrade anything for just over a year now!).

Easter's the first points round yes, and the first event for the class in a formal fashion - there's a few guys in similar stages of build, thrashing to be ready in time .

Chevyonfuel

Yesterday started at a very wet and windy trailer, with a rolling chassis and many many nuts, bolts, washers, brake lines, fire bottle lines, harnesses and tin work still attached, along with the back axle which is a 3 man lift and hurts if dropped on your tootsies...

                                                                                                                                                 

After lots of spannering, coffee, jammie dodgers and discussions about the weather, the chassis is now ready to go off for blasting (fine glass - so as to remove the paint but leave the chassis in a nice smooth state).

Next up - the body, engine, transmission, clutch and associated bits will be sailing across the pond, hopefully for early December to start thrashing over the winter .

Chevyonfuel

Just a quick update, the chassis should be back in the workshop this weekend following blasting, to get it back to bare chromoly. In the mean time, the body is complete, crated and ready to ship.

Today I collected some chassis / body related goodies. A mixture of fittings and fixtures for mounting the body, and brackets, springs, wheelie bar components and the like.

There should be a proper update on Sunday with a bit more detail about what makes the chassis rather a good choice

Chevyonfuel

Yesterday the chassis came back from blasting. The paint and primer are gone, all that's left is bare, unprepped chromoly (which is a bit rough). This will be acid treated once all the welding and fabrication jobs are completed.

Onto the bits that make the chassis a great start point for the car.

Most Funny Car / Altered chassis' are rigid, they may have bolted A-Arm front ends like this one, but in the area of the car working particularly hard between the motor mid plate and the back axle, more often than not everything's welded.

In this case, the cross braces are slip jointed to allow the chassis to flex. This enables the torque to be transmitted through the chassis and to the back wheels. As there's no suspension system or shock absorbers, it plays a big role in getting the car to hook-up.

Next up...the body, engine, transmission - I'm getting a little behind with shipping and there's issues to sort before we get into winter weather and boat delays etc. Fingers crossed something gets resolved in the next few days .

Chevyonfuel

Brief update...

The chassis is back on the jig which it was born on. After a dimensional check, it's in remarkably good shape (over time, chassis rails start to sag ever so slightly). There was a very slight difference between right and left top rails, which is an easy fix, as an adjustment on the front A-Arms (see below) would dial out the deficit between the two sides.

The next job is lowering the back axle. The chassis was originally built for a 36" tyre as per big show Funny Cars. With Nostalgia FC rules dictating a 34.5" tyre, it drops the chassis sufficiently that it would ground out at its lowest point. The corrective action is to drop the axle 1.5" - 2" and re-mount the motor, mid plate etc to ensure everything sits in a straight line. This involves a line-up bar (not very scientific). The new mid plate arrived last week (4130 chromoly) - it's drilled for this engine combination and features some very tidy fabrication, despite being a relatively straightforward piece.

                                                                                                                                                 

That's likely to be it for this year in terms of updates, but I do have some parts inbound that'll be worth waffling about briefly.

As it stands, the body is awaiting shipping, as is the engine, transmission etc. With Christmas to get out of the way, it'll be mid to late January by the time, those bits surface.

I'd hazard that Easter is unlikely as a debut due to losing a month of programme due to logistics issues, but we're trying to be ready in time for the 2nd event of the season, in late April .

Chevyonfuel

The first of the big hardware spares to appear, is the spare clutch. In reality, there’s not much call for a complete spare as you’d generally carry spare friction discs and floaters, along with springs and levers, but this was a good opportunity to pick up an all titanium unit with spares, for the cost of a new, lesser spec unit. It’s a 10.5” 3 disc glide-style unit built by East West Clutches. The fundamental design of the lockup clutch hasn’t changed since the 1960’s Crowerglide design, the only real difference is the throw-out of the levers under centrifugal force is controlled by a bearing when you’re talking about big show cars that are trying to harness 8000 horsepower. In Nostalgia racing, we still operate the clutch the old fashioned way.

                                                                                                                                                 

When you only have 2000-3000 horsepower, good old fashioned nuts and bolts (literally) do all the work. As the clutch is essentially no different to a twist-n-go moped, you add or subtract weights (the nuts and bolts you see fixed to the fat ends of the 6 levers). The centrifugal force rotates the levers, and the radius of the lever (sat within the hat / top cover) contacts the discs, compressing the pack and locking the clutch up. You can get quite fancy with the levers, and they’re a bit like cam lobes in that different ramps, radii etc are available, but the crux of it is, more weight locks up the clutch quicker (about 2 or 3 seconds into a run, you’d expect to be fully locked-up).

Two over variables to help with fine adjustment are stall speed and air gap. Stall speed is controlled by winding in the 6 springs you see. These control the initial lock-up of the clutch, which dictates how much off throttle creep you’d have if you were to let go of the brake (a bit like in a regular automatic transmission equipped car).

                                                                                                                                                 

Air gap is as the name suggests, the physical gap between the clutch pack and cover. At the hit of the throttle, the force going into the moves the clutch pack in the available space – a small gap will ensure it starts the lock-up process (about 0.040”). A larger gap (say a maximum of 0.060”) will make the clutch hit harder and is an option when the track has good traction over the first 60 feet or so.

The actual clutch I’ll be using is still being built by the good folks at Titanspeed in the US. It’s inherently similar to the spare, but a more modern design. Still 3 discs, still centrifugal but a bit smaller, lighter and lower maintenance (as much as these things can be). Once it arrives, I can explain the differences. In theory, there should be a new puke tank, axle mounting brackets, front wheels and host of small bits arriving shortly...

Chevyonfuel

A few days earlier than expected, the primary clutch arrived yesterday. The differences between this and the 10.5" spare (above) are mostly visual, but have some performance and usability benefits.

                                                                                                                                                 

Unlike the spare, this is primarily of aluminium construction. The only titanium parts are the 6 stands, which feature upgraded 9/16" stand bolts. The stands themselves, along with the top hat, are the standout features that set the Titanspeed design apart.

R&D has shown that the square drive stands are stiffer than circular ones and therefore deflect less, allowing reduced warpage of the floaters that sit between each disc. The top hat design and relocated levers allow for some weight reduction (around 10lbs), which although not a lot, makes a difference when considered as rotating mass. Less mass being bounced around on the end of the crank, helps the rear main bearing and lowers the force being transmitted through it.

The nature of the design makes adjustments and basic housekeeping a bit simpler than 'regular' glide clutch designs. Since you're adjusting the clutch every run to essentially zero it due to disc wear after each run, the less movement and quirky activity to distract from just checking disc wear and air gap, the better.

Back in the Fuel Altered days, the Titanspeed kit was becoming the hot ticket, but I was never in a position to upgrade to one, so it's been nice to crack on and do it properly this time around.

Next up, hopefully in a few days, the new axle mounting brackets should arrive (another Baumgartner Race Cars fabrication job), along with a new puke tank from S&W Race Cars. Piccies soon...

Chevyonfuel

One last update (last of the year I expect).

The back axle has been lowered 1 3/4" to cater for the smaller tyres. There was quite a bit of work involved, including adding a secondary bottom transverse bar as the pinion of the diff now encroaches into what's termed a tech bar i.e. one that has to be there for the chassis tag.

The motor mid plate was dropped in to see what work is needed in terms of ajustment. It's almost there right out of the box.

                                                                                                                                                 

After that a dummy block (borrowed from a big show Funny Car) was dropped in, and a line-up bar put through it to simulate the centreline of the drivetrain. This provides a straight line so the back axle in its new location, can be rotated to be in line with the rest of the drivetrain.

The body and engine should be on the sea and floating their way here over New Year - so by the end of January, there should be a curvy Corvette body being mocked up...

On a personal note, thank you chaps for taking an interest in the build and the thread, it's been nice to branch out and talk to people outside the very small racing community about what goes into a car of this ilk.

Merry Christmas chaps