Mechanical Modifications

"One of the most beautiful conquests of the automotive guild" - is the direct translation from the Italian Irmscher senator brochure (full brochure on literature page), which I feel just about sums this car up!

I was lucky enough to pick up an original Irmscher Senator CD. Spotted on Auto Trader, the seller forwarded me a photograph:

I was sold on looks alone and the rarity of the beast. No MOT, no TAX...minor work needed for a certificate. Lots of oil coming from front of the engine and the sills were is a sorry state...and it hadn't run for 6 months....errrm.

History:

First registered to the dealer Steven Thompson Cars Ltd. as a Vauxhall Senator 3.0 CD on 06/09/88 with it's original registration mark of F708 YDH. Private plate STC 818 transferred to the vehicle on 31/10/88 when the Irmscher conversion was completed. The car was then featured in the magazine article shown below. The private plate was transferred, to an Astra of all things, on 25/05/89 when the DVLA issued F726 HUE to the Irmscher. 15/6/92 sees the change to it's current plate RIB 8027.

1 Steven Thomas Cars Ltd Demonstration Car (F708 YDH to STC 818 to F726 HUE) 06/06/1988

2 Taylor Hutchinson & Partners, Liverpool 7/06/1989 ( to RIB 8027)

3 Barry Brown Cars, Wigan 22/11/1993

4 Russell, Glenrothes 26/1/1994

5 Nigel, Wrexham 12/01/1994

6 Tony, Doncaster 11/04/1996

7 Me 12/04/2002

Engine modifications:

The originally over square bore x stroke 95mm x 69.8mm stroked to 85mm resulting in 3615cc capacity. Associated long stroke crank, rods, forged pistons and cylinder head modifications. Reprogrammed Bosch LE-Jetronic fuel injection.

Result: 206bhp/5000rpm (+16% over 3.0i ) and 226lb ft/4200rpm (+27% over 3.0i ). In comparison the later 3.0i 24V engine produces 204bhp/6000rpm and 199.2lb.ft./4200rpm.

Suspension:

Lowered all round –25mm. Wheels 8 x 18 Irmscher Spoke Racing (apparently one of only three sets in UK) . Tyres 235/40 ZR18. Rear wheel spacers (+15mm). Front brake upgrade to 324mm x 30mm (using Wilmot callipers, apparently the same specification as a BMW 850).

Bodywork:

Front air-dam with integrated bumper and radiator grille. Bonnet badge. Side skirts including rear door lower panels. Rear apron and spoiler. Modified inner rear arches to accommodate wheels and spacers.

Interior:

Leather & wood capping. There are in fact two wood kits for the early Senator B, one set fits the very early cars which came with no wood trip as standard (above the glove box for instance) the other is fitted in addition to the standard trip. The veneer is an African hard wood known as Bubinga.

Irmscher 4-spoke wooden steering wheel, available in mahogany only, with integrated horn buttons (leather with Irmscher logo) it is 360mm in diameter.

Thought to be one of only 5 cars Irmscher modified for the UK market. The car has the 8 x 18" Irmscher Spoke-Racing-Design alloy wheels, Irmscher body kit, Irmscher 3.6l engine and suspension (springs). Irmscher wood and leather interior. The brakes are Wilwood superlite aluminium 4 pot brake callipers working on 12.8" vented discs (on detectable hubs) up front, with standard senator discs at the rear. Standard Bosch ABS system. The discs and pads had quite a bit of meat left on them which is probably a good thing as they look expensive!

The standard CD specification Senator 3-mode adjustable shock absorbers work with the upgraded Irmscher springs. Yet again I had managed to find one with a digital dash (although standard at the time, a analogue dash was available as an option!)

When I got the car it had been un-used for nearly a year and looking a little sorry for itself. Here's the list!

The alloy wheels had been painted gold and were flaking a bit, but otherwise were in good condition with minimal curb strikes.

The rear electric windows were seized.

The sunroof would only tilt and not slide.

The interior fan was stuck on "slow" no matter what the selector was set to, even off!

The passenger door was dead-locked shut, and the boot was also locked. The central locking had no effect of either of these. I only had a key for the ignition, the key didn't fit anything else.

The sills both looked in a bad way. New sill skins needed all around.

The handbrake was broken.

Last but not least the engine was running very very rich, we are talking clouds of black smoke and a very poor idle with over-fuelling induced miss-fires. We botched a repair by cranking around the air-flow meter spring a complete revolution which at least stopped some of the black smog cloud! Half way home she sprung a water leak at a BP forecourt! Not a simple hose split...no...the gasket between the thermostat housing and the head had decided to let go. At first I thought it might be a cracked housing but a new gasket was fabricated out of the front cover of a A to Z and filled up with tap water we made it home...still spluttering. The solution to this problem was traced to the engine ECU and that story is told on the LE-Jetronic page.

Of course the air conditioning was not working, this runs on the now illegal R12 refrigerant. The "climate control" system seems to work OK. I really want to get the AC system working and will look into converting the system to R138a or using the drop-in replacement RS23.

I got a lot of paper work and a set of Irmscher 16" alloys with the car and she had obviously been cherished before being laid up.

Irmscher recommended tyre pressures for larger wheel/tyre combinations on Carlton B (Omega A) and Senator B models. It's not often you see this sort of information from manufactures.

The Autocar review of this car, 23 March 1988!

I thought I would document this project from the start, mainly for my benefit, so I know how much this car has cost me!

The engine is based on the Vauxhall/Opel 30NE 12V straight six and is designated 36NE. This is a early non cat version (the cat version is C30NE and C36NE). Standard 30NE injectors and ignition system are used. Irmscher chose both ECU and air-flow meter modifications to compensate fuelling for the larger capacity.

Wheel Bolts

Because of the front brake conversion longer wheel bolts are required for front wheels. The rear wheels have spacers fitted and require even longer bolts. Ian Marsh had found a source of long (43mm) wheel bolts with the correct thread M12 x 1.5 and the 60º taper. The supplier http://www.autobahn.co.net also supply a locking bolt in this size. Both types have 17mm heads so you only need one brace! Prices are £1.50 and £5 respectively. I had the bolts cut down by my local machine shop to the correct size. I also painted the bolt heads black using Hammerite smooth spray paint.

Irmscher Omega A (Carlton B)