This is
my 1973 MGB that was
purchased in July 1999. The car had been nicely restored by
Walter Smith, the talented previous owner, who had started with a
(cockpit) fire damaged unit. The body colour is now a VW/Audi red.
This is
my 1973 MGB that was
purchased in July 1999. The car had been nicely restored by
Walter Smith, the talented previous owner, who had started with a
(cockpit) fire damaged unit. The body colour is now a VW/Audi red.
The interior was completely redone during the winter of 2001/2 using a kit from Victoria British which helped achieve a class win at the MG Car Club of Toronto "Tire Kicker" event in 2001.
Excessive oil consumption (a litre per 200 km), plus the absence of an overdrive gearbox, led me to investigate a new drive train. An engine rebuild was one option and whilst good OD gearboxes were much sought after, those seen at local fleamarkets were generally offered "As is" with no guarantee as to their condition.
Surfing the web identified the option of fitting a 5-speed conversion and sources were found in the US, UK and New Zealand. A kit produced by Hi-Gear Engineering Ltd. in England, which uses a Ford type N (Sierra) 5-speed gearbox was selected – this had been reviewed positively in an UK magazine article on a modified MGA fitted with a 2.2 liter MGB engine. The ratios match the MGB original box well with a 10% higher second gear and 5th gear the same as the OD at 0.82. The 5-speed conversion kit, a refurbished gearbox and a "club" engine were all sourced from the MGOC in Swavesey, England (close to Cambridge, my hometown). The following pictures summarize the work which was undertaken with the aid of a borrowed engine hoist.
The new engine was unpacked and prepared prior to looking at the gearbox and conversion kit. Removing the flywheel from the old engine proved a challenge – one of the bolts had to be drilled out – but it was eventually installed on the new engine together with the original backplate and a new rear oil seal. This was followed by a new clutch assembly, carefully aligned using the official tool. The first words on the 5-speed kit instructions were "Remove the clutch cover and driven plate….". OK – the practice was useful. Removal was required to replace the crankshaft bush since the Sierra box has a smaller layshaft diameter. The new clutch was reinstalled following modification of the alignment tool to match the new bushing diameter.
The Sierra gearbox was bolted to the transition housing, the original clutch release lever installed and the assembly attached to the engine using the new hardware provided. The new drive shaft had a spline on the nose for insertion into the back of the Sierra gearbox and a flange at the rear matching the one on the rear axle (unlike the MG driveshaft which has the sliding spline between the front and rear universal joints). Installation of the new engine and gearbox into the car, including insertion of the drive shaft splines, went smoothly and was the only operation where it was felt prudent to have some assistance (my adult son). The kit included a rugged new crossmember that supported the rear of the gearbox utilizing the existing tapped mounting holes in the frame. The remaining under-car work included mounting the original clutch slave cylinder on the bell housing, connecting the speedometer cable to the gearbox, wiring the reversing light switch (which required a change from spade to bullet connectors) and bolting up the rear drive shaft flange. Fitting of the gearshift lever from inside the car located it dead center in the tunnel hole, validating the offset. Installation / connection of the remaining auxiliaries, carburetors, exhaust pipes, wiring and piping went smoothly.
The kit provided instructions on how to determine the speedometer drive parameters and suggested that recalibration of the head would be required. Calculations indicated a speedometer drive calibration of 1197 turns per mile, which would be within 6.5 % of the original specification of 1280 turns per mile.
Cranking without plugs, as recommended, demonstrated good oil pressure though it was a nerve racking few seconds waiting for the gauge to register. The new engine started OK and several rounds of timing and carb adjustments soon had it running sweetly - oil pressure was a solid 70 psi with 50+ at idle. A test drive proved that all 5 gears and reverse could be found, which was a relief (the shift pattern matches the VW Golf daily driver). The opportunity was also taken to install a Pertronix electronic ignition module in the distributor as a contingency against future points problems. Progressively longer drives were taken and rpm increased as the new engine bedded in. It is understandably much peppier than the tired original and the 5th gear makes 100 kph driving at around 2900 rpm seem quite leisurely. A detailed check of the speedometer calibration has yet to be done however it appears to be quite close since most vehicles still pass me on the highway at an indicated 60 mph! As of November 2002, 3000 miles had been accumulated on the new drive train with many smiles and zero problems.
The 5-speed conversion was truly a bolt-on kit with no modifications required to the car body and the drive train could easily be returned to original by any future owner should purist tendencies prevail. The total cost was no more than having the engine rebuilt locally with the addition of a good OD transmission assuming one could be found.
To send comments or for further information, please e-mail me at bquartermaine@cogeco.ca