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+--- Thread: Choice of Rear Axle (/showthread.php?tid=1289)
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Choice of Rear Axle - Jamie - 05-06-2018
Good afternoon.
I have recently purchased a Ruby chassis, running gear and matching V5. From memory, it is late model, a 1935 version, I think. As it has no body or engine, I plan to build a new shell to and find a suitable engine. I intend to keep the machine to use, not to sell on again, so wish to make it to my tastes. Although I could source and rebuild another A7 engine, I understand that with some minor modification, a Reliant engine can be fitted which I believe could prove cheaper than a decent rebuilt A7 engine.
Does this necessitate a change of the rear axle or does the gearing on Ruby axle suit it the Reliant engine?
Thank you.
Jamie.
RE: Choice of Rear Axle - Phil Kingdom - 05-06-2018
I have seen a few specials and saloons with Reliant engines and all use the standard A7 back axle, if you are thinking of using a 850 OHV Reliant engine they are only 40 BHP when new and plenty of A7 racers can put that sort of power out and more without any trouble. The Reliant engine can be fitted fairly easily to an Austin chassis if you fit it forward and high on top of the chassis rails you can use the original prop shaft, if you fit it between the rails a shortened prop is needed and a non pre engaged starter motor, you will also need to modify the exhaust, throttle and make a clutch pedal as well as making engine/gearbox mounts. Also choice of wheel size will also make a difference as to how the car performs
RE: Choice of Rear Axle - Jamie - 05-06-2018
(05-06-2018, 05:48 PM)Phil Kingdom Wrote: I have seen a few specials and saloons with Reliant engines and all use the standard A7 back axle, if you are thinking of using a 850 OHV Reliant engine they are only 40 BHP when new and plenty of A7 racers can put that sort of power out and more without any trouble. The Reliant engine can be fitted fairly easily to an Austin chassis if you fit it forward and high on top of the chassis rails you can use the original prop shaft, if you fit it between the rails a shortened prop is needed and a non pre engaged starter motor, you will also need to modify the exhaust, throttle and make a clutch pedal as well as making engine/gearbox mounts. Also choice of wheel size will also make a difference as to how the car performs
Phil.
Thank you for your reply, which is reassuring. I was not sure whether the ratios would be entirely to cock or not. I confess that I am not sure what size wheels are on it yet.
I strongly suspect that the answer is "no", but does the Austin gearbox fit onto the Reliant OHV engine, by any chance?
Regards,
Jamie.
RE: Choice of Rear Axle - Phil Kingdom - 06-06-2018
I don't know if the early SV Reliant engines would fit an Austin gearbox, but the later ones will not, using the Reliant box makes life so much easier and the output flange fits the Austin prop shaft, you only need to extend the gear lever and make a pedal box for the clutch cable,the handbrake lever has to be tweeked a bit but you can use the original Reliant gearbox mounting bracket. I have seen one installation where the engine and box were mounted above the chassis on two pieces of 2 inch angle iron across the chassis the front angle iron being bent up at the ends to take the angled rubber engine mounts as simple as that, although to me it did not look right! The engine has to be above the chassis rails to clear the front pulley and the chassis nose piece if you don't want to shorten the prop shaft. Installing the engine between the chassis rails is a little bit more complicated, to give clearance to the sump the engine has to be moved back so the prop has to be shortened, when I installed mine I also moved the steering box back to clear the pre engaged starter this also meant shortening the brake adjuster rod and lengthening the drag link arm, the hand brake lever was also moved backwards, this is fairly easy to do by cutting down the original lever to clear the gearbox and fitting another complete lever assembly to a plate further along the rail and connecting them with an adjustable rod.
RE: Choice of Rear Axle - Stuart Giles - 06-06-2018
Re. the starter motor issue on the Reliant OHV motor, the engine plate at the rear of the motor can be reversed so that the starter then sits on the passenger rather than the driver side. It's necessary to cut a small chunk out of the gearbox bellhousing to provide clearance for the starter's Bendix when the starter is fitted on the left hand side. Pretty well all the Reliant engined F750 cars were set up like this as the driver usually sits alongside the motor.
RE: Choice of Rear Axle - Jamie - 06-06-2018
Phil: Thank you for the guidance on whether the Austin gearbox could be fitted to the Reliant engine. As there is no shell on the car, it will make access a lot easier.
Stuart: Thank you for this information, which is encouraging. I shall look into the F750 cars, primarily for interest.
Regards,
James.
RE: Choice of Rear Axle - Phil Kingdom - 07-06-2018
Thank you for that information Stuart, with the OHV Reliant engine mounted between the rails on a Ruby chassis the starter motor is in the way of the steering box fitting the starter on the other side would be the ideal answer to this problem. I am currently having one of those I wish I had thought of that moments LOL.
RE: Choice of Rear Axle - Jamie - 24-06-2018
(05-06-2018, 05:48 PM)Phil Kingdom Wrote: .......... Also choice of wheel size will also make a difference as to how the car performs
Phil,
I have checked and found that they are 17" wheels.
Jamie.
RE: Choice of Rear Axle - AustinWood - 24-06-2018
On the whole, with the Austin engine & gearbox the lower the back axle ratio the better. They tend to be overgeared.
RE: Choice of Rear Axle - Stuart Giles - 24-06-2018
(24-06-2018, 03:30 PM)Jamie Wrote:(05-06-2018, 05:48 PM)Phil Kingdom Wrote: .......... Also choice of wheel size will also make a difference as to how the car performs
Phil,
I have checked and found that they are 17" wheels.
Jamie.
Early Ruby rear axle ratio is 5.25:1 that works out at just under 15 MPH/1000 RPM in top gear with wheel/tyre @ 26" diameter. The OHV Reliant motor is much more free revving than a standard A7 motor, should be OK at a sustained 4000 RPM as long as there's reasonable airflow to the sump or have an an oil cooler installed if not.