Which wheels

[stevejgreen]

Re: Which wheels

With regard to possible handling problems here are a a few thoughts.
There are two different diameters of torsion bars. The Standard for all saloons was 21h5747 at 19mm diameter, vans and HD pack were 21h5437 20.6mm diameter.
Through the years there were five different Marina damper ratings available, it is my guess that the Triumph Herald rears used by Marlin were chosen because they fitted, rather than for their specific damping qualities, though of course these can be changed to Spax adjustables.
The unladen weight on the front axle of my Roadster was around 400kg, I have no similar front/rear axle weight figures for a Marina but, the Roadster will have less body weight than a Marina and with the Roadsters engine mounted further rearward, there is even less weight on the front axle.
This means that there is a likelihood that the Roadster front suspension is already very stiff, and my supposition that a lot of the ride comfort will come from the sidewalls of the tyres deflecting, rather than the torsion bars or Herald rear dampers.

I remember that Jez Cox did some suspension calculations published either on the Forum or Pitstop.

To further illustrate my point about sidewall deflection being significant, the standard post 1975 Mk2 Marina Tyre pressures range around F26/R28psi here or there using the standard 165/70/13 tyres here or there.
The accepted recommended tyre pressures for a Mk2 Marina Roadster on 13" wheels, that can be found on this forum or in Pitstop, are in the range of F18/R20psi, a full 8psi (30%) lower. That drop in pressure will result in a more compliant side wall.

The original Marina suspension calculations (however flawed back in 1971) are no longer appropriate and any more changes made will always result in a further compromise between appearance, comfort and handling, all of the installers personal choosing.

That is not to say that any correct PCD wheel/tyre size combination, that can be safely fitted to a Marina/Triumph hub, with regard to centering on the hub and not via the wheel studs, while clearing the bodywork and suspension components etc, is not possible.

The wheels on eBay, given that they originated from YKC, are (unconfirmed) 1/2" offset and profiled to suit a Marina hub (and possibly a Triumph) so should fit safely. The tyres themselves could be in excess of 5 years old and UV light could have compromised their safety, even though they may have full tread, so you are really buying 5 rims so should be discounted from a financial decision.

[Jonathanjeades]

Re: Which wheels

eBay listing ended so I've contacted the seller. Picking the wheels up soon having confirmed the pcd and offset. Will be changing for the 13" kn diamonds currently on my Roadster. So they've gone to a good home ;-)