Morning all.

I'm in the process of doing a full restoration on a '69 Sprite, and whilst I'm there upgrading it with a 1.8 VVC K series, type 9 and Caterham based rear suspension. All that side of things is fairly straight forward and simple-ish. The problem I have is what to do with the front suspension.

I could keep the stock uprights and their trunnions, but I'd rather not. They wear out and are generally a PITA to get rid of the play. However, a more modern upright with BJs and bigger brakes would be ideal. Since my wishbones are knackered, I either need to buy or make some new ones anyway, so I can make them to suit what ever upright I have. I already want to make upper wishbones and new mounts to do away with the lever arm dampers and fit telescopic shocks, so again, I can make them to suit and/or to fit round a coil over. The main issue really is what to do with the steering. The Sprite has it's rack mounted high up, and the steering arms are at the top of the upright.

So far, the two easiest options appear to be Sierra or MX-5 uprights. Both are cheap, widely available and have cheap brake upgrades. So what do you lot reckon? Is the weight of the Sierra upright worth it? Is the MX-5's geometry ok? Is there better one out there that I don't know about? Whilst I could probably make my own uprights, I would rather not. I could do with a start point, and should I ever come to sell the car, recognisable easily sourced parts are better for a road car like mine.

Or, if someone already has a bolt on kit going for a tenner, that would be lovely!

People used to race these, what did they do?

Nothing wrong with trunions so long as you keep them greased about every 1000 miles.

With MGs the problem is usually the king pin corroding/ wearing due to water salt & dirt ingress, which is a pity because the geometry isn't too bad for a light weight car.

Problem with replacing it with something else that will give a decent amount of KPI and castor, because they are designed for heavier cars both the popular Ford solutions won't allow that. From a web search I know the MX5 front end can except more than 5 degrees KPI but I couldn't find the factory KPi, camber and castor settings.

KPI and Castor are closely linked as they have a big effect of camber in turns

Were not the later versions of Spridgets Triumph based?
Perhaps those might yield 'slightly more moderne' bits than the pre war Morris Minor ones used in early midgets?

The Sprite/Midget didn't use any Triumph front end parts nor did it use Morris Minor front end parts, it all came from the Austin A35 & A40 parts bin.

Prior to 1948 Austin and Morris were not the same company although key personnel (including Len Lord and Alex Issigonis) did move between the two. All the main mechanical components we think of as BMC in origin were in fact from the Austin side of the merger A, B and C series engines, gearboxes and axles.




[Edited on 28/3/11 by britishtrident]

As BT says, the standard set up isn't too bad at all, it just wears out quicker than I want it to. What I'm looking for is a fit and forget option. This will be my only car, and as such I don't really want to be spending time greasing it all the time if I don't have to.

As for the racers, all they really did was fit a proper upper A arm to the suspension, if the regs allowed, and carried on. Greasing a race car regularly is no bother however.

So the MX-5 stuff might be a goer then. Now all I need to do is figure out a way to overcome the top mounted steering arm set up, and I might be able to think about mocking something up.

Triumph front end may use trunnions but would get rid of the king pins, it works fine on 1960s /70s Lotuses.
Not all Triumph front ends however are the same later Herald & Sptifire got a cheap version that isn't nearly as adaptable.

Caterham has an improved Triumph upright, you could also consider Fortd Cortina uprights. Not sure how the connection to the steering rack is realized.