AC Dodd
Turbo Mini Forums

My first RTS was not right after sending it for machining and balancing etc to people not too familiar with minis. I decided to start over and using new parts sent all the bits to AC Dodd who agreed to machine and balance the assembly.
It needed refacing as the flywheel was distorted even though it was a new minispares item, the horns needed a skim to get the diaphragm flat and finally the complete assembly was balanced.

Got it back, very happy with the excellent service from AC. Clutch works perfectly with no issues.


I would not hesitate to give him any of my engine work.

Don't let him balance your rods...

is this a bad review of minispares too?
about to build an RTS and wondering if you could post a breakdown of the costs of having AC Dodd build it?
(Or can PM, would help alot!)

Edited by Will on 16th Dec, 2016.

A few people have said the Minispares billet flywheel distorts once the ring gear is fitted to it. Mine was like that. AC said all the ones sent to him are like that

I built the Rts myself, i only had AC do the machining and balancing to put the flywheel right

Thanks for the plug!

Please explain Vegard?

Ac

Yes I call I a crude balance. Still do it this way. This is explained to customers before the work commences.

Ac

Crude balance, as in "NOT balanced"?
*facepalm*

Well, you might as well leave them alone then.
I stand by my comment.

If you buy this and a proper scale, you can do it properly. Why not?

https://www.ebay.co.uk/itm/321405704866

Edited by Vegard on 23rd Dec, 2016.

Original rod sets are 2 to 3 grams variation. This is reduced to within 0.1 gram. This Is considerably better than stock. Its a similar argument to those who.also say you cannot statically balance a flywheel and clutch. Clearly you van if you try it (as I have for 25 years). Not saying tho mehod os the correct way to do it either but it does improve things a great deal. Nothing is perfect, the work simply moves the components much closer to optimum.

Ac

Also to this is my hobby and simply do not do the volume to warrant an expensive jig. My work is focused on road engines that rarely see over 6.5k rpm this method works perfectly well in the window I operate in.

Ac

I did a set of rods in this manner for Tubbs, and can feel no difference between her engine and the one in Betty which is bog-standard in terms of smoothness.
I can see the thought behind matching the cap weights and the beam weights, but without knowing where the excess weight actually is, you could well be making the overall balance far worse...

Without knowing how the caps & beams were selected in the factory, we're guessing as to the component selection.
With a pile of raw castings, did they weigh the bits individually and match them as best as possible before assembly, or have a crude end-to-end rig with generous tolerances ?
We know the overall weights are matched to within a few grams, but without checking a pile of untouched rods it's a big question mark...

Sometimes, a good rule of thumb is to remember that the Factory generally did know what they were doing.

Metric is for people who can't do fractions.

Good point and I do have an answer. In the last 4 weeks I was discussing this with Neil Slark and he was able to show me an original factory weight table for A+ conrods which were graded into colour coded sets. The colours painted on each rod. They were then selected by a matched colour set. These sets were 2 grams apart. There was not end to end balance process. Simply weight alone.

Ac

Interesting.
I'd love to know the order of assembly/machining of the rods. I'd guess that boring the big end would be last, with the little end next to last.
Would they drill the bolt holes first, or after machining the faces ? I'm guessing that drilling first would allow the halves to be placed on a fixture for quick machining.

Anyway, through the rambling I'm getting towards the point that BMC/BL/Rover would be aware that balance is a good thing, and would set up their mass production to get it as close as possible (assuming high quality castings) without actually balancing anything.

Comes back to checking a stack of untouched rods...

Metric is for people who can't do fractions.

Big ends are machined after the caps are in place.
Selective assembly is the technique used by the factory. The actual varience in the rods is around 30grams. Selecting them gets this down to 2 grams. Remember mass produced cars are built to a price. Rover ase rods to a nominal 30gram difference and used selective technique to get a balanced set within 2grams. 2 grams was what the factory deemed acceptable and cost effective given reliability/warantee issues in the reve range the engine was designed to operate in.

Ac

Welcome to the forum AC. There is some good Turbo info on here.

I'll be honest, my rods are only balanced like AC described. If I was in the 7.5k+ territory, I'd do it differently...

Thanks for that turbodave, I know other engine builders do the same too.

Ac

Well let's not fool ourselves, the best way is to balance end-to-end.
I just don't see it as essential with my builds; I'd sooner put my efforts elsewhere.
Kind of like running a wedged, bladed crank... 100% stock 6581 crank here (not even reground) and am happy to be called a Luddite LOL, but again, if 8k + was on the radar, things would be different.

Edited by TurboDave16V on 25th Dec, 2016.

Anyway, back to this MS billet flywheel buckling; is that the same as the MED one?

Edited by TurboDave16V on 25th Dec, 2016.

I had the MED Verto billet flywheel, the one they were selling a couple of years ago and my machinist said the pedestals were all different heights. The ring gear was also wonky. I would not buy one of these from MED again. Different flywheel to the one i recently bought from minispares

Edited by dazibee on 25th Dec, 2016.

Not tried the MED one. However thin section flywheels with offset ring gear will all warp when the ring gear is fitted. They need to be machined after the ring gear is fitted to ensure flatness.

Ac

I just looked at the MED site; definitely different to the Minispares version being they are machined through on the lightening pockets... The interesting thing about the MED is they use m6 screws to Dutch / scotch (whatever your preference in lingo) the ring gear to the flywheel. This likely means very little intereference fit, which means little warpage.

http://www.med-engineering.co.uk/products/...-light-flywheel


http://minispares.com/product/classic/C-AEG422.aspx

Edited by TurboDave16V on 25th Dec, 2016.

MED modified their verto flywheel a few years ago to try and stop this problem.. Not sure how well it worked. I have an alloy one which lots of people said wouldn't work but it appears fine so far.

Agreed, if the interference fit is reduced then the warp should refuce/dissappear. That MED one looks like it could be just the ticket. You would need to check one and see what gives. In any case it still may not change the need to machine, as you will still need to check that the horn height is correct for the diaphragm and friction disc combination you are using.

Ac