Bent Crank Shaft?
Discussion
I am rebuilding a Lotus Twin Cam, crank was reground by previous owner with +10 mains, and all the journals are good and round, but when I bolt up the main bearings caps to the right torque the crank is far too tight. I'm asking myself if the crank is bent.
I'm thinking how to check this at home, if I remove the bearings and caps from 2, 3 4, and bolt up bearings 1 and 5, and put a dial gauge in turn on 2, 3 5, any run out on these bearings would indicate, either that the crank is bent or that the regrind was not done in line.
Is my thinking right or is there some other DIY check.
Thanks
I'm thinking how to check this at home, if I remove the bearings and caps from 2, 3 4, and bolt up bearings 1 and 5, and put a dial gauge in turn on 2, 3 5, any run out on these bearings would indicate, either that the crank is bent or that the regrind was not done in line.
Is my thinking right or is there some other DIY check.
Thanks
I suspect the regrind is not straight, i.e. not all the bearings have been ground on the same axis, that's what I meant by 'bent when it was reground'. i don't know who did the regrind.
The Elan is one of only three in S E Asia, the previous owner spent a fortune, spyder drive shaft, mick miller water pump conversion, uprated cams, etc, but it was built by a butcher, water ways blocked with sealer, metric nuts forced on UNF studs, and the rebore was not in line.
Block has been rebored correctly. I was looking for an easy check on the crank, with what I have in the garage, so 'turning' the crank with a dial gauge is a first step as I have these, everything I read talked about doimg it on a surface plate with v blocks, but I thought it could be done in situe.
Plasgauge is next but that means a day trip to drive out to a specialist supplier.
After the previous owner had the car rebuilt, it never ran right and stood, he then died and the car stood for 7 years under cover in Mellaca, before I bought it. Rust is not an issue, but there were 5 carrier bags of bones on the 'transmission tunnel' where the rats lived.
All the bearing caps are correct and aligned right, they where all marked on the original casting, and were stored in order.
Ok -10 or +10, bearings are refereed to as +10, so lets not get pedantic.
Your advice appriciated
The Elan is one of only three in S E Asia, the previous owner spent a fortune, spyder drive shaft, mick miller water pump conversion, uprated cams, etc, but it was built by a butcher, water ways blocked with sealer, metric nuts forced on UNF studs, and the rebore was not in line.
Block has been rebored correctly. I was looking for an easy check on the crank, with what I have in the garage, so 'turning' the crank with a dial gauge is a first step as I have these, everything I read talked about doimg it on a surface plate with v blocks, but I thought it could be done in situe.
Plasgauge is next but that means a day trip to drive out to a specialist supplier.
After the previous owner had the car rebuilt, it never ran right and stood, he then died and the car stood for 7 years under cover in Mellaca, before I bought it. Rust is not an issue, but there were 5 carrier bags of bones on the 'transmission tunnel' where the rats lived.
All the bearing caps are correct and aligned right, they where all marked on the original casting, and were stored in order.
Ok -10 or +10, bearings are refereed to as +10, so lets not get pedantic.
Your advice appriciated
Put crank back after checking everything, and it now turns nicely by hand with a rag on the crank timing wheel, with the pistons in place, before I had to put a spanner on the crank to turn it even before I fitted the pistons, Only difference is that first time I used new old stock bearings bought locally, were as now I have new bearings from Paul Matty. The old bearings all look fine.
So not really sure what the issue was but all OK now.
So not really sure what the issue was but all OK now.
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