277 replies to this topic

[ed4ran]

well if it was a good one i could use it when i get to the point of putting it all back together,
but at the moment i need one to measure up,
unless i can get something special made up out of alloy which would make things alot easier.

[mrbell321]

Really shouldn't hijack Ed's thread but...

The gearbox's input needs to have no load very little inertia so that the synchros can match it to the output side being driven by the road wheels. I think that means a clutch, but some very clever electrics could set motor speed to match.

We're going to hijack it anyway, so....

W/o using the clutch, I don't believe the synchros are really engaged anyway. At least not in the same capacity they are w/ the clutch. It easy enough to pull a car out of gear w/o the clutch. The engine speed will drop and will eventually match the speed of the next gear. At that point, it should slide right into gear. Basically, you're using patience(waiting for the speeds to match on their own) as a replacement for the synchros(which match the speed for you). The syncros probably help for that last bit, but at that point, the speeds are already really close anyway.

[Ethel]

we'll be getting a ticking off from a mod anytime soon

Why not start a thread for your cunning plans ,we've had another 'leccy Mini project- rwd, though not seen any activity on it for a while.

Yep getting the 2 halves of the synchromesh running at the same speed is what you need. Doesn't it defeat the point of changing gear if you wait until you've lost enough road speed to slot the next cog in. I still think you need a clutch or some clever electrics to actively get the motor going at the right speed for the next cog.

As far as mounting your motor over the box - at a rough guess you'd have about 120mm clearance from the axis of what would have been the crankshaft to the gearbox internals. That's from the engine stroke + half a big end.

[mrbell321]

Yep getting the 2 halves of the synchromesh running at the same speed is what you need. Doesn't it defeat the point of changing gear if you wait until you've lost enough road speed to slot the next cog in. I still think you need a clutch or some clever electrics to actively get the motor going at the right speed for the next cog.

Well that depends if you're accelerating or decelerating, but the real answer is "no".
Say you've gotten up to 50mph in 4th gear, and you want to be in 5th. I'm going to pick arbitrary RPMs here, 50mph=4000rpm in 4th gear. 5th gear will be lower RPMs so 50mph=3000rpm. Pop it out of 4th, wait for the RPM to hit 3000rpm and it will slide right in. The only time you waste is waiting for the engine to drop(while not powered) from 4k to 3k and your input and output shafts are going to be going the same speed. Of course you're going to lose a bit of vehicle speed so we'll say it actually matches up when you've hit 2900rpm which would be about 48mph.
When you're decelerating. you're cruising at 3k in 5th(50mph again) and you want to downshift to 4th. Just pop it out of gear, rev the motor to 4k, and it should slot right into the lower gear.

I really don't know how bad this is for syncrhos or dogs, but i know it works, and it's not TOO much slower than an average shift.

[mighty mini jack]

Any update mate ?

You shall be having a few Pm's from me

[ed4ran]

No not really, waiting for replies to emails etc. I dont have easy access to it at the moment so that doesnt help either.

[mighty mini jack]

Ah, thats a bummer...

Hope you get some done soon matey, ive started saving already, will be getting the engine at christmas and can machine the bits at my b-tec diploma soon got that bit sorted, did you get the crank ends machined in the end, i might be able to help?

[ed4ran]

In the process of sorting that out, just waiting on replies.
Still determining the most suitable method of doing it without compromising strength, but trying to minimise engine modifications.

[mighty mini jack]

Yeah, just really cant wait to do this, should be good designing it all agian lol.

Do you live in lincoln ?

How long do you think you are away from getting it in and roughly running

[ed4ran]

Used to live in lincoln, moved away 6 months ago to start a new job, but family are still there so i go back often.
Should be sorting a garage soon so will have to room for playing with engines and cars again.

I couldnt say how long it would be to get the engine running on the gearbox,
but it all waits on measurements from the crank end to get the flanges in place then everything else can be done.

[mighty mini jack]

Ahh right... would be pretty cool to see it when its up and runnings, im only in grimsby

[ed4ran]

Not been up to much, apart from getting stressed with house stuff not getting very far.

Tinkered at the weekend with this but there still isnt much i can do until the end is sorted.
I have trimmed the flanges between the engine and transfer case, and have also managed to bodge the crank end (from SwiftMini) on,
at least now its stable and doesnt wobble giving me something to line things up with.
You can turn the engine over with it so its pretty stable.

I have done my best (due to not having precision measurment tools) to check the true-ness of the crank end and it seems pretty good!

Main thing is to know the distance between the end of the engine and the transfer case as this is the only real variable the rest just lines up and cant / wont change.

Ed

[mighty mini jack]

Any progress?

[MIGLIACARS]

Any progress?

did this ever get finished as it was a nice idea

[bigchief3679]

c'mon ed. hit us wit an update man! how are u bolting up the nose? i used metric allen head bolts that were countersunk to avoid fouling the bronze bushing, how bout the oilpipe n stuff?!

Edited by bigchief3679, 01 February 2009 - 03:51 AM.