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Does an engine need to be level?
speedyxjs - 28/10/09 at 02:54 PM

My engine is sitting level atm but the sump is hanging about 2 1/2" below the chassis.

Im thinking about getting some plates made to raise the engine a bit but i cant raise the gearbox due to lack of room.

Will this cause any problems?

cd.thomson - 28/10/09 at 03:02 PM

i suspect people will say yes BUT the natural environment for my XE is at right angles to the car and cantered over at 7 degrees.

XE god Yukspeed was pretty definite I should fit it upright in my car though so it cant make a huge difference.

[Edited on 28/10/09 by cd.thomson]

matt_claydon - 28/10/09 at 03:09 PM

It's fine to tilt it side to side by rotating on the crankshaft axis, but you shouldn't tip it forward and back as your diff input flange and gearbox output flange will be no longer parallel. This causes cyclic speed fluctuations in the propshaft and therefore vibration and fatigue.

belgian2b - 28/10/09 at 03:10 PM

Hello,

position of the engine itself is not a problem.
you have to watch out for oil level in your sump and about oil suction system position in your sump.


Gerardo

speedyxjs - 28/10/09 at 03:29 PM

Its not side to side, its lifting the front up

matt_claydon - 28/10/09 at 04:22 PM

quote:
Originally posted by matt_claydon
It's fine to tilt it side to side by rotating on the crankshaft axis, but you shouldn't tip it forward and back as your diff input flange and gearbox output flange will be no longer parallel. This causes cyclic speed fluctuations in the propshaft and therefore vibration and fatigue.


Most people get away with very small misalignments, but it's hard to say how much is acceptable.

[Edited on 28/10/09 by matt_claydon]

Ivan - 28/10/09 at 04:28 PM

quote:
Originally posted by matt_claydon
It's fine to tilt it side to side by rotating on the crankshaft axis, but you shouldn't tip it forward and back as your diff input flange and gearbox output flange will be no longer parallel. This causes cyclic speed fluctuations in the propshaft and therefore vibration and fatigue.


I agree with this, however there are two ways around this, you could use CV joints instead of universal joints on the propshaft or tilt your diff to match.

In a mates Cobra the CV jointed propshaft made for a super smooth ride and withstood 12 second 1/4 mile runs and is still working ten years on.

MikeRJ - 28/10/09 at 05:55 PM

quote:
Originally posted by Ivan
In a mates Cobra the CV jointed propshaft made for a super smooth ride and withstood 12 second 1/4 mile runs and is still working ten years on.


You'd have to have CV boots capable of withstanding the much higher speeds of a propshaft though, and CV joints do have a greater power loss than UJs.

snapper - 28/10/09 at 06:12 PM

The Pinto sits front end up in the Sierra only car it sits flat in is a Seven

matt_claydon - 28/10/09 at 08:31 PM

quote:
Originally posted by snapper
The Pinto sits front end up in the Sierra only car it sits flat in is a Seven


I suspect the diff sits front-end up to suit, otherwise it's pretty poor design.

RAYLEE29 - 28/10/09 at 08:52 PM

The really correct way is to have it at the same attitude as in the donor, having said that most inlne installations have the engine sloping down at the back and as for all this propshaft stuff take a look at a transit prop

matt_claydon - 28/10/09 at 10:51 PM

quote:
Originally posted by RAYLEE29
[...]

as for all this propshaft stuff take a look at a transit prop


Parallel input and output flanges are not the only way to eliminate speed fluctuation, but it's the simplest for most people to implement. I'm not familiar with the Transit arrangement but I suspect it either uses a double-Cardan or CV joint at one end or uses the not-so-common 'broken back' shaft arrangement.

If you don't understand the input/output speed fluctuation of a Cardan joint, the problems it causes and the ways it is eliminated, read some of these:

http://www.4xshaft.com/driveline101.html
http://en.wikipedia.org/wiki/Universal_joint
http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html
http://www.custompistols.com/cars/articles/ts_ujoints.htm

Propshafts are one of the most dangerous and yet most misunderstood parts on amateur-built cars. It's no coincidence that we read about such a relatively high number of prop failures on here and yet it's almost unheard of on production cars.

[Edited on 28/10/09 by matt_claydon]

norfolkluego - 29/10/09 at 09:34 PM

quote:
Originally posted by matt_claydon
It's fine to tilt it side to side by rotating on the crankshaft axis, but you shouldn't tip it forward and back as your diff input flange and gearbox output flange will be no longer parallel. This causes cyclic speed fluctuations in the propshaft and therefore vibration and fatigue.


How do you(or what's the best way to) check they're parallel?

Bluemoon - 31/10/09 at 05:34 PM

I think I used an adjustable spirit level to check. I measured the angle between the diff flange and then engine on a machined horizontal surface (i.e top of block, top of head etc), i.e this should be 90 degree between flange and engine top.. I probably used other methods two, (can't remember what!).. From memory the alignment should be to 1 degree or better, this might not be correct though..

I should really re-check this soon, as the engine/gearbox can drop at an angle and require slight adjustments after it settles.

IMHO worth looking at this properly other wise you could have real trouble, also you might get away with it but it's not worth the risk (snapped prop)...

Cheers

Dan

quote:
Originally posted by norfolkluego
quote:
Originally posted by matt_claydon
It's fine to tilt it side to side by rotating on the crankshaft axis, but you shouldn't tip it forward and back as your diff input flange and gearbox output flange will be no longer parallel. This causes cyclic speed fluctuations in the propshaft and therefore vibration and fatigue.


How do you(or what's the best way to) check they're parallel?

Bluemoon - 31/10/09 at 08:34 PM

^^ Just remembered the above is not the whole story you also need to check that the engine is straight (i.e. engine crank/gear box 90 degree to the diff flange)..

Dan