Board logo

engine angle
t.j. - 30/1/06 at 09:29 PM

Hi,

Is it a good idea to get some extra ground-clearance by placing the engine in an angle. If yes what angle is max. for de propschaft.
Can the old rubber "hardy-disk" this angle hold?

My idea is 3 deg. better is 4.30 deg.

I'm using the MT75 with the old sierra DOHC.

Thanx for the answers

Johnmor - 30/1/06 at 09:37 PM

I had the same thought.
Check recent posting under "engine/diff alignment"

Chippy - 30/1/06 at 11:27 PM

The problem with laying over an engine that is not designed to be in the first place, is that you can get oil starvation due to the pick up being in the wrong place. I converted a couple of deisels to go in a boat, and had to make up sumps that had their base level, when the engine was at the required angle, in my case 15 deg's, and then mod the pick up to the new sumps. With a carb engine you would also need to mod the inlet manifold, to get the carb back to it's original angle. To be honest, not worth the effort, unless you just love making work.

Kissy - 31/1/06 at 09:55 AM

You need to make/obtain a winged sump with revised pick-up, or go for a dry sump set-up, which will shorten the engine and allow you to tilt as required.

JonBowden - 31/1/06 at 10:12 AM

Some Caterhams (eg those with vauxhaul engines) appear to have the engine angled so that it is lower at the front / higher at the rear. Presumably this is to obtain ground clearance and to get the front of the engine under the nosecone. Rescued attachment CatEng.jpg
Rescued attachment CatEng.jpg

PaulBuz - 31/1/06 at 02:17 PM

HI T.J
I'm also using a sierra DOHC & an MT75 box.
Have you chopped the sump yet?
I had to chop around 1.5" off and extend the rear forwards to restore capacity, if you know what I mean.
Everyone says tha dohc is a tall engine,but alot of it is in the sump.
Crankshaft centres to top of rocker cover, the dohc is only around 10mm taller.

[Edited on 31/1/06 by PaulBuz]

MikeRJ - 31/1/06 at 02:38 PM

The angle needs to be shared equally between the two propshafts UJs, otherwise you may get vibration.

JB - 31/1/06 at 05:02 PM

Props canrun at quite an angle. The higher the angle the shorter the joint life, the more critical the balance.

The important point is that the UJ at each end of the prop works at the same angle.

Therefore if the engine / gearbox is pointing down at the back 4 degree, the diff should point up 4 degree. Basically if there was a flange on the gearbox output this would always be parallell to the diff flange.

Uj`s are not constant velocity joints therefore the speed of the shaft actually changes as the shaft rotates. The angle must be the same each end to cancel out the variations in speed.

John

t.j. - 31/1/06 at 06:57 PM

quote:
Originally posted by Johnmor
I had the same thought.
Check recent posting under "engine/diff alignment"


Thanx, i really learned a lot. So if my gearbox-end is pointing 4 deg up and my diff zero, then one UJ is 4 degr but the lenght isn't compensated by the UJ at the rear because that angle is zero. So i should point the diff. 4 degr down .

JB - 31/1/06 at 08:44 PM

Yes diff should be 4 deg down.

John