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Old 03-07-2003, 05:22 AM   #1
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I thought I would ask you this, seeing as you're the guy i see most on MR4 threads.
I have a terrible screeching coming from my rear diff housing, everything is free without a pinion on it.
As soon as i put the pinion on, it almost seizes up and the diff slips if i try to turn the rear wheels, the mesh is fine as well.
The motor is a brand new Orion Core Stock.
Any ideas what is causing this?
By the way, its a MR4 TC Worlds Edition with a normal front diff but with the centre oneway still there
I am about to order new diff pulleys and bearings for it as well.

TIA
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Old 03-07-2003, 06:26 AM   #2
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Hi Mort.

Mt first reaction is that you appear to have something wrongly assembled, probably in the rear of the car.

If you remove the pinion, will the car roll freely on the ground?

Just thinking aloud for something stupid, do you have the same mesh pinion and spur, inother words both 48dp or both 64 dp?

There are two layshafts, one for assembly with the centre one way and one for the fixed gear. re you sure you have the correct match. I spend ages seeing that I get my spur gear to run in the middle of the recess. it's another possibility.

Also what about your diffs. you don't think one of the diffs may be reassembled wrongly?

Just a few thoughts. And here's an obvious one. You don't have a small stone trapped somewhere in the rear gearbox do you?

Actually if you had this in the MR4 thread you may have got more ideas from other MR4 owners.

Let me know after you have checked out all these things.

Regards

Joe from sunny Malta.
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Old 03-07-2003, 06:44 AM   #3
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I thought it might be the diff slipping, so i tightened it up, hat helped a little.
I checked for grit etc, found one piece in the pulley so got that out.
Made sure the spur and pinion are both 48DP
Changed the pinion but that didnt help either.
Made sure the diff is in the right way round.
I have a spare pulley and some spur gears, i might build up another diff tomorrow and try that, if that doesnt help i will change the spur gear.
Thanks for replying so quick John
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Old 03-07-2003, 07:31 AM   #4
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Latest update John.
I just tried a different motor in it wired to a 4cell pack, the thing is as quiet as anything.
Now I'm really stuck.
It could be the speedo i guess, i have just put in a GM V12 one with the drive freq set to 4khz.
I'm sure there was a thread on here about it.
Have to look there next

Last edited by Mort; 03-07-2003 at 07:36 AM.
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Old 03-07-2003, 07:41 AM   #5
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MORT.

If thew noise has gone since you changed motors, then that's where your problem must have been.

Where are you from. Writing this time you must be from Europe somewhere.

Good luck.

Joe from sunny Malta.
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Old 03-07-2003, 07:45 AM   #6
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Thanks for the advice John
Could be the motor, i'll strip it later and see if anything is stuck in it.
I'm from the United Kingdom
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Old 03-07-2003, 10:53 AM   #7
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Hi,

I think your diff is unwinding because it is the wrong way round. Make sure that the screw side of the diff is on the left side when looking at the car from the back.
This happened to me once but when I used practice packs it didnt.
So ofcourse it only started screeching during the race.
Having a brand new core stock will also help it unwind.

Trevor
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Old 03-07-2003, 11:36 AM   #8
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I checked in the build book for the car,
the diff adjustment screw head is supposed to the on the right-hand side when looking at the car from the back.
It didnt make that noise when i put the first Core Stock motor in it though. This will be the second one i have now
it could be a combination of new motor and new/better speedo doing it i guess.
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Old 03-07-2003, 06:06 PM   #9
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BAM!

Thats exactly the problem. Think of which way you unscrew a nut and then think of the way your diff is rotating now. Just try putting the srew in from the other side.

Ah and i got a manual supplement with mine saying to put the screw in the left side, contradicting the original manual! So just give it a go and then if it still does it then at least youve eliminated one thing

Another problem is that you might have the smooth side of the diff on the wrong side.

Hope you fix it.
Trevor
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Old 03-07-2003, 10:12 PM   #10
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Yah I had a big notice saying the diff goes the OTHER way around. So yeah try it the other way.
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Old 03-08-2003, 03:43 AM   #11
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Well, I did have it in the other way round, i found out when i went to adjust it.
But the noise is there with the diff either way round.
I think it's something to do with the motr, because when i put a different motor in it powered directly from a 4 cell pack, the thing was as quiet as a mouse.
Thanks for all the replies guys.
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Old 03-08-2003, 07:57 AM   #12
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Well guys,
I just rebuilt the rear diff, with new bearings as well, put it in as per the manual, its quieter now though the noise is still there just not as loud.
Guess i'll have to live with it.
The only thing i haven't changed is the rear belt.
I'm going to wait until tuesday when i race it again and see what its like then.
Also i should have my other motor back then, which was quieter so i'll try that in it as well.

Thanks for the replies anyways guys
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