Re: Howling sound from diff or?

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Post by Phil Bradshaw » Club admin » Tue May 19, 2020 1:03 am
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
Any possibility of a youtube clip with audio to demonstrate the 'howling'?

Single taper leaf springs -

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Bushes in both ends of the spring and in the top of the shackle are identical: GM 8824201

Worn front eye bush can magnify small noises through the chassis frame; worn bush may not be clear until the weight of the vehicle is lifted from its rear springs.

Pinion meshing -

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Pinion position in relation to the crownwheel is determined by shims between the axle casing and differential carrier bearings and pinion rear bearing. If the setting is incorrect then the axle will be noisy.

Is there is any movement in the pinion at the propellor shaft flange? Any oil leaking from the front of the axle?

Is the exhaust system complete? System missing the second (muffler) box or with tailpipe cut too short can howl.
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  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Howling sound from diff or?

Post by CFsleeper » Subscribing Member » Tue May 19, 2020 2:12 pm
Joined: Thu Apr 02, 2020 9:03 am
Posts: 46
There is no movement in the propeller shaft axel.
On the left brake it's a little greasy.
Exhaust is complete.
Sound is defenately in the drivetrain.
Made a clip as asked. 😁



I changed the load so you can hear the difference.

Re: Howling sound from diff or?

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Post by Phil Bradshaw » Club admin » Tue May 19, 2020 3:58 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
I don't know why I didn't suggest youtube earlier: got it in one - final drive whine.

Usually caused by worn bearings or worn pinion and crownwheel teeth or both.

Bearings are all taper roller with ID numbers on them that bearing specialists will recognise. New shims, gear sets, compressible spacer, cover gasket and pinion oil seal are just about extinct.

It may be easier to find a quieter axle but there is a number to choose from according to model: CF230 has the lightweight Bedford axle; CF250 model with heavier Bedford axle has larger rear hub bearings and also thicker leaf springs.

Standard ratios are 7/37 or 8/37; other ratios exist. To check axle ratio without dismantling rotate the propellor shaft with one rear wheel raised from the ground: chalk mark the shaft and raised wheel and start counting -

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Or fit very thick carpet...
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  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Howling sound from diff or?

Post by CFsleeper » Subscribing Member » Wed May 20, 2020 1:45 pm
Joined: Thu Apr 02, 2020 9:03 am
Posts: 46
Very thick carpet is an option but while investigating the other option, changing the diff for a quieter one, I stumbled into some other spare parts. I can buy a 1,9 petrol Opel Record engine ( apparentely overhauled). It’s in a CF truck that will be dismateled. I’m not interested in the automatic transmission that’s on it but the diff and rear axel look a lot like mine. One spring leave. Have to check the ratio. Further the seller has a CF with Opel diesel with a 5gear transmission, propshaft and diff, complete.
He offers me the 1,9L, the 5 gearbox (should fit on the crackcase of the petrol?) the propshaft, and diff. Together with the engine mounts of the diesel ( should fit the 1,9 ) because the 1,9 is now not in line with the truck. Would this be a good swap? I would gain about 9HP, quiete diff and a fift gear.
Last edited by CFsleeper on Wed May 20, 2020 2:39 pm, edited 1 time in total.

Re: Howling sound from diff or?

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Post by Phil Bradshaw » Club admin » Wed May 20, 2020 2:18 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
ZF 5-speed for diesel usually has 1:1 5th speed and very low geared 1st speed. Check the plate on the transmission for 5th speed 0.8:1 for 'overdrive'.

ZF for GM diesel has the correct main drive pinion (longer than for Vauxhall OHC engine).

Clutch housing is basically the same for Opel petrol and GM diesel apart from the timing pointer for diesel only. (9964973 housing for both on CF2 models.)

Changing from Vauxhall OHC petrol to an upright engine requires either new engine mounting posts welded to the front axle beam or an axle beam for diesel or Opel petrol engine.

Opel petrol engine has to be installed at an angle to the vehicle for manifolds clearance one side, starter on the other; standard for CF2.
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  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Howling sound from diff or?

Post by CFsleeper » Subscribing Member » Wed May 20, 2020 2:27 pm
Joined: Thu Apr 02, 2020 9:03 am
Posts: 46
So looks like they installed the Opel engine the right way (at an angle). We thought they use the wrong mounts...
So do I need the 1:1 or 0,8:1 5th speed?
Which ratio diff would be the ideal on for this setup? Should question be in conversion and modifications?

Re: Howling sound from diff or?

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Post by Phil Bradshaw » Club admin » Wed May 20, 2020 2:41 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
0.8:1 5th speed for lower engine rpm at cruising speed.

8/37 ratio is standard for short wheelbase with Opel CIH petrol + ZF 5-speed.
CFsleeper wrote:
Wed May 20, 2020 2:27 pm
... Should question be in conversion and modifications?
Strictly speaking, yes... :)
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  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

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