Atlas diff rebuild

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ollyw
Posts: 2081
Joined: Tue Jul 29, 2008 6:40 pm
Car(s): 1984 B Reg 2.8i rebored to 2922cc near concours condition. Restored from near scrap condition.
1983 A Reg 2.8i Caspian Blue over Silver. Ongoing now roadworthy project from scrap condition
Location: England

Atlas diff rebuild

Postby ollyw » Fri Jul 21, 2017 8:05 am

Hi everyone.

Unfortunately after a lot of expense in the last 2 years to try and solve the transmission judder on my 2.8 (new flywheel, 3 new clutches, a complete gearbox rebuild professionally done, prop bearing and new doughnut bush) it appears the problem is still there. I have also where available used genuine Ford bits.

It is noticeable when you pull away as a tiny knock as the power is applied. This sounds similar to someone tapping their finger lightly on the rear floorpan. I have ascertained that this tap is coming from behind me and towards the centre of the car.

If you sit in traffic and crawl the problem gets much worse to the point you can't avoid it and the transmission shakes violently.

The original flywheel was badly scored and had cracked lightly on the surface. Changing this has helped no end, 95% better, but the problem is still fundamentally there.

I refuse to believe 3 clutches could all be faulty with the same issue. The prop is now absolutely textbook and is lovely and tight, so I think by making the rest of the transmission good I'm slowly exposing the fault. Also after unbolting anything and making a repair the fault goes away entirely only to come back as a slight knock as described after 50 miles.

I do have diff whine at about 70mph. I replaced the rear wheel bearings about 800 miles ago, they are quiet and are not leaking oil.

So having replaced everything (!!!) that just leaves the diff. I took the Rear cover off yesterday to change the oil and gasket. The crown wheel is shiney across the teeth but I'm not sure if the wear is equal. I'm wondering by undoing the propshaft I'm unloading the pinion gear and the crush washer which the manifests itself after a while when it's put back together and driven.

2nd opinions welcome!

Has anyone had one of these professionally rebuilt (non lsd) and what sort of cost was involved?
I've got a feeling it could be more than the bearing kits sold on eBay. I can take the diff out over winter but I'm reluctant to rebuild it as I've seen lots of stories about 0.003 shim accuracy to set the backlash etc.
Equally with the cost of second hand axles it is now getting to the point where repair is better value.

Thanks for reading this massive post and to any replies.


Olly W

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nigecapri
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Joined: Mon Jul 28, 2008 6:31 am
Car(s): Black 2.0S with supercharged bike carbs.
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Re: Atlas diff rebuild

Postby nigecapri » Sat Jul 22, 2017 9:06 am

You're taking the right course of action going for a pro rebuild. I did mine a few years back and it's not an easy job.

Details of recommended axle refurb companies would, I'm sure, be most welcome by all on the forum.

Paul G
Posts: 662
Joined: Fri Jul 03, 2015 5:21 pm
Car(s): MK 3 3.0S needing restoration, 2.0S, 1.6 Laser (nearly ready), Fiesta mK2 pop plus, Skoda Octavia VRS, Rover SD1 Vitesse.
Location: High Wycombe

Re: Atlas diff rebuild

Postby Paul G » Sat Jul 22, 2017 9:31 am

After a defective clutch, the most common cause of judder is the engine mountings. Have you tried renewing both engine mountings and especially the rear gearbox one?

ollyw
Posts: 2081
Joined: Tue Jul 29, 2008 6:40 pm
Car(s): 1984 B Reg 2.8i rebored to 2922cc near concours condition. Restored from near scrap condition.
1983 A Reg 2.8i Caspian Blue over Silver. Ongoing now roadworthy project from scrap condition
Location: England

Re: Atlas diff rebuild

Postby ollyw » Sun Jul 23, 2017 8:40 am

Hi.

Yes the gearbox mount was replaced as part of the refurb. I'm driving it around currently and I'm becoming more suspicious of the prop again although having taken it off earlier in the week and examined it thoroughly i still can't see what's wrong. The centre bearing and doughnut are new and fitted correctly.

Could do with borrowing another prop from a 2.8 , fitting it and seeing if there's any difference.

Is it possible to bend a prop through clutch judder? Like I said it's historical now, I recon I'm living with the aftermath. For the amount of viabration I'm getting it would only have to be very slight.

Incidentally taking the car out of gear and coasting reduces the viabration but only slightly. Wheels are balanced aok too.

ollyw
Posts: 2081
Joined: Tue Jul 29, 2008 6:40 pm
Car(s): 1984 B Reg 2.8i rebored to 2922cc near concours condition. Restored from near scrap condition.
1983 A Reg 2.8i Caspian Blue over Silver. Ongoing now roadworthy project from scrap condition
Location: England

Re: Atlas diff rebuild

Postby ollyw » Sun Jul 23, 2017 8:42 am

Paul G wrote:After a defective clutch, the most common cause of judder is the engine mountings. Have you tried renewing both engine mountings and especially the rear gearbox one?



The gearbox yes, not done the engine mounts yet but I have checked the nuts are tight on them.

Paul G
Posts: 662
Joined: Fri Jul 03, 2015 5:21 pm
Car(s): MK 3 3.0S needing restoration, 2.0S, 1.6 Laser (nearly ready), Fiesta mK2 pop plus, Skoda Octavia VRS, Rover SD1 Vitesse.
Location: High Wycombe

Re: Atlas diff rebuild

Postby Paul G » Sun Jul 23, 2017 9:23 am

I read the problem as clutch judder but if you have vibration even when coasting I would guess the problem is in the prop. Did you renew the UJ's in it when you did the bearing and was it re balanced? Also is it aligned correctly?

I would guess you need to send the prop to a specialist to get it checked and balanced. The only other thing could be a bent half shaft but that is extremely rare unless you've badly kerbed the car or been driving like a ****.

ollyw
Posts: 2081
Joined: Tue Jul 29, 2008 6:40 pm
Car(s): 1984 B Reg 2.8i rebored to 2922cc near concours condition. Restored from near scrap condition.
1983 A Reg 2.8i Caspian Blue over Silver. Ongoing now roadworthy project from scrap condition
Location: England

Re: Atlas diff rebuild

Postby ollyw » Mon Jul 24, 2017 8:15 pm

Paul G wrote:I read the problem as clutch judder but if you have vibration even when coasting I would guess the problem is in the prop. Did you renew the UJ's in it when you did the bearing and was it re balanced? Also is it aligned correctly?

I would guess you need to send the prop to a specialist to get it checked and balanced. The only other thing could be a bent half shaft but that is extremely rare unless you've badly kerbed the car or been driving like a ****.



Thanks for the thoughts! I used to drive like a **** back in the day (not in this car) but I leave that to BMW and Audi drivers these days :lol: :lol: I've decided to get the prop into a specialist to check the alignment, balance, UJ's out. I'm thinking of these guys near me http://www.propshaft-services.co.uk/home

I've been slowly restoring this 2.8 from a bit of a wreck, I think its had a pretty hard life.
Something very struck the front lower half of the car some time ago and it was clearly patched up and sold on. The engine crossmember was bent forward, the front valance was pretty folded up and had about 10mm of bodged filler in it. Also as I've said the flywheel was scored to heck and I've rebuilt the gearbox, so I'm just working my way back down the issues! Flywheel clutch and gearbox done, now its the prop clearly!


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