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 Re-sleeving rear brake drums.
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Derek
V4 Guru

United Kingdom
2018 Posts

Posted - 30 May 2021 :  14:32:02 Show Profile Reply with Quote
I suspect that the technical argument would revolve(sic) around relative thicknesses. An original drum isn't very thick and the wear amount before reaching the limit is small. To put a sleeve in you'd probably have to remove about half of the thickness left before shrinking in an insert. That too would be very thin and even thinner after machining. On the road the insert and the drum would have to have exactly the same expansion characteristics to stay as one piece. In use I think that the insert would expand quicker and probably crack itself or even the now very thin drum.
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melle
V4 Guru

United Kingdom
3342 Posts

Posted - 30 May 2021 :  15:27:56 Show Profile Reply with Quote
I agree, a sleeve isn't probably a good idea as I wrote in an earlier post, but I think spray welding and re-machining is a perfectly usable solution. If it's cost effective is another matter, not many companies do this kind of work any more. An then liability, a typical British/ American obsession it seems (although NL apparently is the most over-insured nation in the world, perhaps that's why it doesn't bother us so much...).

I'm not sure how much wear Andy's drums have, but welding a blob onto the brake shoe carriers is perhaps the easiest solution. If the brake surface is clean and free of major damage or glazing, they won't even need machining I suppose.

www.saabv4.com
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chris steeden
V4 Fan

United Kingdom
145 Posts

Posted - 30 May 2021 :  18:30:14 Show Profile Reply with Quote
They are always breaking 96's on Ebay (you know the ad's - Breaking saab 99p for a wheel nut kind of thing). Might be worth a gamble if your late model has the same drum Andy.
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andydeans3
V4 Guru

United Kingdom
1491 Posts

Posted - 31 May 2021 :  22:52:42 Show Profile Reply with Quote
Thanks for all your inputs guys.
I was really just musing as to whether it was possible.

I'm already using extended adjuster wedges, so I'll wait until I can buy new ones from the SAAB Klubben.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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melle
V4 Guru

United Kingdom
3342 Posts

Posted - 01 Jun 2021 :  08:12:16 Show Profile Reply with Quote
If you (have someone) put a bit of weld on the brake shoe carriers you no longer need extended wedges. On mine I think I added some material on the wedge end as well as the cylinder end on both carriers. With your annual mileage new drums may make sense though, Andy!

www.saabv4.com
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SAAB96L
V4 Beginner

United Kingdom
98 Posts

Posted - 01 Jun 2021 :  08:40:59 Show Profile Reply with Quote
Hello Andy / Melle,

Jonathan at J&E Engineering Services sent me an email to cover the issues with lining a brake drum. I have pasted this FYI and hope it is of assistance.

Regards.

Richard.

With regards the Saab brake drum problem, as you know I am not familiar with the Saab specifics but I would assume it is a cast iron drum that is badly scored and grooved which is why re-lining is being considered. If this is the case then I am assuming that there is not enough material to accommodate a normal drum skimming.

In any case any grooving, corrosion, scoring and damage will need to be removed (Skimmed) in order to achieve a good platform for the new liner to sit and adhere. This wont be possible if there is not enough parent material in the first instance. The liner material should be the same as the drum material and I would suggest a centrifugally spun cast iron which would carry a fair cost at the diameter required.
The interference or shrink fit of the liner inside the drum is also of extreme importance as it could slip inside the drum if the fit is not adequate or indeed the parent drum material is too thin. This would be a brake failure.

Also of consideration is the machining, material and fitting time/cost as well as safety consideration with this method. I would suggest a thorough study of a brake disc and drum suppliers catalogue in order to find a drum that meets or is close to the dimensions of the original drum.

The wheel bolt pattern and spigot can be easily altered to suit the Saab so I wouldn't worry too much about that. Internal diameter is the main consideration. Yes a certain amount of work is required to make them fit but this should be considerably less than that of fitting a liner into an old drum. Just my thoughts.

Edited by - SAAB96L on 01 Jun 2021 08:42:16
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melle
V4 Guru

United Kingdom
3342 Posts

Posted - 01 Jun 2021 :  10:37:11 Show Profile Reply with Quote
His reasoning makes complete sense to me Richard.

www.saabv4.com
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andydeans3
V4 Guru

United Kingdom
1491 Posts

Posted - 01 Jun 2021 :  18:35:08 Show Profile Reply with Quote
quote:
Originally posted by melle
If you (have someone) put a bit of weld on the brake shoe carriers you no longer need extended wedges. On mine I think I added some material on the wedge end as well as the cylinder end on both carriers. With your annual mileage new drums may make sense though, Andy!

www.saabv4.com


Aye, I do make much use of my lovely old 96.
Not quite as much as in earlier years, where I was doing 10 000 miles, some years.
I'm trying and share the summer time miles with my trusty old MGB, or my wife's Nissan Figaro.
Winter time I only have the SAAB , or the old work horse, the "Classic" Renault Twingo. (which is still chugging away after 13 years with us, and 200 000 miles on the horizon!!)

Last couple of years it's only been 5 or 6 000.
Hoping to go to Sweden next year for the festival in early July. That'll put 3000 miles on her, in 2 weeks!!!!!

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 02 Jul 2021 22:29:42
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kinloch
Starting Member

United Kingdom
23 Posts

Posted - 02 Jul 2021 :  22:14:50 Show Profile Reply with Quote
Hi Andy
Been ages since I've logged in and just came across this. Had the same issue with my 96 rally car and solved it by getting thicker linings fitted by Questmead, they can do any thickness and material you require. Needed a wee bit of fettling but works fine. Hope this is some help.
David
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andydeans3
V4 Guru

United Kingdom
1491 Posts

Posted - 02 Jul 2021 :  22:38:21 Show Profile Reply with Quote
Thanks David, but as soon as these problems with importing stuff from the SAAB Klubben in Sweden are sorted out, I'll probably buy new drums.
We have a common friend who does gearboxes! (but don't mention his name!!!!)

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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Derek
V4 Guru

United Kingdom
2018 Posts

Posted - 03 Jul 2021 :  13:09:17 Show Profile Reply with Quote
Once drums wear down to the prescribed limits the amount of heat dissipation is already much reduced. For rallying this is obviously important. Thicker linings may seem to help but are unlikely to make the heat dissipation any better.
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kinloch
Starting Member

United Kingdom
23 Posts

Posted - 04 Jul 2021 :  23:03:06 Show Profile Reply with Quote
The linings I use are VG 95 comp spec and although my car is only used on historics and navigational events, not stages, never had any issues with brake fade. Really try not to use them as brakes only slow you down!!!!! Our mutual friend was up a few days ago checking up on the progress of my model railway project, doing well despite the hip.
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andydeans3
V4 Guru

United Kingdom
1491 Posts

Posted - 05 Jul 2021 :  19:39:15 Show Profile Reply with Quote
Our mutual friend has a date for his hip replacement.
11th August.
I'm sure that like most people that have this operation done, he'll be transformed.
Aye he was telling me about your train set!!!
I think he was jealous.
I fancy a wee road trip up to the highlands, if you don't mind I might come up to see your train set sometime?

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 05 Jul 2021 19:42:24
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andydeans3
V4 Guru

United Kingdom
1491 Posts

Posted - 05 Jul 2021 :  19:44:25 Show Profile Reply with Quote
quote:
Originally posted by Derek
Once drums wear down to the prescribed limits the amount of heat dissipation is already much reduced. For rallying this is obviously important. Thicker linings may seem to help but are unlikely to make the heat dissipation any better.


You're right Derek.
I'll just wait till this "unable to ship to the UK" guff, from the SAAB Klubben gets resolved.
They confirmed me today that nothing has changed.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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kinloch
Starting Member

United Kingdom
23 Posts

Posted - 05 Jul 2021 :  23:00:01 Show Profile Reply with Quote
Hi Andy
Be delighted to see you any time you fancy a trip up. You know who can give you my mobile number, give me a call.

David
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