FRONT Subframe tower bolts & studs ,why the difference

[goff]

Good question , Why did they use both bolts & studs ?????? , What was the reason ????? , why didn't they just use one or the other across the complete range , again subframes !! some tapped 3/8 others 5/16 Hydrolastic , Dry & Auto , anybody know why ??????

Goff

[Exminiman]

My guess is two factories, two production engineering departments, two design departments, both wanting to go their own way......and not follow the each other.

Surly bolts are easier, especially after the Minis left the factory ?

[Dr S]

I’d guess this would be down to what was easier on each line. Did Moz have something that Austin didn’t or vice versa?

[wild_willy]

Seems to me that early cars were bolts (up to circa 1962) and later were studs. See the other thread on this topic.

[bwaminispeed]

No, bolts were right up to the end of 4 bolt subframes.......My 74 998 rod change Mini had bolts.......

[dodge44]

My guess is two factories, two production engineering departments, two design departments, both wanting to go their own way......and not follow the each other.

Surly bolts are easier, especially after the Minis left the factory ?

In the back of my mind I have it that Cowley fitted studs and Longbridge bolts. Could always do a finger in the air poll - My Nov '62 Cowley SDL has studs and nuts.

[Peter Laidler]

Not an answer to the original querie but I learned the hard way when removing/replacing my steering rack to rebuild it with ph-bronze bushes. It was a whole lot easier to re-align the sub frame tower bolt holes with the crossmember with studs than try to do it with bolts!

Mine is an Austin with bolts and I only lifted the body 3/4" or so to free the rack........ What a b-----d it was aligning the holes centrally afterwards. Have you ever tried finding almost hidden holes in the dark.......!

[Costafortune]

Not an answer to the original querie but I learned the hard way when removing/replacing my steering rack to rebuild it with ph-bronze bushes. It was a whole lot easier to re-align the sub frame tower bolt holes with the crossmember with studs than try to do it with bolts!

Mine is an Austin with bolts and I only lifted the body 3/4" or so to free the rack........



What a b-----d it was aligning the holes centrally afterwards. Have you ever tried finding almost hidden holes in the dark.......!

Only if there was hair around it.

The only Minis I ever saw with studs was a 1961 car. I thought it was one of BMC's good ideas that they dropped.

[InnoCooperExport]

Just to stir the pot, though only a handful of you will care, Innocenti used studs right until the end of production in Jan 1975. One of the things they retained from the earlier models to their version of the Mk3 shell.

[Mini Mad Swede]

Just to stir the pot, though only a handful of you will care, Innocenti used studs right until the end of production in Jan 1975. One of the things they retained from the earlier models to their version of the Mk3 shell.

Well, here's one that cares!
Never even noticed it on mine.
Will have to check that out asap!

Do have two subframes with studs, but absolutely no idea from what year or if they've been remowed from an Austin or Morris.
Last one was a couple of months ago, there was also what is be to be belived a rear seat from a -59 Morris 850 Deluxe.
But if there is any connection at all between these two (three) parts..

[Tds76]

I can offer a manufacturers view - I have worked in manufacturing engineering in the car industry for a frightening 30+ years, though never with BL/ARG etc.
The differences could be for a variety of reasons, but most likely will be existing infrastructure (too costly to change), line speeds or operator preferences in the assembly plants. Whenever I have worked on vehicle lines built in multiple locations there has always been something that has prevented 100% common engineering or production solutions.

There are common methods for body to frame marriage.
1. Lower the body onto the sub-frames arranged at floor level. Studs would be the normal preference as they give you a free guiding feature instead of having use tooled guides.
2. Raise the sub-frames up to the body suspended from an overhead conveyor. Studs are less important with this method but would still be preferred.

From the engineering department views for stud vs. bolt in this case it would be something like this:
Manufacturing Engineering: Primarily stud for reasons above.
Industrial Engineering: Bolt - One thread to fasten with a bolt, two with a stud and nut so the bolt is more time (and money) efficient.
Product Engineering: Bolt - one bolt is cheaper than a stud and a nut and also less parts to manage on the bill-of-materials.

Operator/Production preferences. Operators will always gun-start fasteners if they can and with the Mini tower bolts the likelihood of cross-threading the bolt is low whereas the nut to stud is high - so the operators would prefer the bolt. Just about all of the screws/studs/bolts on a modern car have a dog-point to allow gun-start and minimising cross-threading.

The other possible reason for the change could be the introduction of wet suspension - the use of bolts would eliminate the risk of the hydro hose rubbing through on the stud. Having never seen the stud application i'm not sure if this is a real risk.

Cheers, Paul.

[ivor badger 3]

My guess is two factories, two production engineering departments, two design departments, both wanting to go their own way......and not follow the each other.

Surly bolts are easier, especially after the Minis left the factory ?

In the back of my mind I have it that Cowley fitted studs and Longbridge bolts. Could always do a finger in the air poll - My Nov '62 Cowley SDL has studs and nuts.

Reckon you are correct. But I think around hydrolastic they both went to bolts.

[goff]

Some interesting posts , BUT nothing substantial and i guess we will never know , i have 3 front subframes here at the moment , two fitted to cars and spare one , one is dry and fitted bolts , next is auto hydrolastic fitted studs and the last is hydo manual fitted studs , maybe Nick Rogers as the answer ?

[bwaminispeed]

According to AKD Manuals, Austins and all Coopers/Ss were bolts, all Morris (except Coopers/Ss) were studs.......

This was same for hydro or dry cars.....

This was up till late 67, when all Mini production ceased at Cowley......

From that point forward, all were bolts till advent of two bolt subframes in 76....

There were of course, some exceptions to this, but, basically the above info is correct...

This is not guesswork, or, speculation, it is right out of the AKD parts manuals....

[MiNiKiN]

....
From that point forward, all were bolts till advent of two bolt subframes in 76....
There were of course, some exceptions to this, but, basically the above info is correct...
This is not guesswork, or, speculation, it is right out of the AKD parts manuals....

..except for Italian built cars up to '75-ish which were fitted with studs according to AKD5230 parts catalogue.
Sorry for bringing in more confusion again

Subframe_mounting.jpg

[bwaminispeed]

Was only talking about UK built cars, that's all I have info on.....

[dodge44]

According to AKD Manuals, Austins and all Coopers/Ss were bolts, all Morris (except Coopers/Ss) were studs.......

This was same for hydro or dry cars.....

This was up till late 67, when all Mini production ceased at Cowley......

From that point forward, all were bolts till advent of two bolt subframes in 76....

There were of course, some exceptions to this, but, basically the above info is correct...

This is not guesswork, or, speculation, it is right out of the AKD parts manuals....

It's a nice theory but my Austin was assembled at Cowley and has studs so the factory site is far more likely to have a bearing on what was fitted than the niceties of what it says in the parts list. No way the production line which is assembling both marques on the same conveyor at the same time is going to switch between the two attachment methods to suit Morris or Austin. Worth saying that Cowley only assembled bog standard Saloons, Longbridge did everything else regardless of marque.

[agricola]

I m struggling to understand this. Apart from making it easier to assemble what difference does it make? Its implying bolts are stronger so had to be fitted the Cooper S ?

[winabbey]

For what it's worth this is what Somerford Mini say on its website.

'Solid' Front Subframe Mountings
1959-75

Bolting the subframe suspension towers to the dash crossmember of the car would seem to be a very simple process, but as you've probably
guessed already the Mini, being assembled with different detail parts at different factories in the 1960s, makes things rather more complex
than need be.

Please read on...

Models up to 1962 approximately (i.e. those with the very earliest types of dash crossmember) could have the subframe towers held to the dash
crossmember by bolts or studs and lock tabs which initially didn't, and then did, allow access to the rubber cone compression nuts. After this time
bolts were used exclusively on cone (dry) suspension cars. Hydrolastic (wet) suspension subframes were also held to the dash crossmember by a
choice of bolts or studs. The only real consistency is that bolts were always used to attach the subframe towers on the Cooper and Cooper S.