14 replies to this topic

[spanners]

I'm just refitting the gearbox to my 1275 and have realised the ARP studs and nuts hit the gearbox webs. I've shortened the studs flush with the nuts and clearanced the webs as much as I think I can but there's still not enough room. I probably need a about another 2.5mm to be safe. Quick google mentions leaving out the washers at both ends which would probably do it.

 

My question is is it preferable to do that and shorten the studs more or clearance the webs more? I'm a bit worried about breaking through the case at the pulley end

This is for a fast road 1330.

 

Thanks

 

Will.

[nicklouse]

Grind clearance in the box.

[spanners]

Ok, and you can get enough clearance at the front? is there potential to end up with a JB Weld situation?

Edited by spanners, 05 April 2022 - 08:44 PM.

[nicklouse]

Ok, and you can get enough clearance at the front? is there potential to end up with a JB Weld situation?

Have a read https://www.theminif...date-it/page-52 over half way down the page.

[Spider]

i get why you've replaced the bolts and I'm sure they cost a pretty penny too, but the standard bolts will take anything you can dish out in an A Series.

[mini13]

the above is true, but i do prefer a stud rather than a bolt.

 

more impontant is the cap dowels, I use the billet ones on all my builds now.

 

https://swiftune.com...cap-dowels.html

 

[spanners]

The MED ones are different, they don't use washers so the height is less by I'd guess about 2.5 mm but you can only use them with their steel caps which was out of my budget for a road engine. The ARP option was a good halfway house.

 

Talking to a few experts this morning seems like leaving out the washers and shortening the studs more is fine for a road engine as the caps are the weakest link or clearancing the case and rebuilding the webs with tig weld.

[GraemeC]

The MED ones also need the 'box clearancing sometimes.  Both Nick and I have been there and got the t-shirt - see his link.

Edited by GraemeC, 06 April 2022 - 09:43 AM.

[spanners]

Nothing is ever easy even on a Mini! General consensus seems to be leave out the washers, no one I've talked to so far has ever had a problem with that even on race engines.

[spanners]

By the way Nick that is a serious bit of kit there, very impressive.

[sonscar]

Not an experienced engine builder at all but buying uprated bolts then cutting them down and removing load spreading washers seems like a potential for failure to me.If your ashtray fails it is inconvenient,if your engine fails it is even more so.Just my bodgers view,Steve..

[PoolGuy]

Not an experienced engine builder at all but buying uprated bolts then cutting them down and removing load spreading washers seems like a potential for failure to me.If your ashtray fails it is inconvenient,if your engine fails it is even more so.Just my bodgers view,Steve..

I agree with Steve, IMO the washers are important to stop the nuts/bolts 'settling' into the caps. I use the ARP washers even on low rent engines, it's cheap insurance. Another option if you want ARP fasteners is to use ARP 743-2500 bolts which come with appropriate washers.

[nicklouse]

The MED ones are different, they don't use washers so the height is less by I'd guess about 2.5 mm but you can only use them with their steel caps which was out of my budget for a road engine. The ARP option was a good halfway house.

 

Talking to a few experts this morning seems like leaving out the washers and shortening the studs more is fine for a road engine as the caps are the weakest link or clearancing the case and rebuilding the webs with tig weld.

Check you have the arp studs in the right way round. IIRC they can fit two ways. One give interference the other less so.

[PoolGuy]

Check you have the arp studs in the right way round. IIRC they can fit two ways. One give interference the other less so.

 

 

They only have the Allen key fitting in the top. But it's not uncommon to have to tap the threads a little deeper in the block to get the ARP studs to sit nicely.

[spanners]

I've opted for removing the washers front and back and some clearancing on the case. The nuts I have are flanged and the washer is exactly the same size as the flange so it's not going to effect the loading. I imagine they are there primarily to provide a  same material/friction surface to the nut base so that torquing is a known quantity and any main cap material variations removed.

There is plenty of thread on the stud and no need to sink them lower in the block so I'm basically removing the top part of the stud that extends above the nut, that reduces the overall height by about 5mm when the washer is removed.

For my intended road use I think this will be fine. Ideal world I'd have them but that's not possible here. I've always upgraded bolts to studs and nuts on anything I've built (V8's mainly) it always seems a better option technically.

Edited by spanners, 06 April 2022 - 03:50 PM.