Leaf Spring centre bolts What thread???

[jai_landrover]

Leaf Spring centre bolts:

What thread???

I have two here very fine thread and a more coarse thread but it doesn't look like M10 its too fine to be metric? So I'm guessing BSF or even Whitworth??? anyone know for sure I will be getting a couple of dies tomorrow to extend the thread to fit my now 5 leaf springs.

 

[The Mad Hat Man]

cant yu measure the other two, to find out what thread it is?

 

[Fur Trapper]

Just buy 2 new bolts the right length and but then in, Would use fine thread as they torque up better

 

[jai_landrover]

will take it to get the correct die failing that I'll be turning some bolts down in a lathe cos I need to get my rear springs fitted loosly to my salisbury ready for the swop over.

I have this weekend to hammer out the strengthened MSA legal front out riggers/rollcage mounts and attach the 90 front axle to leafs.

 

[jai_landrover]

Cannot buy bolts off the shelf. I did ask for parabolic centre pins (shorter) with enough thread but the std ones the nuts bottom out about 5 mm from the springs being fully compressed.

Was hoping to just extend the threads furthur down the bolt and cut off the excess. I'll have a look see what I can sort tomorrow failing that it'll be making new ones Saturday morning!

 

[Fur Trapper]

Cannot buy bolts off the shelf. I did ask for parabolic centre pins (shorter) with enough thread but the std ones the nuts bottom out about 5 mm from the springs being fully compressed.

Was hoping to just extend the threads furthur down the bolt and cut off the excess. I'll have a look see what I can sort tomorrow failing that it'll be making new ones Saturday morning!

Then use a couple of flat washers and a lock washer(split washer) to make up the difference . little tip use a large c-clamp to pull the bundle together make tightening the nut easier.

 

[jai_landrover]

I'll keep an eye out for me dies or make new ones. I dont like using washers as they will have to be within the bottom plate. Will try and keep the nut and indeed the spacer washers from sticking down and being wiped out from the Ubolt plate/shock mount plate.

 

[Fur Trapper]

I'll keep an eye out for me dies or make new ones. I dont like using washers as they will have to be within the bottom plate. Will try and keep the nut and indeed the spacer washers from sticking down and being wiped out from the Ubolt plate/shock mount plate.

Then use washer under the bolt head if they get in the way , the other way

 

[jai_landrover]

lol the head locates into the axle putting washers here is not great because it lifts the axle higher away losing ground clerance (yes I know its only 5 mm but more of a worry is that it might affect the clamping action of the springs because it wouldn't allow the spring to bolt up firmy on on the saddle.

 

[Oldseadog]

You will find that on an early Series it will be a BSF thread, on later models they used UNF. Whitworth (BSW) would not have been used as the thread pattern is too coarse for the use, and could strip!

Do not use a standard metric threaded bolt as the threads are too coarse and may have a tendency to strip ... even if you use the high tensile ones.

Measure the diameter and then contact these people, who should be able to supply you with the right fastenings. Click here

Hope this helps.

OSD

 

[jai_landrover]

cheers old sea dog. I'm working today but will see if i can grab one somwhere on my travels

 

[jai_landrover]

Ok Thanks Old Sea Dog I have found out that it is indeed 3/8 x 20 BSF.I will extend the threads tonight.

Cheers
Jai

 

[Johnny_Regis]

M8

I bought new spring dowels recently. Bit of an emergency so I ordered both the metric and imperial one, in case the head of the dowel didn't fit the axle on one. Turned out they were identical bar the thread of course, both fitted the hole.

I went with the metric one because I had M8 nylocs handy.

 

[Oldseadog]

M8

I bought new spring dowels recently. Bit of an emergency so I ordered both the metric and imperial one, in case the head of the dowel didn't fit the axle on one. Turned out they were identical bar the thread of course, both fitted the hole.

I went with the metric one because I had M8 nylocs handy.

You would heve been better off using the finer thread of the imperial as it gives better 'clamping power' than the coarse metric which might strip!

I hope that you have used high tensile bolts!

That's why the imperial threads were developed, instead of a 'one size fits all' of the metric, as each thread formation was used for specific applications! For example head studs used a coarse thread into the block (soft, brittle cast iron or xast aluminium,) with a fine thread to clamp the head down.

OSD

 

[jai_landrover]

surley once its clamped by the U bolts the centre bolt is pretty much redundant

 

[Oldseadog]

Agreed. However, you have to pull the leaves together first, which is why a fine thread is better than a coarse one.

OSD

 

[Johnny_Regis]

You would heve been better off using the finer thread of the imperial as it gives better 'clamping power' than the coarse metric which might strip!

I hope that you have used high tensile bolts!

That's why the imperial threads were developed, instead of a 'one size fits all' of the metric, as each thread formation was used for specific applications! For example head studs used a coarse thread into the block (soft, brittle cast iron or xast aluminium,) with a fine thread to clamp the head down.

OSD

Yeah its fine, brand new LR U bolts and lock nuts clamping it up.

 

[jai_landrover]

My old man used to do alot of R&D on Renault trucks military and commercial. Many a time he brought a fire engine home on his lunch break after a brake test or day at a test track. He told me last night they used to change springs regularly they used to make a set up tighten the centre bolt up to the torque figure quoted. Then clamp the U bolts on double check the centre bolts and all seemed good. After a ride upto Milbrook and back they could wind the centre bolts up a fair few turns after a good run. Pics of him taking an 8x8 tipper on the alpine circuit front wheels dangling in the air at one of the peaks used in a promotional shoot. Apparently the french rep in the passenger seat almost cacked himself!