Banjo bolts

orezok · Jan 27, 2025

One of the double piloted check valves on my TNT started leaking. I took it apart and went to my “local” hydraulic dealer for seals. He provided two O rings at no cost and sent me on my way. I got back and went to reinstall and can’t find the banjo bolts. I believe I set them somewhere on the tractor while I went to the shop to take the DPCV apart and see what seals were needed.

It was a week or so til I got to the hydraulic shop (60 miles away). I forgot about the bolts on the tractor and now they are somewhere on my 26 acres.

The bolts are 5/8 20 (sae) but I can’t find them any where. The hydraulic shop and a second one nearby and didn’t have them either.

Everything I find online in that size is aluminum, made for fuel systems. I’m pretty sure the 2500 psi hydraulics would just blow them apart. I need steel.

Anyone have suggestions?

etpm · Jan 27, 2025

Are you sure they are 5/8-20? 5/8-18 is the standard fine thread 5/8 size. What you call SAE should be 5/8-18 TPI. Looking online I found lots of 5/8-18 banjo bolts.
Eric

orezok · Jan 28, 2025

etpm said:
Are you sure they are 5/8-20? 5/8-18 is the standard fine thread 5/8 size. What you call SAE should be 5/8-18 TPI. Looking online I found lots of 5/8-18 banjo bolts.
Eric

I’ll double check, but I put a thread pitch gauge on them and it indicated 20.

oldnslo · Jan 28, 2025

They could be metric threads. M16 x 1.25 is very similar to 5/8-20

kennyd · Jan 28, 2025

All the DPOCV's I've seen or heard of use BSPP threads, and usually 3/8" size.

etpm · Jan 28, 2025

oldnslo said:
They could be metric threads. M16 x 1.25 is very similar to 5/8-20

Yes, very close. Only .004" larger in diameter and the pitch is off by only .0008". I did find one M16x1.25 banjo bolt online so maybe it could be used if it's steel. The description didn't say. Link: Banjo Bolt - 16x1.25mm
Eric

WranglerX · Jan 28, 2025

This may (or may not) help....

WranglerX · Jan 28, 2025

etpm said:
Yes, very close. Only .004" larger in diameter and the pitch is off by only .0008". I did find one M16x1.25 banjo bolt online so maybe it could be used if it's steel. The description didn't say. Link: Banjo Bolt - 16x1.25mm
Eric

Also....

Metric Banjo Bolt High Flow Transfer Cohline Series 8091/93

Bel-Metric sells metric hardware & specialty automotive supplies worldwide. Visit our website to purchase metric fasteners, nuts, bolts, screws, washers & more.

belmetric.com

MtnViewRanch · Jan 28, 2025

Can you post a picture of your cylinder and check valve please?

etpm · Jan 28, 2025

orezok said:
I’ll double check, but I put a thread pitch gauge on them and it indicated 20.

The threads could also be 3/8 BSPP. 3/8 BSPP thread is .656 O.D. and 19 TPI. So the thread is just slightly 1/32" over 5/8". And 19 TPI is awfully close to 20 TPI. Still, you may indeed have 5/8-20 banjo bolts. Have you contacted the manufacturer of the TNT? If you were close to me I would be able to just make the bolts from scratch. I would use 17-4 PH stainless steel to make the bolts because it is pretty corrosion resistant and threads beautifully, and I think I have some in my shop. In any case, do you have calipers? if so you could measure the I.D. of the hole the bolt threads into. The tap drill size for 3/8 BSPP is .602" while for 5/8-20 is .578", a .024" difference, which would be easily measured with a typical digital caliper.
Eric

orezok · Jan 28, 2025

I originally tried the 16mm 1.25 but it wouldn’t thread in after a turn or 2.

I’ll do some measurements as instructed and post tomorrow.

orezok · Jan 28, 2025

kennyd said:
All the DPOCV's I've seen or heard of use BSPP threads, and usually 3/8" size.

I think you may have the answer. I found a site that shows a DPCV that looks virtually identical to mine

TMGT · Jan 28, 2025

If it's an AMA top link it is most likely BSPP, I have two of them and a lock valve for one. They are all 3/8 BSPP

etpm · Jan 28, 2025

orezok said:
I originally tried the 16mm 1.25 but it wouldn’t thread in after a turn or 2.

I’ll do some measurements as instructed and post tomorrow.

If a 16x1.25 wouldn't thread in then a 3/8 BSPP wouldn't either, being .032" larger. Since the pitch difference of a 16x1.25 is less than .001" and the pitch dia. being only .004" larger I suspect you have a 5/8-18 thread because I would expect the metric bolt to go in more than just 2 turns. Anyway, try a 5/8-18 bolt if you have one easily at hand, maybe it will thread in easily. If it doesn't then the existing thread is very close to minimum dimensions, pitch dia. wise. And is probably 5/8-20 as you first stated. I wish I was close, I'm a retired self employed machinist and could easily determine exactly what you have.
Eric

SmallChange · Jan 29, 2025

I'm waiting for somebody to post where exactly on your acreage the bolts wound up.

Seems impossible, but I don't know, you get some pretty tough questions answered here on this forum....

orezok · Jan 29, 2025

OK, did some measurements. Thread diameter is .646 in. Double checking thread pitch a 20 or 18 aren't an exact match, so I think it's 19 (I don't have that on my thread gauge). Based on that I think etpm nailed it at 3/8 BSPP.

etpm · Jan 29, 2025

If it is 3/8 BSPP then you are in luck, it seems like they are available cheap from more than one vendor. Maybe your local hydraulics place will have them. Considering that they can be had for as little as 2 bucks maybe a couple spares would be a good idea. I sure hope they are 3/8 BSPP, it will make life easier for you.
Eric

orezok · Jan 29, 2025

etpm said:
If it is 3/8 BSPP then you are in luck, it seems like they are available cheap from more than one vendor. Maybe your local hydraulics place will have them. Considering that they can be had for as little as 2 bucks maybe a couple spares would be a good idea. I sure hope they are 3/8 BSPP, it will make life easier for you.
Eric

Unfortunately both of the closest hydraulic suppliers (60 miles away) did not carry any banjo bolts. I did order a couple of them online to $2.50 as you suggested. If not corrrect no big loss.

I’m hoping that the model/serial number with 3/8 shown indicates BSPP

etpm · Jan 29, 2025

orezok said:
I’m hoping that the model/serial number with 3/8 shown indicates BSPP

I think it does. If the threads do turn out to be 3/8 BSPP then hooray for another problem solved on TBN. I love this site.
Eric

kennyd · Jan 29, 2025

We have 3/8" BSPP to JIC adapters with a built in restrictor if you need that, hell we may be able to build you all new hoses for what a few bolts may end up costing.