Different length threads on front subframe bolts

[oragex]

I was not aware there were different thread lengths. Tasca has the genuine parts and is only listing the long thread one, I'm guessing it should fit all 4 corners ? https://www.tascaparts.com/oem-parts...bC1sNS1nYXM%3D

[stuart bowes]

Originally Posted by b1mcp

I would go with the new bolts that have been sent to you. That would be way preferable to getting random bolts from ebay.

If 2 different Volvo dealers have said they are the right bolts, and VIDA also lists only one part no. for front subframe bolts (985111 - I checked) then that's what I would believe - regardless of what you have there now.


I'm not saying it's the case with these, but sometimes different parts are fitted to cars at the factory than are fitted afterwards because of assembly constraints or process.

Generally I would agree, but in this case the new 'correct' bolts literally dont go all the way in, I can feel it hitting the end of the thread and jamming, it wont go any further in. I didnt want to force it but bear in mind thats with an impact wrench so Im not pussy footing it either.. I'm left with an inch or so sticking out

the old bolt, with the thread all the way (or near enough) just goes smoothly in all the way no issues..

so I'm still leaning towards believing that I need 2 types of bolts as per the picture above. for whatever reason




as you can see, the 'blank' part of the bolt is wider than the inner part of the thread, so without more thread it would be impossible for it to move deeper into a threaded hole

I suppose I could stick it on the lathe and narrow down the last couple of inches but that's not the point (plus being hardened I'm wondering if my tooling would even cut it)

[b1mcp]

Hmm. How weird.

This won't help you, but just to add to the debate...

I removed the subframe bolts on my daughters car last year to replace the Brake Servo (2002 V70 T5). Just found the old bolts in my "scrap" bin. They're all the same. Can't be certain but I believe these are the original bolts.






May be you do have a Frankenstein car. Don't know what to suggest.

[stuart bowes]

so strange! thanks for looking though, definitely need to get to the bottom of it

when you look at yours like my most recent picture above, is the narrower 'inner' part of the thread the same width as the blank bit at the bottom of the shaft?

i.e. would it be able to screw into and past threaded section, if you see what I mean.

I'm wondering if the shaft should be slightly narrower so they can fit all 4 bolts the same rather than 2 different types (Reduction of supply and manufacturing costs)

mine is a 2001 so one of the earlier P2's

[b1mcp]

i.e. would it be able to screw into and past threaded section, if you see what I mean.

Yes I know what you mean, but the answer is no.


Just thinking if there is some other aspect of the design that could be different on yours?

Here's some pictures I took of the front and rear bushes when I did the Brake Servo job. You can see from them that the non threaded part of the bolts would not protrude outside of the bushes in this car.






Do your bushes look the same as these - same brackets, washers etc?

Is it the front or rear bush on yours that needs the longer thread?

[stuart bowes]

it's the front one that needs the longer thread.. I do like your method with the stud and nuts to support the lowered subframe though on a side note, that's pretty ingenious

One thing I will note is I only tried on the front left (passenger side) bolt

the drivers side also had the longer thread, but I didn't try and fit the shorter threaded bolt into that hole. so it's still a remote possibility that side would be ok with these shorter threads . I just didn't bother trying because I assumed it would be same both sides

what i saw of my car is identical, except in terms of the underlying design / layout I couldn't really be too sure, because I didn't actually pull the frame away from the car I did one bolt at a time. All I really saw was the bush with the big round washer taken away, so if there's a tubular part that protrudes from the bodywork into the bush, for example, I wouldn't have seen it. quite how that would work I'm not sure anyway because the bush wouldn't be doing it's job as effectively

how much of a risk do you think it is still having the old bolts in? I only took them out to put the inserts in, and when I put the back in I didn't over tighten, just torqued and thread locked. car done about 56k

torqued according to this source with an extra maybe 5deg instead of 120 deg

[IainG]

Hi
Could and old or previous bolt have sheared off in the top of the hole stopping the longer bolt now threading in fully?
Iain

[stuart bowes]

That was my first thought but no, the old bolt that came out is the same length as the new one, it's definitely the length of the thread causing the issue

I appreciate everyone's time and attention by the way, thanks for the suggestions and pictures etc

[b1mcp]

I do like your method with the stud and nuts to support the lowered subframe though on a side note, that's pretty ingenious

I can't really take credit for the ingenuity. It's the volvo approved method - except they use a special volvo tool rather than £10 worth of threaded bar and nuts/washers.

so if there's a tubular part that protrudes from the bodywork into the bush, for example, I wouldn't have seen it.

Ah yes, good shout. I looked at my pictures again. The front left is different and has a locating spigot. So I guess that's what is stopping your short thread bolt. But why does it not interfere on this car? I don't know, maybe Volvo changed the design early on, so the spigot bit is threaded on yours but not on later cars?




It would be sub optimal, but I think I'd be happy enough with 3 new bolts correctly torqued and 1 reused bolt.

[stuart bowes]

AHA!

thanks

ok maybe I'll try the new bolt on the passenger side and see if that goes in. at least it's one good new bolt I can get in there to FT (F... tight)