Volvo Community Forum. The Forums of the Volvo Owners Club

Forum Rules Volvo Owners Club About VOC Volvo Gallery Links Volvo History Volvo Press
Go Back   Volvo Owners Club Forum > "Technical Topics" > S60 & V60 '18> / XC60 '17> / S90 & V90 '16> / XC90 '15> General

Notices

S60 & V60 '18> / XC60 '17> / S90 & V90 '16> / XC90 '15> General Forum for the SPA-platform 60- and 90-series models

Information
  • VOC Members: There is no login facility using your VOC membership number or the details from page 3 of the club magazine. You need to register in the normal way
  • AOL Customers: Make sure you check the 'Remember me' check box otherwise the AOL system may log you out during the session. This is a known issue with AOL.
  • AOL, Yahoo and Plus.net users. Forum owners such as us are finding that AOL, Yahoo and Plus.net are blocking a lot of email generated from forums. This may mean your registration activation and other emails will not get to you, or they may appear in your spam mailbox

Thread Informations

V90 cc towbar

Views : 2890

Replies : 37

Users Viewing This Thread :  

Reply
 
Thread Tools Display Modes
Old Jun 16th, 2018, 20:58   #21
Quacker
Premier Member
 
Quacker's Avatar
 

Last Online: Nov 22nd, 2021 01:53
Join Date: Feb 2017
Location: West of Carmarthen
Default

Quote:
Originally Posted by gaby View Post
I never would have guessed how much can be deduced from just looking at (pictures of) these items.
And to do so without studying them in detail! I cant, and I certainly wouldn't go as far as discrediting the
commitment to safety from Volvo, safety being their mantra. Would they sacrifice safety by mounting a
towbar of compromised design while they could bolt or weld the ball to the existing and assumed safe beam?
That seems even more unlikely to me than being able to asses the propertie of these beams from afar.
But of course it's not impossible...

They must compromise when it comes to the different properties that are necessary for a rigid and stressed tow bar compared to dedicated energy absorbing structures, which are by necessity removed and replaced by the tow bar.

You do realise that the removed deformable beam is made of aluminium of course and that the tow hitch is made of thick walled high strength steel?

It seems to me that you think I'm guessing this and guessing wrongly. I can assure you that I am not.
__________________
XC90 D5, 2017 Inscription. Dark Grey. Xenium pack. Winter Plus with HUD. Black leather interior with alloy trim inserts. Ownership ended June 2020, Happy motoring times!

Last edited by Quacker; Jun 16th, 2018 at 21:03.
Quacker is offline   Reply With Quote
Old Jun 16th, 2018, 22:30   #22
Quacker
Premier Member
 
Quacker's Avatar
 

Last Online: Nov 22nd, 2021 01:53
Join Date: Feb 2017
Location: West of Carmarthen
Default

Quote:
Originally Posted by gaby View Post
Perhaps the stifness of the rear bumper beam isn't all that important:
https://www.youtube.com/watch?v=q-1cjw25E7A
https://www.youtube.com/watch?v=NRzMhk9WX70
The original beam is designed to deform, augmented by the crush cans, in order to absorb the energy and minimise its transfer to the people inside the car. The non-deformable part is the safety cage that surrounds the passenger compartment.

Removing the rear deformable energy absorbing units and replacing them with a very strong and rigid tow bar does not compromise the safety cage at all. Indeed it probably strengthens it. At the expense of not dissipating the energy that the original design does. A rear end shunt will be felt much harder, although all the active safety features, like seatbelt pre-tensioning, pre-crash brake actuation and hazard warning activation should all work perfectly and the safety cage should work at least as well as without a hitch.

Energy absorption is not entirely lost when the hitch is fitted, because the mounting pads on the chassis [where the original crush cans were bolted on and also the hitch frame] are also somewhat crushable and the round hitch cross bar is welded at that point to the pad extensions only at the back, with a small void in front. This is not some artistic license by the designers. It is to make a joint that will fail under a specific impact force with the void allowing the weld to stretch and dissipate some energy as it does so. No way can it be as effective as an extruded aluminium box profile mounted to deep crush cans of course, but I'm sure they have done their best commensurate with the durability and strength constraints of integrating a drawbar capable of long term integrity with pulling, pushing, twisting and lateral loads that comes with towing two tons with probably a four times overload/failure safety factor.
__________________
XC90 D5, 2017 Inscription. Dark Grey. Xenium pack. Winter Plus with HUD. Black leather interior with alloy trim inserts. Ownership ended June 2020, Happy motoring times!
Quacker is offline   Reply With Quote
Old Jun 16th, 2018, 22:51   #23
Clan
Experienced Member
 
Clan's Avatar
 

Last Online: Today 14:09
Join Date: Jun 2007
Location: L/H side
Default

Quote:
Originally Posted by Quacker View Post
The original beam is designed to deform, augmented by the crush cans, in order to absorb the energy and minimise its transfer to the people inside the car. The non-deformable part is the safety cage that surrounds the passenger compartment.

Removing the rear deformable energy absorbing units and replacing them with a very strong and rigid tow bar does not compromise the safety cage at all. Indeed it probably strengthens it. At the expense of not dissipating the energy that the original design does. A rear end shunt will be felt much harder, although all the active safety features, like seatbelt pre-tensioning, pre-crash brake actuation and hazard warning activation should all work perfectly and the safety cage should work at least as well as without a hitch.

Energy absorption is not entirely lost when the hitch is fitted, because the mounting pads on the chassis [where the original crush cans were bolted on and also the hitch frame] are also somewhat crushable and the round hitch cross bar is welded at that point to the pad extensions only at the back, with a small void in front. This is not some artistic license by the designers. It is to make a joint that will fail under a specific impact force with the void allowing the weld to stretch and dissipate some energy as it does so. No way can it be as effective as an extruded aluminium box profile mounted to deep crush cans of course, but I'm sure they have done their best commensurate with the durability and strength constraints of integrating a drawbar capable of long term integrity with pulling, pushing, twisting and lateral loads that comes with towing two tons with probably a four times overload/failure safety factor.
the New xc90 towbar has a lazer cut slot cut in the main mounting bracket each side to give presumably the same impact absorbing quality as the removed beam .
__________________
My comments are only based on my opinions and vast experience .
Clan is offline   Reply With Quote
Old Jun 16th, 2018, 23:24   #24
Quacker
Premier Member
 
Quacker's Avatar
 

Last Online: Nov 22nd, 2021 01:53
Join Date: Feb 2017
Location: West of Carmarthen
Default

Quote:
Originally Posted by Clan View Post
the New xc90 towbar has a lazer cut slot cut in the main mounting bracket each side to give presumably the same impact absorbing quality as the removed beam .
This is the slot or void I mentioned several times that is welded only at the back of the tube. Yes, again I will say that it is designed to absorb 'some' energy, but in my opinion it can only be a small fraction of the potential energy absorption of the factory alloy box-profile which is designed solely and specifically for that purpose.

The following is a direct copy and paste from the message of mine that you actually quoted but obviously has not read and understood. QUOTE..
"Energy absorption is not entirely lost when the hitch is fitted, because the mounting pads on the chassis [where the original crush cans were bolted on and also the hitch frame] are also somewhat crushable and the round hitch cross bar is welded at that point to the pad extensions only at the back, with a small void in front. This is not some artistic license by the designers. It is to make a joint that will fail under a specific impact force with the void allowing the weld to stretch and dissipate some energy as it does so." END And so it continues.

I'm not sure why this is in the least contentious. It is what it is, and a tow bar of necessity has to be rigid and strong and durable as first priorities.
__________________
XC90 D5, 2017 Inscription. Dark Grey. Xenium pack. Winter Plus with HUD. Black leather interior with alloy trim inserts. Ownership ended June 2020, Happy motoring times!

Last edited by Quacker; Jun 17th, 2018 at 00:20.
Quacker is offline   Reply With Quote
Old Jun 18th, 2018, 21:35   #25
gaby
Premier Member
 
gaby's Avatar
 

Last Online: Today 08:35
Join Date: Aug 2009
Location: Belgium
Default

I found a drawing of a Westfalia towbar, not for the V90 but for the XC90.
It seems that the corners of the car are left unprotected since the towbar
doesn't extend to the mounting flanges.
https://www.pfjonesebay.co.uk/instructions/VL53Q.pdf
__________________
2018 XC90 T5 (5 seater)
gaby is offline   Reply With Quote
Old Jun 18th, 2018, 22:25   #26
Clan
Experienced Member
 
Clan's Avatar
 

Last Online: Today 14:09
Join Date: Jun 2007
Location: L/H side
Default

Quote:
Originally Posted by gaby View Post
I found a drawing of a Westfalia towbar, not for the V90 but for the XC90.
It seems that the corners of the car are left unprotected since the towbar
doesn't extend to the mounting flanges.
https://www.pfjonesebay.co.uk/instructions/VL53Q.pdf

Good point ...They don't give safety a thought , no foam block between bumper and towbar either ..
Attached Images
File Type: jpg 90.jpg (17.8 KB, 10 views)
__________________
My comments are only based on my opinions and vast experience .
Clan is offline   Reply With Quote
Old Jun 19th, 2018, 01:21   #27
Quacker
Premier Member
 
Quacker's Avatar
 

Last Online: Nov 22nd, 2021 01:53
Join Date: Feb 2017
Location: West of Carmarthen
Default

To an extent I disagree. It is probably one of the safest towbars available, but could never absorb the energy of the original dedicated relatively soft progressive crush system that was removed. Nevertheless it does have some absorption characteristics. The main safety cage that protects the passengers is not compromised in any way.

I would confidently say that Volvo has one of, if not the very safest rear end collision scenario cars fitted with a tow hitch.

How long or far down the road would you expect foam blocks or crush cans to last before the hitch dropped off if attached to them?
__________________
XC90 D5, 2017 Inscription. Dark Grey. Xenium pack. Winter Plus with HUD. Black leather interior with alloy trim inserts. Ownership ended June 2020, Happy motoring times!

Last edited by Quacker; Jun 19th, 2018 at 01:24.
Quacker is offline   Reply With Quote
Old Jun 19th, 2018, 09:20   #28
gaby
Premier Member
 
gaby's Avatar
 

Last Online: Today 08:35
Join Date: Aug 2009
Location: Belgium
Default

Quote:
Originally Posted by Clan View Post
Good point ...They don't give safety a thought , no foam block between bumper and towbar either ..
I made this remark (and the previous ones) so that the OP has a better idea of what the difference in price
and quality between the OEM and an aftermarket towbar can mean, so he can make the best possible deciscion.
Of course it doesn't make the Volov towbar cheap, especially not the retractable one.
But it may help to appreciate the price. Installation of hard - and software in our car was included.
__________________
2018 XC90 T5 (5 seater)
gaby is offline   Reply With Quote
Old Jun 20th, 2018, 14:28   #29
Quacker
Premier Member
 
Quacker's Avatar
 

Last Online: Nov 22nd, 2021 01:53
Join Date: Feb 2017
Location: West of Carmarthen
Default

Quote:
Originally Posted by gaby View Post
I made this remark (and the previous ones) so that the OP has a better idea of what the difference in price
and quality between the OEM and an aftermarket towbar can mean, so he can make the best possible deciscion.
Of course it doesn't make the Volov towbar cheap, especially not the retractable one.
But it may help to appreciate the price. Installation of hard - and software in our car was included.
Good point. With aftermarket towbars fitted by independents, the car would need a trip to the Volvo dealer to install software and/or switch on the towing mode features. This would inevitably be at extra cost, which should be added to the cost 'saving' of having non-genuine hardware and fitting in the first place.
__________________
XC90 D5, 2017 Inscription. Dark Grey. Xenium pack. Winter Plus with HUD. Black leather interior with alloy trim inserts. Ownership ended June 2020, Happy motoring times!
Quacker is offline   Reply With Quote
Old Jun 20th, 2018, 15:24   #30
gaby
Premier Member
 
gaby's Avatar
 

Last Online: Today 08:35
Join Date: Aug 2009
Location: Belgium
Default

Quote:
Originally Posted by gaby View Post
I made this remark (and the previous ones) so that the OP has a better idea of what the difference in price
and quality between the OEM and an aftermarket towbar can mean, so he can make the best possible deciscion.
Rereading my own reply, I now realise that of course it should have been "all remarks/replies", not just my own.
__________________
2018 XC90 T5 (5 seater)
gaby is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 17:45.


Powered by vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.