Emergency Braking with a TGB

[Anthony]

Wow is any one still using this part of the forum?

I am very soon, I hope, going over to Europe to bring back a
Volvo C304 TGB 13 command car 5 door, that I have recently bought.

I have some concerns with how the braking system operates.

With the C303/304/306 etc the brake system is complicated with the engagement of the front axle during heavy braking. I am not sure at what stage or how heavily one has to brake in order to bring this about. I understand that this is a safety function designed to prevent the rear wheels locking up before the fronts during heavy or emergency braking.

Other vehicles use a combination of supplying less braking force to the rear together with a Brake Proportioning Valve BPV which fine tunes the braking effort dependent on load. The Pinzgauer uses this system as does my LR 101 FC.

I am only interested in how this Volvo safety system functions on normal hard surfaced or public roads and highways not so much off the highway but on.

My concerns are that normal engagement of four wheel drive is not usualy an instantaneous affair. Also disengagement of four wheel drive is not normally instantaneous either especially on surfaced roads. That this might bring about unsatisfactory braking in an emergency where the rear brakes might lock up because the Volvo system does not engage quikly enough. The contrary is also a concern in which the Volvo safety system has engaged the front axle but might not release fast enough.

I can imagine a scenario where by my Volvo TGB 13 is being driven on wet narrow poorly cambered roads. I brake to avoid something and the rear wheels lock which might result in a skid. :?:

I am traveling on the same road having effected rapid retardation but the TGB still remains in 6x6 all wheel drive mode after I have released my brakes and does not does not revert to normal drive. I am rapidly approaching a series of tight bends. Will the TGB respond to the steering wheel? :?:

Normally if all wheels drive is operating steering can become difficult especially when negotiating tight bends as found on country roads here in Wales. The TGB with all axles engaged especially a 6x6 might be reluctant to turn into the corner resulting in a possible collision.

Are my fears unfounded? :?:

Do other members find the system operates safely at all times? :?:

Do others find that this system is faulted and might have brought about worrying moments? :?:

I would greatly appreciate some feedback and discussion about this.
I am wondering if at some stage that I might need to adapt a LPV to fit the TGB in order to have safe braking especially if I should fit disc brakes.

It is intended to use this vehicle frequently on and off road.

[Anthony]

Any one in here---------hello---hello----hello

Is kind of er empty in here hello----hel

Were is every body hiding hello ------------ hello---------heel


common you guys its spooky in here ------------------hello-----he


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whats that -- --- -- --- -- -- -------------------------------------
ahhhhhhhhh

[Ghostbear]

Anthony,

The Volvo part of this forum isnt as active as the Pinz sections.

Not saying that you wont get an answer, but there just isnt alot of Volvo owners that are frequent posters here. So, you might have to wait a while for them to cycle back through and get your answer.

[Anthony]

That is most considerate of you Ghostbear it was getting sort of cold in here. It is OK I know it is not used that often. I was just amusing my self while I wait, a bit naughty so I will have to go and stand in the corner if I can find it. I guess that Dennis will stumble on me eventualy I know he has a look in here every now and then. He may even let me out. Just joking.

[Jim Molloy]

Anthony,

The Volvo braking system has proven to be perfectly safe in all weather conditions (including ice, snow, freezing fog and rain) for the 80,000+ miles I have put on my TGB11 since 2004. I do not think you will have much of a problem with the TGB13.

Hope this helps.

Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com
http://www.volvo4x4.com

[Anthony]

Thank you most kindly Jim for reassuring me and especially from someone who has a lot of experience with these trucks and covered a good milage. When go and get it in a few weeks I shall put it to the test. The brakes will be used a lot here, steep hills lots of narrow twisty ill cambered roads rain and most of all agricultural tractors and milk tankers. The later two suddenly and unexpectedly appear half on my side of the road and they do not take any prisoners.

I did not think it would be that long before some one would come along to my assistance. Cheers!! we could do with some more Emoticons

Anthony,

The Volvo braking system has proven to be perfectly safe in all weather conditions (including ice, snow, freezing fog and rain) for the 80,000+ miles I have put on my TGB11 since 2004. I do not think you will have much of a problem with the TGB13.

Hope this helps.

Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com
http://www.volvo4x4.com

[Jim Molloy]

Anthony,

Glad to be of assistance. Keep us informed as to your final purchase. If you are looking for a more active Volvo C-series list, I think you will find the following more to your liking.

http://autos.groups.yahoo.com/group/Volvo303/

Others of interest include:

http://www.universalteknik.net/
http://www.terrangbil.net/
http://autos.groups.yahoo.com/group/valpclub/
http://disc.server.com/Indices/54728.html
http://volvovalp.ifokus.se/
http://www.c303.de/c303-forum/index.php

Enjoy!

Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com
http://www.volvo4x4.com

[Anthony]

Hi Jim,

I am on these groups having contributed for a little while on the first two for a little while, terrangil.net is difficult even with a translation service but I do try to follow it especially the images and Video clips. I am regularly on Michael's pages. I can post an image to your e mail address if you would like it but it is large. I have no means of putting it on here or any other web site as I believe one cannot post images from ones files and in any case I have absolutely no idea how to reduce them to an acceptable size for this and other web sites.

http://www.c303.de/c303-forum/index.php
http://autos.groups.yahoo.com/group/Volvo303/

http://www.terrangbil.net/


The other ones I am aware of but they are not as easy to follow so have not joined them.


Thank you so much for the assistance. It is a shame that the Volvo pages here have died because I have been a member of these pages for a few years. New owners are always passionate so perhaps I might be able to promote some fresh interest.

Forward control vehicles are not new to me having owned a LR 101FC radio body since 1990, so very nearly 18 years and have also owned with a Unimog 406 DoKa for a few years before letting it go. The 101 will also leave my ownership once the new machine arrives.

It is very strange for me I first came onto this board looking for a Pinzgauer, a 718K to be precise but not in the right place at the right time. I had thought about one of the older Pinzgauers always looking at the 6x6. I am happy to come the Volvo way as I think it will suit my need better. Over the years I will i hope do a few things to it, which is easier than with the pinz as that is such a specialised machine with little easy options.

I shall gladly let you know how I get on and by the 24 of this month will be driving the TGB 13 for the first time in Germany driving it back via the Euro Tunnel to Wales.
I have a few very large images of the TGB 13 already which were posted to me but I do not own a Digital Camera so any other images will have to be via friends for a while.

Thank you again Jim,

Anthony

Anthony,

Glad to be of assistance. Keep us informed as to your final purchase. If you are looking for a more active Volvo C-series list, I think you will find the following more to your liking.

http://autos.groups.yahoo.com/group/Volvo303/

Others of interest include:

http://www.universalteknik.net/
http://www.terrangbil.net/
http://autos.groups.yahoo.com/group/valpclub/
http://disc.server.com/Indices/54728.html
http://volvovalp.ifokus.se/
http://www.c303.de/c303-forum/index.php

Enjoy!

Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com
http://www.volvo4x4.com

[mad_as_hec]

Sorry to revive such an old thread, but I would like to just confirm that my perception of "how it works" is how it REALLY works.
1. The transfer case on the Volvo does not have a front propshaft disconnect, the transfer is ALWAYS turning the front propshaft.
2. There is a vacuum operated front AXLE disconnect to engage/disengage 4x4
3. When the braking system goes into "4x4" mode it simply connects the axles to the hubs, which are already rotating, meaning that there is mi nimal lag time between disengagement and engagement.
4. Because the driveline is locked solid under heavy braking conditions, the back brakes effectively assist the front brakes in retarding forward momentum.
5. No brake proportioning valve makes a more effective braking system.
I hope that someone can confirm my assumptions.
My questions are:
Where is the axle disconnect activated from? Is there a pressure operated switch or some other means when braking?
Does this system still work if a disk brake conversion is carried out?
Does this system still work if there are driveline modifications made?
I am negotiating the purchase of a C303 cab chassis model in Australia which needs a braking overhaul, and I was looking to go disks and possibly change to Landcruiser engine/transmission/transfercase at the same time.
Please advise me if my ideas are stupid/foolhardy/impossible.

[Jim LaGuardia]

How it works is very simple, Front axle(4x4) is engaged at transfer case, when no vacuum is present at Transfer case diaphram, and automatically in Low range(vac is vented), 4x4 can be engaged in High range by Pushing the button below the far right indicator lamp.
Diff locks are actuated When vacuum is applied to Diff Diaphrams The lights above the switches will illuminate when engaged.
Front drive shaft is parasitically driven by diff untill power is coupled at the transfer case.
My advise to you is drive the damn thing before you worry, wonder, or jump to conclusions, if the engine is healthy, the braking system will work just fine.
I see no need for Disk Brakes on these trucks if they are adjusted properly.
Top speed is 60MPH....................................................
If you are planning to transplant a non factory engine/driveline, it is not an easy task and the engine goes in from the bottom.
Look at my posts on engine rebuild and EFI.

[mad_as_hec]

Thanks Jim for your input. I eagerly read through your EFI thread and I can see why that is an appealing option, although for my purposes, a diesel with overdrive is the best option. I am thinking that some Toyota DNA would be a good investment as in Australia, Landcruiser parts can almost be bought at the local grocery store (ok, SLIGHT exaggeration) and Volvo parts are nearly impossible to locate. The Vehicle that I am looking to purchase has no brakes and I would much rather put a few extra thousand dollars into a decent brake upgrade than into refurbishing an old, marginally safe drum setup.

[M Wehrman]

Well Jim,I see all that time with a Volvo is paying off!! My TGB stops suprisingly well,and as Jim said,adjustment is important,MORE important in a hard braking situation. On a scarey side note,my truck can break 80mph w/ 315/85 tires. Just like pushing a house down the road,sucks a lot of fuel. At a steady 60mph I have seen 12mpg many times using an old mechanical FI,looking forward to results from Greg. Overall, I prefer my Volvo to my 712,my wife feels otherwise..
Mark

[Jim LaGuardia]

The stock brakes are Land Rover and Aston Martin parts, you can't tell me there is a shortage of Land Rover parts Down Under, just say it isn't so
Even with all the import tariffs, it may be more cost effective to just replace missing parts than convert.
You also have to understand the logic behind the diagonal split braking system As a fail safe it essentially ensures 3 wheel braking if one circuit fails.
upper wheel cyls are on same circuit as one rear brake, lower front wheel cyls on the other rear brake.
But you will follow whatever dream your wallet and time can provide. Have fun and post often It will be interesting to see the end results

[mad_as_hec]

The stock brakes are Land Rover and Aston Martin parts, you can't tell me there is a shortage of Land Rover parts Down Under, just say it isn't so
Even with all the import tariffs, it may be more cost effective to just replace missing parts than convert.
You also have to understand the logic behind the diagonal split braking system As a fail safe it essentially ensures 3 wheel braking if one circuit fails.
upper wheel cyls are on same circuit as one rear brake, lower front wheel cyls on the other rear brake.
But you will follow whatever dream your wallet and time can provide. Have fun and post often It will be interesting to see the end results

Thanks for the encouragement Jim. The $6000 purchase price allows me a bit of leeway as far as rebuilds/upgrades goes. Just trying to explore all options. And yes, Landrover parts are comparatively rare when talking Landcruiser parts. Here in Oz, you might have 1 Landrover for every 30 Toyotas on the road. Of course the ratio goes to about 1:1 when you go to a workshop. I have to consider "worst case scenarios" and as this is the vehicle that I plan on travellig the Canning Stock Route with, it has to be either reliable, or have plenty of easily accessible parts. Since the CSR is a trek of 1900km (1200 miles) offroad (no gas stations or service centres in the desert), all things must be considered. If I keep the old braking system, I will certainly be calling for some expert advice.

[mad_as_hec]

Well Jim,I see all that time with a Volvo is paying off!! My TGB stops suprisingly well,and as Jim said,adjustment is important,MORE important in a hard braking situation. On a scarey side note,my truck can break 80mph w/ 315/85 tires. Just like pushing a house down the road,sucks a lot of fuel. At a steady 60mph I have seen 12mpg many times using an old mechanical FI,looking forward to results from Greg. Overall, I prefer my Volvo to my 712,my wife feels otherwise..
Mark

Hey Mark, how much guard clearance do you have with the 315 tires? I have a set of 325/85R16 Michelin XML on my landcruiser and I was going to swap them onto the Volvo when I get it. Also how does it handle? Or is that a bad joke?