Hi all,
Can anyone give me a safe percentage for an unladen brake test?
I’ve just got hold of the inspection report from my last six weekly and the brake test came back at 22% for the service brakes and 10% for the park brake. I’ve called the dealer and asked for more information and they are saying the numbers are so low because the truck was unladen when it was tested. I can understand that.
What they can’t or won’t tell me is what a bad reading on this test is.
Can anyone help?
The sheet will probably say insufficient load on lift and drive ,you’ll only get a reading worth thinking about from the front steer .
At work 4x2 tractor with 4 park brakes std reading 35/25/15 percent
4x2 tractor 2 park brakes 35/25/4
First figure service
2nd figure secondary
3rd figure park
Average effort readings on front wheels when they lock unladen 1700/2000kg, rears can be as low as 450kg, mid axle can struggle to get 350kg.
Obviously they vary, even the weather can have an effect, wet tyres wheels lock out earlier, but again only when unladen.
Basically all ■■■■■ readings because truck is empty, the purpose of the test is really just to see if the brakes actually work, brake evenly across an axle and dont bind etc
If you speak to the service guy he wont know what you are talking about, and if you ask a fitter he will either go into great detail and bore you to death or just think you are stupid, grunt and walk off 
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.
As long as there’s a (L) down the right hand side of the results then it’s fine (probably).
Own Account Driver:
As long as there’s a (L) down the right hand side of the results then it’s fine (probably).
(Probably ) but not always ,had rear lift problem recently ,n.s. Was hot enough at the bottom of a long hill but the o.s was notably not as hot ,however both sides locked out on test ,but the heat difference was enough to perhaps of earned a delayed prohibition had the gestapo used a thermometer on it , it turn out to be the drum which was on when I bought it out of shape/ worn and although through the back plate all looked good the middle 4 inches was the only area making contact out of 8 , had it not been for aly wheels iam not sure I’d have picked up on this as soon .
did they lock out?
It’s been awhile but near sure you take an artic for PSV in NI without trailer they refuse test!!!
I used to take the agg trailer with 8T stone over the rear axles and that fair helped the braking scores!!!
Sent from my SM-J500FN using Tapatalk
For an inspection I would look for a piece of paper with “brake test” at the top and “passed” on the bottom.
All wheels locked is also what I would look for unladen.
cav551:
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.
Tapley wont tell you about imbalance
Tapley wont tell you if you have brake bind issues, even minor bind which can cost you dear in the long run
Basically tapley is a load of old carp, many people dont even know how to carry out a tapley test correctly so the readings can be off the scale so are pointless.
Trickydick:
cav551:
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.Tapley wont tell you about imbalance
Tapley wont tell you if you have brake bind issues, even minor bind which can cost you dear in the long run
Basically tapley is a load of old carp, many people dont even know how to carry out a tapley test correctly so the readings can be off the scale so are pointless.
Swings and roundabouts. Tapley benefits from being closer to reality by being a dynamic test RBT gives you more information on individual wheel performance. Although we do find the imbalance results can be unreliable when everything locks outs. Unladen a Tapley is probably more meaningful than RBT. Brake testing a solo unit you might as well slam the brakes on some loose gravel and take a picture, on your phone with a date stamp, of the six skid marks, but always a better box tick to have a brake test printout of some sort.
What we do with customers we PMI but don’t RBT is use a Tapley with a printer option and print the results at MOT time you can then benchmark to see if there’s been a deterioration in braking since and investigate. Most 4x4 passenger cars are still MOTed with a Tapley.
Punchy Dan:
Own Account Driver:
As long as there’s a (L) down the right hand side of the results then it’s fine (probably).(Probably ) but not always ,had rear lift problem recently ,n.s. Was hot enough at the bottom of a long hill but the o.s was notably not as hot ,however both sides locked out on test ,but the heat difference was enough to perhaps of earned a delayed prohibition had the gestapo used a thermometer on it , it turn out to be the drum which was on when I bought it out of shape/ worn and although through the back plate all looked good the middle 4 inches was the only area making contact out of 8 , had it not been for aly wheels iam not sure I’d have picked up on this as soon .
Infra red thermometers are pretty cheap it’s worth having one for the few minutes it takes to check wheel temps. As was saying above RBTs aren’t the be all and end all, the only thing they definitively tell you is the truck is ok at passing a RBT.
cav551:
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.
Not an ATF but they do have an MOT trailer. I’ve told 'em to put that on it next time it goes in and give me numbers I can actually interpret.
Thanks for all the explanations guys.
nsmith1180:
cav551:
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.Not an ATF but they do have an MOT trailer. I’ve told 'em to put that on it next time it goes in and give me numbers I can actually interpret.
Thanks for all the explanations guys.
Hopefully it should still come back locking on all axles although often the middle one won’t with everything tip-top as new.
Own Account Driver:
Trickydick:
cav551:
Is this main dealer an Authorised Test Facility? If they are surely they have a loaded trailer available for use on the MOT lane. Roller brake testing an unladen tractor unit tells you little more than the fitter should have already deduced from his inspection and a blast across the yard. A print out from a Tapley test tells you as much if not more.Tapley wont tell you about imbalance
Tapley wont tell you if you have brake bind issues, even minor bind which can cost you dear in the long run
Basically tapley is a load of old carp, many people dont even know how to carry out a tapley test correctly so the readings can be off the scale so are pointless.Swings and roundabouts. Tapley benefits from being closer to reality by being a dynamic test RBT gives you more information on individual wheel performance. Although we do find the imbalance results can be unreliable when everything locks outs. Unladen a Tapley is probably more meaningful than RBT. Brake testing a solo unit you might as well slam the brakes on some loose gravel and take a picture, on your phone with a date stamp, of the six skid marks, but always a better box tick to have a brake test printout of some sort.
What we do with customers we PMI but don’t RBT is use a Tapley with a printer option and print the results at MOT time you can then benchmark to see if there’s been a deterioration in braking since and investigate. Most 4x4 passenger cars are still MOTed with a Tapley.
Where I used to work it was tapley time, but once you knew what the figures were for a scania 6x2/6x4 etc there was little point in actually doing the test.
They then went to everything using the RBT mainly as an arse covering tactic and if it said pass no matter what happened from then on when it left the shop you were in the clear.
Where I am now its also RBT every time and also after any brake work pads/shoes etc again arse covering as thats how the world is getting.
Where i take my 4x4s they do still use the tapley.
I think where the tapley fails is you always get a pass unless the thing is totally fubared, now on the rollers especially with the merc 4x2 tractors and the scania/daf 6x2 middle axles if the brakes arent warmed up its a fail, whereas on the tapley they would have passed.