theduck
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| posted on 7/5/15 at 11:02 PM |
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Lack of power to one wheel
During my IVA the car was on the rollers in order to test the speedo. During this test the tester drives the car up to certain speeds to check the
speedo accuracy. Now from what I understand they would normally put the car in 3rd or 4th to do this without having to work up through the gears
because the rollers offer little to no resistance. When the tester tried this, the car would just cut out. So he then tried working his way up
through the gears, but it still bogged down and died when changing to 3rd. I was stood on the offside of the car so at this point I cant say for
certain what the nearside wheel was doing, but can assume based on what happened later it was acting as you would expect, however, the offisde wheel
would slow very quickly when he changed gears, almost to an immediate stop.
We advised the tester of this and he, like us assumed a binding brake drum, so we tried moving each wheel by hand, and they span freely. So he tried
again, only this time the nearside wheel span up fine, but the offside did not move at all, at which point we abandoned that part of the test assuming
a knackered diff.
Later on during the test when I was required to drive the car, when changing from 1st to 2nd the car seemed to noticeably slow, again like a stuck on
brake.
I have another known good diff sorted, so I can change it, but I was wondering if the great minds that are the rhocar membership had any other ideas
on what else could have caused these symptoms?
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joneh
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| posted on 8/5/15 at 05:18 AM |
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Perhaps you should ask on Rhocar? 
Sounds like normal behaviour for an open diff where one wheel is binding however if you can spin by hand it must be further in... So would have to
check the diff out.
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mark chandler
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| posted on 8/5/15 at 05:19 AM |
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When you are spinning by hand the car is jacked up so it could be a handbrake cable issue that when lowered it binds up in which case this would
immediately show as a heat difference on the discs.
alternatively make sure the half shaft is not binding up, assuming a Sierra rear diff you should be able to move the half shaft left to right
1/2"
Faulty rear wheel bearing jamming up under load.
A faulty diff sounds unlikely, stuffed planet gears would appear more like a locked diff.
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theduck
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| posted on 8/5/15 at 07:28 AM |
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We were spinning the wheel by hand on the rollers, so weight was on the wheel.
My mind had also gone to wheel bearing as a possible issue so glad to hear that could be a possible. Will have to try and replicate at home.
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40inches
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| posted on 8/5/15 at 07:42 AM |
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Sounds like normal open diff behaviour. When I had the 2B tested the speedo reading was all over the place, the pick up magnet was on a drive shaft
and the wheels kept slowing down from one side to the other. Works ok if the pick up is on the prop.
Can't help with the problem in higher gears though. Engine problem? Gearbox?
If you have another diff, possibly try it? That will confirm or eliminate the diff.
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britishtrident
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| posted on 8/5/15 at 08:13 AM |
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Don't start random part swapping. It is a brake binding -- why it is binding is what you you have to investigate. Normally it is a case of just
pulling the drums and checking the wheel cylinder and checking the brakes shoes and handbrake mechanism is correctly assembled but master cylinders
are not unkown as a cause brake binding problems on home built cars. Make sure you have a return spring on the brake pedal and that is returning the
piston in the master cylinder fully.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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theduck
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| posted on 8/5/15 at 08:26 AM |
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But if it was brake binding surely we would hve felt that when trying to turn the wheel by hand?
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40inches
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| posted on 8/5/15 at 09:20 AM |
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You say the engine cuts out? You mean it stops and has to be restarted? Brake binding wouldn't cause that, brakes locking up completely possibly
would.
You are allowed to drive it on the road for remedial work.
[Edited on 8-5-15 by 40inches]
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gremlin1234
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| posted on 8/5/15 at 10:07 AM |
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one thing to check
if the inside of the offside tyre was just touching the edge of the roller pit? check for wear marks on the side of the tyre
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theduck
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| posted on 8/5/15 at 10:16 AM |
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We checked that while on the rollers, and as said, it moved freely by hand on the rollers so wasnt catching.
Yes, engine stalled because it couldnt get the wheels spinning in 3rd and 4th
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40inches
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| posted on 8/5/15 at 10:46 AM |
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quote:
Originally posted by theduck
We checked that while on the rollers, and as said, it moved freely by hand on the rollers so wasnt catching.
Yes, engine stalled because it couldnt get the wheels spinning in 3rd and 4th
Have you tried it on the road?
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theduck
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| posted on 8/5/15 at 11:45 AM |
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Tried it around the test centre and it slowed massively when changing gear.
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adithorp
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| posted on 8/5/15 at 12:03 PM |
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quote:
Originally posted by britishtrident
...It is a brake binding -- why it is binding is what you you have to investigate...
Not sure how you can be so sure of that conclution. Especially as it passed the IVA brake test which would have shown up a dragging brake and the
wheel was free to rotate when transmission not under load.
Not sure what it could be though. I'd be looking at the hubs, shafts and uprights for clearance issues first.
BT is right to say find the problem first rather than just throwing parts darts at it hoping to hit the right thing.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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40inches
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| posted on 8/5/15 at 12:41 PM |
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quote:
Originally posted by theduck
Tried it around the test centre and it slowed massively when changing gear.
You said that it was when changing up to third, is it ok in 1st and 2nd, will the engine rev freely in those gears? If so, I would be looking at
gearbox issues.
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kj
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| posted on 8/5/15 at 12:55 PM |
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Are you using a back axle from a sierra 4x4 ? it could be the viscous diff, wrong oil or too much. Worth checking.
If it is a viscous diff it would be difficult in a light car as it would virtually lock up.
[Edited on 8/5/15 by kj]
Think about it, think about it again and then do it.
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britishtrident
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| posted on 8/5/15 at 02:21 PM |
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A few years back a fellow Locoster had problems with his car that gave the same symptoms, he was convinced it was a problem with his English axle
and istr he change the axle and diff twice and was so convinced it was an axle problem he was going to swap an Atlas axle in.
It was the same problem that has been encountered by more than a few Locosters of the brake master cylinder piston push rod being too long and not
allowing fluid to return to the fluid resevoir
Link to thread
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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ianhurley20
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| posted on 8/5/15 at 04:49 PM |
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quote:
Originally posted by 40inches
You say the engine cuts out? You mean it stops and has to be restarted? Brake binding wouldn't cause that, brakes locking up completely possibly
would.
You are allowed to drive it on the road for remedial work.
[Edited on 8-5-15 by 40inches]
allowed to drive it .......Where on earth does it say you can do that in the legislation?
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theduck
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| posted on 8/5/15 at 05:06 PM |
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Thanks all, got a list of things to check now starting with pushrod.
As for driving on road to get remedial work done he is correct, is in the iva paperwork.
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ianhurley20
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| posted on 8/5/15 at 06:46 PM |
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quote:
Originally posted by theduck
As for driving on road to get remedial work done he is correct, is in the iva paperwork.
can you post or email me a copy of the iva paperwork that says that as my local 'traffic' roads policing unit says the opposite - ie you
can't drive a non registered, non taxed, non iva 'd vehicle on a road otherwise than to or from a pre arranged iva test and then only for
the purposes of that test?
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theduck
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| posted on 8/5/15 at 07:05 PM |
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I'll grab a copy but the part that says you can drive to the iva says that if you fail you can then drive to a prebooked appointment for
remedial work.
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theduck
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| posted on 8/5/15 at 07:11 PM |
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I take it back, the brake is binding! Not the push rod fault though though.
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robinj66
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| posted on 8/5/15 at 07:16 PM |
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quote:
Originally posted by ianhurley20
quote:
Originally posted by theduck
As for driving on road to get remedial work done he is correct, is in the iva paperwork.
can you post or email me a copy of the iva paperwork that says that as my local 'traffic' roads policing unit says the opposite - ie you
can't drive a non registered, non taxed, non iva 'd vehicle on a road otherwise than to or from a pre arranged iva test and then only for
the purposes of that test?
Have a look at section 22 (3) of Schedule 2 of the Vehicle Excise and Registration Act 1994
here
It specifies when you can drive on the road without a VEL (road tax). You still need to have valid insurance.
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40inches
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| posted on 8/5/15 at 11:00 PM |
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quote:
Originally posted by ianhurley20
quote:
Originally posted by 40inches
You say the engine cuts out? You mean it stops and has to be restarted? Brake binding wouldn't cause that, brakes locking up completely possibly
would.
You are allowed to drive it on the road for remedial work.
[Edited on 8-5-15 by 40inches]
allowed to drive it .......Where on earth does it say you can do that in the legislation?
It is stated clearly in the IVA paper work you get back, that you can drive, if the vehicle is insured, to and from the IVA test and
for any remedial work needed in the event of an IVA fail.
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rusty nuts
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| posted on 9/5/15 at 06:27 AM |
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If the car is found to be in a dangerous condition during the IVA test VOSA can stop the car being driven anywhere
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ianhurley20
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| posted on 9/5/15 at 08:10 AM |
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So to clarify the legislation says -
Where the relevant certificate is refused on a compulsory test [F57, or a reduced pollution test,]of a vehicle [F58or as a result of a relevant
re-examination,] the vehicle is an exempt vehicle when it is being used solely for the purpose of—
(a)delivering it (by previous arrangement for a specified time on a specified date) at a place where relevant work is to be done on it, or
(b)bringing it away from a place where relevant work has been done on it.
- So you can take the car for a pre arranged repair or to and from a test but you can't just drive it on a road 'for remedial
purposes' and VOSA can stop you driving anywhere if they think its dangerous. You still have to have insurance obviously.
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