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Jack it up under the suspension rather than the chassis, that will keep the drive shaft straight.
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I used to go trialling, until I broke a diff pin by excessively spinning one wheel. That meant the planet wheels spun on their shaft, until the resulting friction caused them to fret on their shaft, causing it to shear the diff pin. This allowed the planet wheel shaft to come out far enough to knock a hole in the diff casing! Result, no gearbox/diff oil.
Yes the gearbox/diff oil was up to level.
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I'd raise the drive end of the car, block it on solid wood preferably, and run both drive wheels.
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I'd raise the drive end of the car, block it on solid wood preferably, and run both drive wheels.
Not sure that'd be that much different.
If there's a difference in brake drag I'd think that might stop one wheel and let the other one spin, though I can't remember if I've ever tried it.
Background/Context: I taped some thin plastic sheet (not Clingfilm but that would probably be better and I might try that later) around my torn CV boot as "first aid" pending fitting a replacement boot, and ran it as above to see if it snagged anything on full lock both ways.
Seemed OK but I noticed the hub got quite hot, suggesting the brakes are binding, so I fancied comparing both sides using an IR thermometer.
One could do a road test, but any use of the brakes (difficult to avoid entirely) would invalidate the results, plus you'd need the wheels on and they'd get in the way.
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I used to go trialling, until I broke a diff pin by excessively spinning one wheel. That meant the planet wheels spun on their shaft, until the resulting friction caused them to fret on their shaft, causing it to shear the diff pin. This allowed the planet wheel shaft to come out far enough to knock a hole in the diff casing! Result, no gearbox/diff oil.
Yes the gearbox/diff oil was up to level.
Don't trials cars have "twiddle brakes" so you can brake the spinning wheel only, or does that only apply to the purpose-built classes?
Sounds like it could be a problem, then. Maybe I'd better not do it.
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Don't trials cars have "twiddle brakes" so you can brake the spinning wheel only, or does that only apply to the purpose-built classes?
Yes, that's 'sporting trials'. I was doing PCTs (Production Car Trials) in a KIA Pride, that was surprisingly competitive. A working diff was tested for by putting rollers under one driven wheel and getting you to spin them up in gear.
You think you've got supply problems where you live, try finding a scrapyard with a KIA Pride gearbox in the UK!
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Ford Festiva here, now thinning out a bit, and manual gearboxes will be quite a lot rarer, though they did exist, at least for the Mk1.
If I ever get another RWD car I quite fancy fitting it with twiddle brakes, for that rugged, go-anywhere illusion.
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Is it a recognised technique to use the brakes to stop a wheel spinning on a FWD car?
It works a bit with an unmodified handbrake on a RWD car, but that would obviously do nothing on FWD unless its a SAAB with the handbrake operating on the front wheels (I understand that's why those SAAB's do it that way - I'd guess that'd make them a good production trials choice, if allowed)
The main brakes, operating on all 4 wheels, might be too much braking force to overcome.
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Is it a recognised technique to use the brakes to stop a wheel spinning on a FWD car?
It works a bit with an unmodified handbrake on a RWD car, but that would obviously do nothing on FWD unless its a SAAB with the handbrake operating on the front wheels (I understand that's why those SAAB's do it that way - I'd guess that'd make them a good production trials choice, if allowed)
The main brakes, operating on all 4 wheels, might be too much braking force to overcome.
yes, no other way to stop the driven wheels as they dont stop as the rears do, gearbox oil drag will keep them moving but slow, one will rotate backwards as the other one stops or carries on forwards depending on car, though never had a car that a driven wheel stopped altogether
Im assuming I read you correctly?
Edited by bolt on 05/10/2019 at 17:34
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I meant when driving in slippery conditions as in trials events.
I THINK you might mean with the wheels off the ground.
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I THINK you might mean with the wheels off the ground.
YES, sorry, misunderstood as it had drifted from original subject......
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OK, still of interest.
I'm thinking that, although the trials example suggests you can damage the diff doing this, if I don't run it like that for too long (say more than 5 mins) and keep it in first gear to keep the rotation speed down, I should be OK.
Unless I'm not
Now I just have to find my IR thermometer....
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OK, still of interest.
I'm thinking that, although the trials example suggests you can damage the diff doing this, if I don't run it like that for too long (say more than 5 mins) and keep it in first gear to keep the rotation speed down, I should be OK.
Unless I'm not
Now I just have to find my IR thermometer....
If its a standard diff I dont see any problems.
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Ed, Google Tim Hunkin's "The secret life of Machines". This was a TV series some years ago, in one episode he ran a car with one front wheel jacked up and applied the brake till the disc ran red-hot.
I found this about 19 minutes in on the YouTube episode entitled "The Car". (Several other episodes on YouTube, all worth a look).
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OK, thanks, I'll have a look.
From your description, though, I'd expect that to feed significant torque to the grounded wheel, causing the car to lurch forwards off the jack or stand.
Maybe they had it tied to the QEII (or otherwise restrained), out of shot.
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OK, thanks, I'll have a look.
From your description, though, I'd expect that to feed significant torque to the grounded wheel, causing the car to lurch forwards off the jack or stand.
Maybe they had it tied to the QEII (or otherwise restrained), out of shot.
Only on a limited slip diff, if you notice when a car is stuck in the mud or on oil one wheel spins but the other stays still whereas a limited slip diff prevents that, so unless you have lsd one wheel off the ground is the only wheel that will spin
bearing in mind if the brake is applied for a long time the disc will get red hot, only enough time to stop it at speed is all you need which wont hurt
but then you already know that
Edited by bolt on 07/10/2019 at 08:37
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OK, thanks, I'll have a look.
From your description, though, I'd expect that to feed significant torque to the grounded wheel, causing the car to lurch forwards off the jack or stand.
Maybe they had it tied to the QEII (or otherwise restrained), out of shot.
Only on a limited slip diff, if you notice when a car is stuck in the mud or on oil one wheel spins but the other stays still whereas a limited slip diff prevents that, so unless you have lsd one wheel off the ground is the only wheel that will spin
The braking effect on the jacked-up wheel will cause some torque transfer to the wheel on the ground, so Ed's comment about restraining the car from movement is valid.
(If a slipping wheel suddenly grips, the stationary wheel will get traction, as when a mat or grit is thrown under the spinning wheel).
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The braking effect on the jacked-up wheel will cause some torque transfer to the wheel on the ground, so Ed's comment about restraining the car from movement is valid.
My point was made on the assumption that the wheel was only spinning to check on the cvj boot, after that the engine would be either shut down or foot on clutch to disengage engine from drive, personally I raise both wheels for the unpredictability of diffs, simple as that
if the op wants to tie it to the QE2 thats his choice but I dont see the point when its easier to raise both wheels off the ground, safer!
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OK, thanks, I'll have a look.
From your description, though, I'd expect that to feed significant torque to the grounded wheel, causing the car to lurch forwards off the jack or stand.
Maybe they had it tied to the QEII (or otherwise restrained), out of shot.
Only on a limited slip diff, if you notice when a car is stuck in the mud or on oil one wheel spins but the other stays still whereas a limited slip diff prevents that, so unless you have lsd one wheel off the ground is the only wheel that will spin
The braking effect on the jacked-up wheel will cause some torque transfer to the wheel on the ground, so Ed's comment about restraining the car from movement is valid.
(If a slipping wheel suddenly grips, the stationary wheel will get traction, as when a mat or grit is thrown under the spinning wheel).
Yeh, I believe that's how twiddle brakes work.since they give independent braking of both driven wheels, usually on RWD
In the above scenario, BOTH driven wheels are braked.
OTOH an unmodified handbrake does work to defeat a slipping wheel and give you some traction with rear wheel drive, so why don't the main brakes do this on FWD?
My only/best guess is that the additional braking from the rear wheels might be too much braking force to overcome..
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Right, now we are all confused (or at least I am) I now have a better reason to be doing this.
I took it for a trip to the coast, maybe 50k including some expressway, and the rythmic steering kick I noted when I took it in for the 6-monthly test seemed to be getting worse.
Thought it might be run-out from a mis-mounted wheel but I cleaned up the hubs since and that didn't fix it.
I suppose the obvious suspect is a deteriorating CV joint following the boot split, though that seems a bit rapid onset if its a direct consequence of grease loss/contamination.
Marked (maybe a couple of cms angular steering wheel movement) at low speed, probably 1 per rev, turning into an apparently lower amplitude but of course higher frequency vibration at speed. Present when driven and when coasting.
Going to try one axle at a time, wheel on/off, to see if I can narrow down the source.
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Right, now we are all confused (or at least I am) I now have a better reason to be doing this.
I took it for a trip to the coast, maybe 50k including some expressway, and the rythmic steering kick I noted when I took it in for the 6-monthly test seemed to be getting worse.
Thought it might be run-out from a mis-mounted wheel but I cleaned up the hubs since and that didn't fix it.
I suppose the obvious suspect is a deteriorating CV joint following the boot split, though that seems a bit rapid onset if its a direct consequence of grease loss/contamination.
Marked (maybe a couple of cms angular steering wheel movement) at low speed, probably 1 per rev, turning into an apparently lower amplitude but of course higher frequency vibration at speed. Present when driven and when coasting.
Going to try one axle at a time, wheel on/off, to see if I can narrow down the source.
If your talking about steering wheel wobble ie steering is moving from left side to right on its own,? that can be caused by tyre tread out of straight against the carcase of the tyre its forcing the steering wheel to turn as the out of line tread hits the road
it still happens on new tyres as well as worn where the new tread is ok, but as it wears it goes out of straight line
just a thought!
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Thanks. Didn't know that.
In that case I'd expect it to go away with the source wheel off the ground, which would be nice.
These are well-worn marginal tread tyres and should perhaps be moved to the back now we are entering the dry season, best-tyres-on-the-back stylee, and to even-up wear.
The current rear tyres are the same age but have a lot more tread, since I've been lazy about swapping them seasonally..
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I've been lazy about swapping them seasonally..
We have so many pot holes around London, I really dont bother changing them front to back as they either get punctured eventually, or the pot holes wear the tyres really badly, even when the roads have been repaired (if you call it repairs lol)
theirs not much difference between after and before repair, just a bit of tarmac plopped in the hole and on to the next one, and our government have got the front to want vehicle road fund licence increase to pay for roads to be resurfaced
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Steering wheel kick wasn't apparent running in 2nd gear with NS axle (the one with the bad CV boot) off the ground , but rather noticable (no way of measuring it, since I don't have a dial guage thingy) run out wheel wobble was.
I cleaned up the hub (which wasný bad) and disk using beer can. Unfortunately the wobble seemed to be coming from the hub, and wheel wbble is still present with the rear wheel swapped to the front.
I'd guess this implies bearing failure,
Replacement seems to involve a lot of puller, press and mandrel SST's, plus a bearing of course, none of which are likely to be readily available.
There doesn't seem to be much free play when pulling on the top and bottom of the wheel.
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I've been lazy about swapping them seasonally..
We have so many pot holes around London, I really dont bother changing them front to back as they either get punctured eventually, or the pot holes wear the tyres really badly,
Roads here aren't too bad I suppose. Typhoon damage but that's mostly in the mountains, and no frost heave, which I THINK causes a lot of the damage in the Yook.
Got a lot of punctures on my Sierra. None so far on the Skywing (touch wood, etc).
Probably just chance, but the Sierra tyres were wider (so I suppose statistically more likely to encounter nails) and I parked it on campus, where I suppose it was statistically more likely to encounter disgruntled students that I'd failed.
With nails.
No evidence for that though and it probably isn't true.
Punctures aren't necessarily a big deal here anyway since those sticky string repair kits are readily available and work.
If I thought the car was likely to last much longer I'd try and get another wheel and match the spare, which is a younger Chen Shin heavy duty commercial tyre in a slightly different size, running the 4 Bridgestones on the front as alternating dry/wet season pairs.
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Temperature rise of 4 parts of the hub assembly (wheel off on stand, other wheel grounded, 2nd gear at about 2,000 rpm) monitored with Astro IR thermometer (bought in Japan) for about half an hour
Calculated 10 minute temperature rise (degrees C.)
Passenger side (suspect bearing)
shaft end 10
Inner hub 10.4
Caliper 7.6
Pad back 11.6
Driver side
Shaft end 4.1
Inner hub 3.7
Caliper 3.2
Pad back 3.3
Difference is probably brake binding, the original motivation for this test. IIRC the driver side rotated in neutral, the passenger side didn't. No clear indication of a bearing problem, though it can't be ruled out.
Driver side tyre had a bulge and is unservicable even by my standards. When moved to the back, a regular vibration was still felt on the test track, but the "kick" through the steering had gone.
Edited by edlithgow on 15/10/2019 at 14:26
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I once has a Triumph 1500, the drive shafts had rubber doughnut couplings, if one sheared (a common fault) the car would stop completely, all the drive would go to the broken side, leaving one stuck.
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I once has a Triumph 1500, the drive shafts had rubber doughnut couplings, if one sheared (a common fault) the car would stop completely, all the drive would go to the broken side, leaving one stuck.
Yes, I suppose it would.
I was in a syndicate that had one when I was working at Leeds University and staying in Hunslett Grange ((though a 1300 IIRC). We bought it at auction. It had a crack in the bottom of the engine sump causing the engine oil to leak into (and subsequently out of) the diff/gearbox housing underneath, due to someone dropping the engine onto the transmission and the oil pickup pipe clouting the casing..
These days I'd probably be able to bodge that quite easily and effectively, but then I thought one should do things properly, so we got another diff/gearbox from a scrappy and arranged with some very large men who had a crane on the back of a Transit, to take the engine out, which was a heavy old lump..
I'd loosened the bolts on one of those donuts, which were very tight, with a 15 foot scaffolding pole on a breaker bar. I forgot the other one.
Show stopper.
One of the very large men reached over and undid it one handed. Think they charged us an extra fiver but nobody felt like arguing with them.
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