Broken Gearbox - But broken where?

[Slugman]

Hi everyone.
I guess I am only asking this thru morbid curiosity, but would I be correct in assuming that either my gearbox output-shaft or diff is broken? :confused:

I am guessing it is one of them, from the following symptoms;

Clutch works fine (Been checked by someone I trust).
Driveshafts, CVs & Hubs are fine (Checked by same person).
Engine runs fine, except when it is in gear, then it sounds (Only slightly) like it is under a tiny load, like when you are almost at the clutch engagement point.
I have drained the oil, & not found chunks of metal in there.

Oh, & the last symptom is (Drumroll) . . . . I can put it in any gear with the engine on, & the car remains STATIONARY.
I.E. I can put it in 4th gear, & if I take the handbrake off, it rolls downhill, or can be pushed around freely.

I'm not a happy man at the moment. A 200Hp, 800kg car, & I STILL haven't driven it apart from a 200 metre drive up the road & back in a very bad state of tune, just before I trucked it to the tuning shop. The only person that HAS driven it said;

"No mate, sorry. I only pushed it into the shed, tuned it, then pushed it out again. We didn't drive it at all."

I am going to drop the engine & gearbox out this weekend anyway, but I wanted to hear any expert thoughts on the matter. OK, so asking on the internet for experts is fraught with danger, but most of you are pretty damn good in this forum. :)

[ECU-MAN]

sounds like the clutch is fried to me.

[Slugman]

Unfortunately not - I can put it into any gear when it is turned off by using the gear lever, then the car remains stationary when I start it.

[aaronng]

Unfortunately not - I can put it into any gear when it is turned off by using the gear lever, then the car remains stationary when I start it.

How do you know that the clutch is not worn out?

Can you confirm if the gears are actually engaging/meshing?

And how do they push it into a shed, tune it and push it out? Tuning the engine for idle RPM only? :p

[Slugman]

Gears appear to be meshing. I checked the gear lever right through to the selector rod at the back of the gearbox - It is all working fine on the outside, & it feels as though the gears are meshing.

The clutch could be worn out, but that shouldn't affect it once it is in gear should it? - Or will it make everything slip?

aaronng - That was basically what I was after - Basic tune using an oxygen sensor only, just to get the car running OK so it would pass emissions. I am using an aftermarket ecu - "EMS 8860" - Don't ask why, it would require me to beat my head against a brick wall & scream "I'm sorry for being ignorant" again.

The car was running, but only on the base map that came with the ecu - It was running so badly that I could smell the petrol coming out of the exhaust pipe, it would stall at idle unless revved a little, & when I took the plugs out to have a look, they were so covered in soot they looked like they had been dropped into an old campfire. Apparently they don't often bother to test the emissions here when going over the pits, but if it is a) A VERY modified car, & b) so bad that you can smell it . . . . .

I had left VTEC unplugged (& it still is), as I only wanted the car to run for basic driving at this stage - 140 to 160 hp should be OK for a little while. I have to put it over the pits & get it inspected for engineering, roadworthy etc, so I was just trying to get it done before my "Approval in principle to modify a road car" time limit ran out, as it does in January. VTEC & a proper dyno tune could come later, once I had sorted out all the bugs & gremlins.

I'm just cranky that he lied to me. :( My poor little baby is damaged!

[ECU-MAN]

Unfortunately not - I can put it into any gear when it is turned off by using the gear lever, then the car remains stationary when I start it.

all the more reason to say your clutch is shagged

[vinnY]

did you pull out the driveshaft from the gearbox when it was checked? a few members have had somewhat the same problem, turns out the driveshaft splines has been worn down and the gearbox was free spinning leaving the shaft stationary

and how did they manage to 'tune' the thing without having it on a dyno? guestimating figures or something?
would have been driven on the dyno

[aaronng]

Gears appear to be meshing. I checked the gear lever right through to the selector rod at the back of the gearbox - It is all working fine on the outside, & it feels as though the gears are meshing.

The clutch could be worn out, but that shouldn't affect it once it is in gear should it? - Or will it make everything slip?
You've only confirmed what's on the outside, but you can't confirm if the gears are meshing without getting some form of drive. The selector forks might even be in the wrong place?

On a car with a totally worn clutch, you can start the car in gear without the whole car jerking hard if the pressure plate was also weak from old age.



aaronng - That was basically what I was after - Basic tune using an oxygen sensor only, just to get the car running OK so it would pass emissions. I am using an aftermarket ecu - "EMS 8860" - Don't ask why, it would require me to beat my head against a brick wall & scream "I'm sorry for being ignorant" again.
That would still require the car to be moving. I doubt that the mech you used had done any tuning, but that is just my sense of skepticism. So after the "tuning", is the car still idling badly with a rich exhaust smell? Personally, I would have tried to source a stock ECU instead, especially if there is a risk that it needs to be emissions tested when over the pits.

[Slugman]

Vinny - I haven't got it apart yet - Going to do that this weekend.

aaronng - A stock ecu was $1200 new, I didn't bother trying to find a 2nd hand one, as I am missing many of the normal sensors that you would have (Note the type of car in my sig), & it so would throw a code & be running in 'safe' mode anyway - The ecu I got can run the car, & was cheaper than getting a honda ecu & then a hondata as well. The guy that got the clutch working didn't mention anything about the pressure plate, & as he had to connect up the clutch cylinder after replacing it (Cracked around the nipple after the trip from Japan), I think it is OK.

The car seems to run OK now - Starts first time, every time. Blip the throttle & it revs nicely. It just doesn't go anywhere. I must admit that I am rather sus about what he actually did to the car though . . . .

[barefootbonzai]

Can you put the car into reverse and try to push it forward or put it in 1st and try to push it backwards?

You said someone checked the clutch... but then you said you've never taken anything apart... That's impossible.... you need to take off your gearbox to check the clutch.

I think you're a little confused.

[JohnL]

This is a Mini with a Civic engine?

It's not impossible that the clutch is utter toast and failing to transmit any torque due to slippage. However, I would expect at least some residual grip if this were due to worn friction linings, accompanied by the smell of cooking clutch. Another clutch possibilty could be that the driven plate is broken (maybe sheared splines or metal between splines and friction material).

I once 'drove' a Fiat 124 Sports (nice cars those, between the rust...) that had a totally shot clutch (no further than required to move the car from one workshop to another nearby), and to get this car mobile we'd engage 1st gear then sit with the engine doing maybe 3000rpm with the clutch getting hotter and hotter (and smellier and smellier). After maybe 20 seconds the clutch would start to grip (at least enough to move the car), probably due to things getting hot, expanding and clearances getting tighter.

[online]

Pull a driveshaft out and check to see whether your diff pin is broken..

[Slugman]

Not confused - Just didn't want to type an epic post. :)
Barefootbonzai - Car can be in any gear, then pushed forwards or backwards with the same resistance as I get in neutral, which is not much. They checked the operation of the pedal, & the clutch system on the outside of the engine. Clutch pedal still feels the same as it did when it worked - Unable to get inside the engine until the whole front sub-frame is removed from the car. Since the engine bay is a little cramped (Understatement of the year) I need to remove everything in its correct order, just to get enough room to drop the frame & engine out the bottom. Rather than them charge me for working out how to do that particular puzzle, I am doing it myself. I have already got most of the ancilliaries out of the engine bay in just a few hours work. After next weekend, I can give them the whole engine, so they can open it up, & hopefully fix it.

JohnL - Yep, one little Mr Bean car with a B18C. Well, OK, not a round-nose, but one of the ugly flat-nosed ones. There is no "Burnt Clutch smell" in the engine bay. Because I didn't find any metal when I drained the oil, I was hoping that it was a relatively simple problem, but apparently 4th gear is a direct drive through the gearbox, hence the title of my initial post. It might indeed be the clutch that is stuffed, but I don't think it is the pad material. It would have to be a mechanical failure of some sort.

online - You just exceeded my mechanical knowledge. :) I have the ability to do that, (I put the driveshafts into the outer CVs when I put this thing together) but wouldn't know what to start looking for once I got it off, apart from "Looking for anything broken". I think I might as well just drop the whole thing out anyway, as even if you are right, I would still have to drop the engine out to fix it, so removing the Hub & then the drive-shaft assembly would just be an extra step - If I do it, I might as well have the engine off the car at the time, as it is easier then. I don't have a hoist.

[JohnL]

Assuming it is the clutch, I'd also be surprised if it were the friction material, it does sound more likely to be something actually broken.

Your car sounds like just the sort of Frankenstein that appeals to me!

I used to vaguely know a bloke who raced a Mini fitted with a 300bhp Mazda rotary driving the front wheels through a Hewland transaxle. It was very fast but not as quick around a track as hoped, it was somewhat 'traction limited', so less powerful but more conventional Minis were not much slower, and it still struggled against the RWD sports sedans. .

[vinnY]

is it a hydro box or a cable box?
long shot but maybe the release fork is stuck or something and not pushing on the pressure plate enough

guess we won't really know until you get the chance to pull it apart to see whats up

hit up youtube johnl and search for honda mini's, seems to be plenty in the uk afaik

[ECU-MAN]

so did you pull the gearbox out on the weekend ?? did you fond the problem ??