AndyP's_P1

iTrader: (1)

Driving along today at around 40mph, went to select 5th, felt a bit dodgy and when i backed off the throttle it popped out of gear. When i select 5th gear it gives a little crunch like the synchromesh has departed and 5th gear still pulls fine if i hold the gearstick in place. But if i let go and take foot off throttle then it pops out again.

Every other gear is still ok. Anyone have any suggestions as to what could be the problem?

Looks like this weekend will be spent removing a gearbox

Thanks in advance

APIDavid

iTrader: (4)

Andy, The 'BIG NUT ' on the back of the mainshaft comes loose and causes problems such as you have. Fortunately you can take the back off the box in situ and tighten it back up again, without needing to take the box out of the car.

Jack it up nice and high from the back crawl under remove the linkage from the box undo all the obvious bolts and it is off.

Take the nut right off, clean it and the mainshaft threads with something that air dries [ cellulose thinners is good or brake cleaner will do.] Loctite it to death and put it all back again.

Occasionally the wear causes damage to the little interlocks in the synchro slider, They can fall right out [ which can make things fiddly. ] BUT that is only a maybe not a certainty.

We do it while u wait here in about 3 hours but we do have the benefit of a ramp.

Good luck - nothing to lose . David APi

AndyP's_P1

iTrader: (1)

Excellent reply David. Many thanks for that. I will give it a go tomorrow and see if that fixes the problem.

AndyP's_P1

iTrader: (1)

Could this fault happen intermittently tho? Just that today i was driving the car to my folks house to work on it and it was fine again. All gears selecting as they should.

Must have done about 50 miles in it today then tonight it started playing up in 5th gear again.

tan v5sti

this is a common fault on sti 5 and p1.it will crunch every time u give it some in 4th and then shift to 5th.change slowly frum 4th to 5th or double clutch this way u wont get a crunch.300 quid for a 5th gear synchro frum david hendry cars inc fitting.drain out front diff oil and get the metal pieces so u dnt damage further

PeeVee

iTrader: (1)

As David has said, if it is popping out of 5th when you back off, then the stake nut has come loose.

Phil

AndyP's_P1

iTrader: (1)

Barretts....would this make the crunching noise when i try to get into 5th? Also is it possible that the problem could be intermittent?

APIDavid

iTrader: (4)

l'll jump in here if that is OK. What is happening is that the 5th gear assembly, which is a stand alone outside the main gear case, is floating backwards and forwards, because its retaining nut is loose.

So, sometimes it happens to end up in the right place and other times it has moved away from its correct position. It'll never get better of its own accord.

In fact if the distance continues to increase as the big nut comes more undone you stand the chance of losing the interlocks out of 5th / reverse slider and they fall into the bottom of the box. If you are lucky it will still move - if you are unlucky it'll be a trailer job..

Get it done sooner rather than later, as it is doing damage right now and you might just catch it. We are doing one in the workshop right now.

Good luck - David

AndyP's_P1

iTrader: (1)

Ok once again thanks for your help. I will look into it as soon as i get back onshore. Easy enough job to do? Just simply remove the linkage from the box, take nut off, clean, locktite and reassemble?

APIDavid

iTrader: (4)

Yeah, that's about it. You'll need to wiggle the main selector rail out from where it connects to the 3 selector shafts when you split the rear case off from the main gearcase. And MAKE SURE that it has re - engaged once back on. Don't build it all up without checking gear selection at a very early stage of re-assembly.

Good luck ! Call me up anytime for help if you get stuck.

David

PeeVee

iTrader: (1)

Depends on how "Intermittent" it is, you say that it was dropping out of 5th on the over run, did it only do it the once? or has it been more of a problem?

Ver V & P1's suffered with two faults within the gearbox.

1. 5th gear would crunch when selected at high rpm's.

The fix for this was to remove the gear box and fit a modified 5th gear and selector hub & baulk rings. At this point a modified stake nut was also fitted to stop it coming loose.

2. The stake nut on the mainshaft would come loose & cause crunching into 5th + dropping out of gear when you lift off the throttle.

The factory fix for this was to remove the gear box & strip it to inspect 5th gear & the selector hub assay for damage. A modified stake nut was the fix, but if any damage had been done to the gear or selector hub, then the modified 5th & hub etc was fitted.

In reality a reason was always found to fit the whole of the mod kit so that it was brought up to the latest spec whilst the car was in warranty & being repaired at no cost to the customer.

It is, as has been said, possible to re tighten the stake nut with the gearbox in place by removing the transfer case to gain access to the 5th gear assay.

The torque setting for the nut is 118 Nm or 87 Lbft. + Loctite

If you have never had one of these boxes apart then there are a couple of things that are a bit fiddly, especially if the box is in the car & not bolted to a stand where you can walk around it and see what you are doing.

Getting the selector rail to engage correctly with the selector shafts as you slide the transfer case back on is a pain in the a**e. As you try and locate the rail into the shafts & then slide the case forward it will want to move one of the shafts forward and engage a gear, if this happens it won’t select any gears when it's all bolted together as the rail will then drop into the gap now left by the misaligned shaft. As David has said, you need to check that you can select all gears once the transfer case is bolted back on before you finish rebuilding everything else or you will gutted when you have finished the job and then find that your gear lever won't move & it all has to come apart again.

There is a large metal horseshoe shaped retainer that sits behind 5th gear, it has a recess machined into the back of it & it sits on the mainshaft bearing....When the transfer casing is in place, it pushes against the retainer and stops the mainshaft & bearing walking backwards into the transfer casing... The problem is that there is nothing to hold the retainer in place & without the case to hold it into position it very easily slides off the bearing and drops down a couple of mm behind 5th gear assay (at this point it looks like it is still located properly) This can be very annoying because as you slide the casing back on and you're wiggling things about to get the selector in the right place you hear the retainer drop & you then have to take the casing back off to relocate it.... The only plus side is that you can't get this bit wrong, as the transfer case physically won't slide home if the retainer is not seated properly.

One last thing to remember is that if the transfer casing won't slide home by either pushing it or tapping lightly with a soft mallet then something is wrong... Don't be tempted to force it home by tightening the bolts!

Good Luck
Phil

AndyP's_P1

iTrader: (1)

Thanks for the reply.

By intermittent i mean that when it happens it happens all the time when selecting 5th gear. Low or high revs it will do it every time.
It first happened on the thursday and then i nursed it home and left it in the garage all day friday. On saturday morning i took the car out to my parents house and on the way there i selected 5th. It went into 5th without any crunching and never popped out when i lifted off. Only difference i noticed was that the gearstick didnt seem to travel the full distance into 5th.

Then on saturday night it was back to the crunching and popping out of gear again. Ever since then it has been sitting in my garage.

PeeVee

iTrader: (1)

Yup, in that case the nut is loose.

AndyP's_P1

iTrader: (1)

Oh well at least that might be plus. Will be looking into it this weekend if i get off this rig.

Cheers

Don Clark

MOD: Transfer Case Removal/ "5th gear pops out" fix - ScoobyMods

AndyP's_P1

iTrader: (1)

Excellent link. Thanks

Eprom

David at API has just done this on mine, however the box had done 118 thousand miles so not bad, it's also worth looking at the bearings in that area whilst it's apart.

APIDavid

iTrader: (4)

" We are doing one in the workshop right now."


Quote: David at API has just done this on mine, however the box had done 118 thousand miles so not bad, it's also worth looking at the bearings in that area whilst it's apart.[/quote]


And we got away with it - Phew !!



David

AndyP's_P1

iTrader: (1)

Problem all sorted now. Thanks for your help lads.