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Peugeot BE4 gearbox went bang. Why?

Peugeot BE4 gearbox went bang. Why?

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Discussion

Sensibleboy

Original Poster:

633 posts

49 months

Friday 4th August
quotequote all
I had my BE4 gearbox fitted with a shorter final drive about 300 miles ago and all was well until it suddenly went bang.

Was doing about 35mph in 3rd with very slight throttle applied at there was a massive bang and the car stood on its nose briefly.

The box had been behaving perfectly up until this point. No noises, gear change was perfectly smooth too.

It's not been stripped down thoroughly yet to see which gears have broken but there's definitely a load of gear teeth been broken off.

So does anybody know what can cause this to happen? It's like it's tried to select two gears at the same time.

Edited by Sensibleboy on Saturday 16th September 20:15

GreenV8S

24,949 posts

208 months

Friday 4th August
quotequote all
Sensibleboy said:
So does anybody know what can cause this to happen?
Pointless to speculate until it's been stripped down.

Old Merc

1,926 posts

91 months

Saturday 5th August
quotequote all
Favorite on these Pug boxes is the diff gears.Excessive wear in diff housing, sun & planet gears out of line and break up,bang! car stops.Everyone I`ve seen there is a hole in the diff housing part of the box.

Sensibleboy

Original Poster:

633 posts

49 months

Saturday 5th August
quotequote all
Crown wheel and pinion are fine in this one.

Old Merc

1,926 posts

91 months

Saturday 5th August
quotequote all
I would be having a strong word with who ever built this box ?
I bet all those "bits" are whats left of the diff gears. They are A B C D in this image.
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stevieturbo

12,727 posts

171 months

Saturday 5th August
quotequote all
Sensibleboy said:
So does anybody know what can cause this to happen? It's like it's tried to select two gears at the same time.
That would be one to ask whoever took it apart to swap the diff and exactly what they done at that time

Sensibleboy

Original Poster:

633 posts

49 months

Saturday 16th September
quotequote all
Gearbox is now dismantled. Every single 3rd gear tooth is completely stripped. The mechanic who built it originally and stripped it down this week just said he didn't know what had caused it. No suggestions were offered...

I'm trying to work out why it happened. The gear lever wouldn't engage any gear and when the car was pushed it kept catching on something. I don't know if one of the selector forks has come off the selector shaft or something. No information was being volunteered at all. All of the other parts including forks look fine.




stevieturbo

12,727 posts

171 months

Saturday 16th September
quotequote all
If something didnt get into the teeth to cause it, then it could just be a case of st happens. It is french after all.

But if all bearings are good, shafts are good, then there shouldbnt be a cause on that level.

227bhp

5,824 posts

52 months

Saturday 16th September
quotequote all
You weren't being very sensible with that were you boy? tongue out

lucido grigio

31,496 posts

87 months

Sunday 17th September
quotequote all
Definitely forked that is.

Thank me later.

Mr2Mike

17,962 posts

179 months

Monday 18th September
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I predict it definitely won't be something left floating around the box when the shorter final drive was put in. At least that's why the guy fitting the final driver will say...

Sensibleboy

Original Poster:

633 posts

49 months

Sunday 22nd October
quotequote all
I had the shafts stripped down further last week.

It wasn't initially obvious to me why things had gone bang but to anybody familiar with gearboxes it would have been.

My mechanic said he didn't have a clue what caused it.

First gear had obviously got very hot and almost welded itself to the shaft - it normally freewheels on the shaft until the synchro engages it. So it had effectively engaged first gear at the same time which is why third stripped the teeth.

I'm thinking there might be two reasons for this. I found some sealant in an oil gallery in the shaft. Another reason is the output shaft was fitted with a later fat roller bearing plus a needle roller bearing when it should have kept the original thinner bearing which left room for the needle bearing. I suspect this meant things were tighter than they should have been.

stevieturbo

12,727 posts

171 months

Monday 23rd October
quotequote all
Interesting to hear and well done with the stripdown and diagnosis.

Sensibleboy

Original Poster:

633 posts

49 months

Monday 23rd October
quotequote all


So next step to getting the car back on the road is to buy another donor gearbox from a 206 GTI 180 / C4 VTS to provide a new 3rd / 4th gear pinion and a 3rd gear.

I also need a gearbox to donate a 17x81 CWP from a 1.8 Grand Picasso. So I'll certainly have a good stock of spare bits when I'm finished.

Edited by Sensibleboy on Monday 23 October 12:47

CrutyRammers

8,610 posts

122 months

Monday 23rd October
quotequote all
Interesting, thanks for posting.