5-Rib Reverse Failure

Moderators: Sluggo, Amskeptic

Post Reply
User avatar
Jaffa
I'm New!
Status: Offline

5-Rib Reverse Failure

Post by Jaffa » Mon Jun 29, 2020 3:42 am

All,
My trans has been making whines a bit and makes a slight grunchy whirring noise in reverse, especially on overun when depressing the clutch.
Well, when reversing up our moderate slope driveway last weekend it popped out or reverse. I tried again same thing happened, it gets going then pops out. I thought it maybe just the shifter so tried again and held the gear lever to stop it popping out. Bad mistake I think as it popped out twice on the run up the drive. So I gave up and went down, turned round and drove up forwards. It reversed on the flat although a bit more noisier than before.
This got me to thinking that maybe the reverse gear had stripped a tooth, especially as the third time it popped out twice but was still moving like as the gear turned it skipped a missing tooth.
I haven't removed it yet but drained the fluid today and ran a magnet inside over the bottom. No big chunks but a fair bit of small stuff. Looked into the fill hole on the side and saw this gear. Question is is this the reverse gear I'm seeing, and If I only go forward is it OK to drive to the mechanics to have the trans overhauled?.

Thanks for any advice.
Attachments
IMG_6023.JPG
IMG_6023.JPG (952.54 KiB) Viewed 8141 times
IMG_6022.JPG
IMG_6022.JPG (810.56 KiB) Viewed 8141 times
IMG_6021.JPG
IMG_6021.JPG (820.88 KiB) Viewed 8141 times
IMG_6020.JPG
IMG_6020.JPG (922.68 KiB) Viewed 8141 times
IMG_6019.JPG
IMG_6019.JPG (837.27 KiB) Viewed 8141 times
Craig

Image

User avatar
asiab3
IAC Addict!
Location: San Diego, CA
Contact:
Status: Offline

Re: 5-Rib Reverse Failure

Post by asiab3 » Wed Jul 01, 2020 8:40 am

Yes that is one of the reverse gears. Reverse is the only gear set in your transaxle with straight/flat teeth, hence the normal gear whine when backing up. Fortunately, it’s also the only gear set that isn’t in constant mesh, so you should be able to drive it to the shop, but I would push instead of using reverse, lest any addition damage occur.

Good luck!
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Wed Jul 01, 2020 11:58 am

Thanks Robbie. Off I go.

Cheers.
Craig

Image

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 5-Rib Reverse Failure

Post by Amskeptic » Sun Jul 05, 2020 10:37 am

Jaffa wrote:
Wed Jul 01, 2020 11:58 am
Thanks Robbie. Off I go.

Cheers.

Note that the 5 rib transaxles have known weak points, one of which is the devilishly difficult reverse gear adjustment. Too far back and you have stationary parts contacting rotating parts. Not enough, and you have lousy mesh that is prone to jumping out of gear. The Bentley manual talks about preloading the parts as you set the reverse fork, who knows if people follow it. Also, loose bushings/bores in the transaxle can allow imperceptible movement which gets rid of perpendicularity in the gear teeth over time ... then they become little wedges or ramps that throw it out of gear during loading or unloading.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Sun Jul 05, 2020 6:15 pm

Well this tranny has slowly been getting noisier in reverse over the years with a definite nose like gears rubbing against each other. A bit whiny now and again and needs the left side seal replaced anyway as this is leaking. But It's being booked in for a rebuild in the next couple of weeks.
Craig

Image

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Tue Nov 23, 2021 2:42 am

Well, bus has been the shop three times now.
First: replace the reverse gear set. All ok except now there’s a whirring in first. Not there before. Second: look at the whirring in first. Can’t find anything but adjust reverse setup slightly as this may help. Well it didn’t i now I can’t reverse up my drive. A gradient of 10 - 13 degrees.
Third: in to look at putting the reverse adjustment back how it was. Noise in first still there and it still won’t reverse up a gradient >9 degrees.
Going in again tomorrow, fourth time to show them that it doesn’t reverse up a hill!!!

Crickey dick what an episode.
Craig

Image

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 5-Rib Reverse Failure

Post by Amskeptic » Fri Nov 26, 2021 10:54 am

Jaffa wrote:
Tue Nov 23, 2021 2:42 am
Well, bus has been the shop three times now.
First: replace the reverse gear set. All ok except now there’s a whirring in first. Not there before. Second: look at the whirring in first. Can’t find anything but adjust reverse setup slightly as this may help. Well it didn’t i now I can’t reverse up my drive. A gradient of 10 - 13 degrees.
Third: in to look at putting the reverse adjustment back how it was. Noise in first still there and it still won’t reverse up a gradient >9 degrees.
Going in again tomorrow, fourth time to show them that it doesn’t reverse up a hill!!!

Crickey dick what an episode.
Yikes. People are lost here. There is no cause and effect between whirring first and what I have to assume here is a new penchant for kicking out of reverse? Adjusting reverse set-up to help a whirring in 1st? No. Damage is occurring every time you have a failure to stay in reverse.
You may need a new 1/2 slider and a new reverse gear, and I cannot answer for the whirring in 1st, except to ask, does it whir on acceleration? deceleration? engagement? hot vs cold?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Wed Dec 01, 2021 7:48 pm

Not fixed yet.
Whirring is worse on acceleration and goes when you coast but stay in gear. This suggests longitudinal ahaft/gear movement, maybe worn bearings? Noisier after it warms up.
When it pops out of reverse it locks up the gear shifter usually taking a bit of wiggling and in/out of reverse to get it free.
I drove it away from the shop to return the next day but only got ~500mtrs before the whole transmission locked in gear whilst I was slowing down for a stop, changing gears as I went. Maybe in third as I was able to move off the road by slipping the clutch a bit.
The man said it could be that because the noise cone has been welded and machined this could be effecting the setup in the jig and it may need the nosecone attached for proper setup?.
A second opinion is being sort from another expert by the man.
Thing is it didnt pop out of reverse until the reverse setup was changed from original settings?.

Craig
Craig

Image

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Thu Jan 20, 2022 4:44 pm

Well, picked up the bus just before Christmas. Wasn't game to try reverse until I had completed my camping trips.
SUCCESS! I can now reverse up my driveway no trouble at all. I do still have a slight noise in first gear though, Grrr.
As it turns out the whole transaxle was sent to another mechanic who specialises in off-roaders and VW transaxles. This chap set the whole box up from scratch I'm told and set the reverse with the nose-cone and shift forks installed/connected.
The transaxle sounds and shifts soo much nicer and the gear shift doesn't foul up in reverse anymore.
Craig

Image

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 5-Rib Reverse Failure

Post by Amskeptic » Wed Feb 09, 2022 8:45 am

Jaffa wrote:
Thu Jan 20, 2022 4:44 pm
Well, picked up the bus just before Christmas. Wasn't game to try reverse until I had completed my camping trips.
SUCCESS! I can now reverse up my driveway no trouble at all. I do still have a slight noise in first gear though, Grrr.
As it turns out the whole transaxle was sent to another mechanic who specialises in off-roaders and VW transaxles. This chap set the whole box up from scratch I'm told and set the reverse with the nose-cone and shift forks installed/connected.
The transaxle sounds and shifts soo much nicer and the gear shift doesn't foul up in reverse anymore.
Glad to hear it.
Who knew, since we last talked, that I would become proficient in transaxle rebuilding. And let me tell ya, setting up reverse is a real treat ...
Colin

Image

Image
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

User avatar
Jaffa
I'm New!
Status: Offline

Re: 5-Rib Reverse Failure

Post by Jaffa » Thu Mar 10, 2022 11:07 am

Thanks Colin,

Yes I've done several trips and reverses up my driveway and everything is behaving as it should. Although as mentioned still a slight whirring in first.

Craig
Craig

Image

Post Reply