Haffy Transmission repair

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OhioPinz
Posts: 160
Joined: Fri May 13, 2005 9:41 am
Location: Middletown, Ohio

Haffy Transmission repair

Post by OhioPinz » Tue Aug 28, 2018 8:50 pm

My Pathfinder gearbox functions great but the synchro does not work downshifting from 3rd to 2nd. I have to slow way down and it often grinds a bit. Should I just live with it, or tear the gearbox down and repair? Anyone in the States that can do the gearbox? What a good oil for the gearbox?

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rmel
United States of America
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Re: Haffy Transmission repair

Post by rmel » Tue Aug 28, 2018 9:22 pm

Best Tranie guy (among many other things) would be Jim L http://goatwerks.com/home.htm
You would have to ship your tranie to him, which he is accustomed to dealing with.
Puller: 710K 2.7L EFI
Follower: Sankey MK 3, 3/4 Tonne
Driver: Ron // KO0Q

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TechMOGogy
Canada
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Location: Ontario, Canada

Re: Haffy Transmission repair

Post by TechMOGogy » Wed Aug 29, 2018 8:40 am

x2 for Jim L
Some parts are hard to find but he sometimes has spares
http://goatwerks.com/home.htm
72 Pathfinder | 75 710M 2.7i | 94 350GDT | 96 350GDT Worker

63rover
Canada
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Location: Mt. Hope, Ont., Canada

Re: Haffy Transmission repair

Post by 63rover » Wed Sep 26, 2018 9:02 am

Another option to expensive repairs, which may or may not solve you problem, is to used double clutching.

Many older vehicles did not even have any syncromesh. You can shift down by double clutching the shift. (double de-clutching if British)

The process is:
1. Use clutch to shift to neutral. Release clutch pedal.
2. If going down one gear, blip the throttle a little (a small audible quickly released tap of the gas pedal should do). If shifting down 2 gears, use more blip. This will pick up the revolutions of the transmission which will be needed to match the lower gear to the revolutions of the output shaft to the axle.
3. Depress the clutch and gently select the lower gear. If it doesn't select easily don't force it; release the clutch pedal and repeat step 2 before trying 3 again.

It takes practice and getting a feel for the vehicle. Each vehicle is a little different. Practicing in a parking lot or quite trail is recommended. Just trying it in a tricky situation can cause problems.

Double clutching can also be used to smooth up-shifts. The process is similar; just leave out the throttle blip. The clutch pedal release and reapplication is used to slow the transmission this time.

Driving many older vehicles, cars, trucks and even tractors offer requires this technique to smooth out and speed up shifting. It is also recommended for all downshifts of 2 or more gears on all vehicles to help reduce wear in the syncromesh mechanisms and over-stressing the same.

Really good drivers, usually truckers and bus drivers, when I was a kid (last century) could take this process to the next level. They would shift to neutral with the drive-line balanced perfectly between drive and over-run, blip the throttle and slip the transmission into the lower gear at just the right moment, again without the clutch. It was impressive to see. The claim was the clutch lasted much longer since it was only used to pull off from a standstill. I only practiced this with one old car I was about to sell. The risk is not as great as it seems. The gear leaver will give you all the feedback you need. The sweet-spot does not have much resistance shifting in or out of gear. A gentle pressure on the shift will pop the transmission out and into gear when everything lines up just right. The trick is gentle pressure. Forcing the shift could cause enormous damage!

Good luck

Cheers, Clive

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TechMOGogy
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Re: Haffy Transmission repair

Post by TechMOGogy » Wed Sep 26, 2018 5:24 pm

I think the Hafi tranny is fairly weak compared to Alison commercial transmissions and the sort. I would be worried about damage during the “learning” part of this. Perhaps best to learn on something else like a tractor?
72 Pathfinder | 75 710M 2.7i | 94 350GDT | 96 350GDT Worker

63rover
Canada
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Joined: Thu Oct 10, 2013 8:18 pm
Location: Mt. Hope, Ont., Canada

Re: Haffy Transmission repair

Post by 63rover » Wed Sep 26, 2018 5:54 pm

Dan,

Double clutching is easier on all transmissions. It can be practised on any manual vehicle. The key is nice and easy, gentle, don't break it. All of this is normally absorbed by the syncro which is why it fails. BTW syncro rings are only brass or similar material and not the hard steel of the gears. Let's learn from the professionals. Double clutch is also why race drivers heal-toe. This allows them to brake and double clutch downshift. All part of the art or driving.

All the best!

Clive

PS I practised on a Lada 1500s and a Niva

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Garrycol
Australia
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Location: Canberra Australia

Re: Haffy Transmission repair

Post by Garrycol » Wed Sep 26, 2018 8:22 pm

Go to Jim - even from Aust I have sought his advice and parts and he is exceptional to deal with

Just remember that even with perfect synchros you have to slow right down to change down from 3rd to second - almost a stop. So maybe it is something you have to accept - 2nd gear on my vehicle is really equivalent of first because first is just too low to use on a day to day basis. What I do is go out of 3rd and hold the lever at the gate for second with just a little pressure on the lever - if you are going too fast you can get the lever in but if you force it, it will crash. When you haf has slowed down to a speed the gearbox likes the lever will go into 2nd - gently does up - just like you had to do when you first met your new girlfriend and you were getting to the fun bits - hmm enough said - so nice and gentle - if the synchros are gone it will not let you into second at any speed without crashing it, where if they are OK you can move the lever into second once your speed has slowed right down.

Being a Series 1 Landrover owner - yes you can double shuffle (or double declutch as it is sometimes called) - if done wrong it can get noisey and as mentioned possible cause damage - I have double shuffled my Haf gearbox successfully but it does not like it.
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"

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