Shakes and shutters at deceleration

All Models and Years
Post Reply
User avatar
recessbilly
Posts: 145
Joined: Mon Jun 08, 2015 7:22 am
Location: Ashland, OR

Shakes and shutters at deceleration

Unread post by recessbilly » Sun Dec 03, 2017 9:29 pm

I just replaced the bellhousing seals and mated up a different 4-speed tranny and diff with a fresh pilot bushing and throw-out bearing, refabbed clutch disk, and filled it with Redline MT-90 Gl-4 gear oil. No more leaks, but I am getting a shaking when I let off the gas from acceleration or downshift. Giving it gas is strong and responsive and smooth.

Could this be the shim alignment at the tranny mount's geometry not correct? The original Transaxle has more shims.

Or a faulty trans/diff? :dontknow:

I didn't have this with the prior setup and am using the same axles and u-joints. When on the lift, there is no binding.
Also I took it on the Freeway and I have the carbs dialed in really well, at least that's a positive. :tu:
1963 Monza Spyder 900 powered by a 1964 110HP and 4-speed MTX

User avatar
bbodie52
Corvair of the Month
Corvair of the Month
Posts: 7499
Joined: Mon Aug 06, 2012 12:33 pm
Location: Lake Chatuge Hayesville, NC
Contact:

Re: Shakes and shutters at deceleration

Unread post by bbodie52 » Mon Dec 04, 2017 7:59 am

A caution about your gear lube selection...
66vairguy wrote:Tue Nov 07, 2017 11:32 am

To correct an error in Bodie's post -- DO NOT USE Redline MT-90 in a Corvair transaxle. Redline's site specifically states that MT-90 is NOT approved for hypoid gears (differential). So it is NOT acceptable for use in a Corvair transaxle since protection for the ring and pinion differential gears is inadequate. Redline does make a modified GL-5 lube that is suppose to work with brass synchronizers called - 75W90 NS GL-5 and states it's approved for transaxles with brass parts. NOTE: Redline NS GL-5 is different vs. their GL-5 which is NOT approved for transaxle use.
For further discussion on this subject, click on the following link...

:link: viewtopic.php?f=55&t=13615&p=94322&hilit=redline#p94322

It sounds like your clutch is slipping whenever engine braking is applied during deceleration or downshifting coupled with deceleration. Based on your description it sounds like the clutch is locking up properly under normal drive or acceleration conditions. I have not encountered this type of problem before, but perhaps the troubleshooting chart below may reveal some possibilities. Is it possible that an error was made during assembly of the clutch mechanism? Could the clutch disc somehow be a mismatch or installed incorrectly (with the wrong side facing the flywheel)?

Left-click the image to enlarge for better viewing...
Clutch Disc Installation.jpg
Image

Left-click the image to enlarge for better viewing...
Clutch Troubleshooting and Diagnosis.jpg
Attachments
1961 Chevrolet Corvair Shop Manual - Section 6b - Clutch.pdf
1961 Chevrolet Corvair Shop Manual - Section 6b - Clutch
(459.77 KiB) Not downloaded yet
1964 Supplement - Chevrolet Corvair Shop Manual - Section 6b - Clutch.pdf
1964 Supplement - Chevrolet Corvair Shop Manual - Section 6b - Clutch
(256.53 KiB) Downloaded 1 time
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

User avatar
recessbilly
Posts: 145
Joined: Mon Jun 08, 2015 7:22 am
Location: Ashland, OR

Re: Shakes and shutters at deceleration

Unread post by recessbilly » Mon Dec 04, 2017 9:41 am

Thanks Brad, the redline info is new news and I appreciate it. I was using MT-90 for the last year and hope it isn't doing damage. The flywheel side of the disk is to the flywheel. I took it for a drive last night and in a downshift, had a big boom and thought I lost the tranny out the bottom. It stayed running and I limped it home in 1st and 2nd. I guess I gotta pull them apart again. Oh well, live and learn.
1963 Monza Spyder 900 powered by a 1964 110HP and 4-speed MTX

Post Reply

Return to “Ask your Mechanical Questions here”