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1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Paul S ()
Date: January 17, 2018 03:37PM

I've adjusted the clutch and the shifter yet I still get a bit of grinding shifting into 4th gear? Is there any help?


1964 Corvair Spyder
1966 Corvair Corsa
Fresno, CA.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Phil Dally ()
Date: January 17, 2018 03:46PM

Good to see you Paul!!! thumbs up

Classic Saginaw 2nd & 4th crunchy.

Did you put new gear oil in it yet?

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Paul S ()
Date: January 17, 2018 03:54PM

Hey Phil! I'm running Amsoil 75w-90 GL-4. It's topped off and I can't have more then 5,000 miles since the rebuild. Thats a high estimate


1964 Corvair Spyder
1966 Corvair Corsa
Fresno, CA.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: davemotohead ()
Date: January 17, 2018 04:01PM

Is that a 64-65 trans? did you replace the synchro's with NOS GM or Clarks?





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Paul S ()
Date: January 17, 2018 04:03PM

It's a 1966 Saginaw. I wish I knew what the guy who rebuilt it used but I don't.
QUESTION- Is there an adjustment I've missed or should I just run it untill I cant?


1964 Corvair Spyder
1966 Corvair Corsa
Fresno, CA.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Phil Dally ()
Date: January 17, 2018 04:19PM

That is the good stuff.

Is it getting worse with time?

If not drive the wheels off it!!

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: 66vairman ()
Date: January 17, 2018 04:51PM

Considering 66-69 trans parts are getting harder to find I would take the transmission out and find the problem before something expensive happens.

Dan Drommerhausen in the SCC club (L.A. CA.) has been doing transmissions for decades. He built up two 66-69 units for me. A lot more to it than just changing the bearings.

The other issue is using an earlier ring and pinion shaft in a 66-69 differential - it will cause clearance issues until - KABOOM.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: v8vair ()
Date: January 17, 2018 07:11PM

Some of the Saginaws have too much end play in the main shaft causing a 4th gear crunch.You can lower the front of the transmission and remove the front crossmember,cover and front bearing. Then as Ted Trevor discovered,install a .030 shim between the input gear and bearing and use a thinner snap ring. If your up to the task I can send you the shim and snap ring. It’s not a guarantee but I’ve fixed a few with this repair. Mike

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Re: 1966 LM Saginaw 4 speed. Grinding in
Posted by: Paul S ()
Date: January 17, 2018 07:16PM

Thanks guys I'll see how things turn out


1964 Corvair Spyder
1966 Corvair Corsa
Fresno, CA.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: flat_six ()
Date: January 18, 2018 05:53AM

My 4th gear grinds too. Actually, all four will grind after the fluid heats up. I've always just assumed that the synchros were smoked. Should I try a fluid change? Probably original fluid in there. 95K.

How do you drain/fill a 66 transaxle?

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: coleslaw31 ()
Date: January 18, 2018 06:04AM

You have to suck it out with a pump from the side plug. Replace fluid until it leaks from the side plug also. I would assume when replacing the transmission fluid you are also going to need enough to replace the diff fluid since they share it.

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: steve c goodman ()
Date: January 18, 2018 07:27AM

The CORSA tech guide has an article about drilling and tapping for drain plugs
in both bottom of diff and trans. Very specific points to drill too, cannot just drill anywhere on either.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: 66vairman ()
Date: January 18, 2018 09:49AM

flat_six Wrote:
-------------------------------------------------------
> My 4th gear grinds too. Actually, all four will
> grind after the fluid heats up. I've always just
> assumed that the synchros were smoked. Should I
> try a fluid change? Probably original fluid in
> there. 95K.
>
> How do you drain/fill a 66 transaxle?

Few ever changed the transaxle lube which definitely leads to failures.

Putting in drain plugs is nice. If that's not practical for you, then there are inexpensive pumps you can put on a simple electric hand drill. Hook up some vinyl hose from the hardware store and you can empty the transaxle quickly.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: RobertC ()
Date: January 18, 2018 10:23AM

Guess I will pose this question:

I know nothing about gear lubes, but I have always wondered if synthetic gear lubes were "too slippery" for old transmissions / diffs?

Rarely changed the gear lube over the decades - just added...

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: v8vair ()
Date: January 20, 2018 03:44PM

As far as gear lubes are concerned, the Redline NS 75 / 90 is advertised as helping weak syncros and posi’s.
I’m running two quarts of Penzoil synchromesh with two quarts of 75 90 gl5 in my 64 to help shifting, working very well smiling smiley mike

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: v8vair ()
Date: January 20, 2018 03:44PM

As far as gear lubes are concerned, the Redline NS 75 / 90 is advertised as helping weak syncros and posi’s.
I’m running two quarts of Penzoil synchromesh with two quarts of 75 90 gl5 in my 64 to help shifting, working very well smiling smiley mike

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: dryenko ()
Date: January 21, 2018 06:13AM

Yes, some times the more slippery oils will cause syncro crashing.
Had this happen with a Mazda transmission when I thought I would gain 0.5 HP [ GGG ] in my RX3 Racer.
Nope, instant grinding.
Changed back to Dino type gear GL4 oil and it stopped.
Posi additive can also help.
In any case use a true GL4 gear oil, not GL4 "compatible".
If you don't want your syncros to corrode.
I use Brad Penn 80W-90.
Available online through Amazon with free shipping if you have Prime.
also here : [www.ebay.com]

Bob C aka Dryenko
Dobson, NC 27017



Edited 1 time(s). Last edit at 01/21/2018 06:14AM by dryenko.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: jjohnsonjo ()
Date: January 21, 2018 06:29AM

I switched to the Brad Penn "CLASSIC" after trying various others, including Red Line. Mine has never shifted better than with the BP.


[4speedtoploaders.com]

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: Paul S ()
Date: January 21, 2018 07:12AM

Thanks for all the input guys. I'm hesitant to drain the gear oil only because it was expensive and really doesn't have many miles since I put it in but maybe sitting a year has broken it down? I don't know. It's Amsoil 75 90 GL4


1964 Corvair Spyder
1966 Corvair Corsa
Fresno, CA.

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Re: 1966 LM Saginaw 4 speed. Grinding into 4th
Posted by: jjohnsonjo ()
Date: January 21, 2018 09:19AM

That's good oil, so that is not your problem. How new is the clutch disc, do you get any grinding when going from neutral into gear when starting out.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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