Doug Nash 4+1 hard to shift when hot

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GuysMonteSS
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Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Thu Jul 16, 2015 7:08 pm

Freshly rebuilt original DN 4+1 5 speed street tranny,clutch,pp,flywheel and TOB all either new or like new.
Filled with GM Synchromesh fluid.
Mechanical linkage adjusted properly.
Hurst V Gate II shifter,bushings all good and it is well lubed.
Works fine when cold but after app a 1/2 hour drive and it is warmed up it is hard to get into gear and shifts hard,both up & down.
And when it is hot it shifts OK with the engine shut off.
Any ideas on what could be causing this problem ??
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by fdicrasto » Thu Jul 16, 2015 10:29 pm

Does it grind going into reverse either hot or cold. Sounds more like a clutch issue to me.

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Fri Jul 17, 2015 7:16 am

It does grind going into reverse when hot,but not if you put it into first again then reverse.
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Fri Jul 17, 2015 7:20 am

fdicrasto wrote: Sounds more like a clutch issue to me.
What would cause the clutch to act like this when hot but not cold ??
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by fdicrasto » Fri Jul 17, 2015 1:59 pm

Is the clutch linkage mechanical or hydraulic?

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Re: Doug Nash 4+1 hard to shift when hot

Post by fdicrasto » Fri Jul 17, 2015 2:02 pm

fdicrasto wrote:Is the clutch linkage mechanical or hydraulic?
Sorry, I see that you have mechanical. It still sounds like the clutch is not fully disengaging. The big clue to that is the reverse problem.

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Re: Doug Nash 4+1 hard to shift when hot

Post by sidestep » Fri Jul 17, 2015 2:37 pm

Are you able to measure the distance from throw out bearing to pressure plate fingers. What kind of bell housing is it? How did you set pedal free play. Have you considered a different gear oil such as mt90 or sta lube 80/90 gl4. Would like to see if I can help just need more info of set up, pressure plate style and such

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Re: Doug Nash 4+1 hard to shift when hot

Post by sidestep » Fri Jul 17, 2015 2:57 pm

If this is for the set up in your signature the following is from center force on proper geometry

Block/bell flange to pivot stud calls out 4.75 / 4.625 w/block saver plate
Flywheel friction face to crank flange of flywheel calls out .95

So if your flywheel measured .92 after a surface job with no block saver plate the pivot stud distance to back of block would be 4.725 / 4.595. They want an 1/8 th to 1/4 from throw out bearing to clutch fingers because they will grow(close up that gap) as the seat. Also check to make sure you have the right length throw out bearing. Typically the short flat face is used for three finger, short flats face/ conical depending on type of diaphragm. I did have to use a long style flat face for a Borg and beck in a 55 Chevy to get everything right. That type wAs used stock in mid sixties gm trucks I think N1466 is the number. I would look into an adjustable pivot stud thru Lakewood as well

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Fri Jul 17, 2015 4:37 pm

I have a LuK clutch;
http://catalog.schaeffler-aftermarket.u ... &qualfier=
Lakewood bellhousing;
http://www.summitracing.com/int/parts/l ... /chevrolet
And it does have a block plate.
Hays TOB;
http://www.summitracing.com/int/parts/h ... /overview/
GM flywheel that has been neutral balanced;
http://www.summitracing.com/int/parts/n ... /overview/
At the moment I am unable to measure anything.
I adjusted the pedal freeplay with the pushrod between the Z bar and the clutch fork and it is app 1/4-1/2 inch.
The bellhousing did have an adjustable pivot stud at one time but the threads were stripped so we set it to where it seemed to work best and welded it in place.
The whole thing is a bit "Bastardized" as my 1986 Monte SS didn't come with a manual tranny.The clutch pedal assembly is from a 1980's Iraqi Taxi Malibu;
"In 1981, General Motors of Canada in Oshawa produced a special order of 12,000 4-door Malibu sedans for Saddam Hussein's Iraqi government. The deal was worth 100-million dollars to GM. These special order Malibus carried the unusual combination of GM's lowest-power V6, the 110hp 229ci (3.8 l) engine mated to a unique 3-on-the-floor stick shifter. All of the cars were equipped with air conditioning, heavy duty cooling systems, tough upholstery and 14-inch (360 mm) stamped steel wheels with trim rings and "baby moon" center caps. They were the ultimate Iraqi Taxis. In 1982 with 7,000 Malibus sitting on a dock in Halifax ready to ship and 5,000 more waiting for the train in Oshawa, where they were built, the Iraqis cancelled the order. Excuses reportedly included "quality concerns" or the supposed inability of the local drivers to shift a manual transmission. GM President-at-the-time Donald Hackworth said GM would still try to sell the Halifax cars overseas. Of course the real reason the Iraqis backed out was their escalating hostilities with Iran which required diversion of funds to support the ramping Iraqi war effort. In the end, the orphaned Iraqi Taxi Malibus were sold to the Canadian public at the greatly reduced price of about C$6,800 and over the years have acquired a low-key 'celebrity' status. "

The clutch fork has been cut and re-welded for better floor clearance.
The Z Bar has been cut and welded to clear the headers.
I tried a Chevelle type clutch fork but the angle was completely wrong.
If I thought it would make a difference I would try a different trans oil.
I just don't understand why most of the time it works perfect then sometimes it dosent... :?:
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by sidestep » Fri Jul 17, 2015 6:06 pm

Is the pedal clamped to a splined shaft under the dash, could be worn or loose, possible deflection somewhere in the pedal linkage. Check that pushrod between z bar and fork for any play also where the rod thru firewall to z bar meet. Take all the slop out, I like to use various thickness of washers and cotter pins. When driving is better or worse at a certain speed/rpm

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Fri Jul 17, 2015 7:12 pm

I don't know if there is a splined shaft under the dash or not.
I do know that the firewall does flex when the clutch pedal is pushed.
Also the bracket on the frame that holds the Z bar bends a bit.
But it does this all the time...
Maybe the flexing gets worse as it gets hotter,but it only does it sometimes.
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by sidestep » Fri Jul 17, 2015 8:11 pm

Yes, I think your losing leverage/ mechanical advantage when those points flex. Maybe it gets worse as you drive cause of the conditions of the road and the engine/trans moving a bit as well. It might be worth trying to brace those areas and c if it changes.

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Sat Jul 18, 2015 6:49 am

Thanks sidestep,
I think your diagnosis may be right on the money.
It works fine most times but gets worse around town or when doing more shifting.
When time permits I will see if there is anything I can do to reduce the flex that is going on.
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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Re: Doug Nash 4+1 hard to shift when hot

Post by VMC » Sat Jul 18, 2015 7:01 am

Did you index the bellhousing?

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Re: Doug Nash 4+1 hard to shift when hot

Post by GuysMonteSS » Sat Jul 18, 2015 7:03 am

VMC wrote:Did you index the bellhousing?
Yes the bellhousing is almost perfectly indexed.
Guy
'86 Monte SS,513 BBC,AFR heads,Bullet solid roller cam,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 inch Rearend.

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