View Full Version : Doug Nash 4+1 (5 speed )


wetatt4u
09-24-2008, 08:35 PM
Hey Guys

Can anyone tell what will be needed to install DN 5 speed into a 55 chevy?

I had a three speed in it original from the factory,changed out to an th350 many moons ago and want to change back to a straight drive.

Main question is ....

1)will in fit in the trans tunnel ?

2)what about the cross member?

I still use the front motor mounts,

Can anyone tell me if I'll need the back side mounts ,I think I've gathered all the parts needed ,

But just trying to make sure before I take it apart that I have all the parts and don't want to wait around to find any last minute parts..

Hope this make sense,

Thanks to all in advance for any help...

thehazmatguy
09-24-2008, 08:46 PM
You should be able to fit the DN trans into your car without any trans tunnel modification.

I'm just about done getting a Tremec five speed in my 55 sedan. Unless you have scored a deal on the Doug Nash I would recommend checking out the Tremec.

Cross memember? How do you have the current engine and trans in the car now? You should not be using front mounts and a rear trans crossmemeber. Either use the front mounts and the bellhousing side mounts, or convert to engine side mounts and a trans crossmember.

hotrodladycrusr
09-24-2008, 08:46 PM
It's been awhile but if my memory serves me right from my past Corvette days, those transmissions were/are junk. Mid '80's Corvette I think??

32v
09-24-2008, 08:49 PM
they are a five speed but not overdrive

gumbydammit
09-24-2008, 08:49 PM
The 4+1 5 speeds were race transmissions. The 5 speed OD were not all that hot. The 4+1 Is a pretty sturdy piece. They even made one with "torsion bar " shafts to absorb the pounding. A buddy of mine ran one in a 67 stang stocker. Used to leave the line @ 8500RPM and shift @ 9800 !

Oh, and you shouldn't have much trouble installing it in your Chevy.

OldSub
09-24-2008, 08:51 PM
Hey Guys
1)will in fit in the trans tunnel ?

2)what about the cross member?
I have no idea if it will fit in the trans tunnel, but its big in the tail shaft and could easily be a challenge.

As long as it is, and as heavy as I imagine it is near the output shaft, I'd think a rear cross member might be required, but I don't know that with certainty. I've been under a Corvette with one of these from the factory and can't remember if it has a crossmember or not, but it did have the torque arm that does provide some stiffness and support for the transmission.

I'm not sure I'd try to use one of these transmissions. I say that having driven one today, which I do most days. Its not a popular transmission among Covette circles and you read more about replacing it than anything else.

It is a Super T-10 with an overdrive, and that's a nice thing, but its not like driving a 5-speed. The computer controlled OD doesn't behave quite how most people would like. I assume you are going to control it manually, but still you're driving a 4-speed with a switch for OD.

Lotek_Racing
09-24-2008, 08:58 PM
It's been awhile but if my memory serves me right from my past Corvette days, those transmissions were/are junk. Mid '80's Corvette I think??

Yeah, has to be junk if Richmond bought the design and is still using it to make the 5 and 6 speed Richmond gear boxes.

My buddy has a DN 4+1 in his Ram Air III T/A and it's held up to more of a beating than the ST-10 in my T/A has.

80's vettes were probably using T5's or something, DN 4+1 transmissions were aftermarket units. DN DID make the goofy 4+3 semi-automatics that were installed in some of the 'vettes. They were a Super T-10 with a 3-speed automatic box hanging off the back.

The DN4+1 is a 5-speed with an ultra-low 1'st gear and 1:1 5th so you can use highway gears and still get good performance.

Shawn

CrkInsp
09-24-2008, 09:09 PM
Anyone out there have one of the MLM clutchless conversions?

hotrodladycrusr
09-24-2008, 09:15 PM
DN DID make the goofy 4+3 semi-automatics that were installed in some of the 'vettes.

Shawn

Thats the one I was thinking of.

draggin'GTO
09-24-2008, 09:21 PM
I had a DNE 4+1 (not a Corvette trans, not an overdrive) in a '57 Bel Air Sport Coupe.

Ratios in the street 5-speed: 3.27, 2.14, 1.57, 1.23, 1:1

Fits in the trans tunnel no problem, no mods needed other than to cut a hole for the shifter.

Uses a TH400 output yoke.

As already mentioned, either use the stock front engine mounts/bellhousing mounts or convert to side engine mounts and add a trans crossmember.

Also used to run a DNE 4+1 in my GTO, it was a nice trans and could take a beating pretty well. Still have the trans, soon it may find its way back into one of my Pontiacs again.

Larry T
09-24-2008, 09:30 PM
The older DN 5 speeds were crashbox type race transmissions. They used square cut gears and no synchronizers. Not very street friendly. Richmond makes one that has synchros for roadracing and street driving.
Larry T

spiderdeville
09-24-2008, 09:33 PM
GM NEVER installed a T5 in a corvette
they could barely handle a 305

Lotek_Racing
09-24-2008, 10:04 PM
GM NEVER installed a T5 in a corvette
they could barely handle a 305

Didn't know for sure, not a corvette guy.

The 80's DID give us the 305 'vette though.

Shawn

wetatt4u
09-24-2008, 10:29 PM
To answer some questions

I already have the DN and have used it in a 68 firebird and it is the 5 speed like dragginGTO spoke of. and I do have the th400 yoke..

I have the trans cross member in my car now with the th350 auto transmission...

Its not a overdrive trannie ,but a true 5 speed ,with low 1st thur 4th and then 5th for cruzin...

Richmond did buy the design years ago ,however for the most part they are still making the trans ,they call it the richmond 5 speed and even designed the 6 speed after it...

QUESTION ....
Will the th350 auto cross member work for the DN?

Lotek_Racing
09-24-2008, 11:21 PM
QUESTION ....
Will the th350 auto cross member work for the DN?

I believe it will, they were designed to be a bolt-in replacement in the second-gen Camaro and Firebird. The ST-10 uses the same crossmember as a TH-350 so I imagine the DNE trans would use the same.

If not, how hard is it to make a crossmember?

Shawn

zman
09-25-2008, 06:07 AM
The advice about using the side mounts on the engine is right on...

wetatt4u
09-25-2008, 09:07 AM
I know I can re fabricate,the cross member ,

just trying to get my ducks in a row before I get started...

Thanks to EVERYBODY that replied with helpful information...................

Larry T
09-25-2008, 09:21 AM
OK. I just went and measured. The DN 5 speed transmission mount is around 22 1/2" from the back of the block. Looks like it's about 2" further back than a 4 speed or Turbo 350 and not as far back as the Turbo 400 (somewhere around 27").

Overall length looks to be around 27 1/2" on the 350 and 28 1/2" on the 400 and the DN.

If you use a front mount for the engine, you'll have to use the stock bellhousing mounts. If you want to eliminate the bellhousing mounts, you'll have to go with side mounts on the engine.

wetatt4u
09-25-2008, 11:51 AM
Thanks Larry T
Thats exactly what I needed to know !

Pete1
09-25-2008, 01:00 PM
Something no one has mentioned about this transmission is that ALL
the individual gear ratios can be changed independently to tailor it to any application.
Keep in mind that 5th is direct and that will usually dictate changing the rear end ratio to suit your type of driving.

Panneton Bros. Racing
09-25-2008, 04:06 PM
Hey Guys

Can anyone tell what will be needed to install DN 5 speed into a 55 chevy?

I had a three speed in it original from the factory,changed out to an th350 many moons ago and want to change back to a straight drive.

Main question is ....

1)will in fit in the trans tunnel ?

2)what about the cross member?

I still use the front motor mounts,

Can anyone tell me if I'll need the back side mounts ,I think I've gathered all the parts needed ,

But just trying to make sure before I take it apart that I have all the parts and don't want to wait around to find any last minute parts..

Hope this make sense,

Thanks to all in advance for any help...
I have and H pattern Hurst shifter if your interested

Panneton Bros. Racing
09-25-2008, 04:10 PM
I have and H pattern Hurst shifter if your interested
PS. as long as your at it you may want to incorporate a
devise to keep the engine/trans from moving forward
and backward in the car (side engine mounts will help),
or keep a spare distributor cap/rotor. If you yahoo it real good in low gear they can move enough to bang the distributor into the fire wall (especially big cap/HEI)
and then you S.O.L.

Paul Y
09-25-2008, 04:15 PM
You probably have all the info you need now but just to add my 2pennys worth...

I run the 4 + 1 in my 56 chevy.

Fits in without any modification of the trans tunnel, if you are going to continue to use the front mounts you will need to make up some side mounts to fit onto the tabs on the chassis. If you just use the front mounts on the engine and a rear mount on the gearbox you will put a lot of strain bellhousing especially if you have a lot of HP.

Can I recommend the Long HG1000 shifter?

Just fitted one of these and it has cured all of the issues I was having with the gearbox, well worth the investment.

I am very happy with my gearbox, I am sure you will be too.

P.

wetatt4u
09-25-2008, 06:28 PM
Pete1

Panneton Bros.
Racing

Paul Y

Thanks guys ,I appreciate all the information,

Thanks for the offer of the shifter , However I already have a Hurst competition
5 speed shifter that I'm going to try to use,

But I'll keep ya in mind if it doesn't work out...

Also thanks for the heads up on the distributor cap hitting the firewall

Pete1
09-25-2008, 08:02 PM
I forgot to mention, the Long shifter is far better than the Hurst for this transmission.

draggin'GTO
09-25-2008, 08:20 PM
I forgot to mention, the Long shifter is far better than the Hurst for this transmission.Big time!

twinturbo496
09-26-2008, 02:26 AM
What engine? Which transmission? Is it a dog ring type crash box, or a street trans? One area of concern would be the limited shifter options, you may not get the shifter to fit without cutting a larger hole in the floor.
I believe that all of the dog ring type crash boxes have a 30 spline Mopar output, and I think the street version all had a 32 spline TH400 spline, so you will need a yoke. The Nash is very close (but not exactly) the same length as a M22 Muncie.

If you have a dog ring transmission, you may not like the way it shifts on the street.

wetatt4u
09-30-2008, 06:11 PM
The engine is a small block 350 and
the transmission is the street version Doug Nash 4+1
with a long Hurst composition shifter,
already HAD a four speed in the car a few years back,so I not worried about the hole in the floor.
I also already have the th 400 yoke.
I have the front motor mount now ,and it will be no problem to add the side mounts.
I have the 350 AUTO transmission cross member in now and was wondering if it would need to be modified?

draggin'GTO
09-30-2008, 08:14 PM
The engine is a small block 350 and
the transmission is the street version Doug Nash 4+1
with a long Hurst composition shifter,
already HAD a four speed in the car a few years back,so I not worried about the hole in the floor.
I also already have the th 400 yoke.
I have the front motor mount now ,and it will be no problem to add the side mounts.
I have the 350 AUTO transmission cross member in now and was wondering if it would need to be modified?You'll have to move the crossmember towards the rear of the car, it could need some modification as well.

The mount on the DNE trans is quite a bit further back compared to the TH350.

UncleMike57
12-16-2009, 03:51 PM
A couple of things you need to be aware of. I put a richmond 5 speed in my '57 2 door post. I swapped out a m-22. The first thing that you need to know is that you will have problems with the shifter if you have bench seats. The output housing on which the shifter adapter plate mounts is further back on the richmond than the muncie. Also, whether you use front mounts with chassis mounts to the bell or side mounts on the motor you will still need a rear trans cross member. You can use the muncie one that is in your car with some modifications or order a new one from williams chassis in california. To make the shifter fit with the bench seat you will have to have a new adapter plate made by a machine shop. I don't know of anyone who makes or sells one. I made my own and got it right on the 3rd try. Good Luck

PS - You will love it when you get it in. The car will launch like a rocket

Desoto291Hemi
12-16-2009, 04:10 PM
I have the competition model in my Challenger,,you can't hurt it.
It uses the Mopar main shaft,,and the Hemi spline pilot,,again,,you can't hurt it.
There are some differences from stock tranny dimensions,,and mount locations.
It was a replacement that was used on many different applications,,a racing tranny to fit whatever you needed.
The street version is another bird altogether,,takes a lot of Chevy pieces,,,,Racing version used Mopar pieces.
Mine has the center bearing on the cluster to help it stay together.
Yes,,,I have the shifter from Leonard Long,,(V-Gate),,it is a work of art.
PM me if you need any help.

Tommy

zman
12-16-2009, 04:14 PM
I love when the newbs respond to old threads. It's entertaining. Wonder if the tranny ever made it into the car.

rascal55
12-16-2009, 04:40 PM
Theyr'e tough as anything out there except for a Lenco
or a Jerrico if you got big H.P. and big $$$$$$$!
Richmond still has parts or get em on the Eway
Race version is non synchro,
Street version is , You can pretty well pound on
both unless you got a monster under the carb!!!!!
GRIP IT AND RIP IT !!!!!!!

Truckedup
12-16-2009, 04:54 PM
No T-5's in Vettes.Used the Doug Nash 4+3 ,a Super T-10 with an automatic 2 speed overdrive bolted to the back.It was somwhat complex and expensive to repair.

wetatt4u
12-16-2009, 05:57 PM
For anyone who gives A real rats ass ,

The trannie is in the 55 and doing fine !

Thanks for all the love over the years and a pat on the back to those with real helpful info on the questions that I asked for.

MERRY CHRISTMAS to everyone !

Happy New Year

God Bless & have a safe Holiday.