4.25 "Pumpkin"

[Scott Rodrigues]

Hi everyone, was a member eons ago under the handle Espyrus, now back to try and restart and finish my project, started as a pretty rusted SV and wound up a much nicer SIV car with all the rebuilt bits in her (long story).

I know this is the Modified forum, but this is a modification... if it actually exists and is true. I think I remember someone on here redoing their rear pumpkin so the ratios would be 4.25 on all four gears. If this does exist, how do I do it or is there a better option for it? My car's a 1725 and I'd like to keep it as Sunbeam as possible.

Any ideas? Thanks in advance!

 

[DanR]

Don't understand your question in regards to 4.25 in all gears?

 

[Scott Rodrigues]

I am probably misremembering it. I remember (or I THINK I remember) someone talking about a pumpkin that had or made or something or other this and had better ratios. It has me a bit confused and I apologize if it sounds like I'm a bit nuts. I am but that's beyond the point

 

[DanR]

Two rear gears common to the Alpine are 4.22 and 3.89

If you have an overdrive the 4.22 maybe a good gear for you.

If not, the 3.89 can be a real good option.

Some have even gone to 3.70

 

[Bill Blue]

What you seem to remember can not possibly exist. It would be beyond the laws of physics. So lets forget it and start from scratch and see what we can do.

What do you want to achieve with the magic pumpkin?

Bill

 

[Scott Rodrigues]

Sounds like a plan . Thank you for your patience.

Basically DanR's response. I have whatever the standard is on mine but I also have the OD and driveshaft in the trunk (came with the car when I bought it, missing the 'plate' for it) and have considered installing it. Obviously I know little to nothing about this part of the car and figured I'd ask before I ventured out or did something stupid. I had the silly idea that it would improve the transmission from gear to gear since first gear is so damn horrible on this car.

Feel more than free to educate me. Hell, please educate me. And thank you!

 

[Ashfried]

I too would love to know what I would need to change from 3.89 to 4.22. What parts I would need to find (can I get gears from SS or are they out of a different car or series)

 

[Bill Blue]

First of all, lets get it straight that I am not the person to discuss this with. I know very little about the specifics of the Alpine drive train, especially the overdrive, so hoping that others with chime in and I will drop out. However, we do need to determine exactly what you find so detestable in your tranny's first gear.

One thing to remember when working on 50 year old cars, what was original equipment or is supposed to be there means nothing. Who knows what has been installed or removed on a particular car? Not even the Shadow knows.

Bill

 

[Barry]

I too would love to know what I would need to change from 3.89 to 4.22. What parts I would need to find (can I get gears from SS or are they out of a different car or series)

Both 3.89 and 4.22 gearsets were used in Series Alpines.

Please explain why you want to change from a 3.89 to a 4.22 gearset.

 

[jumpinjan]

I recommend using the 3.70 ratio (with over drive) if you want to spend the money. Otherwise the 3.89 is fine. A 4.22 gear set is good for the metal recycler
Jan

 

[Bill Blue]

I think it is important to know the issue(s) before making recommendations.

Bill

 

[65beam]

I recommend using the 3.70 ratio (with over drive) if you want to spend the money. Otherwise the 3.89 is fine. A 4.22 gear set is good for the metal recycler
Jan

The 3.70 gear set from the fast back Alpines is the only 3.70 that is worth using. The gear sets from Holland make a LOT of noise regardless of what you do. They're a waste of money.

 

[jumpinjan]

I think it is important to know the issue(s) before making recommendations.

Bill

I'm beyond the "issues" and my conclusion is what I typed. Been there and done it.
Jan

 

[Bill Blue]

I'm beyond the "issues" and my conclusion is what I typed. Been there and done it.
Jan

What are you talking about? What if the guy installs a 3.70 because it is the "best" but is wanting more acceleration??
Bill

 

[65beam]

I'm beyond the "issues" and my conclusion is what I typed. Been there and done it.
Jan

Jan,
I agree on using the 3.70 gear as I have 3 cars with this gear ratio. The difference is that all of mine are genuine Rootes gears. The result is that I don't have the noise issues that you get when using the after market pieces.

 

[Alpine 1789]

I had the silly idea that it would improve the transmission from gear to gear since first gear is so damn horrible on this car.

Scott: First, welcome back! It is good to have you back online. Bear with us and we'll get your straightened out. Putting an OD transmission on my SV was probably the single best improvement I have made to the car since I bought it in 1978. But, the OD only works in 3rd and 4th gear, so the improvements don't have anything to do with 1st gear. And, I don't recall ever hearing of anyone complaining about 1st gear in a working transmission, so you may have a problem with the one in the car. Presumably, the OD in the trunk won't have the same issues, so that should take care of you, but to be sure, can you tell us why you find 1st so horrible? I am sure you can get some good advice from there.

 

[husky drvr]

Hi Scott,

I'm going to make a wild guess about your trans. You state that you now have a sIV with a 1725. Do you know which transmission you have installed?

Is reverse on the shifter down and left or down and right? My guess is down and left making your trans the sIV and earlier model trans. I'm also

guessing that your main complaints about your trans are that it makes an excessive amount of gear whine in first and that you are unable to shift

back into first gear until the car is completely stopped without clashing gears.

If those are your main complaints, your best remedy will be find a good sV transmission and change out the trans. The early series transmissions have

those issues by design. First gear is NOT synchronized and are made with straight cut gears which are naturally noisy due to way the gears engage each

other. The later sV transmission has a first gear synchronizer and bevel cut gears which go a long way to improving the noise and shifting issues of the

earlier style trans.

HTH and have fun,
Don

 

[65beam]

The first question concerning first gear is whether it is synchronized. Can you drop the trans into first while moving or does it sound like you just stripped the gears? If not it could be a non syncro for an early series 4 or earlier series. First gear would probably be noisy and could be used to pull a tree stump. I have a non syncro trans in a couple cars and I can start out from a stop using second gear instead of first. Is the over drive unit connected to a trans or just in the trunk? Is the car drivable and if so does the trans now in the car have an over drive unit? If not you can't install the over drive to the trans in the car due to a different out put shaft being required. The out put shaft has to have the cam lobe to operate the O.D. pump. Tell us a little more about the trans in the car and also the car itself.

 

[jumpinjan]

What are you talking about? What if the guy installs a 3.70 because it is the "best" but is wanting more acceleration??
Bill

Huh? More acceleration? Yeah right....LoL...Maybe get a Tiger, Bill? what do you think?
Jan

 

[alpine_64]

First gear in any rootes trans is very low. The series 3 had a "close ratio" box but 1st is still short and non synchromesh ( also s3 was the only model from factory to fit the 3.89 diff regardless of OD or not which gave it the longest cruise gearing)

All alpines (execept series 3) used a 4.22 diff when OD was factory fitted.

Most USA sepc series V alpines had the shorter 4.22 rear end. This helps acceleration from standstill but makes 1st gear very short, reduces top speed and makes higher rpm at any given road speed bs the 3.89.

The late SIV and SV all had a full synchro trans and the gearing was similar to the S3.

A non- syncro trans will have reverse to the left of the shift a syncro trans to the right.

If you have a non syncrho trans the 1st gear will whine and unless you double declutch you cant move into 1st while moving.

If you have an overdrive unit you need the longer mainshaft to fit it to a standard trans and will need the adaptor plate, have to shorten the tailshaft along with getting a switch, loom, speedo gear and speedo.

Early non synchro overdrives have a stronger mainshaft thats less prone to twisting.

Early overdrives you manual cancel, series 3 onward they self cancel when movimg from the 3rd/4th plane to the 1st/2nd plane.

Later rootes arrow series cars were available with a 3.70 gear. This increases top speed, more relaxed cruising and lengthens the effective gearing in 1st. It will also reduce acceleration a little.

If you want good high speed cruising a 3.89 diff should be easy to find ( check and replace all the lock tans and washers and ring gear bolts) add an overdrive and it will be very relaxed. Add 14 or 15" wheels with appropriate tyres and the gearing will become very cruisy.