0.64 Fourth Gear in a 4-Speed?

[Bob B.]

Hi all,

I was wondering if it is possible to widen the gear ratios in a T-10 transmission so that fourth gear would be 0.64 instead of 1.00?

Happy Thanksgiving!

Bob

[Joe L.]

Re: 0.64 Fourth Gear in a 4-Speed?

Hi all,

I was wondering if it is possible to widen the gear ratios in a T-10 transmission so that fourth gear would be 0.64 instead of 1.00?

Happy Thanksgiving!

Bob

Bob------


There's no way I know of to change the 4th gear (direct drive) ratio in either a Muncie or T-10 to 0.64:1 or, for that matter, any other ratio.

If you want an overdrive high gear you need to go to an aftermarket 5 or 6 speed transmission or and "add-on" overdrive unit.

[Duke W.]

Re: 0.64 Fourth Gear in a 4-Speed?

I think there is some outfit that makes new guts for vintage four-speeds with an overdrive fourth gear. Third is 1:1, and the gap between all gears is about as wide as 3-4 on a WR four-speed.

The original shift pattern could be maintained with a shift lever on the trans that is 180 degrees out from OE.

Sorry I don't remember the name, but some creative googling will probably reveal it.

Duke

[Terry D.]

Re: 0.64 Fourth Gear in a 4-Speed?

Duke is right I looked into this before I bought a 5 speed. I'll try to find the name of the company, think they were in Michigan. Anyway I drove a Chevelle that had one and did not like it, too wide a gap between gears, reminded me of the old three speeds with overdrive. If all you were going to do is go on trips it would probably be OK.
Just my two cents
Terry

[Terry D.]

Re: 0.64 Fourth Gear in a 4-Speed?

Bob
Name of the company is Riverside Gear and they are located in Eaton Rapids Michigan. It ends up a .87 forth gear and it is for Muncie's. Maybe they are doing T-10's by now. It was a couple of years ago when I checked them out.
Terry

[Tom P.]

Re: 0.64 Fourth Gear in a 4-Speed?

There is an OD gear set for the Muncie.
4th gear remains the same (1:1), and THIRD is the overdriven gear. Thus, the shift lever for 3-4 is flipped over.
This puts the shift pattern (on the side cover) 1-2-4-3. This makes a giant gap from 2nd to 4th (which has become 3rd gear), and then a "normal" gap from 3rd to 4th (which is now OD).
Did I confuse you?

[Joe L.]

Re: 0.64 Fourth Gear in a 4-Speed?

Bob
Name of the company is Riverside Gear and they are located in Eaton Rapids Michigan. It ends up a .87 forth gear and it is for Muncie's. Maybe they are doing T-10's by now. It was a couple of years ago when I checked them out.
Terry

Terry------


I don't think going to a 0.87:1 4th gear would be worth the effort and cost. If one couldn't get to at least 0.75:1 I don't think it makes sense to do the conversion. The only way it MIGHT make sense is if one was using a real numerically high rear gear ratio (like 4.11:1 or 4.56:1) and felt that even a little better highway performance would be worth it. I'd change the rear gear ratio before I'd do this, though.

[Terry D.]

Re: 0.64 Fourth Gear in a 4-Speed?

Tom
I just checked Riversides web site and there is no mention of this flopping of shift pattern. Also when I talked to them two years ago, they never mentioned it then either. That would be very confusing after driving 40+ years with the old pattern. Glad I went with a 5-speed. Where did you find this info?
Terry

[Joe L.]

Re: 0.64 Fourth Gear in a 4-Speed?

There is an OD gear set for the Muncie.
4th gear remains the same (1:1), and THIRD is the overdriven gear. Thus, the shift lever for 3-4 is flipped over.
This puts the shift pattern (on the side cover) 1-2-4-3. This makes a giant gap from 2nd to 4th (which has become 3rd gear), and then a "normal" gap from 3rd to 4th (which is now OD).
Did I confuse you?

Tom------


I wouldn't "touch a conversion like this with a 10 foot pole". I wonder how many of these things that they've sold? If it's more than a few, there are some real strange people out there.

[Terry D.]

Re: 0.64 Fourth Gear in a 4-Speed?

Joe
I agree that's why I went with a Tremec 5-speed, best of both worlds, in town it's like having 4:11's and on the highway at 70 I'm taching a little over 1900 rpms. Plus in my case I would have had to buy a Muncie then change gears and end up with basically a 3 speed with only .87 overdrive.
Terry

[Domenic T.]

Re: 0.64 Fourth Gear in a 4-Speed?

Tom------


I wouldn't "touch a conversion like this with a 10 foot pole". I wonder how many of these things that they've sold? If it's more than a few, there are some real strange people out there.

Joe,
More like a 20 foot pole, can you imagine the wear on the cluster gear when it is under constant use as a final gear. Most people are not aware that 4th gear in a 4 speed is actually the mainshaft being linked to the input by use of the syncro clutch.

DOM

[John S.]

Re: 0.64 Fourth Gear in a 4-Speed?

Guys,

You are missing the point. Dom hit it on the head. There is no gear train for fourth gear (therefore no gear ratios to change) on these transmissions. All fourth gear on the lever does is link the input shaft in direct "coupling" with the output shaft. Tend to agree with the earlier comments about it being more trouble then it's worth. Drive em and have fun!

John

[Tom P.]

Re: 0.64 Fourth Gear in a 4-Speed?

Joe,
More like a 20 foot pole, can you imagine the wear on the cluster gear when it is under constant use as a final gear. Most people are not aware that 4th gear in a 4 speed is actually the mainshaft being linked to the input by use of the syncro clutch.

DOM

Several of the OD MANUAL trannys are like this. The final, or OD, gear is the cluster driving (or applying power to) another gear on the mainshaft. Thus, in the final (OD) gear, the cluster is ALWAYS being loaded. The ONLY time this condition does not exist is when there is an INDEPENDANT OD unit BEHIND the output shaft, sort of similar to the OD unit of the EARLY 3spOD trannys of the 50s-early 60s.

If the ultimate goal or objective is to have a final drive gear ratio that is very high, and contributes to improved fuel economy, then I have found that a very acceptable combination is to have a very hight gear rearend (3.08, 2.73, 2.56, etc) and a very low range in the first gear of the tranny, ie 2.90, 3.20, etc. A wide ratio Muncie works very nicly with a 3.08 rear. For the EARLY cars with 283 engines and a 3.08 rear, I admit it may take a little additonal feathering of the clutch (EXCELLENT justification for an 11in clutch), but once the car is rolling 5-10mph, it becomes quite effortless. And in 4th gear on the Interstate with a 3.08 rear, it sure is nice to have the lower rpm's and better fuel economy.
My Cutlass has an EXCELLENT combo. The rear is a 2.41 posi and the tranny is a Richmond 5sp. First gear is 3.27 and 5th is 1:1. Thus, in 5th, with a 2.41 rear, it's the equivalent of an OD in other cars with a somewhat higher rear gear and the 3.27 1st gear mates nicely with a 2.41 rear.
I mention all of this because with a tranny that has a 1:1 final drive, the cluster is not loaded when cruising, thus it also is not generating heat from the gears meshing constantly.

[Tom B.]

Re: 0.64 Fourth Gear in a 4-Speed?

I remember an article in one of the car mags some years ago about the 3/4 swap with 3rd ending up as the overdrive top gear. There are just too many good options today to mess with something like this now.

Tom