Maybe this one will stump you?

[Jack A.]

I am restoring a 61 315 hp fuelie. I have changed the rear end from a 3:70 posi to a 4:11 posi. My question is this .What plastic Speedo Gear goes into the T 10 four speed transmission? The one that came out of it was white/clear. In looking into the guides and products catalogues they show several possibilities. Each with a diffeent color. Red, Green, Brown, etc. Each color representing a different gear with a different number of teeth, for all of the different differential gearing possibilities. I can't find anything that tells me which is correct without trying them out. Any ideas?

Regards,

Jack Alexander 35730

[Ray G.]

Re: Maybe this one will stump you?

I am restoring a 61 315 hp fuelie. I have changed the rear end from a 3:70 posi to a 4:11 posi. My question is this .What plastic Speedo Gear goes into the T 10 four speed transmission? The one that came out of it was white/clear. In looking into the guides and products catalogues they show several possibilities. Each with a diffeent color. Red, Green, Brown, etc. Each color representing a different gear with a different number of teeth, for all of the different differential gearing possibilities. I can't find anything that tells me which is correct without trying them out. Any ideas?

Regards,

Jack Alexander 35730

Hello Jack;
Maybe this will help.

http://www.tciauto.com/Products/Techinfo/speedo_gears.asp

Ray

[Mike E.]

Re: Maybe this one will stump you?

Any old GM Corvette parts book has the colors that correspond with the gear ratios.

[Wayne W.]

Re: Maybe this one will stump you?

Going from 370 to 411 is about an 11% change. Take the number of teeth on the original and multiply by 1.11 and you will have the number. However there may be another problem. When changing gears, sometimes the drive gear in the transmission also has to be changed.

[Edward J.]

Re: Maybe this one will stump you?

Going from 370 to 411 is about an 11% change. Take the number of teeth on the original and multiply by 1.11 and you will have the number. However there may be another problem. When changing gears, sometimes the drive gear in the transmission also has to be changed.

Wayne I think that there is only two different drive gears for the t-10 one is for 308 to 351 the other is from 370 to 456

[Bill M.]

Re: Maybe this one will stump you?

My parts book has yellow, 24 teeth, for 4.11 and has
you should now have a green one, 22 teeth for 3.70

[Ken A.]

Re: Maybe this one will stump you?

Yellow is correct

[Jack A.]

Re: Maybe this one will stump you?

Gentelmen this has been great. I was confidend you all could not be stumped. As usual you all have come thru with flying colors. It looks like in this case it is Yellow. I'm quite sure the original one was wrong. This was a drag car for part of its life and there were a lot of, shall I say interesting, configurations in it when I first got it. Thei is one of the very last things to be corrected and I thank all of you for it. What you have all saved me in time and money in this oriject is considearble and I am gratefull to all of you for it.

Regards,

Jack

[Clem Z.]

Re: Maybe this one will stump you?

if just changing the driven gear does not work you can have a speedo shop build a geared adapter that goes between the trans out put and the cable input to correct the problem

[Jack A.]

Re: Maybe this one will stump you?

Thanks Clem,

I'm not sure I have a problem just yet. Once the correct gear goes in there I hope to be OK. If not I appreciate your expertise on the fix.

Impressive Resume' by the way. You have helped me in the past and are always right on.

Thanks,
Jack