Drive In, Drive Out Diff Exchange

[Adtheman]

I was lucky enough to drive in at 9.00 and drive out at 4.30 with a full diff exchange from my rev happy 3.70 to a 3.08. Where in the UK can this happen? One place only. 'Corvette Kingdom', I was there all day only to help with the lifting out and back in again whilst i watched the master at work, honestly guys what Scott doesn't know about vette's no one needs to know. Even the gear drive for the speedo was replaced. My 350 L82 manual used to wail at 4250rpm at just under 70, now revs are a lot lower gears are taller and the whole car drives so much nicer. A complete transformation. Thanks Andy (aka Forrest Gump) for your info on this prior to me taking the plunge, best money i spent on the car so far.
I got Scott to replace a lot of the bolts that were rusty and horrible all of which he had on the shelf, this truly is a very slick operation. Ive put a few photos below. Theres one in there of a very dubious looking skeleton in the diff crossmember. God knows whether that was American or British. Ive still got to sort the rev counter out as its reading too high but I think its been replaced at some point with the wrong one so i'm hoping with the correct on in there all will be well again. Thats my winter dash out project.

 

[Oneball]

Can’t identify the dead thing!

 

[Corvette Kingdom]

Always a pleasure working with you dude!

we should think of a name for that Corvette rat....

 

[James Vette]

Scott is the dumbledore of corvettes.

 

[Adtheman]

Always a pleasure working with you dude!

we should think of a name for that Corvette rat....

Theres a few out there take yer pick

 

[Mad4slalom]

I was lucky enough to drive in at 9.00 and drive out at 4.30 with a full diff exchange from my rev happy 3.70 to a 3.08. Where in the UK can this happen? One place only. 'Corvette Kingdom', I was there all day only to help with the lifting out and back in again whilst i watched the master at work, honestly guys what Scott doesn't know about vette's no one needs to know. Even the gear drive for the speedo was replaced. My 350 L82 manual used to wail at 4250rpm at just under 70, now revs are a lot lower gears are taller and the whole car drives so much nicer. A complete transformation. Thanks Andy (aka Forrest Gump) for your info on this prior to me taking the plunge, best money i spent on the car so far.
I got Scott to replace a lot of the bolts that were rusty and horrible all of which he had on the shelf, this truly is a very slick operation. Ive put a few photos below. Theres one in there of a very dubious looking skeleton in the diff crossmember. God knows whether that was American or British. Ive still got to sort the rev counter out as its reading too high but I think its been replaced at some point with the wrong one so i'm hoping with the correct on in there all will be well again. Thats my winter dash out project.
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Nice work and I presume better mpg due to lower revs ?
what is the approx lead time for a similar job at CK ?

 

[Adtheman]

Nice work and I presume better mpg due to lower revs ?
what is the approx lead time for a similar job at CK ?

im hoping so, not driven too far as CK only 30 miles from me. so much nicer now at 60-70 cruising speed. I know Scotts busy but give him a call i'm sure he'll fit you in somewhere.

Can’t identify the dead thing!

It had been there sometime whatever it was

 

[Forrest Gump]

Well done Adam and nice work CK.

Chatting with me can result in expenditure ££ Glad you are pleased with the result though

Any joy with a speedo drive gear to give correct speedo reading with the 3.08 ratio?

 

[Adtheman]

Well done Adam and nice work CK.

Chatting with me can result in expenditure ££ Glad you are pleased with the result though

Any joy with a speedo drive gear to give correct speedo reading with the 3.08 ratio?

It had a 19 tooth drive in there which was reading wrong. swapped it out for an 18 and its spot on to 40mph. it reads a little low at a true 70 but only 3-4 mph. Want to get the rev counter sorted so i know where i am with it. Really happy though so far, you can stay in the gears for much longer now.

 

[Forrest Gump]

It had a 19 tooth drive in there which was reading wrong. swapped it out for an 18 and its spot on to 40mph. it reads a little low at a true 70 but only 3-4 mph. Want to get the rev counter sorted so i know where i am with it. Really happy though so far, you can stay in the gears for much longer now.

Hmm, I've got an 18 tooth at the moment which gives me a slow speedo reading. Don't think there is a 17 tooth. Maybe my speedo is out of calibration then.

 

[teamzr1]

Yes there is a 19 tooth

Use this to figure out if needing the inner, outer, or both speedo gear changes



Calculate
Speedo Gears

 

[Adtheman]

Hmm, I've got an 18 tooth at the moment which gives me a slow speedo reading. Don't think there is a 17 tooth. Maybe my speedo is out of calibration then.

Hi Andy. Sounds like there is one. They are only a few quid it may just make it right. If the roads dry out this morning I’m itching to get out and go for a blast.

 

[Forrest Gump]

Thanks Team ZR1. I have never seen a 17 tooth from any of the Corvette parts suppliers, but just googled it and sure enough they do exist - purple 17t. Common on Pontiac and camaro. Theoretically and according to the chart 18 should be the correct one, but for some reason it’s not giving me a correct reading.

 

[Forrest Gump]

Hi Andy. Sounds like there is one. They are only a few quid it may just make it right. If the roads dry out this morning I’m itching to get out and go for a blast.

Yes, learn something every day!
Let us know how you get on. You’ll be saying you need more torque next….did I mention stroker cranks?

 

[kentvette]

im hoping so, not driven too far as CK only 30 miles from me. so much nicer now at 60-70 cruising speed. I know Scotts busy but give him a call i'm sure he'll fit you in somewhere.

It had been there sometime whatever it was

Only 30 miles from CK!? What joy! Looks so much nicer than the few days June & I spent struggling under the car to remove and re-fit the diff!

I'm contemplating an 800 mile round trip for Scott to take a look at our '78......

 

[teamzr1]

Thanks Team ZR1. I have never seen a 17 tooth from any of the Corvette parts suppliers, but just googled it and sure enough they do exist - purple 17t. Common on Pontiac and camaro. Theoretically and according to the chart 18 should be the correct one, but for some reason it’s not giving me a correct reading.

You could use a GPS unit that also shows speed and at certain speeds like 40 MPH compare what the speedo on dash shows and what GPS says and see what the percentage difference is
Then do the math to see which inner or outer gears are needed to correct or try this :

Speedometer Gear Calculation
Speedo Revs/mile = (20168 x DiffGear x DriveGearTeeth) divided by (Tire-diameter x Driven-GearTeeth)

Or here is another speedo gear calibration calculator

Calculate Speedo Gears

 

[Adtheman]

Only 30 miles from CK!? What joy! Looks so much nicer than the few days June & I spent struggling under the car to remove and re-fit the diff!

I'm contemplating an 800 mile round trip for Scott to take a look at our '78......

I can't imagine doing it without a ramp and all the gear thats quite an achievement. 800 miles is a long way but i guarantee you won't regret it.

 

[Adtheman]

Yes, learn something every day!
Let us know how you get on. You’ll be saying you need more torque next….did I mention stroker cranks?

ssshhh!!! quiet now Andy you've already caused trouble once this year. Been out in it today as the weather not too bad here. its made a huge 'Difference' sorry my poor attempt at humour, said that to Scott yesterday all i got was a look and a really dude is that where we're at now.

 

[curious bystander]

I had my diff. sorted a few months ago. Got all the parts from Scott, but a local garage did the work.
Out of interest Adtheman what did it all cost doing it your way? If you dare tell us

 

[Chuffer]

Scott got me a new 3.08 diff a couple of years back and delivered to my home address . Got local Yank specialist garage to fit it as CK is a bit of trek from me . Was well pleased and great service from Scott as usual .