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T9 Transmission whine


MarkEMark

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If it's a square cut gearbox, the ratios will be rather close. Closer than most reworked helical cut type nines. The typical Caterham supplied straight cut 'box has a 2.04 first gear. They do whine in all gears EXCEPT direct. Not particularly noisy in neutral, maybe just a little. Can you do 60MPH in first gear?

 

If your gearbox is not straight cut, I'd check the circlips under the front nosepiece of the box first. A Broken circlip will allow the input shaft to drift back into the works and whine. Next stop is the roller bearing between the input shaft and the main shaft. Next check the blocker spring and blockers on the 4th gear (direct). Next, the 4th gear balk ring itself.

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Just went out to test. At 6,0000 rpm it's doing just over 40mph. It's not that noisy in neutral, just a bit of a rattle. 5th gear seems no longer than 4th from what I can tell. Its in a 2005 Birkin rather than Caterham

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Whine in all gears except direct?

40+ in first gear @6000rpm?

Slight rattle in neutral?

Very tiny rpm drop from direct to overdrive?

 

It's a pretty good chance you have a square cut gear set, probably Quaife with 2.39 first, 1.61, 1.21, direct, and .87OD ratios. There are other manufacturers offering square cut gear sets as well.

 

If your Birkin has a 3.89 ratio and typical 205-50-15 tyres, a 2.39 first gear would give you ~ 44mph @6000 rpm.

 

I would ring up the builder/dealer/importer and find out for sure what's in your car. If it was originally sold through the usual channels, they may have a record of what 'box was sourced with that particular kit.

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Still trying to track down original build info....

 

If we end up having to take the transmission out (and I suspect I will need to do the clutch anyway) what's the disassembly sequence? I had a transmission place take a quick look and they were talking about the floor coming off. That cant be right!

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The gearbox goes in a Seven horizontally from the front since there are chassis tubes crossing under it.

 

Don't know aboot Birkin but I'd suspect it's similar to Caterham; the engine and gearbox come out as a unit. Very simple.

 

I've heard of some guys pulling the engine first then pulling the gearbox second. That sounds difficult to me. Too many friggin bolts to undo with no space to swing a spanner.

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Not sure if this was asked yet: is the whine new, ie did the sounds change/develop over time, or been there all along? or if the car is new to you,I agree with the straight cut comment.

I put a straight-cut Quaife in my car from new, and as expected, it whined a bit in all gears except the direct, and neutral whine was less than "loaded" in gear whine.

Pop the top cover off and look inside.....

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Car is new to me. Rather impetuous purchase I'm embassed to admit! Access to top panel is very limited, I can only really see the front half but will give it a go at the weekend and post a picture. I always wanted to build a 7, so maybe I need to take out the engine and transmission to partly pay my dues

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Buy a 1 or 1 1/2" "rubber" chair leg or crutch cap at Ace hardware. Use it to plug in the tailshaft as soon as the drive shaft pulls out. This will keep most of the gear oil in the trans as it is pulled out of the car with the engine..

Edited by MichaelD
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Will the drive shaft just pull out of the tail shaft as I move the engine and transmission forward?

 

yes, the male splines on the back of the gearbox shaft are a simple sliding fit into the female splines at the front of the driveshaft. Rig up something to "catch" the front of the driveshaft as the gearbox separates from it. Depending on specific model, there could be several inches of movement before they separate.

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Great. Thank you Ian7. Getting my nerve to pull the engine/transmission. Famous last words, but looking around the engine bay it actually looks relatively straight forward. I do need to decide if I lift the engine, or lift the car. Seem Caterhams you lift the engine, Berkins maybe leave the engine on a dolly and raise the front of the car

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The real job is getting the propshaft yoke back into the gearbox on installation. Be nice to the missus 'cause you'll need her to line up the yoke when re-installing the engine/gearbox unit.

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  • 1 month later...

Final bit of information. After posting my car in "members rides", I was referred to the Birkin Group on Yahoo, and a registry of cars. My car was there, and when I looked through the posts of the original owner, he states the car has a "Taylor*Race straight cut T9". So, given the car only has 2100 miles on it, and I suspect the original tires from 2002 in good wear condition, I'm going to assume no one has managed to shag a race transmission in that time, and I need to just enjoy driving the car. And yes, I need new tyres!

Mark

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