Tremec T45 gear ratios

[Max Allan]

Does anyone know the gear ratios of the Tremec T45 tranny, as fitted to the 4.6 cammer engine? The reason I ask, I intend swapping out the AODE auto box in my Brooklands Ace for a manual and just happen to have a new T45 sitting in my garage. A conversion to marry the box to the '94 5.0L doesn't exist, but I'm reasonably confident it can be done. However, there's little point pursuing the idea if the ratios don't suit my axle ratio (2.88.1).
   
   Surfing the net I've come up with the ratios for every other box - T5 (close and wide ratio), 3550 & T56 – but nothing for the T45. And posting a question on corral threw up a lot of useful info, but nothing about ratios (probably because I never asked!!
   
   Cheers
   
   Max

[Mark IV]

Max,
   Try http://www.ttcautomotive.com/English/products/T-45.asp for the ratio chart.
   
   Rick

[Max Allan]

Thanks Rick,
   
   As I suspected, pretty much the same ratios as the wide ratio T5 and 3550, which is OK but doesn't help with my dilemma. I'm running a high ratio axle (2.88.1) with 17 inch wheels, which, according to my calculations, means at 2,000 rpm I'd be doing 76 mph with a 0.68 5th and 80 mph with a 0.64 5th - great for economy, but too high for performance. The solution would be to fit a T56, but one hears of lots of complains of vibration with the T56. Maybe it's because the Mustang has a live rear axle and they're getting the driveline angle wrong, in which case with IRS I probably wouldn't encounter the problem. On the other hand, is it a fault with the T56?
   
   Cheers, Max

[Mark IV]

Max,
   
   I drove the prototype Ace with the Lotus V8 and a T56 and it was fine. And that was with a bogus rear trans mount (we hand carried two Viper mounts to AC to use).
   
   What about changing the rear diff for a better ratio? You really don't need 6 speeds with the 4.6 and perhaps something in the 3:27 to 3:55 ranmge would would work? You could buy a complete BTR diff and swap it out for the unit in your car.
   
    I think your car was in a shipping rack when I was last at Weybridge in Sept. 99. There were at least 4 painted Ace bodies sitting outside next to the WWII era AC fire tender.
   
   Rick

[Max Allan]

Rick,
   
   I think I might have mudded the waters talking about the T45 box. It's an early car - no. 44 - fitted with an upgraded 5.0L (AFR's etc), not a 4.6. I have a T45 sitting in my garage – hence my thoughts about adapting it to fit the 5.0L.
   
   On the face of it, fitting a 6-speed is probably an unnecessary luxury. However, unless I'm mistaken (please correct me if I'm wrong) the price of a T56 includes the bellhousing, whereas the T5 doesn't. Therefore, based on Summit prices, the actual cost of a T5 is $1,150 plus $190 for the bellhousing. Add in the cost of a lower ratio diff, say $470 (£250) and total expenditure would be in the region of $1,810. Price of a T56 - $2,090. So for an additional $280 I'd get an extra gear and less work - or is my logic flawed?
   
   I'm intrigued as to where the car was going/been when you saw it crated up in Sept 99. I purchased it 6 months later from Duncan Hamilton, only days after he received it from the factory, with just 2,300 miles on the clock. According to documents supplied with the car it was exhibited at the 95 Detroit Motor Show, although I have my doubts. With your obvious knowledge of the comings and goings at the factory are you able to confirm it was.
   
   Unfortunately, before leaving the factory the hood was removed, so I accepted the car with the only remaining hardtop. High on my wish list is to get one made, but without access to a set of frames as a pattern it's nigh on impossible. Anyone know of a written-off Brooklands Ace with a salvageable hood?
   
   Max

[keithjecks]

I have a 4.6 Ace, and have been looking for info on the gear ratios. Can't see anything in the handbook. Come to that, I don't even know what gearbox it has. What I can say is that the top gear ratio appears quite a bit lower than in my Mk IV. In the Cobra there is a massive gap between 4th and 5th gears (it is almost as if it had a 6 speed gearbox that someone removed the 5 th gear from, if you see what I mean). In the Ace, the 4th - 5th gap is much more sensible

[Max Allan]

ace4.6. The 4.6 has the Tremec T45 gearbox with a 0.67 5th gear. Your MK IV had the T5, which comes in several various ratios, but most likely a 5th gear of 0.63. The higher the ratio number, the lower the gear, so the gap between 1:1 (4th) and 0.63 is greater than that between 1:1 and 0.67.
   
   See Mark IV's Tremec link further up – it list all the tremec gearboxes and ratios available.
   
   Max

[Mark IV]

Max/4.6,
   I may have gotten you two crossed...I saw the 4.6 Ace shell in the rack in 99, not the LHD 5.0 Ace. I do however have pictures of the 5.0 LHD Ace at the Detroit show in 1995. In fact I have copies of all the AC display info from the exibition company, H. B. Stubbs (including unpaid bills and communications back and forth between AC/Autokraft and Stubbs. We got Stubbs to agree to work with us in 1999 despite the previous issues by proving that we were not affiliated with the 1995 version of the company.
   Rick

[keithjecks]

Thanks Max. 0.63 to 0.67 doesn't sound so very different, but iy makes a hell of a difference in practice.
   
   Rick: now I have discovered how to do pictures, was this the car you saw?
   
   Keith
   
   

[GRAHAM WHITE]

THE RATIOS ARE AS FOLLOWS
   
   1ST 3.37
   2ND 1.99
   3RD 1.33
   4TH 1,00
   5TH  .67
   REV 3.22.
   WE CAN RECONDITION YOUR GEARBOX OR OFFER AN ALTERNATIVE TRANSMISSION WITH A BETTER 5TH SAY .80.
   WE ARE THE UK DISTRIBUTER FOR TREMEC

[Mark IV]

Ace4.6,
   Yes, I saw that chassis at Weybridge in September 1999.
   
   Rick

[Emmanueld]

About a TKO600? You have close ratios and it can be had with a shorter 5th! .82 I believe. It will take up to 600Lbs of torque and the shifter can be moved to different locations to accomodate you car! Watch out for the T5 unless it's a "world Class" model, otherwise it's a very week box! Even the "World Class" model is only good for 350Lbs of torque!
   
   Emmanuel

[Max Allan]

Thanks for the input Emmanueld. Running a high axle ratio I decided the 6-speed T56 gave me performance in the intermediate gears with the advantage of very low rpm in 6th gear for motorway driving. It'll probably turn out to be an unnecessary luxury and a nightmare to fit. But what the heck – you only live once!!