I’m going to upgrade my gearbox.
T400 w Gear Vendors Vs. 700R4
How large a margin is one of these options better than the other?
Has anyone got the RPM/MPH numbers with their given standard 2.88 ratio or other?
For a pre-facelift 89 xjs 5.3 with a T400
Considering either adding Gear Vendors
Or Johns kit w the 700R4
Note, my gear ratio is presently sitting at 4.11.
Thanks everyone
On the Gear Vendors (GV) side of your question, I looked into it and the reason I never followed through was the unit is way to big for the XJ-S’s narrow trans/driveshaft tunnel. I would drop the driveshaft and do your measuring before spending over $2k on a GV unit. On the other hand if you don’t mind doing floor surgery that I think would be carried on to the interior console… Other than that this might be a great addition.
Size and weight as stated would be my first concern. The TH400
is tough as they come, but big and heavy. The Gear , is time tested and tough. But, big and heavy.
Carl
Has anyone on this forum successfully used a gear vendors unit on either gearbox?
not on this forum ,probably not on any Jaguar forum!
most Jag guys are caught in a box, most rarely venture out into unknown areas!
like you did , you are completly out of norm, YIKES a Toyota truck dually axle,and more!
most her never even heard of Gearvendors!
quick pic of Gearvendors in a Mustang , uses some Gm u-joints and shortened drivshaft,
custom rear mount.
GV bolts up to a GM style output shaft housing, you take off the output shaft housing and bolt to the pattern of trans model!
GV gives many types of boltups, including ways to having the unit with a driveshft before it and after it(like free monunted).
and just cut out the floor and tunnel make room for it, and sheet metal back to cover things.
and do away with that crazy ash Jaguar trans mount, completely, i use a regular Chevy trans mount, $25.bucks Advance auto.
GV has more than one OD ratio , most use a 30% overdrive.
math, divide 30 into 4.11 ,and subtract it from the 4.11, it will give you the final drive ratio.
OK there are many sites that can give you the math numbers, basicly you will have 30% less than 4.11 for final.
Jeez had to use the math, a 4.11 gear with a 30% overdrive gives a great 2.88 final drive ratio. makes you wonder how Jaguar figured that out??
thing to consider is your tire diameter, what is it ?
for your use wouldnt make much difference anyway. unless your swingin a tractor trailer tire?
just checked used GVs, Ebay is loaded with them, good pricing but all over the place.
giving a little more thought , it might just be easier to go GM 700R4, look junkyard for 350 ,Chevy/GMC truck made before 1992, non electric.
someplace you gotta make a choice? 4.11 is a joke for hyway cruising.
last but not least what engine you using?
I agree!
I spoke with a salesman from Gear Vendors this afternoon. The consensus I got was that if I’m looking for better performance throughout each gear range, and a 22% better efficiency, than that would work.
I decided to rather go with the 700R4 instead. Reason being is they are more readily available. And the efficiency could be as high as 30%.
I may change my ratio down to the 3’s as well. But as your math shows, maybe not.?
I’m running 14" duallys back aft, and original 15" forward. Gives sorta a mad max look
I still have the lovely 5.3 engine with 55k miles. I know the purists want to condemn me to hell!!
Gear vendors would not give you the converter lock up either James. Makes a huge difference at cruising speeds to fuel economy.
700r4 is by far the more refined and efficient choice.
Thanks for the reassurance guys!
Why the training wheels?
Haha I like that. Its fun having a dually. Was never into driving trucks…so I just used my imagination.
just checked used GVs, Ebay is loaded with them…
That might be a hint. Why would you suppose so many people who paid
good money for them are looking to offload them?
4.11 is a joke for hyway cruising.
I had a 4.11 in my '83 – but mine was in the original Jaguar diff! I was using
a NWC 5-speed with a 0.73 overdrive – and, frankly, woulda been happier
with taller. Driving around with the original GM400 with a 4.11 must be awful
indeed.
– Kirbert
I love that Jaguar! In the tin a nd as a pun. well, perhaps the ptobocis, not so much. But, the imagination and the skill to implement it, I’m super impressed.
My math skills are limited. But, one way or another, I manage.
And, they were essential in my former profession.
.70 x 2.88 = the final drive in my lump. As good as it gets.
In older days, final drives were “high”. Gear vendors and BW OD’s made older cars and trucks more feasible for the “modern” toads. Many an old classic was made a “touter” by one of the OD’s. GV among them.
Circa 1976, I bought a 51 Willy 4x4 pickup. It’s flat head engine was gone. Never knew f it was the four banger or the alternate six. But, it’s final drive was 5+!!! It’s SBC screamed at 55!!!
Warn made an OD that fit into the transfer case. My neighbor had one in his somewhat similar Willys. I planned on getting one. But, things change…
I think my son has a GV. Salvaged from some past project… I think t was a 460 repowering a milk truck!!!
Carl
Carl
warn
Yeah Kirby it’s quite brutal. Although you wouldn’t know it because the 12 cylinder is so quiet and smooth(even w leg pipes)
45mph Is 2500 RPM
55 mph is 3100 RPM
60 mph is 3500 RPM
70 mph is 4000 RPM
I’ve been giving gas stations a good bit of business
Cannot wait to convert this T400
I like that Carl. Your referring to the proboscis hood scoop on the hood yeah? It somehow works. It does have this really incredible presence. I knew I had to accompany it by hand punching 1200 rivets into the body. (I know I’m going to hell right?!)
.70 x 2.88 = the final drive in my lump. As good as it gets.
For a lump, perhaps. You’ve got lots of low-end grunt to work with. That
might be tall for a V12, though. The V12 is smooth at any RPM – including
pulling away from standstill in 5th gear on a M/T using the starter – but you
might have to put quite a bit of throttle in to go up slight inclines or pull
around someone on the freeway.
When Jaguar introduced an A/T with an overdrive in the facelift, they went
with a different final drive ratio, 3.something, even though they had also gone
to 6 liters.
– Kirbert
the 700r4 has a first gear ratio of 3.06:1 where the 400 turbo is 2.48. still not enough but with slightly lower rear gears and a higher displacement, it was an improvement. the lower first gear isn’t going to be of much benefit with 4.11’s but wouldn’t consider it a deal breaker. g/v would be nice but given those choices I would probably settle on the 700r4. have you considered a 5 or 6 speed manual?
Would a 4L60E fit…?
