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#31
The Lounge / Re: Soliciting thoughts & opin...
Last post by MPlayle - September 06, 2026, 04:00:09 AMI had planned on trying to speak with Jeremy at Jet Motors about their kit on a 998.
The 1275 option is at least as spendy as the turbo kit and it leaves me with the 998 still sitting around. Being in an apartment with detached garage makes storing things like an extra motor a bit iffy.
The 1275 option is at least as spendy as the turbo kit and it leaves me with the 998 still sitting around. Being in an apartment with detached garage makes storing things like an extra motor a bit iffy.
#32
The Lounge / Re: Soliciting thoughts & opin...
Last post by MiniDave - September 05, 2026, 06:53:03 PM1275 motor/gearbox would be my first choice because it's all bolt in. Turbo to the existing engine would be second choice because kits exist that again are (supposedly) bolt on stuff, but spendy ($5K+).
I run a 2:76 in my green Mini, 70 mph is about 3300 rpm, 75-80 is 34-3600 rpm. I only have to downshift to 3rd if it's a really steep hill or if I'm at altitude (Colorado Mtns)
I like turbo motors in general, don't know what to expect from the Jet motors kit on a 998, but the mods you've already done will help quite a bit, I would call Jeremy and see what he says.
I run a 2:76 in my green Mini, 70 mph is about 3300 rpm, 75-80 is 34-3600 rpm. I only have to downshift to 3rd if it's a really steep hill or if I'm at altitude (Colorado Mtns)
I like turbo motors in general, don't know what to expect from the Jet motors kit on a 998, but the mods you've already done will help quite a bit, I would call Jeremy and see what he says.
#33
The Lounge / Soliciting thoughts & opinions...
Last post by MPlayle - September 05, 2026, 06:10:14 PMAs the title implies, I am looking for thoughts/opinions on methods for getting a bit more power out of my 998 engine. I find running with highway traffic at 4K rpm for much time is tiring on me, though necessary for getting in/out of San Antonio. There are also a few hills that Bruce and I go over on our drives to area C&C events where I still lose significant momentum on the uphill.
The engine currently runs very nicely: has good oil pressure, does not overheat, gets me 30 - 33 mpg regularly. The transmission/differential is currently set up such that 4K rpm is 70 mph (3.1 final drive, but non-standard drop gears make it act like a 3.2 final drive)
The engine spec as it is currently: stock pistons and cam; alloy intake manifold supporting a single HS-4 carb with a K&N filter in a modified stock air box; LCB exhaust; Mini Sport "Stage-3" 998 head with mild porting and bigger valves; forged 1.4:1 ratio rocker arm set. The head and rockers were done to boost the power slightly from stock when I changed the final drive to the current setup.
What I would like to do is add more power so I can change the final drive again to either a 2.95 or 2.76 to lower the rpm more when doing highway speeds while still having sufficient power/torque for the winding hill country backroads.
The approaches I know of are: 1) upgrade to a 1275 based engine; 2) overbore and change the cam in the current 998; or 3) add a turbo kit to the existing spec.
Please chime in with your thoughts, pros/cons of the above approaches, any other alternative approaches.
The engine currently runs very nicely: has good oil pressure, does not overheat, gets me 30 - 33 mpg regularly. The transmission/differential is currently set up such that 4K rpm is 70 mph (3.1 final drive, but non-standard drop gears make it act like a 3.2 final drive)
The engine spec as it is currently: stock pistons and cam; alloy intake manifold supporting a single HS-4 carb with a K&N filter in a modified stock air box; LCB exhaust; Mini Sport "Stage-3" 998 head with mild porting and bigger valves; forged 1.4:1 ratio rocker arm set. The head and rockers were done to boost the power slightly from stock when I changed the final drive to the current setup.
What I would like to do is add more power so I can change the final drive again to either a 2.95 or 2.76 to lower the rpm more when doing highway speeds while still having sufficient power/torque for the winding hill country backroads.
The approaches I know of are: 1) upgrade to a 1275 based engine; 2) overbore and change the cam in the current 998; or 3) add a turbo kit to the existing spec.
Please chime in with your thoughts, pros/cons of the above approaches, any other alternative approaches.
#34
Daves Garage / Re: Jeff Shaw Gearbox build
Last post by MiniDave - September 04, 2026, 07:12:57 PMNext I decided to build up the cross pin diff, but first you have to disassemble the entire diff assembly, including pulling the large bearings off each short shaft that the pot joints attach to.
I was disappointed to see that the cross pin housing came with the cross shafts already assembled into it, which meant I had to take it all apart - that's no big, except if the shafts are tight in the bores as there's very little to get ahold of to get them out. The main cross shaft had been driven into place and there were burrs on the ends of the shaft which I had to dress, along with the edges of the bores that shaft went thru, that added quite a bit of time using 1000 grit paper to polish it all to fit.
Once done it all went together smoothly and turned freely......I got as far as installing the crown wheel tonight, and called it. This car has a 3:44 ratio, which I think is perfect for a 998 motored car. More as it happens.
I was disappointed to see that the cross pin housing came with the cross shafts already assembled into it, which meant I had to take it all apart - that's no big, except if the shafts are tight in the bores as there's very little to get ahold of to get them out. The main cross shaft had been driven into place and there were burrs on the ends of the shaft which I had to dress, along with the edges of the bores that shaft went thru, that added quite a bit of time using 1000 grit paper to polish it all to fit.
Once done it all went together smoothly and turned freely......I got as far as installing the crown wheel tonight, and called it. This car has a 3:44 ratio, which I think is perfect for a 998 motored car. More as it happens.
#35
Daves Garage / Re: Jeff Shaw Gearbox build
Last post by MiniDave - September 04, 2026, 07:05:09 PMThe cover plate bolts go thru the case and into the oil pickup pipe flange, I'm not sure the lockplates are absolutely necessary but I always put them in and bend the tabs over.
On the pinion gear end there is a small plate that fits in slots on both the reverse gear shaft and the laygear shaft and is held in place by one of the bolts in the pinion gear bearing retaining plate. The trick here is that the bearing retainer plate has a shim, the shim has to go first, and the locking plate goes in over it, then the bearing retainer plate bolts in - I've seen many a shim bent because people did it wrong. Then more lock tabs need to be bent once the bolts are torqued.
Everything turns freely and smoothly, so ....result!
On the pinion gear end there is a small plate that fits in slots on both the reverse gear shaft and the laygear shaft and is held in place by one of the bolts in the pinion gear bearing retaining plate. The trick here is that the bearing retainer plate has a shim, the shim has to go first, and the locking plate goes in over it, then the bearing retainer plate bolts in - I've seen many a shim bent because people did it wrong. Then more lock tabs need to be bent once the bolts are torqued.
Everything turns freely and smoothly, so ....result!
#36
Daves Garage / Re: Jeff Shaw Gearbox build
Last post by MiniDave - September 04, 2026, 06:50:28 PMWork continues, next step is to assemble the mainshaft - I have a new 2nd and first gears to install, 2nd and 3rd have those same pins the Sprite gearboxes use, however the Mini 2nd gear is smaller in diameter than the Sprite so it was impossible to locate them in the holes in the shaft. So, what to do?
I decided the only way was to slide the gear up, put the pins in, squeeze them in till the gear would slide down past them, leaving them in place. To do that I used some SS safety wire around them, as I tightened the wire it pushed the pins in, then after the gear slid down into place ALL I had to do was cut the wire and remove it - which proved to be yet another "challenge". I managed to get it cut and they popped out. Next I had to push them both in again so that the retaining plate would go down over them - that took about another hour of fiddling till I finally won that battle too. The problem arises because the pins both push against a fairly stiff spring in the center, if you manage to get one in, the other pops out.
Third gear was much easier as it only has one pin, it snapped right into place. With the hard part done it was just a matter of putting all the pieces back where they needed to go, then drop it down into the case. Next was the laygear - as you can see in the pic, the old shaft was just starting to gall and the small bearing had failed. Putting it in is a bit of fiddle too as you have to maneuver the center oil pickup down into place as you roll the laygear into its location, making sure the thrust bearings don't move. a couple extra hands would have helped with all of these tasks!
Once that's all in place install the two main bearings, put the snap ring in the first motion shaft end, and the big nut and lock washer on the pinion bearing end (don't forget the pinion gear!)
I decided the only way was to slide the gear up, put the pins in, squeeze them in till the gear would slide down past them, leaving them in place. To do that I used some SS safety wire around them, as I tightened the wire it pushed the pins in, then after the gear slid down into place ALL I had to do was cut the wire and remove it - which proved to be yet another "challenge". I managed to get it cut and they popped out. Next I had to push them both in again so that the retaining plate would go down over them - that took about another hour of fiddling till I finally won that battle too. The problem arises because the pins both push against a fairly stiff spring in the center, if you manage to get one in, the other pops out.
Third gear was much easier as it only has one pin, it snapped right into place. With the hard part done it was just a matter of putting all the pieces back where they needed to go, then drop it down into the case. Next was the laygear - as you can see in the pic, the old shaft was just starting to gall and the small bearing had failed. Putting it in is a bit of fiddle too as you have to maneuver the center oil pickup down into place as you roll the laygear into its location, making sure the thrust bearings don't move. a couple extra hands would have helped with all of these tasks!
Once that's all in place install the two main bearings, put the snap ring in the first motion shaft end, and the big nut and lock washer on the pinion bearing end (don't forget the pinion gear!)
#37
Daves Garage / Jeff Shaw Gearbox build
Last post by MiniDave - September 02, 2026, 12:33:53 PMI decided to start a new thread on this because it's turning out to have some "challenges" 
I'm pretty much out of the Mini engine/gearbox rebuilding game, but I still don't mind doing one occasionally for a friend, that's how I wound up with this one - the owner intended to do it himself, but then his job changed and they moved him to Connecticut for a year, maybe more - the only hope he has of getting his car back on the road was if I took on the gearbox repairs.
He bought this car about a year ago and has never been able to drive it - it simply would not go into 1st or 2nd gear. Once I got it over to my shop I could see why, both first and second were pretty torn up, and to top it off once I got it taken apart I found the internal shift linkage bound up for the 1/2 engagement.
He ordered a bunch of parts in advance and once I got it apart I gave him a list of small bits plus the cross pin diff, even tho it's rocking a stock 998. In for a penny, right?
I also found a ton of sludge in the bottom of the case, along with lots of tiny bits of gear teeth. I've never seen this much sludge in the bottom of a Mini case before, the owner's dad said the car came from Louisiana making him wonder if it might have been a flood car - hence the complete repaint and new interior. Just speculation tho....
So I got it all apart and today I'm starting to re-assemble. First in was the internal shift linkage - the operating bits that sit on the central pin were rusted to the center support - at least the 1/2 one. I probably managed to knock 3/4 and reverse loose when I locked it into 2 gears to get the nuts off either end of the mainshaft - the ones torqued to 150 ftlbs. Everything got cleaned and polished and moves smoothly now.
Next - he sent a new 1/2 shift fork which is made somewhat differently than the old one, I put it in and don't see where there will be any interference - at least I hope not cause I will have to remove everything to get it back out! I laid the old mainshaft/gear assembly in and it all looks like it will clear.
Then I disassembled the main shaft, and ran into the first real challenge. Like a Sprite the gears are locked onto the mainshaft with some pins engaged into a special washer. They usually require 3-4 hands to get them out and back in place, but I've developed a few tricks to get it done by myself. However......the gear I'm trying to reinstall seems smaller inside than a Sprite - where I could insert the pins after the gear is in place on a Sprite, there just isn't enough room to do that on this gear.
Going to require some thought.....
I'm pretty much out of the Mini engine/gearbox rebuilding game, but I still don't mind doing one occasionally for a friend, that's how I wound up with this one - the owner intended to do it himself, but then his job changed and they moved him to Connecticut for a year, maybe more - the only hope he has of getting his car back on the road was if I took on the gearbox repairs.
He bought this car about a year ago and has never been able to drive it - it simply would not go into 1st or 2nd gear. Once I got it over to my shop I could see why, both first and second were pretty torn up, and to top it off once I got it taken apart I found the internal shift linkage bound up for the 1/2 engagement.
He ordered a bunch of parts in advance and once I got it apart I gave him a list of small bits plus the cross pin diff, even tho it's rocking a stock 998. In for a penny, right?
I also found a ton of sludge in the bottom of the case, along with lots of tiny bits of gear teeth. I've never seen this much sludge in the bottom of a Mini case before, the owner's dad said the car came from Louisiana making him wonder if it might have been a flood car - hence the complete repaint and new interior. Just speculation tho....
So I got it all apart and today I'm starting to re-assemble. First in was the internal shift linkage - the operating bits that sit on the central pin were rusted to the center support - at least the 1/2 one. I probably managed to knock 3/4 and reverse loose when I locked it into 2 gears to get the nuts off either end of the mainshaft - the ones torqued to 150 ftlbs. Everything got cleaned and polished and moves smoothly now.
Next - he sent a new 1/2 shift fork which is made somewhat differently than the old one, I put it in and don't see where there will be any interference - at least I hope not cause I will have to remove everything to get it back out! I laid the old mainshaft/gear assembly in and it all looks like it will clear.
Then I disassembled the main shaft, and ran into the first real challenge. Like a Sprite the gears are locked onto the mainshaft with some pins engaged into a special washer. They usually require 3-4 hands to get them out and back in place, but I've developed a few tricks to get it done by myself. However......the gear I'm trying to reinstall seems smaller inside than a Sprite - where I could insert the pins after the gear is in place on a Sprite, there just isn't enough room to do that on this gear.
Going to require some thought.....
#38
The Lounge / Re: A new game... Post pics fr...
Last post by 94touring - September 02, 2026, 09:55:49 AMIt's hellishly dusty, yesterday in particular with a cold front rolling in. You kind of stop caring after awhile but people make an attempt to keep the dust out.
#39
The Lounge / Re: A new game... Post pics fr...
Last post by Jims5543 - September 01, 2026, 12:26:26 PMWhat is up with all the blue painters tape on many RV and vehicle windows?
Is the dust that bad it works its way through closed windows?
Is the dust that bad it works its way through closed windows?
#40
The Lounge / Re: What did you do in your sh...
Last post by MiniDave - August 31, 2026, 02:52:42 PMThe rest of the parts came in for the gearbox, so I started with the shift parts, cleaned and deburred the shafts and re-pinned the 3/4 shift fork to the rod.
Next I guess I replace the 2nd gear on the mainshaft - it's a bit of a PITA - it has the same pin setup that the Sprites use.
Next I guess I replace the 2nd gear on the mainshaft - it's a bit of a PITA - it has the same pin setup that the Sprites use.